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# Gary Sanders

### Executive Project Manager, Simons Observatory

By David Zierler, Director of the Caltech Heritage Project

August 25, September 3 ,10, October 8, and December 10, 2021

DAVID ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It is August 25th, 2021. I am delighted to be here with Dr. Gary H. Sanders. Gary, it's great to see you. Thank you for joining me today.

GARY SANDERS: Thank you for the chance to talk with you.

ZIERLER: To start, would you please tell me your current title and institutional affiliation?

SANDERS: Right now, I'm called the Executive Project Manager of a project called the Simons Observatory, and I work for the Simons Foundation. The project itself is headquartered at UC San Diego, and I have a Visiting Scholar appointment there. It is led by groups at UC San Diego, Berkeley, Princeton, the University of Pennsylvania, and a few others, but those are the major institutions, working together to build a cosmic microwave background observatory, under construction now at 17,000 feet, in Chile.

ZIERLER: Does that mean that you are an employee of the Simons Foundation, or you're on contract with them?

SANDERS: Today, I am on contract. Next month, I will be an employee.

ZIERLER: It's a transition period. Gary, how long have you been in this role?

SANDERS: I started June 1st. I was first talked to about doing this in April or so, and I started June 1st, so I'm just finishing three months. My first task was to make an assessment of the project and make recommendations on what it will cost, how long it will take, and what adjustments in management and project performance to complete the project and make it more confident in its completion. That's what I'm doing now.

ZIERLER: Gary, where were you prior to June? What was your previous position?

SANDERS: I retired January 4th of this year from Caltech as the Project Manager of the Thirty Meter Telescope, which is run by an independent company of which Caltech sits on the board and is thus one of the owners. I was an employee of Caltech. I was the Project Manager of the Thirty Meter Telescope 2004 through 2020, 16 years in that role. Before that, I was the Project Manager and Deputy Director of LIGO, but also as an employee of Caltech. That was from 1994 to 2004, so that was a decade in that role. So, 26 years at Caltech, doing LIGO and TMT, and then I retired.

ZIERLER: I just want to state at the outset for our readers that our discussion should be read, in its published form, in conjunction with the excellent oral history you provided to Shirley Cohen back in 1998. These can be read as one and two together. Gary, an item I'd like to discuss that we brought up previously but that I'd like to get for the historical record is the trajectory in your career of managing these massive scientific collaborations for which your own scientific area of expertise is not necessarily a central focus. Let's talk a little bit about that and some of the lessons that you've gleaned from being in these very different projects that have very different scientific components to them.

SANDERS: As you know, I started out in the 1960s as an experimental particle physicist, an experimentalist. I wanted to do that since I was a child. I was attracted to the subject matter, the scientific romance, I would say, of elementary particle physics, which still has a lot of romantic attachment to me, and still is a very fundamental field. I worked in that field as a hands-on experimentalist from the 1960s through the early 1990s. I worked at a variety of things in elementary particle physics. But even then, within the field—and this is typical of people in the field—you would go from one instance of curiosity about a problem to another, and sometimes the experiments that you would do would be very different. At times, I was working with an electron accelerator, making a beam that would come out and hit a target. At times, I would work at a hadron accelerator, a very different kind of machine with different kinds of particles coming out and hitting a target. Later on, at a collider. You ended up using very different experimental techniques with different sets of colleagues even though you were working within elementary particle physics. The grand subject matter was unified, to misuse a phrase—

ZIERLER: [laughs]

SANDERS: —but the stuff you were doing, the hands-on touch labor you were doing, the technical problems, the experimental problems you were solving, while there was an overarching approach to experiments and deciding what was a real result and what were the backgrounds, and was it valid, most of what you did every day was different from what you were doing five or ten years earlier, which fostered a kind of versatility, I think, in a lot of people in the field. So you ended up coming into a new experiment that you were doing, and you were intellectually curious about the goal of that experiment, but you hadn't worked in that part of particle physics. You had never worked with an electron accelerator before, or you never worked at a collider before, and so you had to learn all these new techniques and all these new people who worked in there. All the tacit knowledge, the stuff that's not written down, you had to learn that in order to be effective in doing this next experiment.

One of the things that happened over those years, from the 1960s to the early 1990s, was the energies of the accelerators went up, which meant the wavelengths went down, which meant you could probe ever finer things. You could get down to the quark level and so on, instead of just studying protons and neutrons and electrons. As the machines went to higher and higher energy, they got bigger. They got more expensive. You got bigger and bigger government grants. And you had a responsibility to behave and not to squander resources.

Competition for using the accelerators, how many days a year did you get to use the beam, these were very expensive. We would sometimes kid ourselves on night shift about every pulse from the accelerator, what it cost to deliver to our experiment. There was an awareness that this was an expensive business. Over that period of time, from the 1960s, very bright experimental particle physicists who knew nothing about project management, who knew nothing about planning, who knew nothing about managing large sets of resources, had to learn it. Being very bright and being academics, they decided to learn it themselves instead of going to talk to people who actually knew how to build bridges, and shopping centers, and airliners, and cruise ships, who actually knew how to do things like that. So I got to have the experience not only of the evolution of the field, as energies went up, and as the diversity of experimental approaches passed through my career, but I got to witness and participate in the growth of project management in these projects.

I would say the turning point for me, when I saw it, was in the 1970s, working at an experiment at Fermilab. At that point, experiments were getting expensive, and many of them were costing twice as much and taking a lot longer than they had been promised and planned. Again, to see these techniques. But I myself, I was running Monte Carlo programs, writing analysis programs, building Cherenkov counters, building scintillation counter detectors, building wire chambers. I was mostly involved in actually the experimental work. It was in the 1980s when I was at Los Alamos, and we were doing an experiment with inorganic scintillators to look for a conservation law violating decay of the muon, that I and my colleagues, in a relatively small group, were talking about how much it would cost to finish the experiment. I could see that they were off by at least a factor of five. That was maybe a fatal mistake, because I got put in charge, among other things, of trying to figure out what this thing cost, and so on.

By the late 1980s, at Los Alamos, I was the project manager of a new neutrino experiment that was being proposed to the Department of Energy and to the director of the laboratory and got to make my first presentations. I had been building beam lines and things that helped the accelerator controls and working on experiments like the one I talked about for studying rare muon decays, but it was my first time, in the late 1980s, to assess what it took to get a very difficult experiment done, and to present it to the Department of Energy. In came all these folks from Washington and some scientists, including Barry Barish from Caltech. There was this guy, Ed Temple. Ed Temple was the head of the division at the Department of Energy that looked at Department of Energy projects and reviewed what they would cost and how long it would take and whether they were too risky. He was something of an institution, and he kind of invented, in that whole agency, how you would review and follow projects.

So Ed Temple showed up with his reviewers. He needed some scientists, not just Department of Energy people, on the panel. He brought along Barry Barish, who was a professor at Caltech and who I knew slightly from having been at adjacent beam lines at Brookhaven and Fermilab and so on over the years. He had been working on neutrinos. He was the guy on the panel who was the physicist. He recently gave an interview, actually—at the time of my retirement, at the retirement party, he said he remembered that experience when this group showed up to be reviewed, and he was one of the reviewers, and I answered all the questions in the review. He said, "There were a bunch of people there, but every question we asked, Gary answered." That was my first I guess coming out party as a project manager.

And I made a mistake. Barry mentioned this at my retirement party, which I could send you a video of. You've seen the web posting or something. But I made a mistake. I actually told the Department of Energy the truth about what it could cost, and actually got taken aside by Ed Temple and asked about it. I told him it was $40 million. The result was that inside the Department of Energy, they had set a target that was about half that. So the project wasn't approved, and Barry recounted this story at my retirement party. He and I didn't have much contact after that. Then shortly after that, I got involved in the LEP experiment at CERN, with my thesis advisor, Sam Ting, who I had not had much contact with in 20 years, since I got my degree in 1971 and took on a role with vertex detectors to see where the particle vertices were when the two particles of the beams collided. That developed into working with Sam Ting and his large team on a proposal to the Superconducting Super Collider. I became the leader of the central tracker, which is one of the more difficult parts of the project. This is an example of how I was still focused on the technical things, building parts of the experiment, even though I had just had this experience of being a project manager in a formal sense. That project, the L-STAR project, got selected by the Super Collider as one of the two detectors, but Sam Ting had a disagreement with the Department of Energy and the management of the Collider, and I encouraged Barry Barish to come in and join the team, since I knew him from before. In the end, the project was completely reformed, with Barry and I and one other scientist, Bill Willis from Columbia, completely reforming the project and bringing in all the scientists who had been part of the rejected collider detector proposals to the SSC. I found myself one day in 1990 as the project manager of this thing. It was estimated as$750 million in 1990 dollars, and the Department of Energy said, "We want it to be $500 million or less." So I came to Caltech, and worked with Renyuan Zhu who is still, I believe in the Physics Department at Caltech, and Sau Lan Wu, who's a professor at University of Wisconsin now. We spent a long weekend in Lauritsen-Downs, at the blackboard, trying to redesign this collider detector from$750 million down to $500 million. And we did that. We called a big meeting, which was held in Beckman Auditorium on the Caltech campus, of people involved in all the other parts of the collider groups that had been part of Sam Ting's group or been part of the rejected groups, and we proposed to start a new detector collaboration. Barry and I were there. We made our presentations in the Beckman Auditorium, and the GEM collaboration formed. It was a$500 million detector. So, there I was. I was the project manager of a $500 million project, which was a big leap from what I had done before, and a different role, because I no longer had a role technically building a thing that I could touch every day and worry about it at night. Now it was the whole project. We pulled together a group that from late 1990 to October 1993, when the Congress cancelled the Super Collider—Barry and I and Bill Willis pulled together a group that was more than 1,000 scientists and engineers in the collaboration. I think there were 116 institutions in 16 countries. We were, I think within our detector collaboration, doing quite well. The project as a whole, the big one, the$8 to $10 billion project, got into really deep political troubles and was cancelled. But that was my second experience where I had the title "project manager." I was still very close to the technical subject matter as well as the science. I wanted to see the Higgs. I wanted to see the clean four muon decays of the Higgs. That was what I yearned for, which was the gold standard event that we were looking for, and which was ultimately seen in 2012 at the Large Hadron Collider. But the SSC collapsed. I had been doing all of this as an employee of Los Alamos Labs, so I was working actually in the director's office at Los Alamos labs, and I was seconded to the Super Collider project. The director of Los Alamos at the time, Sig Hecker, and Fred Morse, who was the director for research, wanted to be part of the Super Collider. It was a DOE lab, even though they're mostly in the defense business, and they felt that they should support the U.S. Department of Energy and have a role. But the SSC was canceled. So I went back to Los Alamos, and the director said, "Take a year and figure out what you want to do." A generous reabsorption. I'll tell you an interesting story there—I actually got asked to be the project manager [laughs] of a project that had nothing to do with physics, essentially nothing to do with physics, while I figured out what to do during that reabsorption period. I remember leaving CERN in December of 1993, when the Super Collider collapsed in October 1993. We had a big meeting at CERN about whether or not the U.S. team members would join the CERN collaboration at the Large Hadron Collider. I had decided not to, but I went over to this meeting. I remember sitting in Geneva Airport on the way back to the United States to go to Los Alamos again, and there was Bill Clinton, with Hazel O'Leary, the Secretary of Energy, announcing that the U.S. had injected 18 people with plutonium during World War II. These were experiments to study the metabolism of plutonium in humans to see how you excreted it, how quickly your body dumped it, and what damage was done to people. These people were given these injections without consent, which of course in those days that's what happened, because there wasn't informed consent. I watched this on TV while I waited in the lounge at Geneva Airport, and I said, "Goddamit, some poor bastard at Los Alamos is going to be asked to work on this." Because the thing was led out of the Manhattan Project. I got back, and guess what? I was asked to be the project manager of the study, of all of that. So I spent three or four months with a team including doctors from World War II, 80-year-old doctors from World War II and nurses, and records clerks, uncovering a lot of classified material, declassifying it, as there was a big public interest in what happened during World War II. It got into all kinds of things—radioisotope studies with children's schools, Karen Silkwood's bones, and all of that. I worked on that for the lab while I thought about what to do, and I got called a couple of months into this by Barry, who was back at Caltech and had just been asked to be the director of LIGO. Barry went back to Caltech; I went back to Los Alamos and was taking some time to figure out what to do. Barry called me and said, "Would you like to come to Caltech and work with me to do LIGO?" Instantly, my mind said yes. It was the science of LIGO, which was really outstanding. It took a couple of months, and then I left Los Alamos and went to Caltech as the project manager of LIGO. So it's an interesting path. You asked about, in some sense, a transition to being a project manager. From a$40 million neutrino experiment to a $500 million collider experiment to a very interesting publicly aware investigation of human radiation experiments during World War II and the Cold War, including the Marshall Islands and all of that, we investigated all of those things. Then I went to Caltech and worked with Barry, re-baselining LIGO. The previous director had been rejected, in some sense, by NSF, and then Caltech had to remove him. That was Robbie Vogt, who had been the provost of Caltech and then took the job as the director of LIGO but couldn't work with the NSF. Barry and I now had to re-baseline the project. In November of 1994, we got it re-baselined and accepted by the National Science Board. The funding from Congress was restored, and so I spent a decade getting LIGO built, getting it installed and working, and also working, starting in 1997, on the design of Advanced LIGO, which we knew had to happen. You don't wait until you're done with the first one and it's working, because there's a lead time to get it designed, to get it through the NSF. That was another project management experience. But I worked some on the science of each one of these things, as well, and then I was asked by a search committee—since this is a Caltech history, let me give you a little more detail of this. As I worked on LIGO as the project manager, my office was in East Bridge Laboratory, a couple of doors down from the division chair. When I came on to LIGO, the division chair was Charlie Peck, a high-energy physicist. Since LIGO was so visible, especially since there had been this disaster of having to fire a faculty member as a director, and replace him, and NSF had rescinded the funding, and then restored it after a vote of the National Science Board, I had a meeting that was every week with the division chair. My office was just a few offices down, I would meet with Charlie Peck, and keep him abreast. I'm a person who believes in communicating with the boss and the sponsor regularly so there's never a surprise, so that trust is built up, so that when you have trouble and you need help, they know you, and they know to trust you. I enjoyed very much talking with Charlie, and then later he was replaced by Tom Tombrello, who for many years was the division chair. I don't think there was anyone in between. I think it just went to Tom Tombrello. So that was essentially every week, for a decade. As the Thirty Meter Telescope was forming, Caltech, together with University of California, had built the Keck Observatories. Here I am in my LIGO period, 1994 to 2004. Keck Observatories, privately funded by Keck, and funds to Caltech and UC. It was two telescopes, one which had its first light in 1992, and I think the second had its first light in 1996. They were great successes, especially with the synergy with the Hubble Space Telescope at the time. The folks, not surprisingly, at Caltech and UC, led by Jerry Nelson at UC, started to work on the design of the next generation optical and infrared telescope. They called it the CELT, the California Extremely Large Telescope. The idea was to go from the Ten Meter Keck to a Thirty Meter Telescope. They were working with small amounts of money, and they were going to produce a design report for this. In I think it was 2001, they produced a book they called the Green Book. This is an important part of Caltech history. Tombrello was talking to me in my weekly meetings—"Why don't you help those guys on CELT?" And I said, "No, no, I'm busy with LIGO —it's 2001, man! We're just turning on LIGO. We have to make this thing work. No one has ever done this before." I got asked to be on the review panel reporting to the University of California president of the CELT Green Bookand to Caltech, of the CELT Green Book, so I served on this review panel. There was Jerry Nelson. They did a wonderful job. I thought they had a pretty good design. I thought the cost estimate wasn't too crazy. I think it was$500 or $600 million. But what was interesting, and I think this is an interesting aspect of Caltech history but here was this group of a dozen or more people reviewing the thing, chaired by a guy named Ed Moses, who had just led the uncovering of the problems in the big laser fusion project at Livermore, brilliantly uncovered the problems, and he became the director of this laser fusion project, and a guy who, if there was a review panel of 12 or 15 people, it seemed like there was only one person in the room. Ed Moses was that kind of a guy. It was a very interesting review. But in the back of the room were two people from the National Science Foundation. So here was a privately funded Caltech-UC design study of what later was to become the Thirty Meter Telescope. No federal funds involved, but they had decided at the review of the CELT Greenbook to invite the NSF. Wayne Van Citters and Jim Breckinridge, I think, from the NSF, they sat in the back of the room of this multi-day review and listened to it. I knew them. At some point late in the review, I said, "Wayne, why are you here?" He said, "Well, we don't actually know. This may result in a proposal to us, and we were invited, so we're here and we're listening." And so on. The review happened, and at the end of the review, the tradition is you have a half a day where the committee hides and writes an initial report, and then there's an out-briefing to the people, to the project. We did that. When it was over, I was driving back to Oakland Airport to fly back to Los Angeles, and Steve Koonin, who was the provost of Caltech—I think, yeah, he was the provost then—I gave him a ride to the airport. I said to Steve, "Isn't it interesting that the NSF was there? You must have invited them. What's that all about?" And he said, "Well, we at Caltech and UC"—and he was really speaking for Caltech, I think—" want to get this project started. We want to get it funded by private funding." There was already talk about the Moore Foundation being involved in a bigger version of this study and then the project. "And once it's going and it's going strong, we want to go to the NSF and get some funds to help finish it." And I said to Steve, "That's not usually how it works. I've worked with the NSF, and the DOE Office of Science, and they don't usually come in and give significant amounts of money to something where they're an accessory. Because they feel like they're federal owners, and they have federal stewardship, and so on. And this project is big enough, you ought to get NSF involved right away." I had just spent more than$300 million of NSF funds on LIGO, and I know the extent to which they're involved with it, care about it, but make it very clear that it's a federal project.

In the end, and I can take no credit for it, what happened matched my model. In 2003, a four-party collaboration was formed with Caltech and UC contributing $35 million together (from the Moore Foundation) and NSF, via AURA, contributing$17.5 million of effort and in-kind contributions, and a Canadian consortium also contributing $17.5 million of in-kind funding and effort. Four partners contributing equal shares of a total of$70 million in what was described as "Design Development". I was glad that NSF was brought in on the ground floor when I heard this news. I was not involved at all in that process and wondered what was happening in the intervening two years but it seemed to work out as a good start.

Shortly after that review, and I didn't think anything of it, I was asked shortly by Tombrello in one of my weekly meetings, "Will you come and be the project manager of this? We want to put this thing together and make it a big project." And I said, "No, I want to finish LIGO. I'll help you find a project manager, give advice, whatever, but I've got to finish LIGO, and I want to do the science." And so on. These kinds of conversations happened in 2002 and 2003. I lost touch with CELT, didn't know what was going on.

Then again in 2003, Tombrello, said to me in one of those meetings, "Why don't you come over and be the project manager of TMT? We're making a group that is a combination of CELT and the NSF's Giant Segmented Mirror Telescope, GSMT. And the Canadian VLOT, which was a Twenty Meter Telescope, not a Thirty Meter Telescope. And you ought to think about being the project manager." He said, "Actually, what I really want is Ed Moses, but he won't do it, so I think I'm going to ask you." It's the last thing you want to say to someone that you want to attract into something. I said, "No. Look, I'm going to do LIGO. I'm committed to it. But I'll help you find a project manager." I repeated what I said before.

Sometime in the latter part of 2003, they formed a search committee for a project manager, and I was asked to be on it. By that time, LIGO was running and improving its sensitivity, and we were turning out our first science papers. We hadn't detected anything yet, but we were setting limits on things. Things were getting better and better. We were working quite a bit on the Advanced LIGO proposal with the NSF, which was very dear to our heart, because I was convinced you needed to do Advanced LIGO in order to be able to have a chance to detect gravitational waves. I was on the search committee, and we did what search committees do, produced suggested names of people who might do the job. Even let it be known that the position is being searched for, and some people applied. Winnowing down in candidate list to a small group. We actually got down to three or four, I think, by around Thanksgiving of 2003.

The search committee was chaired by Ed Stone, I believe. He had been the director at JPL. There were people from Canada, people from the various groups, on the search committee. I've forgotten all the names of the people on the search committee. Around Thanksgiving of 2003, I got a call at home from Ed Stone saying, "Gary, the committee has been talking without you, and they'd like you to resign from the search committee and consider applying." This happens sometimes, where a search committee turns around the table on one of the members, and apparently, all the things that I had said during the search committee meetings amounted to an interview. I thought about it and decided that at the time, I was 58 years old, that LIGO was in good shape, the team could do this without me, and maybe I could in my career do one more big project. That was literally what it came down to after a couple of weeks of talking.

I went to talk to Steve Koonin about it and I decided to transition to the Thirty Meter Telescope and step away from LIGO. I did that in the Spring of 2004. I've forgotten exactly why it took as long as it did. By then, they had made an MOU agreement between CELT, the Caltech-UC-led proposal; the Canadian VLOT; and the NSF GSMT to form one project. They actually had a committee of engineers who in the interim were leading the design of a single design, taking elements of the three separate designs. Then I started, I think, April 1st, 2004, as the project manager.

The first task was to complete the process of unifying around a single design and then start developing it, and building out the team. I remember the day I left East Bridge Laboratory and I took my administrative assistant with me, and we were brought over to a little basement office in the basement of Robinson. That was the beginning of the TMT project. Then I started interviewing everyone who was working on it, from Caltech, from UC, from Canada, from the NSF folks, and that year, 2004, put together a team.

There was a small amount of cash funding, $35 million, half to UC and half to Caltech, at that point decided by the Moore Foundation. We had this$35 million to do the design, which is actually a significant amount of money to do the design. That led to a proposal to the Moore Foundation in 2007 for the construction funds. The Moore Foundation I think came up with a commitment of $200 million, half to UC and half to Caltech. They would give the money to those two institutions, and then they would dole it out, essentially to me, and Ed Stone, who was the exec director. Ed was really the guy on the board who talked to me and talked to the board, kind of like a CEO but he pretty much left the project to me. Although Ed really understands—boy, he understands project management as well as the science. Ed Stone is a remarkable person. ZIERLER: And he's still going strong. SANDERS: He's still going strong. I must say, one of the highlights—I've had the privilege to work with a lot of first-rate people, seven or eight Nobel Prize winners, and so on. The one that stands out as someone really wonderful to work with is Ed. ZIERLER: Oh, that's so nice to hear. SANDERS: He's remarkable. I've told you the origin story of TMT, I've told you the origin story for me as a project manager, and I've told you the origin story of me involved in LIGO, too. ZIERLER: It has been an adventure, to say the least. SANDERS: Yeah. And I've had fun, along the way, up until the last part of TMT, where it was clear that it was in a Hawaii-based quagmire, and a quagmire with the field of astronomy that was not moving forward. Look, Astro2020, and we're at the end of 2021, and it's not out. It's a field that loves discourse, but not necessarily decisions. But I think the Hawaii situation is really the problem. In the same way that I told Steve Koonin in that ride back to the airport that you're going to need NSF and you've got to bring them in—and they did—at the beginning of TMT, NSF was part of it, through AURA, through the National Optical Astronomy Observatory. But I also told my bosses that "You need to make this an international project," so I was instrumental in getting India, China, and Japan. I made many of the trips in the 2006 to 2010 period to those places. I was used to that, from high-energy physics. That was standard. And even used to it in LIGO, with the Europeans joining. That's another story. But that created an international board of people with different interests. And when things were working smoothly, it was great. When we got into legal trouble, cultural trouble, political trouble then varying interests, imperatives, government perspectives among the sponsors, diverged. Then it did not work well and even the press reported that TMT was indecisive. I think in the last year or two of TMT, I didn't see the reasons for me to continue with a dysfunctional governing structure, despite the best efforts of I and David Goodman and most of all Ed Stone. In fact, Ed Stone was eased out of the leadership of the board over the last three years that I was part of TMT, because he would lead. He would have a discussion and then define a decision. He'd look around and say, "This is what we're going to do," and then we would do it. At some point, some of the international partners said, "I'm not going to do that." What they preferred was indecision, which I've always said is a decision, but that is not well recognized. And this was seen and reported, for example, in the Hawaii press. It got in the way of earning and keeping the support of the authorities in Hawaii, and communities of supporters. So with that, and what I believe is, I don't see how TMT can be built, because I don't think it can be built politically and financially, because the federal funding is best advocated if construction is in Hawaii, and I believe it cannot be built in Hawaii due to the small militant and very effective opposition. I think there will be no more telescopes built in Hawaii no matter what anyone thinks. So I tell you TMT is not going to be built; a year from now, you and I can have a chat, okay? I hope I am wrong. ZIERLER: See if you were right. SANDERS: And that is such a tragedy. That is such a tragedy. ZIERLER: Gary, a very specific question, one that's headline news or about to be—the decadal survey is going to come out probably any day now. What do you think it will say, and what do you think the impact of whatever it says will be on the Telescope? SANDERS: What you want to have, if you want to build TMT—and in fact, you can look back in The New York Times, what I said. I was quoted in The New York Times in March of 2020. I gave a presentation to the decadal survey at the National Academy, and I think it was February 25th or February 26th. Dennis Overbye was there, and he wrote an article in March, and quoted me several times in the article. It was almost the headline of the article. I said something like, in my presentation and to questions to the decadal survey people, "I still mourn the loss of the U.S. community's leadership in high-energy physics that happened with the demise of the Super Collider." Yes, the community does great things, but they go to CERN. They get on an airplane, and they go somewhere else, and they are second class citizens no matter how much they contribute. I regret that and mourn the loss of US community leadership in high-energy physics. And I said, "If we don't do the U.S. ELT, I think we're going to have a second reason to mourn." Something like that. And it was quoted. Dennis Overbye came to me afterwards and took note of that. I was quoted a number of times. So I'm telling you what I'm looking for when I read the decadal survey. I was talking about the U.S. leadership in optical and infrared astronomy. Of course, there's radio and cosmic microwave background and all these other fields. Since Hale, the U.S. has been the lead. From Hale to the 60-inch, 100-inch, 200-inch, Palomar, Keck—I mean, we have been in the lead. I will look to see whether the decadal survey folks feel that the U.S. astronomy community should continue its leadership in the world. What I think is going to happen is they will lose that leadership. The Europeans are building their Extremely Large Telescope. They expect to have it on in 2027 or 2028. It's an extremely capable machine, very difficult to build and operate. I think that will cement their leadership in optical and infrared astronomy. I think it would be very hard for the U.S. to retain a leadership role, especially if TMT comes on a few years or five years later or something. If they don't give a resounding recommendation, it means they're willing to settle back into a secondary role in optical and infrared astronomy. ZIERLER: This sounds like the transition from SSC to LHC redux. SANDERS: That's what I'm talking about. That's what I was saying to them in February 2020. That's what Dennis Overbye picked up and made a main theme of his article. That's what I'm going to be looking for. Now, what do I think they will say? There are two elements that go into what I think they will say, two main elements. One is, is the science of extremely large telescopes so compelling, so important, that it should dominate the next decade of U.S. astronomy, and therefore we've got to do, let us say, TMT and GMT? That's classically what they're supposed to be asking themselves. The other question which has become more and more prominent, overwhelmingly prominent—it's partly generational, partly historical, partly political—is are we willing to do the world's best astronomy on the backs of indigenous peoples? And a significant element in the decadal survey panels are very concerned about the ethical transgression of taking—I used the word "romance" when I thought about my youthful attraction to elementary particle physics—I adore particle physics. We astronomers adore what we do in astronomy. It's amazing what we do! It's so much amazing that it has been overshadowing our awareness of the setting and the places we're doing it. Every new telescope for the last 20 or 30 years—Mount Graham in Arizona, Kitt Peak, even on Mauna Kea before us with the Keck outriggers—has been one where we worked with the power structure, the political structure, the regulatory structure, the social contract, as it's recorded in the law and in administrative law, to overcome any sensitivity that we have to discounting the interests of indigenous peoples. That has now risen to historical prominence. I think it's quite prominent in the decadal survey panels. There's actually a subpanel on the state of the astronomy field in which a lot of socially active and socially sensitive astronomers that give great prominence to these issues. I think that will be a thread, a very important element, in the report. [Postscript note from Gary: Of course, now that the report is out, they nearly completely sidestepped the indigenous people issue altogether. They discuss it but in a detached manner leading to no real recommendations for the future conduct of the field. Since they were presented with two issues related to indigenous peoples, they were able to steer a neutral course right down the middle. What they had was opposition by Native Hawaiians to astronomy on Mauna Kea and fervent demands and support by native Puerto Ricans for continued astronomy at the Arecibo site following the collapse of the radio receiver there. Two native groups on opposite sides of local astronomy issues. This facilitated highlighting consideration of native perspectives but no deep position on the rise of indigenous perspectives seeking self-determination, sovereignty of social equality and justice. The Arecibo issue, while important, became a distraction from the real future pressure on the field.] ZIERLER: Gary, this is to say that the decadal survey will not consider the science in a vacuum. SANDERS: Correct. They will consider it in a social and historical setting, and add in the ethical elements of it, in the same way that scientists have become increasingly and quite properly sensitive to the gender discrimination in the field, underrepresented minorities, and all of the social sensitivities. You do not have a science project now without having due attention, proper attention, to diversity, to underrepresented people, to making sure you are promoting people in a way that creates open opportunities for all, that meritocracies are not color sensitive, ethnic sensitive, racially sensitive, insensitive. This has become very important. The Canadian astronomers have made it clear that they will not support building TMT on Mauna Kea unless they are invited with the consent of the indigenous peoples. That's a tremendously high threshold to cross for TMT, one that I believe can't be crossed, because a threshold has to have a discrete boundary, and the multiverse of feelings, emotions, senses of outrage that are among the indigenous people in Hawaii is diverse, intense, and will make it very hard to get consensus. I actually think the Canadian astronomers are presenting a harbinger of what is also present in the U.S. astronomy community. I'm not criticizing it. I feel that I am an old dinosaur who grew up in an era of expansionism in science with cultural insensitivity. It's particularly important for astronomy because you have to go these wonderful remote pristine and special places, whether it's high mountains, or whether it's, in the case of the Square Kilometre Array, to aboriginal deserts, in Australia and southern parts of Africa, and need to pay attention to those for whom that's their setting. I think there are senior astronomers in the community and certainly junior astronomers, younger people—it is generational at some level—who are worried about whether it's feasible to do ground-based optical and infrared astronomy on very high special mountains in the future. Does the United States have access to those mountains? Chile is a remarkable place. The country of Chile, the government of Chile recognizes their skies as one of their natural resources. They too are extremely sensitive now to the voice, permission of the indigenous people. My interactions, because twice TMT considered Chile as a potential site, originally and then also when we got into difficulties in Hawaii and considered it as an alternate site—I've dealt with government officials, community leaders, and the intendente of the region, and so on. You can't get permission to use a mountain in Chile without the permission—literally, written letters from the small village mayors and so on of the indigenous communities. It is taken very seriously now. So I think in reading the decadal survey, I'm going to be looking for, are we giving up leadership in optical and infrared astronomy? And I suspect we are. I suspect we can't actually keep it anymore because the Europeans have gotten ahead. Second, what is the balance between scientific imperative, scientific priority, and sensitivity to the setting and the indigenous people? I think the outcome is not going to be supportive in a way I would have liked in my youth, for TMT. I think what will come out is not overwhelmingly positive. Something may go forward, but also aside from Astro2020, no matter what they write, I don't see the prospects for TMT being built in Hawaii as very feasible. ZIERLER: Gary, if we can just separate out the science hypothetically and leave the political considerations to the side, and imagine a perfect world where the indigenous people were fully on board and there was not this painful history leading to where we are now, if the decadal survey was like Congress and you had the opportunity to testify before them, just talking about the science, the importance of the TMT, why it should be a priority not just within astronomy but within U.S. leadership in astronomy, what would you say? SANDERS: That's good, because that's actually a fairly simple question, as far as I'm concerned. I would say it is time to go forward with this U.S. ELT in optical and infrared astronomy, and from my standpoint particularly TMT, which I think is the most capable and gets the Northern Hemisphere—that's the first priority—that should go ahead. I think looking further down the line, the next generation VLA and radio astronomy should happen. It's not quite as ready, but I think it should happen and follow close behind. I think in parallel, at some level, the next generation gravitational wave and the cosmic microwave background, CMB-S4, should go ahead. But those have majority support, respectively, from the Physics Division at NSF and from the Department of Energy Office of Science, different funding streams. So if you're talking about astronomy, I would say go ahead with the U.S. ELT, and then as it makes sense, follow it with ngVLA. And then if you expand it a little bit to include the physicists who also contribute to astrophysics, I would say using also the resources of the Department of Energy Office of Science who I think are very interested in CMB-S4, and the next generation gravitational waves which is Cosmic Explorer is the name of the proposal—I would say go ahead with them as the next things beyond that. I think scientifically, in terms of technical readiness, the case can be made quite clearly for that pacing, that cadence, of executing the projects. I wish it were that simple. ZIERLER: I'll reframe the question in the way that taxpayers would get excited about funding this kind of project. What will the TMT tell us about the universe that we don't already know? SANDERS: I think it will do a lot of astronomy with the very farthest galaxies, the very earliest galaxies, the conditions after the Big Bang allowed stars and galaxies to form. The deep universe. I think that will be extremely important. It's hundreds of times more capable in doing that kind of astronomy. I think it's going to do overwhelmingly important work in exoplanets, and that to me is a favorite. Imaging planets around other star systems and learning about them, what they are like, what the conditions are, and in particular looking for what in the popular literature is called the Goldilocks planets, the ones that may host life, which could be quite diverse from the life that we have. To me, those are the two: the very earliest galaxies, and exoplanets. I guess I would also add in studies of dark matter. ZIERLER: The picture you painted, Gary, about the concern of ceding U.S. leadership in astronomy, to what extent is that specifically a comment on land-based observation, and to what extent does it extend into space-based telescopes as well? SANDERS: I am addressing ground-based astronomy. You can do an awful lot of astronomy, fantastic stuff, from space, but it's even so much more expensive. The taxpayer who is part of this conversation needs to realize what it costs to put up this Webb Telescope that's going up, for example, which I certainly hope is successful very soon. But there's no substitute for being high on a mountain, on the ground, with a telescope that you can go up with a wrench and a digital voltmeter and improve it and adjust it and develop it over its 50-year lifetime and do a host of astronomy that you never even thought about. ZIERLER: On that point, for a taxpayer who would say, "What do we need Webb and the TMT for, how do they work in concert, and how are they not simply redundant?" SANDERS: They do work in concert. Above the Earth's atmosphere, you don't have the backgrounds from the atmosphere or the thermal disturbances from the Earth's atmosphere, so you can see farther away. You can see things that are not easily seen from the ground. But those things that can be seen from the ground, you have much better light collection. In using adaptive optics, you can remove a lot of the disturbances of the atmosphere, and you can spend more time, more dwell time, on targets. So to do a complete study, what you'd like is a nice synergy, the harmony, between space-based and ground-based assets. ZIERLER: Going back to the theme of project management, I'm very curious, besides the physics, what you may have learned from Sam Ting about project management, given his legendary reputation in terms of work drive and ethic. SANDERS: Very interesting. This is another area where I may say things that I might want to edit out. I learned to plan carefully. I learned to check everything you're doing, very carefully. I said that, at my retirement party, and complimented him, and I even said it at the Nobel thing on LIGO when he was there. I learned to check what you're doing in the science and to make sure that when you design an experimental thing, that you have the ability to check your results carefully to make sure it's right. That was something I learned very, very clearly from him. Plan, and check. Mainly to check. His project management, I would say I learned that there is a thing called project management, and that you can have big international collaborations in which you recognize the contributions of every participant, even if they aren't from Caltech or MIT, because you really want all of them. It's diverse. There's a lot of talent around the world. You learn how to work across cultures. I also learned that from him. I would say the specific project management techniques that I learned from him, a lot of them were early intuitive implementations. He too was inventing it, like many of us. But goal-oriented, being teleological, planning carefully, checking-checking-checking-checking, and working in an international setting cross cultural and learning how to include everyone in their role. He did that on a big scale. I'll give you an example. On the LEP Collider, the L3 experiment that I joined after that neutrino experiment wasn't approved, the East Germans—East Germany existed then—were part of it. Well, the only thing they could contribute was a bridge crane, a big yellow bridge crane that moved back and forth and lifted things. That was great! They got to participate, and they had scientists in their universities and their institute. There was an institute at Zeuthen just outside of East Berlin. It was an example of a place which wasn't MIT or Harvard or Stanford or something that could contribute the most difficult part—silicon vertex detectors or bismuth germanate inorganic scintillators and those kinds of things—but they were part of the team. They were respected. They sat on the Executive Council and had a voice. That was an important thing to learn, and we learned it in high-energy physics because it was global. That was very important to me in my project management later on. But I would say the specific techniques that Sam had, he was too much of an individual who would override those things and do what he felt was right. Project management and leadership coexist. ZIERLER: A very broad question, Gary—given you came of age in elementary particle physics, and here you find yourself in the world of cosmology, astrophysics, astronomy, do you see your career trajectory unique as it is at least scientifically part of a broader transition of particle physics into these new areas, post-SSC? SANDERS: There's two ways to address that question, for me. One is if you just look at the high-energy physics field, and look at it in October of 1993, just as the Super Collider was being cancelled, most of the people in the field were dedicated to be in high-energy physics and didn't see that they would leave the field or evolve into another field. If you looked at Fermilab—this would be something that would be interesting to look back at—Fermilab was at the time the biggest of the Department of Energy-supported high-energy physics laboratories—and asked, "What science is going on here at Fermilab that isn't hard core elementary particle physics?"—and I think there might have been at that point Rocky Kolb there, head of a small kind of astrophysics group. Just about that time, you began to see high-energy physicists looking at problems that were in adjacent neighborhoods to high-energy physics. But there weren't a lot of them. It looked like a self-contained field. But the demise of the Super Collider—by my estimates, which I don't think I could really justify—I think about 10% of the people in experimental high-energy physics and even some in theory were squeezed out of the field. The size of the support base reduced. Some people left the field and became quants, went off to finance and so on. Some people moved off into the neighboring fields, and others did other things. I know one person who went off to help cell phones figure out where they were by how close they were to various towers. There were a variety of things. But what I saw were quants, and I saw people moving into things like astrophysics. Underground science—looking for neutrino and muon and dark matter things, some of which was related to particle physics, but not accelerator-based. And some was nuclear physics. Then if you looked, for example, at the org chart for Fermilab—some historian ought to do this—and looked at the contribution at Fermilab of people who weren't doing accelerator-based high-energy physics, you see it growing. So the field diversified, partly because it was squeezed in those directions. The support base squeezed it. ZIERLER: Because of the SSC collapse? SANDERS: That's right. And also, because the Cold War ended in the 1990s and the natural priority that high-energy physics had, because it was somehow related to the national defense—that was part of its origins; nuclear physics reactors, accelerators and so on—went away, and it had to stand on its own. High-energy physics doesn't have the priority in Washington that it did in the 1980s. It didn't grow in the same way that it might have continued to grow. So people moved into adjacent fields. I also think, genuinely, the intellectual progress of high-energy physics naturally led it to contributing to broader questions in cosmology, in astrophysics, and so on—the neutrino problem from the sun, dark matter, and then dark energy. So it was natural for people, theorists especially who studied field theory and things like that, to address adjacent things. I think there were two thrusts. One was a resource base and priority that's squeezed, and the second was there was natural intellectual connections that developed. My own trajectory was simpler, I think. I told you that when I first decided that I wanted to be in elementary particle physics, I used the word "romance." To me, wow, that simple particles and that's what the universe is made of, that was a romantic thing to me. ZIERLER: You also came of age at a time when people were discovering new particles every day, it felt like… SANDERS: That's right. Nuclear physics was just becoming particle physics, and I was caught up in that romance. But when Barry Barish called me and said, "Would you like to come work with me on LIGO?" exactly the same romance happened, even though it wasn't particle physics. Exactly the same thing happened when I thought, "I can help do this Thirty Meter Telescope." Because it was going to address these fundamental questions. The word "fundamental" is key. The same thing now with my involvement with cosmic microwave background. Can we see the influence of primordial gravitational waves from the very earliest part of after the Big Bang cosmic history, and their influence on the first light after the first 380,000 years, when light could get out, and changed, influenced that light. Can we see that as a sign of the fact that there was inflation? To me, the romance is there. ZIERLER: Gary, you used the word "romance." I wonder if you've ever reflected on almost the Shakespearean drama of transitioning from the SSC, one of the great tragedies in modern American science, to LIGO, one of the great successes, one of the great triumphs in American science. SANDERS: What was the tragedy? The Super Collider? ZIERLER: Yes, the SSC. SANDERS: Yeah. When you teach a little kid to ski, and the kid falls down a lot, you say, "If you aren't falling down, you're not learning." I often say, perhaps too often, that what we do, especially in big science, is we try to make the nearly impossible routine. In other words, you start out with something like LIGO that no one knows how to do. You start out with something like trying to see the signs of inflation in the cosmic microwave background, which is like LIGO. The first gravitational wave discovery in the late 1960s was wrong. The first discovery of the signs of inflation in 2012 by BICEP2 was wrong. They have these birth traumas. You start out looking for something fundamentally nearly impossible. And yet some years later, you want to be sitting there looking at the data coming in, and it's coming in the same way, every day, day after day. You've made it routine. I tell the story that CP violation was discovered in 1964. Christenson, Cronin, Fitch, and Turlay led to a Nobel Prize, and so on. But 15 years later, I was doing an experiment where we were getting too many CP-violating events. They were getting in the way of what we were studying. ZIERLER: [laughs] SANDERS: We were telling our system to only take one in a thousand, just so we could see them and calibrate on them. That's what we do. When you are at the edge of failure all the time and trying to make it routine, some of the things you are going to do don't work. That can happen at the physics end because nature is not cooperative. It can happen at the technical end because the techniques are very, very difficult. Look at the BICEP2 experience. They failed to understand the lensing caused by cosmic dust in the foreground cosmic space. Or it can be political. And you try to "routinize" in every one of those realms. ZIERLER: Let's really drill down now at the moment where you first consider the possibility of joining Barry Barish at Caltech to work on LIGO. Where were you right then and there when you started thinking about this possibility? SANDERS: I've told that story. In fact, you probably you can find it in something that I've said, maybe at my retirement party. I was back at Los Alamos in early 1994. ZIERLER: You were never an employee of SSC? You were never out of a job after the collapse? SANDERS: That's right. The director of Los Alamos and the director of the SSC exchanged letters, and the director of Los Alamos was in effect seconding me to the SSC. I was the head of a department called the GEM department. There was an SDC department for the other detector. Then there was an accelerator department, and a booster department, and a civil construction department, and so on. ZIERLER: Who were some of the key theorists for GEM? SANDERS: Okay, but let me answer your first question. You asked me where I was. I was at Los Alamos, investigating the human radiation experiments in the early Cold War and in World War II. I was literally in traffic leaving work that day, and pulled into a left turn lane, and got a call on my car phone. In those days, I had a car phone, actually. It was Barish, who said, "Gary, are you willing or interested in coming to Caltech to work with me on LIGO?" The first thought in my head was, "Yes. I'm going to do this." ZIERLER: Did you know what LIGO was? SANDERS: Yeah, I knew it. At the same time that the SSC was in trouble, politically, if you picked up The New York Times and read the science pages, you saw SSC is being taken apart in Congress and they may cancel it, you also saw that those guys at Caltech are screwing up LIGO, and the NSF is very unhappy, and it's not clear what's going to happen to LIGO, and Congress is angry. Senator J. Bennett Johnston, who was a sponsor from Louisiana—he was angry. You'd read all that. So I certainly knew it, but I also knew the science of it. I instantly in my head said yes. ZIERLER: And you saw that Barry would be potentially a savior? SANDERS: I saw that Barry would be a—because he and I had worked to save the Super Collider detector that Sam Ting left. It was in effect rejected by the U.S. high-energy physics community. Regarding LIGO, I knew I was going to do it. Although Barry told the story at my retirement party that he found me to be a hard bargainer over my compensation, pensions or something like that. Because I was leaving the University of California, which had a defined benefit pension, as opposed to a standard 401k thing. ZIERLER: UC, because UC managed Los Alamos? SANDERS: That's right, I was a UC employee at the time. Barry thought I was resisting, but I'll tell you, in an instant, I wanted to do this. So your other question was—? ZIERLER: About the theorists. Who were some of the key theorists on GEM? SANDERS: I remember Ken Lane. There were theorists that you didn't see every day. Right now a lot of the names just don't come to mind. It has been a while. Fred Gilman, who was head of the Physics Department at SSC. He's now at Carnegie Mellon. ZIERLER: Fred Gilman. SANDERS: Yeah, Fred Gilman, who was in effect my boss, but he was a theorist. There were a lot of them out there, talking about technicolor and supersymmetry and the Higgs, what was the right mass for the Higgs, and would we see it at a given energy or given luminosity in the accelerator. There were theorists I interacted with every day—Syd Meshkov and so on—but the real luminaries were out there. Glashow and those folks were out there. I didn't have that much contact with them. There were people who were playing a role called phenomenologists, meaning theorists who didn't just sit and do theory, but they actually did calculations as theorists that were beneficial to predicting what you would see and how you would separate it from backgrounds, and so on. A lot of them were very important. But I have to sit down and refresh my memory on the names. ZIERLER: What was Barry's plan, as he presented this idea that you should come join him at Caltech? What was his plan to save LIGO? SANDERS: First of all, Barry and I had worked together on experiments both together and also separately in our earlier careers, on doing experiments funded by the U.S. Department of Energy, and we knew how to plan a very difficult experiment, get it done, not break the budget, get it done reasonably close to the schedule that we planned. In other words, to work with a sponsor that gave you lots of money but expected adherence to a plan. He and I both had that experience. His plan was two things, I would say. He wasn't going to take the directorship unless he made his own independent judgment on what it was going to take in terms of money and time to do LIGO. He wasn't going to trust the$212 million dollar and so-many-year time span to which LIGO had been approved. LIGO had been approved at $212 million and a certain number of years. He looked at the model for building LIGO and then running it, as a remote facility for example, and thought, "That's not my plan. I have to be convinced in what the plan is." So he immediately started an exercise to re-estimate the cost, the schedule, and the technical risks. He wanted to make it his plan. The second was he wanted to bring what we knew from leading big projects under Department of Energy support to the NSF which had no infrastructure or expertise in building really big projects. They had built the VLA in the 1970s, the set of antennas that are in New Mexico, but hadn't done any big projects expect for the stuff at the South Pole. The South Pole stuff in those days was run by the Navy. The U.S. Navy knew how to do stuff in harsh environments. They knew how to do stuff. The NSF is now in more control of the South Pole. The Navy is no longer running the show there. So inherently, inside the NSF, they didn't have the skills to oversee large projects, and they were, at that time, taking on two of them. One was LIGO, and one was the Gemini Telescope, one on Mauna Kea and one in Chile, the two Gemini telescopes. Congress created a major research equipment budget line so that the funding of these construction projects wouldn't come out of the hide of the budgets that supported university professors doing research in those fields. The second thing Barry knew was that he could bring in what he knew about running big projects from the Department of Energy doctrines, processes, and tailor them, adapt them to the NSF situation, so they would be appropriate. If you brought it all in, it would be too bureaucratic. I knew that, too. What he and I worked on with others in those first six months from March or April of 1994 until September of 1994 was re-baselining the project. That's the word we use. What does it cost? What does it take? Is this the right model for implementing it and running it? Including the operating budget, post-construction. We made a presentation to the National Science Board in I think November of 1994—I might be off by a month or two, but I think it was November—of the revised construction cost and schedule, and a revised operations budget. At that point, the NSF had pulled back, I think,$35 million of appropriated funds, and they had informed the Congress that we were—what's the word they use?—a recision, or rescinding, or something like that. They pulled it back. That's one hair away from being cancelled. In order to go forward with the project, the National Science Board had to do something, and it had to go through the White House to the Congress and tell the Congress that it was restarting.

So we had these hearings, a review in September of 1994. Also Ed Temple, who I mentioned earlier, was on that review, might have chaired it—he took me aside in a room and said, "Can you do it for this new number?" And I said, "Yes. This is what I'll do to"—so and so. We had a conversation. They wrote a favorable report. We went to the National Science Board in November of 1994, and they voted a resolution to approve the construction and the operations budgets. I remember Neal Lane, who was the director of the NSF, came out of the board room, and I was sitting out there with Barry and Rai Weiss and Kip Thorne. Neal Lane came out and said, "I'm pleased to tell you that the Board has approved both the construction and the operations budget, but don't come back for more," he said, with a smile on his face. That news went off to the Congress and so on, and somehow funds were released, and we went forward to carry out that plan.

ZIERLER: How much political and even scientific baggage did you and Barry have to deal with from prior leadership of LIGO?

SANDERS: I'm not sure what you mean.

ZIERLER: In other words, were you operating as if LIGO was essentially a new project?

SANDERS: Ah, very good question. In the scientific community, in the Caltech faculty, I'd walk across campus, and I remember the guy who headed the faculty senate or whatever it's called stopped me on campus and said, "Thank you for coming here and helping us." Because there had been a trauma at Caltech with the removal of Robbie Vogt and then the big warfare between Ron Drever and Robbie Vogt and so on, which was a big faculty bruhaha which they were very uncomfortable about. So I would say among the scientific community and certainly at academic, I felt that Barry and I were very appreciated for taking this on and trying to make it a success.

However, one of the things we did in the successive year was Barry and I went back to Washington D.C. to visit people in Congress, both members of the House and Senate and staff members, to introduce ourselves and tell them what we were doing. We went with April Burke, who heads Lewis-Burke Associates, which is a lobbying firm that works with Caltech among others. Most of these meetings were pleasant and informative and so on, but I remember a number of meetings where a member of Congress or a staffer would look at us and say, "You people are awful! You don't understand." We were painted with the guilt of what had happened before.

A year later, things were back on track, things were working, and yet we were still being blamed for what had happened before. It's just the institutional memory, institutional inertia, and in some sense the ethical stance of the folks—at least in those days, some folks felt they were still custodians of the taxpayers' dollars. There was a long tail on the disorder that was created by the failure of the initial attempt to do LIGO, and we had to deal with that. It wasn't serious.

ZIERLER: What were relations with MIT like in those early years?

SANDERS: That's at two levels. First of all, MIT had never stepped up to be a leader. The MIT administration had never stepped up to be a leader in LIGO. Rai Weiss often tells the story that he went to his provost, John Deutsch, who later went on to become the head of the CIA and had to resign from the CIA because he took classified material home. But when Caltech and MIT were putting together a proposal under Robbie to the NSF, and Rai Weiss went to Deutsch and asked for support, and was literally—the story that Rai tells—is given a piece of paper with a big "Zero" on it. "No." So that guaranteed that MIT was going to be in a sub-award role to Caltech. There was a little bit of resentment, but not much.

I have to say the folks at MIT—the team; I'm not talking about the administration that wrote that "0", but the team—it was really very good. It really was very good. They were so focused on the techniques, the science, the technology, the engineering. There was a sense that "why are we subservient a little bit, to Caltech," but it was never serious.

ZIERLER: Gary, last question for today. Just to foreshadow to 2015, 2016, what timeline were you and Barry operating on? In other words, was that 10, 15 years to detect a gravitational wave, was that about where you were operating? Or that was just beyond your capacity at that point to plan that far out?

SANDERS: We had a pretty good sense that Advanced LIGO would have a good chance to detect. There was very little basis for calculating the event rate. It was on the basis of one or two or three relativistic binary systems in the universe that calculations were done by various people that told us that we had a very, very small chance to see it with initial LIGO, the classic neutron star-neutron star 1.4 solar mass neutron star neutron star inspiral. There was one paper by Bethe—there was no information of any credibility about the black hole-black hole inspiral rate. Whatever estimates we had were pretty bleak about the chances with initial LIGO, but somewhat optimistic, given large uncertainties, about Advanced LIGO.

I do remember that at that National Science Board hearing in November of 1994, one of the National Science Board members asked Kip Thorne, "Are you going to see this thing?" And Kip said, "With initial LIGO, the chances are small, but with Advanced LIGO, we have much more confidence." That board member pressed hard— "So what happens if you do Advanced LIGO and don't see it?" And Kip said something like, "We expect to see it, and even if we didn't, it would have profound implications in astrophysics." Something like that. And it was a commitment that normally theorists don't make, but if you're going to do it, that was the moment to do it. We felt that it was a good chance to see it.

At least speaking for myself—I don't know about Barry—we had no idea about how quickly it would happen. And we learned from turning on initial LIGO that it didn't turn out at its designed sensitivity, but took two, three years to approach its designed sensitivity, so we assumed that with Advanced LIGO, we'd come on and then have to fight its way up. But guess what? It [laughs] found it in an engineering run. When I left LIGO in 2004 to go over to TMT, the Advanced LIGO proposal was essentially through the NSF, to the National Science Board. I felt confident. It still had to go through some hurdles about budgets and what would happen to the LIGO operating budget in the interim. Would it go down and then come back up? And all those kinds of things happened. I didn't have a good sense of how long it would take to build Advanced LIGO, even though we wrote a certain schedule in the proposal knowing that the people who were in charge of LIGO after I left and after Barry left were going to have to weigh running initial LIGO and turning it off and giving up scientific opportunity for several years while they built Advanced LIGO. There's a point at which it's worth—because when you turn on the new thing, it's so much better that it more than makes up. I didn't have a good sense of how that was going to work out.

ZIERLER: We'll pick that up for next time, how that did work out.

[End of Recording]

ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It's September 3rd, 2021. I am delighted to be back with Dr. Gary Sanders. Gary, it's great to see you again.

SANDERS: It's good to be back and to talk with you.

ZIERLER: Let's pick right back up. I wonder, if we could cover just some LIGO 101. We left off where you were talking about the differing prospects between LIGO and Advanced LIGO in terms of actually detecting the gravitational waves. Can you provide an overview? What's the distinction both administratively, chronologically, and of course scientifically, between LIGO and Advanced LIGO?

SANDERS: The biggest difference was the expected or designed sensitivity of the two, and the expectation of whether or not either one of those would actually detect gravitational waves. It was understood that there were many possible sources of gravitational waves from different physical mechanisms, things like the inspiral of two neutron stars, and two neutron stars who pass each other and get captured in their gravitational fields and start orbiting each other, and presumably lose energy by friction, friction with space-time, in other words the emission of gravitational waves. The spiraling—it inspirals as the system loses energy and eventually ends up in a collision.

There was strong evidence, partway through the early years of proposing LIGO, from Hulse and Taylor's observations of pulsars and their loss of energy in such a system I guess using the Arecibo radio telescope, and that the loss of energy was consistent with the emission of gravitational waves, for which they won the Nobel Prize. Rai Weiss used to say, "We've already detected gravitational waves. It just wasn't directly." It's like detecting the heat in a wheel from the brakes. You know there's friction, but you haven't measured it, but you can feel the heat. That's a classic kind of standard candle or something that people thought about, the inspiral of two neutron stars, but there was very little evidence out there of how many there would be.

I think at the time when I joined LIGO, there was maybe only the Hulse-Taylor system, and there were calculations by a couple or a few theorists. The number of relativistic, binary neutron star pairs that were known or expected in the universe was one or two or three. I've forgotten the exact numbers, when people thought about it. It was very scant, but it was used as a standard candle, and it was used to calculate what the strength of the signal might be, relative to the sensitivity of LIGO. Not just its sensitivity buts its sensitivity to whether or not the system that was being measured was directly overhead or off to the side. In other words, the antenna pattern of LIGO. Those calculations suggested that there was a pretty small chance, very small chance. I've forgotten the numbers.

There were other systems—black hole/black holes—that were expected to meet, spiral in, and emit gravitational waves, but there weren't many calculations. I think there was one paper which was part of the way through our work on building initial LIGO, of which Hans Bethe was an author—I've forgotten the other author—and that was an indication. There were scant good calculations, and certainly scant observations. So a lot of this was inferential, but whatever there was suggested that initial LIGO was unlikely to see these.

Then the same I would say thin theoretical reasoning and even less experimental reason suggested that, however, Advanced LIGO, which might have a factor of ten increase in sensitivity, probing ten cubed or a thousand times the volume of space that was surveyed—that would have a good chance. That was the notion. It was very early on—and I think as I recall, written into the early proposals to NSF for initial LIGO—people talked about it as LIGO 1 and LIGO 2, which the NSF didn't like because it suggested that maybe the NSF was obligating itself to LIGO 3 and LIGO 4. The suggestion of an index on the version of LIGO. It's like Windows 7, Windows 8, and so on.

ZIERLER: [laughs]

SANDERS: Maybe I told you that story in the previous interview—I think I did—that at the National Science Board hearing when LIGO was reauthorized in November 1994, Kip was asked whether he expected with Advanced LIGO, if there was one, gravitational waves would be detected, and he said yes, or physics or science would be strongly impacted. In some sense, he was guaranteeing there would be a scientific payoff. So it was well understood, at least by us, that initial LIGO was something to get out there and had a chance, but small, and that we had to work on Advanced LIGO.

We were building initial LIGO 1994 to 2001, with some operations beginning earlier. If you look at the publications in the early years, a lot of them were setting limits on a signal, in other words ever more sensitive measurements without actually a detection. Some of those limits were of interest physically in the sense that they constrained models, but they were limits. It was one of the reasons why David Shoemaker and I in 1997—and that was just before we were even installing technical components in initial LIGO—started to work, with others, on the design of Advanced LIGO, and writing a proposal. I think the first proposal that we put together and actually showed to the NSF was in 1997. There were successive versions of that proposal up until I left LIGO in 2004. My recollection is that the proposal for Advanced LIGO was pretty far through the NSF at that point. It was quite likely to be funded. It had gone to the National Science Board and so on. But I don't remember the exact month-by-month chronology of it. When I left, I was confident that Advanced LIGO was going to happen, and it made it easier for me to depart over to TMT.

Advanced LIGO was expected to be an order of magnitude more sensitive, three orders of magnitude more of the volume of space surveyed, again, based on the scant experimental and a few theoretical predictions. That turned out to be right. The detection was done during an advanced engineering run. However, I shouldn't say it was right, because the estimates of neutron star and neutron star inspiral, which is what we used as our kind of standard candle for talking about LIGO, assumed 1.4 solar mass neutron stars, so things a little bit heavier than our sun. Instead, what they found were things that were maybe 30 times heavier than the sun. I think my recollection is the first detection had a mass of more than 60 solar masses. That by itself was an object that was not expected to be there, and certainly not as copious as we now know it is.

ZIERLER: Gary, given all of the academic controversy and tension with regard to LIGO and Caltech prior to your arrival, what does that say institutionally about Caltech, that it hung on to LIGO, and who do you credit with that?

SANDERS: That's a good question. Clearly, Kip Thorne, really, was committed to it. Robbie Vogt, who as we know was removed as the director of LIGO from Caltech, was clearly very committed to it. Ron Drever was. There was this history that took place before I was there, where MIT was working on the design of prototype gravitational wave interferometers and ideas about a bigger one. Rai Weiss had, in effect, invented the idea, I think it was in 1971, in an internal technical report to the research laboratory of electronics, whatever it was, at MIT, a quarterly progress report. He had sketched out the design, largely the design of a LIGO, in 1971. I'm not sure it's 1971; it might be 1972. They started working on prototypes in Building 20 at MIT, a building that Rai Weiss loves, because it was an old World War II wooden building that he could take a saw and cut a hole through a wall to stick his interferometer through, without calling Buildings and Grounds on campus, I guess.

ZIERLER: [laughs]

SANDERS: Those were the days. And I remember that when I was a student at MIT in the late 1960s, that building was very dense with a lot of experimental work in it. So MIT was working, and Caltech, I believe the history was they recruited Ron Drever to be an experimental counterpart. This was Kip Thorne and others. Barry Barish was involved. Others were involved, on the faculty, in supporting that idea. Drever appeared and had his own ideas. I think Drever contributed an element of the design, the arms of the interferometer would be with Fabry-Perot cavities. In other words, you trap the light between two concave mirrors of a certain size, and they would recirculate over and over again and build up the light power in the arms. Whereas I think Rai's design was a delay line; you have multiple passes between mirrors and the arms. There was a bit of a competition, and Drever, I believe, succeeded in pushing the Fabry-Perot mechanism. Again, if you are going to focus on that, you should talk to people who were there, make sure I got it right.

Drever contributed a key element of the design, but there was a fight that brewed on campus during the 1980s and early 1990s, during which time LIGO was run by a troika of Drever, Weiss, and Thorne. Troikas are not good decisive leadership models, especially when the troika consists of academics. The NSF wanted a director who could make decisions, and that's where Robbie Vogt came in. He led the building of what was a fundable proposal. But clearly there must have been tensions, and on campus there was a big bruhaha with Drever, and Drever was removed from LIGO. That was, I understand, very painful to the faculty on campus, because faculty members at most universities, but certainly at a place like Caltech, are like bishops or cardinals, and they're sovereign in some sense. When they have to act against the interests or desires of one or the other, then it's very painful. The residue of that, plus the removal of Vogt at the instigation of the NSF, was a background when Barry took over and recruited me to come and work with him.

I might have mentioned it to you, but I remember meeting the person who was then head of the faculty at Caltech on campus who recognized me and thanked me for coming. He was clearly interested in the restoration of peace and order. I would say the disruption from Vogt and from Drever continued at some rate, which was annoying, but tolerable. Vogt wasn't removed. He was removed as director, but he wasn't removed from the project. Somehow the accommodation—and this was before I arrived—was Vogt would head the group that built the detectors, and Barry and I would head the project over that. There was clearly an intent by Robbie Vogt to continue to have a LIGO within a LIGO, his LIGO within the newly led LIGO. That was tense. I remember having a number of lunches with Vogt, where he talked about that sort of thing. But it didn't work, and ultimately Barry and I moved him aside, and he left the project.

Drever continued to militate against what we were doing and was quite vocal about the fact that he knew how to detect gravitational waves, and this big thing, LIGO, was in the way and wouldn't succeed. Ultimately, he had such tension with the management at Caltech—I don't know whether at the president's level, the provost's level, a division chair—that they gave him money to build his own prototype interferometer on campus, which he built at what was called the Synchrotron Lab, a high bay area, with high ceiling and cranes and power, under Lauritsen-Downs, and even an underground tunnel. He puttered away, building that thing for years, and while we were doing other prototyping work in that high bay area, we would see him frequently and chat with him. But he was convinced that he was onto the right way to detect gravitational waves, which was unfortunate in his lack of clarity about what was likely to happen. But he was given money and supported by the Institute, which is consistent with the Institute's, I would say, Caltech's frame of mind is to find the smartest people you can and then support them so that they can succeed, and they did that. They were buying peace, but they were also giving Drever his chance, which at some level is just, in an academic world. You can't always support only the people who are totally reasonable.

ZIERLER: [laughs]

SANDERS: That's for sure, because you wouldn't have a place like Caltech. I commend Caltech for its ability to support really brilliant people, some of whom are difficult characters. Those were the early years. We had to deal with the aftermath of the fights on campus. A lot of this is documented pretty well in Harry Collins' book Gravity's Shadow. That's one account of it. Even Kip wrote a book, Black Holes and Time Warps or something, a title like that, and some of that is discussed in there.

ZIERLER: Gary, in those early years, what kind of interactions would you and Barry have with Kip Thorne, and how might we understand that as a microcosm for LIGO's broader achievement as a successful interplay between observation and theory?

SANDERS: Oh, well, it was a quite extensive interaction. Kip, we had regular interactions. I don't know whether it was weekly, but it was frequent. It was not just in theoretical things. There were three ways in which we interacted with Kip, other than his enthusiasm and his advocacy. One was in executing the project, constructing the thing. Kip had been intimately involved with the design, at least at the concept level, understood how it worked quite well. I can't remember whether he attended lots of group meetings or weekly group meetings, but he was well aware of what was going on, and he was looked to, for input and advice.

The second thrust that was being developed was preparation for analysis of the data, which included two things. One was simulations of what different gravitational wave sources would produce in terms of the signals and how to measure those signals. In the case of the classic things like a neutron star-neutron star inspiral, especially this classic 1.4 solar mass type, people were doing simulations of those things in a number of places. There was also a grand challenge NSF funded. I believe it was just NSF funded. Computational relativity project out there at about the same time, led by a guy at University of Texas, Richard Matzner. So people were calculating what the signals would be like in the same way you would calculate the signal from a Soviet nuclear submarine so that your sonar people on an American submarine would have a catalog of templates, signature templates, so you could say, "Oh, that's this class of submarine."

People were calculating these things with various levels of precision, post Newtonian relativistic calculations, and building up these catalogs of templates, and the Caltech group was certainly involved with that, as were many people. There were also people in the community who were building up their capabilities, Bruce Allen among others. The community was rising to the notion of calculating the signals and developing the software to analyze that, and Kip was a major figure in all of that, how to prepare for the community and its capabilities to deal with the data. The classical inspiral-inspiral types, unmodeled burst sources—how do you detect something that blows up but you have no idea what the mechanism of the blowing up is, and how do you separate that out from noise? Signals that were periodic. A sine wave signal that might come out from a kind of a bumpy neutron star that was spinning around and producing a sine wave depending on the eccentricity of that thing. Primordial gravitational waves, in other words the gravitational wave static from the very earliest instances of the universe. Kip was involved in a lot of that, had students and colleagues and was a leading figure in the community.

The third way that Kip I think interacted was novel. He actually got involved in some things, designed things or technical repair issues. There was this business of lining the insides of the vacuum tubes with baffles that had a certain kind of teeth. You'd put a collar inside the beam tube every so often that looked like a ring with sharp teeth pointing inwards. The idea was to prevent light that scattered out of the light from the interferometer, this Fabry-Perot cavity that had light trapped in it, resonant, going back and forth in the arms, and if there was a little bit of scattering from a dust or a gas molecule or something, that ultimately after one or two or three bounces, bounced off the walls of the beam tube, and the beam tube, being in contact with the outside atmosphere, might be vibrating, from sound or external vibrations. We call that microphonic modification of the light. That little bit of light modified by some microphonic stimulus from outside might scatter back into the central optical phase space of the light in the interferometer and mimic a signal.

We lined the inside of the walls with these baffles every so often to intercept such scattered light. Kip was involved in the design of those teeth using diffraction optics. There was a thing in the interferometer; Kip sat down and did mathematical calculations, and he came up with a design. So a very eminent theorist, he was involved in a lot of ways, very broadly. I think aside from being an extremely smart fellow, he was really committed to the success of LIGO. That's the kind of thing that kept Caltech I think involved in it, to come back to your earlier question. Through all of the personality strife and turmoil, the commitment of a person like Kip Thorne is what drives things at a place like Caltech.

ZIERLER: Physically, where did the construction of initial LIGO take place?

ZIERLER: Yeah, where was it? Where did you do all of the tinkering, the building?

SANDERS: There are two observatory sites. One on the Hanford nuclear reservation in the state of Washington, near Pasco, Richland, Kennewick, Washington. And the other site that's a couple of tens of miles outside of Baton Rouge, Louisiana, in a pine forest, near the town of Livingston.

ZIERLER: And these sites were already put together by the time you joined?

SANDERS: When I joined the project, they were selected and they had gone through whatever environmental impact statements and so on. There's a long story of how those sites were chosen that occurred years before I arrived. What the proposers of LIGO did was write down the technical requirements for pairs of sites. You needed two sites. They had to be separated by some minimum distance. I think it was the order of 3,000 kilometers, some number like that. They had to have certain attributes. They were quiet. They weren't highly developed, and yet there was an airport not too far away, and so on and so forth. There were technical requirements. I think the proposers identified sets of site pairs. I think they went through and there was a process of soliciting proposals from entities, whether it was states or counties or cities or even private entities, to be considered as one of the sites. The process ended up with identifying a set of site pairs that would meet all the requirements. What I was told was that set of site pairs was provided to the NSF. Some obscure, unmentionable, and un-documentable political process went on that ended up with the state of Washington and the state of Louisiana. There are stories that talk about Scoop Jackson and J. Bennett Johnston. Clearly, there were high politicians that were involved in all that. All that occurred before I arrived.

When I arrived, the site pair that was selected had been selected. Environmental impact statements had taken place. The proposals from the entities that were proposing them and in some sense owned them, had been received. They included certain commitments. For example, in the state of Louisiana, the commitment from the state of Louisiana included building the roads leading in and out of the site, to certain standards. There were other things that were there. I've forgotten whatever there was related to the DOE site, Hanford Reservation. Undoubtedly, the Department of Energy was involved in that.

When I arrived, the two sites existed. I think no work had been done on those sites. It's possible some work had been done at one, certainly at the state of Washington site. But shortly after I arrived, the first real construction activity on the Louisiana site took place. I remember flying out there and walking on the site with the mayor of Livingston at the time, in this nice pine forest where there were a lot of shotgun shells, empty ones, on the ground. It was clearly a prime hunting location. Shortly after that, what was done was the rough grading of the site. That was probably in 1995, that that took place? I don't think it took place in 1994. 1995. So the grading took place. The two arms at right angles were cut.

I remember a surveyor coming back a little bit after that with a report that suggested that perhaps they had not been cut at a 90-degree angle with each other. That was a shock. If they had been cut at a 85-degree angle, the system still would have worked—it's just arithmetic—but we would have been very embarrassed. That turned out not to be true. I think that was 1995, and that was the first work on the sites that I can recall. There might have been some in Washington.

ZIERLER: Was there any prototyping done at Caltech that was then transferred to the sites, or really everything was done at the sites?

SANDERS: No, no. A very important part, especially of the Caltech story, but of both institutes—Caltech and MIT—involved was that there had to be prototyping, for a variety of reasons. The most important thing was to see whether you could build an interferometer with a particular optical and controls arrangement and achieve anything like the design sensitivity. Now, you couldn't achieve the design sensitivity unless you built the full four-kilometer arms, which you couldn't do on the Caltech campus or the MIT campus. But there were two key attributes that, aside from all the technical things, you could learn in prototype and verify to yourself that you actually could do that. Could you produce a mirror, a test mass of a certain quality, with a certain anti-reflective coating on one face, and transmission through to the other face, and optical homogeneity, optical uniformity? All those little technical things you could do prototype.

But there were two key parameters. One was, could you build an interferometer that had the design sensitivity in measuring the displacement of the mirrors at the end of the arms, the so-called displacement sensitivity? In order to achieve the displacement sensitivity that LIGO needed to measure the strain, in other words the distortion of space/time that would be caused by a gravitational wave, you needed to be able to tell that the separation between these two mirrors changed by a very small amount—I've forgotten—a thousand, ten thousand times smaller than an atomic nucleus. That's called the displacement sensitivity.

Second, the interferometer measures the displacement sensitivity by setting up the two arms and causing a destructive interference between the light in the two arms. In other words, looking at the black fringe in a fringe pattern of an interferometer. You have this black and white set of stripes, and when you change the lengths of the arms, if you constructively interfere in a simple Michelson interferometer, the sine wave light from the two arms, you get a bright spot. Then if you change the length of one of the arms and then you take the two sine waves and oppose them so that they cancel each other, you have a black spot. Those are the interference fringes.

In order to achieve the displacement sensitivity, in other words, the sensitivity of the separation of the two masses, LIGO had to be able to take an interference fringe pattern—bright, dark, bright, dark, bright, dark—and split it to a part—and again, I'm trying to remember the numbers—at the time, a part in a billion. Could you get what we called the phase sensitivity? I think for advanced LIGO, it had to be a phase sensitivity of a part in ten to the tenth, or ten to the 11th. This is really hard, optically, to take an interference pattern and split it to a billionth of the size of an interference. I'd have to sit down and check the numbers; it has been probably 25 or 30 years since I thought about it. But I'm not off by much.

Of course, there was some rivalry or competition between Caltech and MIT. They each wanted to have ways to test the system and they each wanted to be able to educate graduate students and postdocs and so on, so as to build up the academic and intellectual strength of the project. At Caltech, they built a 40-meter interferometer, so 1% of the size of—instead of 4000 meters, 40 meters—on campus. So a 40-meter interferometer was built with more or less the same optical arrangement as the full interferometer, and a lot of prototype electronics and controls and the vacuum systems and all that. That was built over in an industrial part of campus on the north edge of the campus.

Then a smaller interferometer was built at MIT. I think it was ten meters. I think that's right. The ten-meter one at MIT was designed to study the phase sensitivity as I recall, and the 40-meter interferometer was to demonstrate the ability to have the displacement sensitivity, along with lots of other things. Testing the kind of control algorithm that you would need to lock the interferometer, in other words to cause what was going on in one arm to match the other arm and to be controlled jointly, so they would stay in interference. Those kinds of things were also to be tested. Also to build electronics that would do those controls, which presumably would either be the same as what you would put in the large interferometer or would tell you what you needed to know to design the next generation.

Those two prototype activities were active on both campuses. They're well documented, for example, in Harry Collins' Gravity's Shadow book, and I think in Kip's Black Holes book. But they also helped to promote a cultural thing that had to be overcome in order to transition into a construction project, and that too was discussed a lot in Harry Collins' book. I said one of the reasons you wanted these kinds of interferometers on the campuses of these two pivotal institutions was to create the intellectual training ground, to build the intellectual expertise that you needed for the big interferometers. What you're doing is fostering a small science academic research culture.

One of the challenges going on to a construction project is you have to decide what the design is, that it is good enough, even if you can on a given day think of something better, and then commit to building the good enough, and not act like researchers but act like people who are executing a project. That was at the heart, I think, of difficulty in Robbie Vogt's group. One of the reasons that led to him clashing with the NSF and being removed as the director is that the group he built up around him was very academic, very research-oriented, and he inculcated a culture that "We are excellent." Might have been true. It was true. But it didn't transition to a construction project.

I think he in fact—he would object if he heard me say this—he in fact did not understand the necessary transition to routinizing the nearly impossible, which I often say. Here you are trying to demonstrate that you can do something that's nearly impossible, but then you've got to turn around and say, "How do I make this work every Saturday night, the same way?" Instead of tinkering. And the group did not have that skill or even that perspective. It's one of the things that I had to deal with. Robbie was removed I think partly because he had built a research group and did not understand or want to transition to a construction project. The people under him, many talented scientists working under him, didn't understand it, and also were encouraged by Robbie to maintain the—I'll call it the cultural stance that they had. That is written about in Harry Collins' book.

Here's the 40-meter interferometer. I've just told you that it's a platform for measuring the possible sensitivity to displacement of the mirrors at the end of a Fabry-Perot cavity. That's the key. Second, it's a place to prototype things like the electronics modules that you will use to control and read out the interferometer. But third, and equally important to all of those, in the end is it's a prototype to teach a cadre of people how to run an interferometer and get it to run every day and every night and give you reliable or understood data.

The team at Caltech certainly didn't do the latter. They actually believed that the interferometer was a bit of black magic, that making the arms—control loops in the arm, … look—when you watch a baby trying to stand up, they're just at the point where they're trying to stand up and you see them wobbling, you see their legs doing things, there's a bunch of control loops that are going on, sensing, and then calculating the correction, and then implementing the correction, and then doing that over again. At some point, it becomes smooth and fluid. For you, who may not be a controls scientist, I'm telling you the fluidity with which you stand up and walk is something that's learned by putting together a bunch of control algorithms as you learn to stand up and walk, and eventually you harmonize them all. The same thing with controlling an apparatus that is a multiple-input and multiple-output control system. You might get it to lock and work well for an hour, but getting it to work for 24 hours or a week or a month is a whole different kind of thing. Same thing as learning to drive or fly an airplane or something. Fluidity involves a lot of sophistication in the more subtle aspects of the controls.

This group really said, "This is very difficult. It's a bit of black magic. We're constantly experimenting." But they would come in, in the morning—and this has been written about in Collins' book—what I saw, after decades of working in high-energy physics where I would come into an accelerator, a beam line, a very complex detector, was how much we struggled to get it to work smoothly, fluidly, reliably, and to make it work 24 hours a day, and what we did, to understand it analytically, technically, mathematically. We also understood how to get it on and running and to improve it so that it was reliable, and how much damage you did when you turned it off and changed something and came back to—what the struggle was to get it back to a reliable place and a better place. These things are very complicated.

We developed algorithms in high-energy physics—and Barry knew these very well—where, get the thing on, understand it, if you don't understand it do calculations. It's a physical system. It's arithmetic. It's mathematics. Then you can do tests to check your mathematics. Then you can implement the improvements and get the system to work even better. Get it on, run it, day and night. Have people take shifts. Keep logbooks of what they've done. Inform the next shift. Overlap by half an hour so that they talk and understand what they're handing off. By struggling like that, you can make a nearly impossible machine eventually come to the point where it runs for three years, essentially every night. All the time.

What I saw when I came to Caltech was a group of less than half a dozen people who would come in at a comfortable time in the morning, turn things on. The laser had to warm up, so it was changing its state as it warmed up. They'd turn on some things and try to lock it, and they'd do some experiments, change something out. Then maybe they'd break for lunch and turn it off, or maybe one person would stay, and take a leisurely lunch at Chandler, and then come back and work some more. Then by evening, be gone and turn it all off, and do that. [laughs]

Well, I looked at this thing and I said, "It's impossible for this to work." So I actually, as the project manager, joined the team, and said, "I'm now part of the 40-meter team. We're going to work together, and I'm going to help tell you a few things." They really hated that. They hated it for a variety of reasons. First of all, they were convinced I didn't know how an interferometer works. At some level, at that point, that was true. They were very experienced, and I was new. Second of all, they were convinced that they were gurus and they thought this was black magic at some level. They literally used words like that. And how could I come in and in some sense routinize things? I told them that I wanted this thing run around the clock, and I did not want anything to turn off, because I didn't have to want to waste time warming it up again. It changes its state. This went on for a number of months, and there was a lot of resistance. Ultimately, I caused, by a variety of ways, a number of these folks to leave the project.

ZIERLER: Were there any technical challenges with leaving it on all the time—burning it out, using too much energy, things like that?

SANDERS: But then you have to deal with that. If you turn it on for six hours and then find out that something burns out, you ask yourself, "Gee, I want this to run 24 hours a day." Because ultimately LIGO, which the U.S. government is investing hundreds of millions of dollars in, has to run 24 hours a day. That's exactly what the kind of thing is that you want to find. "My gosh, I can't run more than six hours and then this happens"—the vacuum craps out, or something overheats. Then grab that thing, design a fix, put it in, test it, and say, "Now I've got it better." That's exactly the kind of thing I'm talking about. And you don't learn that by turning it off, by not keeping a careful logbook, by not informing your colleagues of what's going on, by not creating a controlled, stable environment. Airplane pilots learn to have a stabilized approach. You get into a pattern, you achieve a certain glide slope, a certain speed, pitch angle, throttle, control. And to do certain things at certain points. You can land a plane without doing any of that. You can just come barreling out of the clouds and just aim for the runway and any good pilot a good fraction of the time can get the damn plane on the ground and land it. That is not the way to get through a career of flying airplanes. So you learn certain techniques. Some of those lessons were hard learned.

The same thing with flying an interferometer, or running an accelerator and a detector. You learn how to make stabilized approaches, stabilized running of the system. Ultimately, it matters to the science! Would you believe a world-changing, world-altering intellectual perspective that comes out of a machine that isn't stable? No. The fact that something ran for a few years and ran the same way and you had calibration signals, and you could show that from day to day it was the same, and it was the same when the amazing signal was seen, that's really important. So it's actually part of the ethical imperative of science, to get stabilized equipment that you really do understand, that's predictable, that you can characterize. I didn't see that, and I think it was evidence of a very strong intellectual research culture that did not understand the transition needed to go to a construction project.

There were times late in this struggle with this team when people in the project—these were people whose salaries were being paid by the NSF, through Caltech, to build LIGO—who said, "It's too soon to be building LIGO. We need several more years of research before we should do it." Yet the project was approved, and there I was as the project manager, with a mandate to get the damn thing built! That was evidence of a cultural mismatch that was surprising to me. That some of the key figures, people who were respected and admired as experts, really didn't buy into that it was time to build the interferometer. In fact, Drever, who was outside of the project at that point, frequently vocalized the same thing.

ZIERLER: To the extent that you're narrating this culture from a Caltech perspective, was your sense that these same challenges were happening on MIT's side?

SANDERS: No. That's a good question. I did not sense in any way that kind of mismatch. I think it was because Rai Weiss had a much better understanding of the kind of transition that was needed. Robbie was a well-respected, highly respected space scientist, built instruments that went up in space on satellites and so on, so he had to interface between his own research culture. What was he? He was a high position at JPL, and then he was the provost at Caltech. So he certainly had experience in which you connected a research culture to implementing things, in space. Rai had worked on COBE, the Cosmic Background Explorer satellite, and so on. So somehow Rai understood that at some point, you've got to stop futzing around and build the thing. And his group really did act like, "It's time to build this thing, and it's time to get it stable." I wasn't as close to them. I didn't see as much of the day-to-day operation of the ten-meter interferometer there. Nergis Mavalvala, Peter Fritschel, Mike Zucker, David Shoemaker—the people who really had their hands on that, all amazingly good scientists—I didn't detect any of that cultural mismatch.

So I think it was Robbie, the people he attracted, the culture he built up at an organization. I've always felt that when you start a team, one of the first things you're going to do in that first year or two is establish a culture. When you do that, it tends to be durable. It's hard to change later. If it's the inappropriate culture, that's a problem, and it was somewhat stressful to have to undo what I think was an inappropriate culture.

ZIERLER: Not to mention being from the outside and not being in the same field as many of these people.

SANDERS: That's right. Parachuting in from high-energy physics. Now, that was made easier by the fact that Barry Barish was also parachuting in from another field, and he was a full professor at Caltech, which automatically meant you had to think twice about disagreeing with him and pushing back. Didn't mean you couldn't, but—so I had air cover from Barry, to be blunt about it.

ZIERLER: Gary, to go back to the prototyping question that took place on campus, in the era before Zoom, how would you coordinate with MIT in terms of a division of labor, in terms of avoiding any redundancies?

SANDERS: We had very intimate communication. Telephones and email did a lot. I cannot remember the pattern of regular and standing meetings that we had, but they were done by telephone. We didn't have video conferencing in those days, or if we did, there was polycom, and there was another competing company that did such things, and they were very awkward, and they used proprietary hardware. We had those things. I think we had it set up in our conference room certainly near the later years of LIGO. But it was a minor thing. We used telephones and there were standing meetings.

I remember having in the 1990s those early cell phones, the Motorola AMPS cell phones that looked like a brick, and then slightly more sophisticated ones as they developed, and using them a lot. For example, the NSF program officer, Dave Berley, in the early years of initial LIGO, I talked to him frequently by cell phone [laughs] when I was driving to work. Within the group, we had lots of telephone conferences. Of course, we traveled a lot. Something we're not doing this year, but I was on the road a good deal of the time. We visited each other a lot.

ZIERLER: How much time would you spend at each of the sites?

SANDERS: Not a huge amount of time. I probably went to the two sites during the years 1995 to 2001, I don't know, we'll at least say ten times a year, among the two of them. There were times in 1998 where I perhaps inappropriately joined the installation team and spent, I don't know, one week a month at the observatory in a bunny suit installing stuff in the vacuum system and so on. I got criticized once by Rich Isaacson from NSF. He said, "We don't pay you for that." But I'm an experimental physicist and I needed to do a few things. I helped to install seismic isolation systems and some of the test masses for the mode matching telescope and so on. That way, as project manager, I actually understood what it looked like from the inside of the guts of thing.

I also always took—and I do this in all of my projects—absolutely responsibility for safety. I did that in high-energy physics, and I did it in LIGO, and I did it in the Thirty Meter Telescope, and am in the process of taking that over now in the cosmic microwave background thing that I'm leading now. Working enough in the lab with people meant I could see what was done in terms of following safety procedures and the safety systems that I insisted be incorporated in the systems.

ZIERLER: What were some of the major safety concerns at the sites?

SANDERS: Laser light. Light that's more than half a milliwatt or so is not eye-safe. Laser pointers. We don't use them much anymore because we use Zoom and so on, but laser pointers were supposed to be built so that these things couldn't damage your eyes, although you could buy some from Amazon now that will. Another 40-Meter story—the first time I walked into the 40-Meter, there was the table on which the laser, and its electronics and optics for smoothing the power and the time dependence, the ripple, and smoothing the frequency of it—the laser was out on a table. There were some plastic shields around it that in principle absorbed the particular wavelength of the laser. At the beginning of LIGO, it was a 514-nanometer green argon ion laser. But there was laser light. I could see the damn thing! When I asked to look at something, people took a cover off, and there was the damn beam. And there were little dots now and then on the walls.

I said, "That's not safe." They said, "Well, the height of the laser beam is at your waist, so to be safe, just don't bend over." I said, "Nonsense! The power of that laser is such that even the fifth bounce—" It could bounce off of several things around, up on the ceiling, on the wall, on that little piece of plastic, and get into my eye and still not be eye-safe. "Oh, well, we have goggles." "Well, are you wearing them?" Some people did. Some people didn't.

I immediately shut the system down. One of the early things I did in LIGO was make it clear that if there was any errant beam, that the lab was shut down, and you had to investigate what it was, and specify what would be done so that would not happen again. We ended up building systems that fully enclosed the beam, and I insisted on double barriers. In other words, you build a system and fully enclose the laser beam in every way, and you wore your laser goggles, so that if you failed in one of those, you still had adequate eye protection.

That was the beginning. It was the 40-Meter. I was aghast at the lack of attention to safety. The idea that all you have to do is just not bend over—the simple mathematics, if you take a ten-watt beam and bounce a couple of percent of the light off on each of, say, three bounces, the amount of light that can reach your eye is still horrible. There were a number of times in the early years of LIGO where I shut the entire laboratory down. There were a number of times when the sites were up and running and had laser beams on in the system and one of the vacuum ports that was covered in a semi-transparent material, Kapton or Mylar foil, and some of the covers, the metal covers over them weren't there. They knew that if I showed up at the lab and walked through the high bay area where the equipment was and saw one of those covers off, that I'd shut the entire lab down, at both sites, for a day or two, until an investigation was conducted, a report was written, and an agreement was made so that it wouldn't happen. I got to the point where some people told me they were afraid to report something that was errant, even though the procedures required it, because they just didn't want me to shut the lab down. I felt that was the right safety culture.

I've forgotten what question I was answering, but I should tell you that one of the reasons for me also working there was to get a good sense of the safety culture. I do believe we built the right safety culture. Later on, when I left LIGO and was at the Thirty Meter Telescope and visited one of the sites for a ceremony, I wasn't allowed in the high bay area, because I hadn't taken my annual training. I thought that was great. I wrote the document or approved the document for that, and it was now being used against me, and I thought that was perfect. Didn't matter who I was; I wasn't supposed to go in there without an escort or without a sweep of the area or without turning things off. That was good.

I did the same thing in TMT. Had arguments with contractors who were designing, say, the telescope steel structure, who felt that a simple padlock was okay. No, I wanted an interlock where if you turned the key and opened the gate, the system went down so you couldn't move the telescope anymore. Otherwise, you could crush someone. I didn't want someone to go flip a switch and then unlock a padlock; I wanted when you turned the key, the system was unpowered at that point, and it couldn't be re-powered until you put the key back in. It's called trapped-key systems. I will be doing some of the same thing in the project that I'm doing now.

Working in the lab was not just a way for me to see whether an appropriate experimental culture was doing done, but also whether people were respectful of the hazards to life safety and to equipment, and to the reputation of Caltech, MIT, and the field. If you kill someone, it's not good. Not just for the people involved; that's primary. But the headline says, "Caltech just killed someone." I didn't want that.

ZIERLER: What pains were taken to ensure that both sites were identical? Because the idea is, if I understand correctly, there needs to be pure redundancy in order to make sure that you're properly detecting a gravitational wave.

SANDERS: Right. There's two aspects to answering that question. One is to what extent they need to be identical on the day you make a measurement that's very important.

The second is how much are they identical as you build them. Let me address the first one. Clearly, from an experimental standpoint, one of the reasons you're building two sites—and in fact in initial LIGO, one of the reasons you were building one of those sites with a full-length four-kilometer interferometer and a half-length interferometer—was ideally, once you remove the noise, you wanted to see the same signal in Louisiana and in Hanford. In the shorter interferometer at Hanford, you wanted to see a signal that was smaller by what you would calculate from the length difference of the interferometer. If you saw all of that, then you knew it was an interferometric signal as opposed to some other kind of noise. Experimentally, you wanted to do that.

A reason not to do that is you might want to try out an improvement, and you might not be ready to try that out. It might not even make sense to make a small improvement at one of the interferometers but hold back from using it until you had done it at all three. You might want to put in a slightly better mirror coating on one of the interferometers and run all three, and account in any signal you saw for the fact that one of them was a little different. So you had to balance those two. But to whatever extent you could control, you wanted them to be the same, within reason. There might be reasons for improvements.

The other thing that's very interesting about a project in which you are building copies of the same thing at multiple sites is, do you build them at exactly the same time? In other words, should I have had the same team at Hanford and an identically capable team in Livingston, on any given day, doing exactly the same installation? Ideally, for the length of the project, and probably for the cost of the project, you might get it done cheaper and quicker if you did both. On the other hand, when you do the first one, you learn some stuff. "Oh my god, this doesn't fit." "Oh my god, this hose fitting isn't really the right thing." Or, "This hose can't quite curve as much as I thought, so I'd better rearrange it." And if you learn something—or, "This electronics box overheats too often, so I really don't want to put this one in the other observatory."

If they're appropriately separated in time, you want to install the first and turn things on as dictated by the schedule, learn lessons, and then take the output of those lessons and incorporate them into what you do at the other site, so you end up with a better result at the other site, and then you can even come back to the first site and retrofit. That asks you a question—it's a question that any project manager of a challenging system with multiple sites and multiple implementations—is what is the right time lag between the two sites? In other words, if they're a month apart, and you learn something at site one, you probably don't have the time to change it and improve it for the second site? Effectively, they're simultaneously. If they're two years apart, you have plenty of time to react what you learned at the first site and put it in, but that's probably not very efficient.

We were about six months apart, roughly, between the two sites. That was good. In many cases, you could redo a box of electronics a little bit and put in an improved version at the second site, and then later retrofit it at the first site, the improvement. You had to do configuration control. Even if you were going to do them simultaneously and identically, you have to have strict configuration control of all the drawings, the specifications, the procedures, and how you brought things up, to know that they were the same. When you do them six months apart and you're incorporating improvements in the second one, that's another reason to have very good configuration control, because you had to be able to look at a drawing, and then look at the drawing of the one implemented in the other site, and see the change. You had to have every one of the boxes and things serial numbered, and then documents that pointed to those serial numbers, and a temporal record of improvements in version. What was the version?

That's a system engineering activity which LIGO did very well. For a group that I told you started out with a research culture and didn't appreciate the need to move to a construction project culture, the group actually really learned it well, and did really good. One of the things I did at the Forty Meter was I actually saw electronics boxes interact that were all supposed to be identical, and when I pulled them out and looked at them, they weren't. I asked for the drawings, and the drawings didn't match. That was one of the reasons one of the people left, because of my insistence on version control. Building two LIGOs, we wanted them to be essentially identical. We wanted to learn from the first what to improve in the second. It required system engineering and configuration control, the ability to repair. The team did a wonderful job in all of that.

But there's one other aspect. I keep coming back to the word "culture." Each one of the teams, even there were people from Caltech and MIT who went to those places, there were people who were hired to be, or moved, to be resident at those places. A person working at LIGO Livingston, or a person working at LIGO Hanford, even though they might have been paid by Caltech, felt like they worked for LIGO Livingston. There was pride. So one of the things I watched, and I didn't predict this, was a pride in, "Let's do ours better than those guys."

ZIERLER: [laughs]

SANDERS: Well, that's good, but it's also bad. It's good, because doing better is good. But it's bad because I want my two observatories to be the same, within certain reasonable limits that we would understand. We had to deal with inter-site culture, inter-site advocacy, inter-site pride. One of the ways that ultimately helped was have people from one site go to work for a while and help at the other site, and vice versa, to do exchanges and so on. Ultimately, it all worked out, but it was an interesting thing to watch, how local pride became something we actually had to manage.

ZIERLER: Perhaps it's an obvious answer, but if two detectors is better than one, is that to assume that three is better than two, and four is better than three, and so on?

SANDERS: That's a situation that the gravitational wave community is dealing with right now. Right now, there are the two Advanced LIGO sites in the United States, and in fact they're undergoing a current set of additional upgrades. There is the Virgo site near Pisa, Italy. Because of a variety of things that Barry and I did along with the leaders of Virgo, they're actually all working together with LIGO and publishing together, taking data together, and all of that. It's the third leg of the stool. It gives, first of all, technical differentiation. It's a different technical approach in some ways. That adds validation to seeing a signal, so that it's not an artifact of a particular technical approach, a particular kind of mirror suspension, or a particular kind of electronics, and so on. But it's separation.

In some sense, you make a triangle on the surface of the Earth with these three interferometers, and the bigger the area of that triangle, the more sensitive you are to different parts of the sky and to different elements of the signal. The ideal network has many nodes, widely separated, and maybe not even oriented the same way on the surface of the Earth. You wouldn't want these three nodes at the triangle all lined up so that the right angle of the arms, if it is a right angle of arms, are all lined up as much as you can, because then that means the antenna pattern at each one of these has got the same call it less sensitive directions, modified by how far apart they are and the fact that the Earth is round and they're tilted somewhat. And so a wide triangle, if you have three, with different orientations, gives you more sensitivity, and you can cover more of the sky.

Now the Japanese have come on and joined the system with KAGRA, which is a three-kilometer-arm interferometer underground in a set of mine shafts near Kamiokande, the neutrino Kamiokande detector in Japan. They have joined. I think they're less sensitive right now, but they will improve in sensitivity. That's a fourth corner of what is no longer a triangle. That adds sensitivity to both signal and to presumably polarization and other attributes of the signal, and reduces the size of the box on the sky, or the spot on the sky that you can localize. I use the word "error box" but it's really a kind of sausage-shaped direction that you can localize, which helps you tell other telescopes and things where to look. Most of those systems can see smaller spots on the sky. LIGO, Virgo, and KAGRA don't create an error box that's very small yet on the sky.

The community is looking towards the third generation of gravitational wave detectors and is debating how many are needed, how many are wanted. Ultimately what gets built will be determined by the funding agencies in the different regions. But right in the middle of studies in Europe and in the United States of what's called the Einstein Telescope and Cosmic Explorer, how many of those, what are the shapes or designs, what would be the third leg of the stool, if there was a third one? One in Australia, maybe, or one in India? That discussion is going on right now. But the U.S., Initial LIGO and Advanced LIGO were built as a U.S., a North American thing, with two sites 3,000 kilometers apart.

ZIERLER: What was your involvement in the initial collaboration with Virgo?

SANDERS: I came in Summer of 1994. Barry joined a couple, three months before. By January of 1995, only a few months later, we had a meeting in Aspen Center for Physics, and I gave a talk on the so-called LIGO User Group, I called it, which became the LIGO Scientific Collaboration. Another model that Barry and I imported from high-energy physics—you build a facility; you need a community of scientists who will use it. They need to talk to each other and have a voice in the direction. I proposed that. It was vigorously opposed, for a while, but we persisted. As part of that, we felt that there needed to be discussion with Virgo, and in March of 1995, Barry and I went over and met with Alain Brillet and Adalberto Giazotto who were the two spokespersons for the Virgo collaboration, and we talked about forming as much of an alliance as we could, cooperation, perhaps even at some point working together.

They wanted to get on faster. They thought their design was better. There was one aspect in which it was. They wanted to compete with us. We thought ours was better. We were building two of them, and we wanted to compete with them. On the other hand, we also recognized, at least Barry and I did—and it was clear that Giazotto and Brillet also understood—that at some point, especially given the birth trauma of the gravitational wave field with the wrong discovery of gravitational waves, there was going to need to be a sense that we were maximizing the scientific reach and reliability of the systems that were detecting gravitational waves. They understood that we needed also to cooperate at some level. I used the word "coopetition."

The one thing we could agree at that meeting, that was easy—you always start difficult negotiations with some confidence-building small step. What we agreed at that meeting in March of 1995 was to start a discussion about the two teams. Even if they were going to compete like crazy against each other, could we agree to write our data on tape in the same format, so if it became necessary and socially acceptable for us to analyze each other's data or with the same software, it wasn't impossible? And that was agreed to. I can't quite remember how quickly, but I think it was agreed to in principle at that meeting.

Then there were successive meetings, and there was also a panel on how to use LIGO that was chaired by Boyce McDaniel from Cornell. It was either in 1995 or 1996. Barry got that arranged. They gave us a lot of advice on how to fully exploit LIGO once it was built and how much it was needed to make sure we had enough people and resources to analyze the data. It resulted in an increase in the budget for the community and for data analysis at LIGO during operations. Very early on, Barry and I—March of 1995, that was about a year after Barry joined. It was six months or whatever after I joined. Almost our first contact with Virgo was to say, "We need to work together." We started with the agreement on the data format. That was a seminal thing. Today, everyone publishes together. Everyone analyzes together, even if the other guy's machine was off. That's one of these non-technical social contributions to the scientific success of the field.

ZIERLER: How involved were you on an annual basis in terms of budgeting questions with NSF? As a corollary to that, what were some of the big lessons learned from the SSC in terms of managing expectations?

SANDERS: One of the things we learned from the SSC was, if you tell the government a cost, for God's sakes, don't come back and keep telling them a different number. Boy, your credibility, it's just—you're done. The SSC did that. They started out with a $3 billion estimate. It ultimately went to five. Then it went to eight. Then it was ten. Every time you said something, the newspapers quoted people who didn't like you with the bigger number. That was a lesson. I think I already knew that lesson, and Barry knew it, because when he was asked to be the director, NSF had approved a budget for LIGO of$212 million. I think that was the number. And that was in, what, 1990 dollars, maybe? That would be in 1990, but as spent dollars.

Barry, one of the first things he said was, "Well, if I'm going to do this, I need to completely review the cost and schedule to get to the point where it's my numbers." We engaged the guy, Richard Fisher, who had been the cost schedule leader at the Super Collider magnet division only months before, and started acquiring people into the team, at least one of whom is still working with TMT, Mike Bartsch. During 1994, a lot of the activity was to redo the cost estimate f or LIGO so that Barry could say, "I now commit to building for this number" and not changing it. We presented that, as I think I said in our last interview, to a review in September of 1994, and then to the National Science Board I think in November of 1994. NSF had to re-approve at the level of the National Science Board and inform Congress and get the appropriate appropriations at the new number, which was $292 million plus four-point-something-million in R&D, so 296, with a certain definition of what's done on the last day that you spent that money. It was approved. There was also an approval of I think$30 million a year for operations, beginning with a small amount of operations [funding] in 1998. I think it started at $700,000 and then it went to$3 million the following year, and it tapered up to $30 million or so. Barry understood once you got a number, you have to look at yourself and say, "I'm going to do it for that." I remember Ed Temple on the review in September 1994 taking me as project manager aside into a room—I hope I haven't told you this story—and said, "Can you do it for that?" Because he was writing a report that said this is okay. I said, "Yes, but I'm going to have to take out some of the auxiliary buildings, so that I have enough contingency." And we did that. We finished the project on budget. I've always felt—get to the point where you're looking at what you are convinced is the right number, modulo black swan events like a pandemic, or a world economic collapse where suddenly you can't buy steel or ship by ocean, and then you have a problem. But modulo that, you have to be convinced you are going to do it for that number, come hell or high water. ZIERLER: A nomenclature question—is the term "Initial LIGO" only understood retroactively, or even during those years it was called Initial LIGO because there was the understanding there would be an Advanced LIGO? SANDERS: We called it Initial LIGO then. When it was approved and re-approved in 1994, the NSF understood that, that it was Initial LIGO, and they understood that they were building a platform for gravitational wave interferometry. They were building an initial implementation of detectors, and that there would ultimately be a proposal for an upgrade to a more sensitive system. By the time 1996, 1997, 1998 came around, there was a different director in the NSF, different deputy director, different mathematical/physical sciences assistant director. Members of the National Science Board had changed. So when we started talking to them about giving them the first version of our proposal on LIGO 2, they said, "What?" And we said, "Well, go back and look at the minutes of the November 1994 board meeting, and you'll see how that was discussed." Because it was clearly understood then. They shuffled around for months until they found a document that referred to it. One of the lessons is, as people come through a federal agency, corporate memory walks in and out the door. Then we got the message, "Don't call it LIGO 2, because we really don't want anyone to think that we're agreeing to an index." ZIERLER: You'll have a whole franchise on your hands. SANDERS: Yeah, right. Which, quite frankly—actually, I would say right now, sitting where I am sitting and seeing how successful LIGO has been, in terms of not only a detection but the amazing number of detections that are made every month, the variety of science that has been accessed by those detections, some of which was not expected at all—understanding now how in the universe gold was made, things like that—it has created an enormous new field of gravitational wave astrophysics. Then seeing how tentative the NSF and the European funding agencies are about taking the next step to the third generation, I'm quite surprised and disappointed. Courage, at the NSF, led to founding an entirely new field of science, where we can now see an entirely new view of the universe. Really! Entirely. It's amazing how transformative this new view of the universe is, and will continue to be. You would think that success begets success, and that you would go to them and they'd say, "Please, come here, please, with your next generation. We're ready to go and take this to the point where—" In the same way that radio astronomy started—the antenna in the backyard of Grote Reber's mother's house in Illinois somewhere and now we have VLA, SKA, ALMA, and so on, you would expect that the funders would understand that there should be a stepwise development of the field over time with enormous scientific payoff. The European folks on Einstein Telescope have struggled hard. They finally got Einstein Telescope to be taken as part of the European Framework Programme for the development of major research infrastructures. NSF is now beginning to support with a few million dollars what they call a Horizon Study on Cosmic Explorer. But I would have thought they would more enthusiastically encourage things. When I was asked five, six years ago to give advice on the governance structure internationally and nationally of the third generation, I said, "Look, we've just created a new field. We all know that to address gravitational wave science, we need a global network of nodes. You can ask whether they should all be the same nodes put together by the same organization in different places, or somewhat different, for experimental reasons. But there ought to be international collaboration and it ought to be at a CERN or a European Southern Observatory or SKA type thing with an international agreement, maybe at the treaty level, maybe at a subtreaty level. We ought to do this in a coordinated way." I was encouraged by a lot of people, but the people who were the advocates of Einstein Telescope in Europe wanted to pursue a regional approach with their one device. My words, which I thought and still think were the wise advice, was viewed as a threat to the internal European success of a regional approach, to build one node. They would even argue that one node was all you needed, which is what you do when you're trying to get money. In other words, you don't tell the truth. At some level, it's salesmanship. Now what's happening is the ET is being embraced at a slow level in Europe—it's very expensive—regionally. And in the U.S., I think a much more appropriate detector, Cosmic Explorer, is being pushed by Matt Evans out of MIT, and NSF is beginning to dabble in support of it, and I think that's wonderful. It's wonderful it's going ahead. It's wonderful that LIGO and Virgo are doing so much science right now. But I think if you take a synoptic view of the entire field and say, "What's the right speed technically, scientifically, in which to develop this amazing field?" there should be some more leadership from the funding agencies, and it should be more global. I think the scientific impact justifies a more global approach. So that's still a conversation that's going on. There's a meeting called Dawn in October where I and a few others on a panel are to give advice on how to proceed with Cosmic Explorer. I think what should have been a global approach is becoming again a—I'll call it a ragtag regional approach to the next generation. I think the scientific impact of gravitational wave ground-based detectors is so big that it merits being supported in a more synoptic way globally. But it is what it is. ZIERLER: Given how Advanced LIGO conceptually was baked into the long-range plan, even from the early years of Initial LIGO, how did that forbearance, how did that planning affect Initial LIGO itself in terms of figuring out what are we going to do now, and what's worth waiting until x number of years for Advanced LIGO? SANDERS: There's a judgment you have to make. You've heard me use this phrase, "We have to turn the nearly impossible into routine." What does that word "nearly" impossible mean? Let's agree that linguistically, [the concept of] impossible can't be turned into a routine. What I'm talking about is the judgment of what is the right technical leap to make that you actually can do. If you are too aggressive, you may pick a leap that you just can't get to in any reasonable amount of time, and you can't turn it into something that you can do. If you make it too easy, then it's incremental and maybe it's not worth being the next step. That's a judgment that has to be made. In the case of the optical telescope field that I left recently, the ten-meter Keck telescopes were a big leap over the five-meter Palomar, 200-inch Palomar, in terms of aperture but also in terms of being able to phase up a smaller set of mirrors and make a diffraction-limited precision in the image, to see farther and fainter but also smaller things, sharper images. A judgment was made that ten meters was about as hard a thing as you could imagine making routine, and it involved a number of new technologies. When it came to the Thirty Meter Telescope, the people who pushed it—there were people who pushed a Twenty Meter, people who pushed a Twenty One, Twenty Four, Thirty. The Europeans actually started out looking for a One Hundred Meter. They called it the Overwhelmingly Large Telescope, OWL. ZIERLER: [laughs] I'm wondering how far the adjectives can go in this field. [laughs] SANDERS: That's right. Yeah. Again, remember salesmanship makes you unrealistic, and I mean that with love. It was very clear to most people in the field that a Hundred Meter Telescope was beyond the reach of the next step. Ultimately, the Europeans came down to 60 meters and then came down to 39 meters. They were converging on the 30 meters that we chose in the United States, but they wanted twice the area, so 30 to 39, it's twice the area, they did that, and I think they're going to be successful. The point I'm making is, you have to ask how much of a leap can you pull off, and it has the increment and scientific reach that justifies the strain and the resources for that leap. I think the people who thought of Initial LIGO realized that Initial LIGO represented what you could credibly, at the limits of credibility, propose, even though it seemed to fall short of what was scientifically sufficient, but to build in a work plan that if you pulled off this initial state, you would now learn enough that the next step actually could be made routine. I think in retrospect, they really made the right choice. At the time that we could make Initial LIGO work, we looked at what needed to be done to make Advanced LIGO—adding signal recycling and power recycling and heavier test masses, and maybe a new test mass material, better seismic isolation down to lower frequencies, higher laser power, so you had better photon statistics, accuracy in the measurement. When those key parameters were set for Advanced LIGO, people really understood you had just learned enough with Initial LIGO that you really could propose that. It would have been much too hard as an initial step. So it's scientific and technical judgment to pick the right next step. ZIERLER: Last question for today. At the turn of the century, the world was coming online. The internet was really being adopted widely. Computation was getting more and more powerful. How did those advances affect the day-to-day for LIGO? SANDERS: First of all, the internet made communication easier. Second of all, I think the computing power needed to run LIGO, to do the control loops and all that, was enhanced, even in the analog electronic era, although it certainly was better to do it digitally. That's one of the transformations that Barry and I introduced, changing the electronics design. I already alluded to the so-called Grand Challenge, the computational, gravitational projects that NSF supported to calculate the templates for gravitational wave signals and how accurately you could make them. Clearly, if you had more and more computing power, you could do a better job. The first simulations of what it would be like if two neutron stars or two black holes collided and emitted gravitational waves, they were done only with head-on collisions. I think that's right. You can interview someone who actually does that. Then what happens if they pass each other and it's not head-on but you're ignoring the fact that they might have spin? As you do computational power, you can turn on more and more of the physics parameters that represent the real world and do a better job calculating the templates and other kinds of calculations that are done. Or go from the Newtonian description of gravity and put in, in a series expansion, what I call the post-Newtonian things that get you closer and closer to the Einstein equation. With more computational power, you can go out further and do a better job. Computation in terms of simulating and predicting the signals and matching the data, which is almost all noise, you've got to remove all that noise, and then you've got something left, and you've got to compare it to a model or—computational power has a lot to do with it. Also, how do you get a worldwide network of gravitational wave scientists to work together and to get the computational power? Bruce Allen understood—he's one of the people; there were others—early on that you needed to have computational resources to do these analyses, and he promoted powerful computational systems, racks of computers at his university, grids. High-energy physicists did that. Grids of computers at remote locations that worked together. That field has progressed a great deal and enabled the generation of needed computational power. I'm not familiar with exactly where things are today, but I know that it's ever better and better, and it's a much bigger enterprise than anyone predicted in the 1990s, in terms of the community and the necessary computational power. ZIERLER: That's a great place to leave for next time, where we'll talk about the origins of your involvement in the TMT and what I imagine must have been a very conflicted decision about leaving one extraordinarily exciting project for another. We'll pick up next time. [End of Recording] ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It's Friday, September 10th, 2021. Once again, I'm delighted to be back with Dr. Gary Sanders. Good to see you again. SANDERS: Good to see you. ZIERLER: Today I'd like to start with the transition period from your work on LIGO to the TMT. Here, I'll ask you to delve really far into your memory and also your powers of prophecy in the sense that when you first started to consider the possibility of transferring from LIGO to TMT, did you have any feeling that you were leaving one fantastically exciting project for one that, to this day, remains shrouded in concern and existential possibility that it might not even come to fruition? SANDERS: On that latter note, there's lots and lots of rumors that the decadal survey will be out by the end of this month because of the end of the government fiscal year, so prophecy may turn out to be reality. Life is sometimes more messy than that. Just to focus on that question, did I have the sense that I was going from one fantastic thing to another—and after I answer that, I want to go back to what led up to me going to the TMT. I really was feeling privileged in late 2003, early 2004, to be the project manager and deputy director of LIGO. We had all three interferometers together. We hadn't busted the budget. We were late maybe by a year in terms of completing the construction project in a number of ways. But we didn't bust the budget. We got it on, and it wasn't at the design sensitivity, but it was moving. It was moving. It was moving. So it looked like, boy, this is ahead of us. As I told you earlier, we already had started in 1997 designing and proposing to the NSF the upgrade, so the Advanced LIGO upgrade, which ultimately carried out the actual detection. So I was feeling pretty good, and I must say privileged. But I was also feeling that I wasn't climbing a mountain. Now, we were walking on the top of a mountain. ZIERLER: To interject, administratively, would that be the case as well? Was all the diplomacy and tension from the transition from Barry taking over from Ron Drever, Robbie Vogt—had that all been sort of smoothed over at this point and you could really just focus on the science? SANDERS: Oh yeah. What I was just talking about was the transition period from LIGO to TMT, so that's late 2003 and early 2004. All of that stuff that we talked about, whatever additional wrinkles there were in taking over with Barry of LIGO back in 1994, so that's ten years earlier, those were gone. Those were over. Those were over by 1995. All of that took place pretty much in the first year. Robbie had been touted to be the leader of the detector in LIGO under Barry and I, and a year later, he was not in the project anymore. Drever was supposed to still have some kind of a role, and as I told you before, he got support from Caltech to go work independently on a smaller interferometer. So those issues were behind us, and the people at the Forty Meter who I felt were inappropriately approaching the prototyping, that was also pretty much behind us by 1995, certainly 1996, when the Forty Meter had been revamped in some ways technically and was actually working reasonably well. What went on in those years was the challenge of the project, carrying out the project. By 2003, the construction project was over. It was over in 2001, and we were in operations. I was functioning less as the project manager of a construction project, and more as my other title, the deputy director of the LIGO laboratory. We were doing the first science. We were engaged with the LIGO Scientific Collaboration. First papers were coming out, and we were operating. I was continuing to spend time on the proposing of Advanced LIGO. I will say that operating a laboratory is less exciting than running a construction project. Construction projects are more teleological, more progressive, more build up, execute, and then deconstruct and transition, and the pace is more, to me, exciting. Operating is usually managing something that you've put into place and you're managing the marginal changes in performance, in budget, and marginal changes, small changes in mission. While I enjoyed it, it was less exciting than leading the construction project. But I was looking forward to Advanced LIGO, so I understood that this was part of the cadence of things. I knew that from high-energy physics. You build something for five years, you did physics with it for three, four, five years, and then built the next thing. So I was pretty happy, and delighted to be feeling lucky to be where I was. ZIERLER: Knowing that you're waiting for Advanced LIGO, does that mean in some sense that you have a vague idea that a decade or so waiting to detect gravitational waves was just going to be too long for you? SANDERS: No, I did not. I was 58 years old when I left LIGO in 2004. Still felt like I was a young guy. I'm 75 now. I'm not slowing down. On the other hand, what I was really looking forward to was the progressive reviews and processes with the NSF until they finally gave us the approval and got the Congressional appropriations. I thought that was soon. It actually took longer than I expected, but that's always the way it is, especially these days, when you don't have regular order in Washington. But I was looking forward to that. Barry was less engaged, far less engaged, because he was leading the global design effort for the next linear collider. But Barry and I always say things pretty much the same, and so I was just doing my thing. So how did I think about going to TMT? I've forgotten whether I told you this story. My first involvement with TMT was to be a reviewer of the California Extremely Large Telescope, or CELT, Greenbook in I think 2001, that was convened by the University of California and Caltech. I think I told you the story that NSF sat in the back of the room and wondered why they were there. Did I tell you that story? ZIERLER: Mm-mm. SANDERS: No? Okay. Let me tell you that to make this transition, there was a long—I'll use the word courtship, though it wasn't much of a courtship. I was in 2001 the project manager of LIGO and we were finishing the construction project, which meant getting both sites to lock their interferometers in coincidence. Things were going reasonably well. I was aware that Caltech and UC were involved in a design study of the next generation optical telescope, which they called CELT, California Extremely Large Telescope. I was invited to be on a review of the report that the CELT group did. It was called the CELT Greenbook. It was held in Oakland and hosted by the University of California, and there was a panel chaired by Ed Moses, who I think at the time was at Livermore. Very forward, vocal guy. Brilliant. He fixed the National Ignition Facility project, so he had quite a reputation. A cast of people on the panel, some of whom I knew, but some of whom I didn't, who were leaders in optical and infrared astronomy. I guess I was on the panel to take a look at it as a project, since I didn't know that much about optical and infrared telescopes. The review took several days. I concluded that it was pretty well done. Jerry Nelson was the leader of the design. He was the guy who invented segmented mirrors, which resulted in the Caltech, UC project, the Keck Observatory. They were thinking about the next telescope, and it was CELT. It was a 30-meter diameter telescope. Bill Irais, a guy from JPL, was the project manager. They made a pretty good presentation. So here was this panel, which was convened by UC and Caltech. Steve Koonin was there, who was the provost of Caltech at the time, and in the back of the room, for the several days of the review, was Wayne Van Citters and Jim Breckenridge, I think, from the NSF. I knew Wayne a little bit, because I had reviewed many, many NSF projects. By the time I even knew, I think, Jim Breckenridge a bit. During the meeting, over a coffee break, I said to Wayne, "So Wayne, what are you doing here?" And he said, "I don't know." And I said, "Is NSF interested?" He said, "I don't know. But we were invited, and I'm here." So that was interesting. It looked to me like there was no mention of NSF really in the review. The proponents described the design and they wanted to raise funds privately, like they had done with Keck, so why was NSF there? And at the end of the review—which was very interesting, because it was dominated by Ed Moses, and the review report was written by him in I think something like 36-point font and sent out as a draft to the panel. Ed was the guy who didn't know how to stop shouting. But again, very brilliant guy. ZIERLER: [laughs] SANDERS: It was an interesting experience. When the review was over, and I was driving back to—I forget—San Francisco airport, Oakland airport, San Jose—I offered Steve Koonin a ride. I drove the car, and Steve was there, and I said, "NSF was there." This is Caltech history, okay? I'm talking about culture. Not necessarily flattering, okay? I said to Steve, "What was NSF doing there?" He said, "Well, we wanted them to be involved and aware of what's going on, but our plan is to have private funding, presumably from the Moore Foundation"—that was already thought about—"and to build up the Caltech and UC team to be really strong, and then when we're really strong and in control"—and I'm paraphrasing—"invite the NSF to also contribute to the project." In other words, NSF should run the project. It shouldn't be owned by NSF. They should come in once the project was rolling. ZIERLER: Isn't this counter to how NSF generally operates, though? SANDERS: That was what I said. I said, "Steve, NSF doesn't fund major projects unless they have"—in some sense, while they'll collaborate with some things like another federal agency, or another government, they pretty much feel responsible and take ownership. "So if you want NSF to be part of this, you've got to carve that out upfront, and they have to feel like they're among the founding owners." Steve said, "Well, we want to build up our strength first." There was some discussion about how to bring in the NSF, which involved bringing in AURA, which is the federal contractor that works for NSF running the other optical telescopes like Kitt Peak and Gemini and so on that were NSF-funded. So they certainly were open to bringing in the NSF, but I worried that they wanted to bring in NSF not as a founding partner. Perhaps it was a strategy to enable the private funding as a foundational act. I said, "Steve, I think if you're going to bring in NSF, you've got to bring them in at the beginning." We chatted about other things, and that was the end of it. ZIERLER: As a matter of contingency planning, was Caltech or Steve or whoever was making these decisions, were they prepared to look for private funding in totem? In other words, would the Moore Foundation pony up a billion dollars if that's what it took? SANDERS: At the time, the estimate was$600 or $700 million, and Moore had given to Caltech—maybe it was by that time already—$600 million. $300 million in, I don't know, stock, or something of value, and then another$300 million of invitations to propose things to the Moore Foundation over the years. So they already knew the Moore Foundation was a big donor to Caltech, and I think they thought of the Moore Foundation as the founding donor and the majority donor. The way I took Steve's remarks, and I hope he meant it the way I took it, was they wanted to get that going with private funding and then invite the NSF as a—I'll use the words "trailing partner." I didn't think that was the right way to approach the biggest elephant in the room, the United States government. But that was the way it was. I must add that in the end, the founding was done in 2003 and all four partners, including Canada, NSF/AURA and Caltech and UC had equal founding stakes. So, it worked out.

ZIERLER: Chronologically, as you're narrating this story, have you already officially transitioned to TMT, or you're still in decision-making mode?

SANDERS: No, no, this is 2001. I am still deputy director of LIGO. I didn't transition until 2004, three years later. I was about to tell you the story of that. I think I've told you that while I was the project manager and deputy director of LIGO, I had a weekly meeting with the PMA—Physics, Math, and Astronomy—division chair. My office was in East Bridge, in one little corner, and the chair was in the other corner. Started out with Charlie Peck, who was a professor, who was the division chair, high-energy physicist, and then Tom Tombrello became the division chair, and I would have my weekly meetings with Tom.

Tom was a guy who liked to be in control of everything in his mind, and spoke freely about that. When I reported to him on the review of the CELT Green Book—as an incidental thing, because my meetings with him were about LIGO; this was in 2001—he said, "Yep, we're going to put that together as a project. The Moore Foundation, we're hoping they will fund it. Would you like to be the project manager?" So this is very shortly after the CELT Greenbook. I said, "No, no, I'm committed to finishing LIGO and getting it to do science. That's what I want to do. But I'm willing to help you find a project manager."

ZIERLER: But what does finishing LIGO mean to you at that point?

SANDERS: They were just finishing the construction, but you need to make the thing produce science. It works, but you've got software to do. You've got collaborators to gain the expertise. You've got to calibrate things. You've got to increase the sensitivity successively in runs. You've got to learn how to write papers. There's a lot of things that go on until you start producing science. Then you do the science with successively better sensitivity, so you either find something, or you set more and more stringent limits on whether or not something happened. If you were looking for the primordial gravitational waves from the Big Bang, and you said they're less than one part in ten to the fifth of the mass of the universe, or the energy of the universe, and then the next year, you said it was one part in less than ten to the sixth, and the year after that, one part less than ten to the seventh, you haven't detected anything, but you just threw a bunch of scientific models out the window, about the early universe. So you could do a lot of science even before you made direct detections of that. There was a lot of work to do, and I wanted to be part of that. I was having fun.

ZIERLER: What kind of conversations did you have with Barry as you started to seriously consider the possibility of transitioning?

SANDERS: I didn't talk to Barry about transitioning to the Thirty Meter Telescope until shortly before I did that. I might have mentioned to him that Tombrello was poking at me to see if I was interested, but I don't recall it. I do recall when I raised the question of the possibility of me leaving LIGO, though, and I'll come to that in a minute. Over the three years, between 2001 and 2004 or two years, between that and late 2003, Tombrello would bring it up now and then—"Are you interested?" and I would say, "No. I love being at LIGO. I will help you find someone."

ZIERLER: What was Tombrello's role for TMT at that point?

SANDERS: He was the division chair of PMA, at Caltech, so I reported to him with a weekly or every-other-week meeting. He was the guy who would tell the president of Caltech how things are going. But Tombrello would always wax widely on lots of things he was thinking about. He would now and then bring up TMT. Then one day in 2003, he mentioned to me that the Moore Foundation was providing $35 million out of that$600 million grant for a design study and to start the TMT project. This was in 2003. Then I learned a little bit later in the year that a four-way agreement had been made between Caltech, UC, the Canadian astronomy committee, and AURA, which was the contractor that works for the NSF running their optical observatories, and each one of those was to put in 25% of the cost of—I think the Moore Foundation contributed $35 million and the others were supposed to match it. I've forgotten the exact formula, in their efforts. By 2003, there was an MOU, and they had astronomers and engineers in those groups beginning to work on a design of TMT. Tombrello reported this to me. The Moore Foundation had come up with$35 million. I knew it was just a starter award, because I knew the price was quite a bit more than $35 million. What they did was there had been three parallel studies in North America of the next generation telescope. There was CELT, which Caltech and UC had been doing. AURA, on its own, had done a study of what they called the Giant Segmented Mirror Telescope. And Canada had done a study of a Twenty Meter that they called the Very Large Optical Telescope, VLOT. Somehow, they had been encouraged to go get married and make an MOU and form a project that they called the Thirty Meter Telescope. I think the Moore Foundation$35 million helped catalyze that. Tombrello reported it to me that there was this collaboration of these four parties and asked me again if I wanted to be project manager, and I said, "No, but I'll help you." Then I got asked to be part of a search committee for the project manager. It was chaired by Ed Stone, who you must know of.

ZIERLER: Of course.

SANDERS: There were a number of people from Canada and UC on the committee, and also AURA, on the committee. I've forgotten all of who they were. We had this search committee, half a dozen, eight people maybe. We had a whole bunch of meetings from the late summer until about Thanksgiving of 2003, going through names. It was a search committee where you tended to try to generate your own list of names of people you knew. I can't remember whether there was an ad and applications, but I think it was mostly a search committee that was driven—it was good dialogue, and we winnowed down the list to a few, like three names. Around Thanksgiving of 2003, I got a phone call at home from Ed Stone who asked if I was willing to resign from the search committee and be a candidate.

ZIERLER: [laughs]

SANDERS: Which I gather is not an uncommon technique. Sometimes if you think you've got a candidate, put them on the search committee, and then at some point rotate the tables, if the rest of the committee is convinced. I don't know. Anyway, he asked me. That's when I had to deal with what you asked me about. Because on that day, before the call, I wanted to stay with LIGO, and I thought, "Oh my gosh, this is very interesting." I thought about it, and in the end I decided to go with TMT, because I said, "You know, I was pretty successful…"

ZIERLER: Right at the time when you decided to commit to this, how did you compare, at that moment of decision, transitioning from LIGO to TMT as transitioning from SSC to LIGO?

SANDERS: Well, from SSC to LIGO, the SSC was dead, and I had gone back to Los Alamos, and the director there had said, "Take a year to figure out what you're doing." In the meantime, I was leading a study of the human radiation experiments in World War II, while I thought. Barry came along and proposed a project to me that I knew instantly had the science that I wanted to do, and I enjoyed working with Barry, so that was an easy one.

The LIGO to TMT one was more difficult because I was dedicated to getting Advanced LIGO on and seeing the science done. I got this call from Ed Stone on Thanksgiving or just before Thanksgiving turning the tables around on me, and I started to think about it. I came to the conclusion that, "I'm 58 years old. These guys at LIGO, they can do this without me. One of the things I helped build was a laboratory, but I also helped build a team, and the team is functioning at least as well as the laboratory is. If I go to this telescope, I probably won't do science with it, because by the time it's done I'll retire, but it's one more chance to do a big project and make that contribution to science." That intrigued me. I was 58 years old at the time, and I said, "This thing is supposed to take ten years." That's pretty funny now. "So ten years, I'll be 68. The damn thing will be working. And I'll be really pleased!"

I remember the day I took my wife and daughter to one of the LIGO sites and we went up on the stairs to the roof and looked over the site, and I thought, "This is really cool." I wanted to do that one more time—take my family and me and just go look at the damn thing and say, "I helped do that." So I decided to transition. I was thinking about it seriously. At that point, I sent an email to Kip and Barry and Rai saying, "I'm really thinking seriously about this. I just wanted to warn you. I'm going to make a final decision soon, but I just wanted to first of all let you know, and second of all get your thoughts." And so on. So that's when I think you asked me about whether I had talked to Barry about it.

ZIERLER: What responses did that email elicit?

SANDERS: I don't remember. Appreciation of me, and, "Do the best thing for yourself." These were good, gracious, appreciative responses from friends and colleagues. But I was also sending a message that it was fairly likely that I would go, and that they ought to be thinking about the transition, what would happen if I left, because I was doing a lot, and you don't want to just—so I've forgotten exactly when I decided. Sometime between Thanksgiving and the end of the year, I decided to make the transition, and make the transition a few months down the road. I think there might have been some milestone that we were working towards. So I made the transition, but my goal was to try to get one more of these big projects done, to lend my skills to it. I also realized that this is the first time I'm going to do something, and I don't expect to be part of the science done with it, which I had always tried to be.

ZIERLER: Talking about skills, obviously it was not your experience in large ground-based telescopes that Ed Stone was attracted to. As a window into what TMT needed at that point, what was the skill set, what was the experience that you had, that was so important to people like Ed Stone?

SANDERS: What they wanted from me was the ability to organize a community and focus them into a project, to get the project properly organized. I remember in 1998 when asked to join or lead the management advisory committee of, at the time the largest radio telescope project in the world, ALMA, what became ALMA, and I said, "I don't know a damn thing about radio astronomy." Other than what I learned in courses as a student. They said, "Well, that's not what we need you for. We've got people who knows about how to make a radio telescope work." So that's the same thing. People were asking me to take a role in something that I wasn't a disciplinary expert in.

ZIERLER: On that point about building a community, at this point, you've come to appreciate that from SSC, and even going all the way back to Sam Ting, the high-energy physics community has its own idiosyncrasies. The cosmology or GR community has its idiosyncrasies. What were you learning in this early period about the astronomy community? What was important for you to understand as you wanted to build up a team for TMT?

SANDERS: There's two things I have to learn when I come into one of these new communities. One is I have to learn the scientific discipline. I have to come into a field and learn the necessary disciplinary part, the part that's written down in textbooks and is taught in lectures and written in papers. But I have to learn the tacit knowledge part, the part that's not written down, and that includes how the field does science, what the history of the field is that's not written down, in terms of personalities.

Then the personalities of the people involved, that I'm interacting with. What I've learned is it can take one, two, three, four months to just watch people, and see how they behave, how they interact, who's pushy, who isn't, who listens, who doesn't. Who's to be trusted in terms of their scientific or technical judgment, or how often they are to be trusted. All of that. So you learn that. I've been through enough communities when I came to TMT that I've learned that not everyone is like the high-energy physicists of the 1960s and 1970s who tended to be in a more pushy community. Now they're more post-modern and more collaborative and consensus-based and so on. I had quite an additional experience, in LIGO, having to deal with Robbie Vogt's people, who were one culture, and MIT, that was one culture. Caltech folks were another culture, and so on. I had to watch those and see how to interact with those.

By the way, you ought to watch a podcast "Into the Impossible." Brian Keating is the host, interviewing Rainer Weiss, if you haven't. Because Rai Weiss talks about the LIGO communities, MIT versus Caltech and so on. I watched it the other day. Anyway, so in TMT, I had to learn all those things, but I also had a particular problem, which is when the four parties agreed in an MOU in the middle of 2003 to form TMT and start looking for a project manager, they formed an interim management group and an interim design group, but they went ahead and started designing. Each of those people came out of one of the three pre-cursor designs, the California Extremely Large Telescope, the Giant Segmented Mirror Telescope, and the Very Large Optical Telescope in Canada. They all came in with designs that more or less did the same thing, but they were very different designs.

They had six to 12 months of working together to try to come up with a design, and how to work with each other. They divided up the leadership of these interim groups among the three parties that came together, precursor parties. One of my first jobs was to pick the design among the three precursor designs, and pick who the leaders were going to be, in the project, given the existing structure of interim leadership. Within a week or two, I recall saying, "Look, guys, I've read all the documents. I've listened to a couple of meetings. It looks like all three of these designs which are different—just look at them; they look different—they all pretty much meet the same requirements. So it almost doesn't matter what we pick. We've got to pick one of them. So let's do a tradeoff study—trade study, we call it—and in six weeks, we're going to pick one. We're going to pick the key design elements and that's what we're going to go forward and baseline on."

We did that. They were good engineers in there. Instead of fighting for their precursor design, they kind of said, "Yep, let's do a trade study." They did all the things that engineers do. They made tables of pluses and minuses and advantages and disadvantages. This costs this, and this is cheaper, and this is more reliable. They worked very hard in those six weeks and produced all the comparisons.

I listened to all of that, and I could see a picture forming in my head. This is one of those things where you bring in referred expertise from other fields. You listen and you bring in some heuristics, some judgment, some value judgments that help you that aren't the numbers in the tables. By the end of the six weeks, I was pretty convinced and they were even gravitating, more or less, in this direction, towards the design that became the design of TMT. Azimuth elevation mount, the elevation axis in front of the primary mirror, and Nasmyth platforms for the instruments on the side, and a particular optical configuration called a Gregorian optical configuration; those were the main parameters, and the diameter of 30 meters, of course. It was about six weeks into this six-week thing; we were done. We had a document. I reported to the board that we're choosing this design.

The other thing I had to do in parallel was choose who were going to be the leaders going forward, because there were people who had various jobs. I watched, I listened, I talked, to a lot of people—"What do you want to do when you grow up?" Those kinds of conversations with people. And also, "What are you spending?" I told people at the very beginning, "You're spending money from your various funding sources." The Moore Foundation or the Canadian money or the NSF funds that were at the National Optical Astronomy Observatory that contributed to this. I said, "Whatever you do, we're starting today." This was April 2004. "We're starting today with the project. Go on doing what you're doing. I'm not going to tell you all to stop." Then I watched for those six weeks to three months or so, and I made some decisions of some activities that I wanted to stop. I did that.

There were a couple of places where it looked to me like people were doing developments that were partly intended to keep their own lab going, partly intended to keep their own technology going, and they didn't look like they were really going to contribute to the developmental work or the design work we needed to do, or that they were less important to those things. So maybe three months in, I started to cut off certain things. In one or two cases, that developed some resentment. There was one case, I won't mention the person, who I really thought they were nest-feathering, okay? And I might be wrong, might be right, but that was my strong sense, that this wasn't a good thing to continue, and it wasn't in the best interest of husbanding the money and focusing in on the design.

So there was this period of three to six months where at the end there was a baseline design—or I would call it a straw man design; it wasn't yet a baseline design. I also had to hire some people who hadn't been involved, people like David Goodman who became the business manager from outside, and others, key people from outside, to build up the team. I had had that experience with Barry when we built up LIGO and hired people like Dennis Coyne and people who were really the anchors for the organization afterwards.

I would say six months into my arrival, the early winter of 2004, we had a team forming, a design, support people joining, and roles were being carved out for the successive groups to contribute. Then we began a cost estimate and study of the instruments that we wanted to include in the first light instrument suite. That took until 2006 for the instrument suite to be narrowed down. We did a study for a year, year and a half, with the community, of a bunch of instruments, a dozen or so, and we selected three in late 2006 to be the first light instrument. That was a very interesting thing, but it also pulled in the community, because they were all interested in getting their ideas, and they were competing. It built up the optical and infrared astronomy community around TMT, because they had what they thought were important contributions. For the most part, they were right. That was the transition time.

ZIERLER: To go back to the initial design considerations, how much variance were there in the options that you and your team had to choose from? Was 30 meters always the baseline, or were there other lengths that were considered?

SANDERS: The baseline diameter of the mirror was 30 meters. We did do a study of how much science you could do and how much money you could save if you cut it down to 25 meters. I've always learned, when you're studying one of these big things, study what a descope would do, because someone is going to come along and say, "I'm going to give you 20% or 30% less money. What can you do?" In fact, when we did the first cost estimate in 2006, I was higher than people thought, and the board asked for that study, and we had already started it. The board concluded that we should stick with 30 meters, that the cost savings reduced the science too much.

We actually published papers, a few of us, on the scaling of the costs with the diameter, for example. Some things don't change. The cost of engineering doesn't change. The cost of the facilities on the summit don't change. The cost of the build does change, because you can make it smaller, the telescope. We did a study of that. But the board decided to stick with 30 meters. It was only in the last few years that they raised the cost of descopes again, but the cost really was ballooning. As time went by, the cost of construction went up. The cost of steel went up, and so on. So 30 meters was pretty stable.

ZIERLER: What was the learning curve like for you in terms of gaining an appreciation for past ground-based telescope projects, just to give you a grounding of what advances TMT would represent?

SANDERS: First of all, compare it to LIGO. LIGO was a much more technically complex thing. To learn the real subtleties of how you lock the cavities and how you modulate the signals and noise sources, that was more challenging to learn anew, even though a lot of it was just basic physics, than optical telescopes. When I took the job, I very quickly read two or three of the books that were out there. There was one book on—I forget the title, but it was something like How to Design a Giant Telescope, something like that. It was a technical book, and I read it, and I also read some popular accounts of the history of giant telescopes. There were several of them out there at the time. They talked about Hale and his 40-inch refractor, and his 60-inch reflector and 100-inch, and then Hale with the 200-inch Palomar, and the story of Keck. I read about the National Optical Astronomy Observatory, and the Magellan telescopes, the folks out of Arizona, and the spun cast mirrors.

I learned the history of the field and the technology of it very quickly. I would say within a couple or three months, I knew the language and I knew the basic designs, and I knew who most of the figures were. What I'm telling you is the optical and infrared telescope field was an easy field for me to learn the history and the technology. The hard area, the more difficult area, was adaptive optics, which had been retrofitted onto Keck and the other telescopes. At about that time, it was beginning to be retrofitted, because adaptive optics was developed by the military in secret and was only declassified in the 1990s. A few of the French actually got a hold of the ideas, or thought up the ideas before that, and so it was beginning to show up in astronomy, and then it got declassified and was retrofitted, because none of the telescopes were designed with adaptive optics in the design.

TMT was in some sense the first time someone decided to design a telescope with adaptive optics so it would be diffraction limited. That was considered to be a very sophisticated field, more difficult to learn. But I have to say—and this is recounted in that little interview paper with Harry Collins, "They Give You The Keys To Drive It"—where in those first year or two, TMT had to decide which adaptive optics system to use. There were some pretty sophisticated choices. Are we going to use piezo stack deformable mirrors? Are we going to use voice coil actuators? Is it going to be multi-conjugate adaptive optics or multi-object adaptive optics? Are we going to use microelectronic machines and make a much smaller system but use adaptive mirrors that have not been fielded before? They're a new kind of thing. There were a whole bunch of designs.

I made the choices that we chose, and in that paper with Collins, I tell how I made those choices, learning what I needed to learn to make the choices, even if I couldn't write down the equations for every part, and listening to people, and making judgments based partly on my expertise as a technical scientist, and my referred expertise from other fields, at what was likely to be successful. I rejected the microelectronic machines, MEMS, because I thought they were too risky. They were too new a technology. To this day, there aren't many mirrors in astronomy with MEMS, so it was the right choice.

I rejected the idea of an adaptive secondary, which if TMT had been built on its schedule would have been the right choice. Now that TMT is delayed so long, only a few years ago I restudied the idea of having an adaptive secondary which uses voice coil actuators, a whole new technology, only because in the interim 15 years, the Europeans had pioneered it and actually made it work. But in the early days, it just was too risky. So I chose the adaptive optics structure. To this day, it's exactly the same architecture that I chose, even though the adaptive secondaries have come along and the Europeans are deploying it, and it has been deployed now on the Gemini telescope. But when we looked at it as a possible design revision a couple of years ago, it was just too expensive to add it, $65 or$70 million to add it. The science that it would buy wasn't worth it compared to the science you would get with spending $65 million on another instrument, to do a different kind of science. So there's an example where I think—and I sometimes said to my colleagues in TMT—I think your technology and the technical challenge is easier than LIGO, and I learned it to the extent I needed to learn it, to be an interactional expert and a management expert. I learned it more quickly, it was easier, and made some choices that were fundamental. I also made choices such as lowering the nasmyth platform seven meters below the elevation axis, which a lot of the traditional astronomers didn't like, because it meant their instruments had to be up on stand on those platforms. But I did that to clear all that stuff away from the air flow across the primary mirror, because the air flow needs to flow across the mirror to keep an air column in front of the mirror at an equal temperature. Otherwise, you get temperature-induced variations in the index of refraction of the air column in front of the mirror. People didn't like it, but it stayed in the design. I shrunk the dome around the telescope. There's only half a meter of clearance all around the telescope as it moves, on the grounds that we don't need a bigger dome. It's expensive. People didn't like it at the beginning, but they've designed to it. I think those were the right design choices. ZIERLER: Right at the beginning, in 2004, what were the siting considerations? Was it always going to be Hawaii, or were there others that were in contention? SANDERS: No, not at all. In fact, that was a major campaign for the first five years. When I joined in 2004, April 2004, the interim group was led partly by George Djorgovski, a professor at Caltech. Since this is a Caltech interview, you might go talk to him. He and a very talented group of postdocs—Matthias Schoeck, Warren Skidmore, Reed Riddle—I'm probably leaving out someone key—they started to build a system that could sit robotically on a mountain and measure the quality of the astronomical "seeing". They built such a system to measure a bunch of attributes, and they built five or six of those. They did a worldwide study of potential sites for TMT—this was in 2003—and settled on five sites? Yeah. Three in Chile, Mauna Kea in Hawaii, and San Pedro Mártir in Mexico. They built these systems and started deploying them on the mountains, and the goal was to try to get three years of data on the quality of astronomical seeing such as the number of nights that were clear. The number of nights where the atmosphere was so stable thermally that adaptive optics would work well. The water vapor at night. Because if you wanted to do mid infrared, you needed very little water vapor above you. How windy was it? Because wind would shake the telescope. And so on. You had to know what kind of wind disturbances you had to reject. By the time I started in April of 2004, they had one at Mauna Kea, and I think they had one in Chile, and they were working on deploying the others. I actually made a trip to Chile to look at the various mountains that they were looking on. I never went to San Pedro Mártir. I went to Hawaii and looked at the site there. That campaign was a major activity. Lots of data, lots of controversy over the analysis, because the data would tell you which politics to deal with. There was also a clear sense, I think, among many people, that it had to be Hawaii, because the Moore family had a house in Hawaii. And of course we have Keck, and our partners had Gemini, and our Japanese partners had the Subaru telescope and Canada had CFHT. So why would anyone think of doing this other than in Hawaii? But then there were people who said, "We have to do this the best." ZIERLER: What about the consideration that the NSF, either in a primary or a potentially ancillary role, would have the expectation that this needed to be built on American soil? SANDERS: Well, remember this partnership at the beginning of TMT was four parties—Caltech, UC, the Canadians, and AURA, which was the NSF contractor for NSF's optical telescopes. NSF was clearly aware, and AURA certainly would be responsible to understand, how important it was to have it on U.S. soil as opposed to other soil. Now, the U.S. had a bunch of NSF-supported astronomy assets in Chile, so that wasn't considered a problem. Chile was so special. Maybe Mexico would have been unfamiliar to NSF. But there were also important political considerations. The state of California has relations with Mexico, in Baja, Mexico. The U.S. has relations with Mexico. The politics of the location didn't seem to be a big issue in those days, however the politics of AURA's participation in TMT was an enormous issue, because in 2003, AURA had signed this initial MOU and taken, in effect, a decision that the NSF community was a supporter of TMT. The people who were working on what they called the Magellan 20, University of Arizona folks, Carnegie folks resented that, even though they were on the AURA board and present at the votes where the president of AURA, Bill Smith, at the time, got authorization to join TMT. After they joined TMT and started spending money on it, with NSF's awareness—and approval, presumably, because you don't spend NSF money without somebody writing a paper that says "go ahead"—the Magellan 20 people wrote a protest letter, organized by Irwin Shapiro at Harvard Smithsonian, and started a campaign to overturn the decision for AURA to join TMT, because they felt they hadn't been given equal time on their design. Which, by the way, I think is not a design that competes with the Keck/TMT/European ELT design, to this day. ZIERLER: Why? SANDERS: I partnered with GMT in the USELT thing, and I think it is the right strategy for the US in the ELT era, but I think the idea of building a giant telescope out of those type of mirrors is a poor design choice. ZIERLER: Explain why. SANDERS: Those mirrors are big, thick, heavy. They're not thermally light, so you have to cool them with fans, so you have a mirror that presumably couldn't maintain the same kind of even temperature. Even though they're smoother in principle than a mirror that's finely segmented, like the Keck mirrors, they have a huge gap. Imagine making a mirror out of seven circles. Think of the gaps between those circles. And yet you're trying to make them act as a single diffraction-limited mirror. Keck knew how to do that. This introduces a serious technical risk. And their instruments are located down into a little platform area underneath the main mirror, which means you're constrained with the size of the instruments and how easy it is to change them, whereas in the TMT design, you have these enormous Nasmyth platforms on the side, and your tertiary mirror can direct the beam from the telescope to any of those within a few minutes. You have much more flexibility in terms of the physical size, the attributes, and the ability to go easily and quickly from instrument to instrument. In any event, they protested, and in the end, the NSF and AURA stepped out of the TMT partnership. That's my view. I don't mind going on the record. Even though Bill Smith and many people felt they had all the authorization and that. So by 2006, sometime in 2006, AURA and the NSF contingent withdrew. They still allowed the NOAO people to go on working on the TMT design, because a lot of what was being done was considered generally useful for the community. For example, the site study was going to produce a catalog of the best mountains in the world, that anyone could use. NSF continued to fund that, at the level of ultimately a contribution of about$12 million, but they withdrew.

From then on, NSF wouldn't touch TMT, for fear of getting yelled at, with one exception when they were directed by Congress to study potential partnerships. Again, these are my blunt words. Because there had been a controversy. That agency is a reactive agency. It doesn't feel that its job is to be courageous. It's all review-oriented and reactive. If you write a nasty letter telling them not to do something, it becomes a serious problem for them and they have to carefully answer it and deal with potential criticism, and that's what happened. So NSF was never a part of it. To this day, NSF still won't take a phone call from anyone in TMT, even though a proposal had been submitted. But until the decadal survey comes out, they don't want to be accused of playing favorites. Even though TMT and GMT are working together on USELT. It's a very reactive organization, the NSF, though there are heroes like Marcel Bardon and Rich Isaacson who championed LIGO when it was a bit of a crazy idea. I have great admiration and love the NSF for what they did in LIGO and love what they do in general. But I think now and then they need to actually have more initiative and make decisions and be a little bolder, take a little bit more risk.

ZIERLER: This is not a political statement you're making. This spans different presidential administrations, different NSF directors.

SANDERS: Yeah. In fact, I think it has gotten worse. They have become more reactive and more timid. You get yelled at a lot from the powerful people in Washington, Congress and the White House, and you're a scientific agency. I think the NSF is the best science-supporting agency in the world and I've interacted with many foreign funding agencies and done reviews for them. NSF is proposals-driven. It is absolutely remarkable what they do, and I admire the dedicated people who work in it. But the culture of the agency is very, very reactive. It was a moment in time when the leadership of NSF supported LIGO in the late 1980s and 1990 and pushed it through—that was courage, remarkable courage. You don't see that very often.

The decadal survey, among other things—P5 for high-energy physics and so on—carries enormous weight because the NSF can't do much unless they have strong guidance from the community. I've been disappointed time and time again about how slow, cautious, and reactive the NSF is, and I wish they would be more courageous. But don't take away any of my affection for the NSF and my regard for what they do. So the NSF dropped out.

ZIERLER: Let's talk about the TMT in the runup to the decadal survey of 2010. Thinking about 2008, 2009, where was the TMT at that point, and what was it hoping the National Academy would come out and say in the decadal for 2010?

SANDERS: If you go back ten years, and I should have mentioned this, when I sat on that CELT Green Book review in 2001, the effort was buoyed by the fact that the 2000 decadal survey put an optical telescope like a TMT at the top of its priorities. Going into 2010, we were convinced we were still on the coat tails of that, and we had chosen the site in 2009. We had the support from the Gordon and Betty Moore Foundation for the $35 million initially that was given in 2003, and in December of 2007, the board of the Moore Foundation came up with I think$200 million more to start construction. In 2009, the site was named. The Moore Foundation had enough money. Other partners were joining, like our international partners, and we announced that we were starting construction. We had chosen Hawaii, and we had gotten the environmental impact statement through and signed by the governor by May of 2010, so we were convinced we were in a strong position going into the decadal survey in 2010.

What happened was—and I think it was probably predetermined—the impetus to do LSST and also the solar telescope which became DKIST, was so strong at the NSF they wanted to do that, and felt that the Thirty Meter Telescope could wait. I heard that from numerous people at the NSF, and it looked to me like the outcome was not going to go all that well. Sure enough—and the Optical and Infrared Subpanel of the decadal survey ranked TMT as the first priority, ahead of LSST and solar and so on. We were the first priority. But the whole panel together lowered our ranking, which they said had to do with technical readiness, which I think was a manufactured rationale. We were as technically ready as LSST.

ZIERLER: You're saying TMT was as technically ready as it needed to be at that point.

SANDERS: It was as technically ready as it needed to be, and it was as technically ready as LSST. I think that some wanted something else, and that was part of what I think may lead to the demise of TMT. That missed endorsement, plus the choice of Hawaii, without really understanding the political situation that was brewing, that was growing in Hawaii, and the belief that by working with the power structure in Hawaii and friendly Native Hawaiians, we could prevail, even though the Keck outriggers process was already sending pretty strong warnings that building another telescope on Mauna Kea was not going to be a cake walk by any means.

I think the NSF, the 2010 decadal survey, NSF withdrawing in 2006, and then the brewing Hawaiian thing, which wasn't understood at all until 2014 and even wasn't understood all that well when our groundbreaking was disrupted, those led to the quagmire that TMT is in now, with an enormous growth in cost and an enormous obstacle to the NSF being encouraging.

ZIERLER: What did the 2010 report actually say, and where did that leave TMT at that point?

SANDERS: I think it told the NSF to work with us to develop our readiness, something like that. I don't remember whether they put us ahead of the Giant Magellan Telescope or not. I think the words were "to work towards the readiness, and to selecting one." What did that lead to? A competition between us and TMT, which the astronomy community, though they called for it, did not want. The astronomy community doesn't like civil war. For my own role, I considered the GMT to be a competitor, and though TMT cooperated intimately with the European Extremely Large Telescope on technology development, on mirror polishing, and even choosing the same segment size for the mirrors as the Europeans so that we could exchange polishers, I blocked—so I'm confessing an attribute of me that people may not like and criticize me for—but I made it clear that there was to be no technical cooperation with GMT. They were our competitors.

I can see that some of the people in TMT were uncomfortable because they had worked with those folks and viewed them as colleagues, but I didn't want to give an inch in that competition, and the astronomy community in general didn't like civil war. I was stung by the Irwin Shapiro letter. So it was not surprising two, three years ago, when Matt Mountain and others came up with the idea of approaching NSF in the context of the next decadal survey with NSF supporting a piece of both. That meant there was no civil war. There was good scientific and technical reasons to do that, so I stopped my blunt opposition to working with GMT, because I realized that we needed to succeed together, and change. Some people didn't understand why I did that, even though I explained it. But there was no competition anymore; we were going to go up or down together, most likely.

ZIERLER: Do you have a specific memory, the first time you realized that the Native population of Hawaii, and the concerns some of the conveyed, that this might be an existential threat to TMT?

SANDERS: The first time I realized it was an existential threat was the groundbreaking. We went through the environmental impact statement. We put people in Hawaii who were resident. They had great relations with the communities. Some of our board members worked with them. Our board chair, Henry Yang, worked extensively, made many trips. The president of Caltech, Jean-Lou Chameau, made several trips with him. But there was a grievous mistake in all of that. The grievous mistake was to work with the power structure and all of the sympathetic Native Hawaiians, and to believe that if you had majority support from the Hawaiians, you were probably going to be okay in the environmental impact statement process and all of that.

What we didn't appreciate was how militant the small minority of Native Hawaiians were, and we also didn't associate it with the rising tide of sensitivity worldwide with the plight of indigenous people. At the groundbreaking, I was standing there, at the site, waiting for everyone to come up, and they couldn't come up, and we were completely blockaded. That day, we thought the militant opposition Native Hawaiians were going to demonstrate peacefully on the side of the road and be loud. That's fine; it's free speech, and we would be aware. We felt we were sensitive. We were told by the governor of Hawaii that we had set a new standard in relation with the Native Hawaiian communities. Indeed, I think we had. But it wasn't enough.

ZIERLER: When you say power structure for the native community, what does that look like? What is the power structure that you were working with?

SANDERS: Two kinds of power structure. Our leaders, our board members—Henry Yang and other board members—felt that if you had Senator Inouye supporting you, if you had the Congressional delegation supporting you, if you had the governor supporting you, if you did a good job on the environmental impact statement, if you had Mayor Billy Kenoi of the Hawaii Island supporting you, and you worked with them—community groups, the Hawaii Island Economic Development Board—the chambers of commerce supporting you—and a number of Native Hawaiian groups supporting you, that the fact that there were some opponents—and you were sensitive, and you made commitments to them—no discharges on the mountain and shutting down four days a year during sensitive times, a number of things. Trying to build up a workforce development program in which Native Hawaiians could develop the skills and actually be part of the workforce at the observatory. There was a whole bunch of things we did. Paying substantial rent, a million dollars a year, when most of the other observatories paid one dollar a year. Paying substantial rent, a million dollars a year, which would be used for the management and preservation of Mauna Kea. There were a whole bunch of things we did, which were breakthroughs. They were tiny compared to what had to happen to deal with the historic tide of resentment, and the rise of Native Hawaiian—desire for Native Hawaiian sovereignty. The sovereignty movement rose, and that became an element of it.

So we were insensitive to it, even though the Moore Foundation commissioned a report that was run by the Keystone group that gave us advice, which told us some of these things. But our leadership felt that by working with the power structure and the majority of Native Hawaiians who were sympathetic, we thought, that we would do a good job, prevail, and be welcome. To me, that was completely shattered at the groundbreaking, when Lanakila jumped off of a rock into the group at the top of the mountain and stopped the whole process. I saw Mayor Kenoi, who had been our supporter, completely cave and take the side of the protestors. After all, they were his community. The idea, in fact, of having a big groundbreaking, with all the dignitaries and a big celebration and a banquet at the Waikoloa Marriott, all of that in retrospect was an utter insult to people who felt that we were a bunch of rich people from outside who were insensitive. I think it was a complete backfire. I think Caltech and UC, and our board, the American members of the board, Caltech and UC board members, got it all wrong. It was a mistake, and it took a long while for people to even understand how bad a mistake, and maybe some of them don't understand it today.

Nevertheless, we went ahead with the legal process, legal challenges, Supreme Court, and so on, and prepared to start construction in 2015. I was in the first car several times of the construction caravan trying to go up the mountain to start construction, and we never got up the mountain, except for one period of a few hours. Very easy for the opponents of TMT to seize control of the mountain. In retrospect now, I see that the insensitivity of scientists who believe in the nobility and romance of what they do, and of the contribution of what pure science, curiosity-driven science, contributes to culture and to mankind, amounts to arrogance, by not paying attention to the historical injustices done to native peoples, and the seeking of ways to have those coexist if they can. Even the word "coexistence" means apart and in parallel, which is an insult. It took me years to understand that. I don't think many of the leaders of TMT still understand it. Some do. And some of our national delegations, like the Canadian astronomy community, thoroughly understand it. And so I'm not convinced that the partnership that constitutes TMT is viable anymore.

ZIERLER: To go back to 2015, knowing what you know now, what did you understand to be the nub of the issue with regard to the most militant opponents of the construction of TMT? What was their problem exactly?

SANDERS: Their claim was that we were desecrating Mauna Kea, that we were insensitive to their plight. I understood that, and I worked very hard with the Kahu Ku Mauna reviewing the design of TMT to try to make it culturally acceptable. That's a group of Native Hawaiian leaders, many of whom are opposed to telescopes. I had many meetings with them and there was a guy named Ed Stevens who was the chair of Kahu Ku Mauna –who I really felt taught me a lot about the Native Hawaiian perspective.

Ed Stevens, every time I talked to him said, "Gary, what we need to see from you is respect, so that we can work together with respect." I thought, by working respectfully with Native Hawaiian leaders, we would be okay. What I didn't understand until later was there's no such thing as a monolithic idea of Native Hawaiian leaders. No matter how much you respect them, there's a segment that believe the only way to respect them is to go away and give them back Hawaii. And that's where we are today.

ZIERLER: On that point, and in recognizing that the opponents do not speak with a single voice, some counterfactual history. Among those who would have been persuadable, what could TMT have done differently that might have made the difference where we would be much further along in the process than we are right now?

SANDERS: Well, I said, we put some people in Hawaii, and worked closely with the community. But I told you, we worked with the community that worked with us. We didn't work enough with the community that didn't want to work with us, and we didn't listen to them. We did engage Native Hawaiian leaders to be our face. We weren't Native Hawaiian. It would have been perhaps better if our face, our presence, our persona in Hawaii were Native Hawaiian leaders. I don't know if that ever would have been possible, but we didn't do it. So we didn't have the right kind of presence in Hawaii. Even though we were told we set a new standard of engagement and attempt to be sensitive, we fell short in that we were still a bunch of folks from the mainland, and foreigners, who were trying to be sensitive. Communities instantly accept someone who's from them. We weren't from them. The astronomers were still largely viewed as those other people who come here, and we did not adequately deal with that. We didn't understand that.

ZIERLER: If Senator Inouye had lived longer, what do you think might have changed?

SANDERS: We might have succeeded because he had the ability to tell people, "Don't do that" and they depended on him. The fact that he died did contribute to making things much more risky and much more negative for TMT. Would we have succeeded? It might have been that even Senator Inouye couldn't swim upstream against the tide of history. That tide is very strong.

ZIERLER: Obviously nobody is going to be on board 100%. No matter what happens, as you say, there are going to be people that protest TMT despite anyone's best efforts, even if there's only one. At what point does TMT say, "We've achieved a critical mass of support among the Native Hawaiians, and we're going to push ahead even if there are some that are going to continue to protest"? What's that critical mass? What does that look like?

SANDERS: Even the last year or two, when polls showed that 65% of people in Hawaii supported us and maybe 50% of Native Hawaiians, some experts would say, "Well, you can't do better than that." When something's contentious and you've got 65% of the population, that's it. But even if Inouye had survived and we had done better outreach and had Native Hawaiian leaders actually act for us and be us—imagine if the director of TMT was a Native Hawaiian. Imagine if—what was his name, the famous Hawaiian navigator—we had Kalepa Baybayan, who's one of the famous Native Hawaiian navigators, speak for us, and he would be vilified by those who were opposed. Nainoa Thompson, even higher, a higher venerated person, if he had come out for us, it might have helped, but he never did. He stayed out of it. I don't know that there were Native Hawaiian leaders that could have come out for us and turned the tide. It's clear that we believed for a very long time, if we had most people in Hawaii for us and followed the rules precisely and didn't cut any corners and were earnest, that we would be able to prevail. And that was a mistake. Not seeing earlier—I think because we really wanted to do TMT and there were powerful interests and institutions who wanted to do it, and the tide of scientific history was with us, we didn't recognize how strong the tide of history of indigenous peoples was against us.

In the United States, the idea of critical race theory, the 1619 Project—you read those books and you realize that America is founded on two very important original sins. Very important sins! And how much of the propulsion of building America depended on slavery, and how much of the propulsion of making America depended upon subjugating and killing and wiping away indigenous people. There are people who don't want to hear it, and they want to think of the glory of America and the old idea that I was brought up with. But we now know that our country—just to talk about the United States—was founded critically on two very important original sins. We have to deal with that. We have to fold that back into how we behave. Well, the TMT plight is part of that.

ZIERLER: Maybe it's an obvious answer, but it's important to hear yours in your own words. Having done all of the due diligence legally, having gotten all of the buy-in and acting in your best faith effort to secure the approval of as many Native Hawaiians as possible, why not just clear the road? If you have the legal right to do so, and enough support however you define that, you're ready to go, you're ready to build, why not just clear the road with law enforcement?

SANDERS: I said, sometimes, that we have competing interests, but our society is based on a social contract, which is the law. We did everything in the law to be legally allowed to build. The government, the enforcement agencies, the political leaders, are obligated to enforce the law and give us, provide us access to the mountain. They didn't. The governor didn't. He tried, at some level. The mayor didn't. They tried at some level, the police, but they folded. Every time it got to a real face-to-face confrontation, they folded. And the reason they folded was in the end, the social contract has to step back to the politics of the moment and to the fact that sometimes the law cannot be enforced in a static sense. Our law, our social contract, our common law, is constantly modified by new currents, in this particular case by the absorption of aboriginal law, the recognition of standing of rights, of past infractions, of remedies that are needed. We know that the law in the United States had to restore humanity to Black slaves. So the law on a given day is evolving towards social justice and towards the politics of the future.

The TMT situation, though we had "the law" that day on our side, we didn't prevail because the politicians and the social currents were actually evolving ahead of the law, to what I believe is the future of the law. The law will incorporate aboriginal perspectives in it in the same way civil rights laws were incorporated into prior common law, which was racist, but it was legal. As a physicist, who uses mathematics, I would say it's not just the law you're dealing with on any given day, but it's at least the first derivative of the law. The law—D law, D time. The velocity of the change of the law. Don't stand there on the law, but the ground under you is changing, and you better be aware of it.

ZIERLER: Because there's essentially no perfect solution and that was probably obvious to you by 2015, 2016, why not just cut and focus all of your efforts on La Palma, at that point?

SANDERS: Well, La Palma wasn't a viable option until a couple of years later. That comes down to the diversity of the board, of the owners of TMT. As project manager, while I had a lot of authority, I was delivering the project to the owners. It's a little bit like you're the architect building the Disney auditorium in Los Angeles, but the owner is Disney. At some level, what I had to do was try to deliver to the owners what they wanted, but also my own personality is such to try to help the owners see what they ought to want. I did a lot of that.

In fact, one of the reasons I left was at some point, I was no longer effective trying to help the owners see where I thought they ought to go. They actually were going in a number of different directions. The owners of TMT had different perspectives, and to this day have different perspectives. Some of the owners, the Japanese, are absolutely adamant about Hawaii, to the point where they told their government that, and every time anyone mentioned an alternate site, they really couldn't do it, because their government was supporting them because they told them it was going to be in Hawaii. So they had to go back and explain. We were banned on spending Japanese money on studying alternate sites at certain periods. At some point, eventually, the Japanese position at the government level was, "If you can't build in Hawaii, it may be okay to build in the Canary Islands." Even though we did the study and compared several sites—Chile, San Pedro Mártir in Mexico, the Canary Islands—and chose through I think a defendable process the Canary Islands as the alternate site, our board members were not by any means treating them as equal options.

Caltech and UC I think were wedded in many ways to Hawaii, although at some point became open to the idea of Canary Islands. I don't think the board chair is open to the Canary Islands. He worked very hard, very hard, to try to make Hawaii work. The Canadians were pushing very hard for Hawaii. And then now the rising tide of sensitivity to indigenous interests have turned the Canadian voice around to where they won't support TMT in Hawaii unless we're—what was the word?—"invited," I guess. Invited into Hawaii. That's also a word that's not easy to interpret. What is sufficient? Invited. With the consent—that's the word—the "consent" of Hawaiians.

So I went to board meeting after board meeting after board meeting, and the vector sum of the desire for the sites, which site we would go to, was never very clear. In fact, we were at one point ready—the board essentially voted to go to the Canary Islands at one point. I've forgotten the exact date when that happened. I've forgotten when in the 2018, 2019 period, the board had a vote. It was very clear, at a special board meeting. The owners were present. The president of Caltech, the president of UC, they were present. A very high person in the Japanese government. In the end, the Japanese wouldn't go along with it. The documents that formed the TMT corporation required unanimity on the site. The Japanese just wouldn't support the move to the Canary Islands. The site required unanimity. Unanimity is not only not possible to reach; it's not even close. The board goes in many, many different directions.

ZIERLER: What you're saying, it sounds like—for those that are most committed to retaining Hawaii as the site, it's do or die, so much so that it's either going to be in Hawaii, or they even accept that the TMT will not be built anywhere.

SANDERS: Yeah, although some of them might say—the Japanese have said that if you really cannot go to Hawaii, and you can prove it—you can prove it, like a letter from the governor, or Supreme Court of Hawaii saying "Absolutely not, never"—then maybe we can consider the Canary Islands. I wouldn't want to box my Japanese colleagues into a corner, but I have to say their fixation on Hawaii was about as complete as you can imagine.

ZIERLER: Gary, last question for today. We'll pick this up next time. But because the decadal report can drop any day now, it's just fun to be able to ask you three questions based on what it might say. For you, as we're all waiting for it to come out, what do you hope it says, what are you fearful that it says, and realistically what do you expect it will say?

SANDERS: What I hoped a year or two ago, as we got into USELT—I think we provided a really strong proposal together with our colleagues in GMT and AURA, and I credit Matt Mountain a lot for pushing the idea. I think it was a remarkable idea. I think we turned in a really good proposal together with GMT, and I really hoped that we would get top ranking as the optical infrared major project. I don't see that happening. I don't even think there's even a small chance of that happening. Because I think the astronomy community cannot push something onto the Native Hawaiians. I think the sensitivity to the Native Hawaiian situation, and I think that the fact that the cost of the two projects has ballooned over the years because of the rising cost, the cumulative cost of the standing armies, the marching armies, and the rising cost of construction. It costs more to do things by a lot now, because of the way the world economy is. What it takes for a steel girder, to buy it in 2010 and to buy it in 2021, it's not just two or three percent inflation. Costs of construction are enormous. Ocean shipping. The costs have really ballooned. I think the NSF and the decadal survey is not used to spending two, two and a half billion dollars on contributions to astronomy assets. And the sensitivity to the Native Hawaiians. I think what will happen is positive words about the science, but weak words or even words of ruling out impacting the indigenous people. I think what will happen is what I said at the National Academy in February 25th or February 26th or 2020, which The New York Times quoted. I think what we will see is the loss of the leadership in optical and infrared astronomy from the U.S. move to Europe, as a result of this decadal survey. I think that's what will happen. I really would be pleased to learn that I am wrong.

ZIERLER: The parallels from the SSC to CERN must weigh heavily on you.

SANDERS: I said—and I think it was quoted in The Times—that I mourn the loss of leadership in high-energy physics in the United States, and I fear that the same thing will happen in optical and infrared astronomy. American astronomers will go to the European ELT. TMT I fear won't be built because of the impasse on the sites and the lack of unity of our partners' perspective. If you don't have a site, you can't get built. I think the NSF is probably all awakening to that. Maybe GMT will get built, even with NSF funds, because they have a site, and they will do some good astronomy, but I'm telling you, I don't think in any way GMT will contribute what I would call leadership in optical and infrared astronomy, when it's compared to the 39-meter fantastic European ELT. I think the leadership in optical and infrared large telescope astronomy will be with the European ELT, and we will go to it the way American high-energy physicists go to CERN. Except the European ELT is not as open to us as CERN is to the U.S.

I think LSST—what do they call it?—Rubin—and DKIST, those will be assets. Small telescope—Keck. I don't know whether the observatories on Hawaii will survive, given the fact that the master lease is expiring, and there seems to be no real action forward in Hawaii on the master lease so that the prospects for the current telescopes to remain look very good. I think the sun is setting on the nighttime astronomers from the U.S. in terms of leadership. I'm very pessimistic about it.

ZIERLER: Well, hopefully for everyone's sake, you're wrong, and we'll pick it up for next time.

[End of Recording]

ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It is Friday, October 8th, 2021. Once again, it is my great pleasure to be back with Dr. Gary Sanders. Gary, great to be with you again.

SANDERS: It's great to be with you, and I look forward to our discussion.

ZIERLER: Just to set the stage for your post-TMT life and your sense of timing and opportunity and things like that, were you looking for new opportunities by the time Simons came around, or did that come out of the blue for you?

SANDERS: No, it came out of the blue. When I retired from TMT, I retired for a variety of reasons, mostly because I did not believe I could contribute to the success of TMT given the way TMT was being governed. I was also realizing that I was ready for retirement and doing other things, so I retired. I was interested in doing some consulting. In fact, Caltech and TMT each told me they were interested in me doing consulting from time to time, and I was open to that, but I considered that to be something that would be a minor fraction of my time. My intent, when I told the owners of TMT and the board that I was going to retire—I told them in November—was to retire.

I have to say I retired actually formally on January 4th, and on January 6th I got a call from an old friend, another person who had led big projects, asking me if I was interested in being the project director of another billion-dollar project. [laughs] I said, "No, I'm retiring." For a variety of reasons, that project wasn't yet funded, so it meant mounting a campaign to get it funded from the NSF and DOE, and it also meant that they wanted me to move to another place in California. I wasn't going to do any of that. I told them, "Let me know what's going on, and let me know what happens after the decadal survey." Then I was retired. I did a little consulting for TMT now and then, but 80% or 90% of my time, I was retired.

Then I got called by a company that has consulted for me in the past on my projects saying they were supporting a project that needed help. Would I be interested? They described the project. This was a call from people who weren't scientists; they were engineers. But they knew me well from having worked with me for 30 years, on and off. They described the Simons Observatory and I realized that this was a small enough project, the science was outstanding, the headquarters was nearby. I live in Laguna Beach; the headquarters is in San Diego. And the project is dispersed, which meant a lot of it would be done remotely. I thought, "Gee, I can probably really make a difference" once I learned a little bit more.

I surprised myself over a period of a month or so with a few meetings and decided to take it on. Even then, I took it on as a three-month consulting gig for a while to see how it goes. Then in the summer decided I would make a multi-year commitment. I was surprised. But it was just the right kind of really exciting science, equal to LIGO, led by really smart people, the kind of people you enjoy working with, who needed some help, and it looked like it was a good match to what I could provide. So, it was a surprise.

ZIERLER: Invariably, there is a hint of modesty in your conclusion that you were not the right person to provide the solutions that TMT was looking for. To what extent, embedded in there, is there the assumption that perhaps somebody else had a rabbit that they could pull out of their hat, versus it really didn't matter who the project manager was in terms of the long-term fate of TMT?

SANDERS: All of the things that you said I think are true, at some level. When I took on TMT 16 or 17 years before I departed, I felt like I had one more big project in me. The science was great. I sensed that the people who asked me to take it on—and I think I told you the story of going from the search committee to being the candidate—I thought they wanted me. I really did think I was well-matched. I don't know if I would say "the" right person, because there's the "the" which has a singularity in it, but it certainly was a good match.

For most of the 16 years, I felt that I was really contributing a lot of leadership and that it was appreciated. I feel like I did lead the building of the team, the design, and the readiness to build the thing, and in fact the execution of some of it was going on. It was demonstrated success. We were producing things. We were just stopped by the site morass. I will say that I never thought we should build in Hawaii. I'll say that now. But when the choice was made in 2009, I recognized that my job was to make the decision of the board successful.

ZIERLER: You were against building in Hawaii; is that out of recognition for the Native Hawaiian issues?

SANDERS: Yeah. It was a recognition of the Native Hawaiian issues even though I told you that I did not understand it well enough. I understood that the lead sponsor, the Moore Foundation, was likely to prefer Hawaii. I understood that Caltech and UC and Japan and Canada, having telescopes on Mauna Kea, would prefer Hawaii because of the synergy of their current operations. But I saw the cultural issues as a real problem. There was this Keystone report that was commissioned by the Moore Foundation that warned of the difficulties. I took it seriously. In retrospect—and I'll say this, and I'll say it publicly—I don't think the owners of TMT, the board members, took it seriously enough. I think they felt that by their political connections, the nobility of what they were trying to do, and the fact that they were going to try and do a somewhat better job than had been done in the past in terms of community relations, that they could succeed.

They misjudged it. To some extent I would say even though I didn't favor—I wouldn't say I was against Hawaii; I want to correct that. I didn't feel it was the lead candidate, because of this Native Hawaiian issue. I felt that Chile, the site in Chile, even though it was a lower mountain and so on, really was comparable, if not better in some ways, than the Hawaii site.

SANDERS: La Palma was not considered in the first round. In the first round of site selection, it was a site called San Pedro de Mártir in Mexico—Baja, Mexico. Chile. There were four mountains in Chile that were under consideration. And Mauna Kea. I was asked in 2007 by the board, by Henry Yang, the chair of the board, while we were doing the site measurements, to measure the astronomical qualities of the various mountains—four in Chile, one in Mauna Kea, and one in San Pedro de Mártir, to lead the process in Chile to get permission to build on a mountain in Chile, so that the board in the Summer of 2009 would have two options on the table ready to go, out of the three, and Chile was preferred to the Mexican site. I don't recall all the reasons now. So I spent a lot of time in Chile getting recognition of TMT as an international observatory under their law, which gave us diplomatic status, gave me diplomatic status. Dealing with the foreign ministry, dealing with the various agencies of the government, and dealing with the University of Chile and the various communities—because we had four mountains—and narrowing it down to Cerro Armazones, and doing the environmental impact statement, the Declaración de Impacto Ambiental, in Chile. We got an environmental impact statement. It was done. We didn't get the concession to use the land for the 50 or 65 years, but we got a letter from the deputy foreign minister, or maybe the foreign minister of Chile saying, "Under these terms, we are prepared to grant you the permission." Took Ed Stone with me to the presidential palace and the foreign ministry and so on. So I understood Chile pretty well, had regular meetings with the governor of—the intendente, the governor general of the region in Chile in which the mountain was. We were ready to go in Chile.

There were some members of the board who felt that I was doing that as a threat to Hawaii. I took it as, "I'm doing this because I want to give TMT options." I took it seriously and did not respect the Board members who took my effort as a threat to Hawaii. But in the course of doing that, while the environmental impact statement was being done in Hawaii, the environmental impact statement, and the community engagement was being done by others—Sandra Dawson notably led that—I always felt that Chile was preferred because there wasn't this what I feared paralyzing indigenous person issue.

ESO, the European Southern Observatory, wanted that mountain, Cerro Armazones, for the European ELT. That's where they're building right now. Probably the one really big 39-meter telescope that's going to be built is built on the mountain that I was advocating for TMT. So there's no doubt that it's a quality site, because when the board decided on Hawaii, I called the director general of ESO and told him of the decision. Which he expected, by the way. He felt that TMT was irresistibly drawn to Hawaii. Literally the next day, they were in the office of the foreign ministry of Chile, making an application to use that mountain. They were just ready to go. Massimo Tarenghi, who was the guy who led that effort, was there the next day. They were very pleased that TMT had given up on that mountain. I think it was a tragic mistake. One could argue that it might have been very hard to get the funding, additional funding from the Moore Foundation or other sponsors by going to Chile.

ZIERLER: Including the NSF, right? The problem with the NSF right now with La Palma is that there's no guarantee that the NSF is going to fund on non-American soil.

SANDERS: Right, except Chile is not American soil, but NSF is already funding, including its current flagship observatory, the Rubin Observatory, in Chile. Chile, while it's not American soil, is recognized as a special place on Earth. It's a little bit like building in Antarctica, at the South Pole. That's where you go. So Chile would not have had the political issue that Spain has. It was only when TMT got stopped in 2015 in Hawaii that TMT once again reopened the site selection, looked at Mexico again, and brought La Palma into the search, and ultimately decided that La Palma was the competitor to continuing in Hawaii.

I favored Chile. No one had any doubt about that at the time. But I also was committed to making Hawaii successful. That's what it was in 2009. There were members of the board, and especially the chair, who frequently would say publicly—and I was somewhat miffed by it—that I had created the threat, the alternate, the competition for Hawaii, to keep the Hawaiians focused. Because the project manager was down in Chile arranging to build the thing in Chile; that meant that they had to pay attention. I knew I wasn't being used in fact that way because it was a genuine search, but I'm not sure that some members of the board didn't feel that I was a prop in this competition. I still believe that if we had chosen Cerro Armazones, we would have overcome the funding issues.

I will say that while Caltech, UC, and maybe the Moore Foundation favored Hawaii, and maybe it was inevitable that they would choose Hawaii, there were some partners, like the Japanese, who were absolutely hard-over on Hawaii. It may have been hard to imagine choosing Chile and walking away from the possibility of a big pile of support from Japan. I can't say that the board didn't make the only decision they could, but I think it contained the seeds of failure. I hope I'm wrong, and I hope that I get to eat a plate of crow a few years from now when we're building in Hawaii, but I don't think so.

ZIERLER: Because it's not about the egos; it's about the science. You're happy to be wrong.

SANDERS: I'm happy to be wrong. In the end, if I turn out to be wrong and we're going to get to do the science with the Thirty Meter Telescope in Hawaii, fantastic. I don't believe that's going to happen, for a variety of reasons, not just the cultural renaissance of the Native Hawaiians, but the ability of those who want to stop a project to stop it is much easier than to get it to go. So many obstacles that can be used in the law, the expiration of the lease in 2033, the lack of support from the existing observatories, who though they want us are more fearful that their lease is going to disappear. And the fact that as an island culture, people aren't decisive and strong. They tend to do everything as a 360-degree set of communications. Because they're on an island. The culture is developed of an island. You can't piss people off too much by making decisions, because you're stuck on the same island with them. I'm simplifying here, but you understand it.

Your broader question to me was did I think I was the right guy. I think when I came to TMT, I thought I was well-matched. I wouldn't say "the" right guy. There were others who could have done the job, and I served on a panel in the last day or so with a few of them, in another field of science. Through most of the post 2009 period, I felt that I really was contributing to leading the team, the design, and that the board was happy that they had me as the project manager. Once we got stuck in the conflict in 2015, which I think was precipitated by what was probably a strategic blunder, the October 2014 groundbreaking—the board made it a big event, inviting all sorts of things, a huge event. It was the perfect lightning rod, the perfect catalyst, for bringing out the opposition. The groundbreaking didn't happen. It got stopped. And that looked like a black swan event, and certainly was, but it completely changed the boundary conditions around TMT. From then on, it was, "How can we get on that mountain and get constructing going on?"

I led the, I don't know, three attempts in 2015 to do that, all of which precipitated the ever-growing and more militant opposition. Certainly, people can blame me for confronting the Native Hawaiians by sitting in a caravan of construction trucks and driving up the mountain, or attempting to, several times, but I felt we needed to go forward. We needed to go forward. The cost of the project would balloon if we didn't go forward and start going into construction. The marching army cost of maintaining the project without being productive is enormous. That has been incurred; now it's an incurred cost. I was hoping that the board would make the relationships with Hawaii and so on, that would make it possible.

In retrospect, both the Hawaiian political system and the board were incapable of dealing with the situation. In retrospect now, I feel that we, TMT, came up against a historic shift in sensitivities having to do with indigenous people anywhere. That Hawaii was a flashpoint and a point that was a good exemplar of it, and that TMT's reliance on "the law," the social contract that's inherent in the law—we did everything right in our environment impact statement. We did everything right under the comprehensive management plan. We applied for the permits. We did everything scrupulously. We had wonderful legal support in Hawaii—Doug Ing and his colleagues. Several Supreme Court decisions—two that went for us, and in effect settled the legal situation. But that's not enough.

There are two things that you don't have, even though you have the Supreme Court saying, "Go ahead, you can build." One is you have a political system that ultimately relies on the support of the people of Hawaii, and the people of Hawaii were divided, and the political system wasn't going to go beyond a certain point to help us get up the mountain. A very weak governor, very dispersed attitudes in the legislature, focused on the community. Which may be right; it's representative democracy.

The second major element that limits the effectiveness of having "the law" settled and on your side in terms of permission to build is that we're relying on the law. The law is the common law. Not everything in the law is just. We know it once was legal to segregate, and the law had to absorb the perspective of social justice, racial equality. Well, "the law" is now facing aboriginal law, indigenous people issues, and it's evolving. We're right in that transition. In Hawaii, it's particularly strong. So it's clear that having "the law" as it exists now cannot come up against the social justice imperative, the baggage of rage, of anger, denied self-reliance in Hawaii. The advantage is to the militant Native Hawaiians who don't have to exert a lot of energy to stop the system. One road, 100 people, and a government system led by, by any standards, a weak governor, but a broader political spectrum of people who, in the end, depend upon getting elected by the people including the people who were opposed. You cannot go against the social wave that's happening, the social wave of self-determination.

This is happening across the world, in many, many locations. The Dakota Access Pipeline is an example, where the law isn't enough. The TMT board felt they did the whole thing properly, cut no corners, followed the law. With that, we want to have the ability to build. And it's just wrong. I don't mean to just blame them; I and they have learned this at a certain rate. I think some of them still don't understand it and still have some hope that having the law on your side, and the imperative to build something like TMT, the scientific imperative, will carry us through. But I don't see those ingredients there at all.

What everyone's hoping is that there will be a very strong vote of priority from the Astro2020 report that will somehow propel these other mechanisms—political, governmental, social, legal, cultural—to help us get built on TMT. Frankly, I will tell you this now—I don't believe TMT can be built in Hawaii. I don't see any way, if for no other reason than that it's actually quite easy for the militant opponents to stop TMT from being built. I don't think it's going to happen.

For my own sake, through most of the 16 years I was there, I felt that—again, I wasn't the one, but I certainly think I built the team and the design and the readiness to build. But I had four thoughts in my head about continuing, so I'll be frank with you. If my bosses were glad to have me, that was one criteria. If I felt that I had a good chance to succeed, that's another criteria. If I was having fun some of the time, that's another criteria. And if there was enough support for the way I was doing things that in some sense I had air cover—someone who would stand up and say, "Look, Gary may have done this in a way we don't want, but look what he has done."

By late 2020, I concluded three or all four of those weren't there. I was trying to lead the board in complete stasis. Board meetings were excruciatingly hard to sit through because they could not decide anything. The different viewpoints that were hardening, some of which had to do with national resentment. The Japanese resented the Californians. I'm being very frank with you. The Indian government—the Indians felt, "You just need to solve this. We don't care. La Palma—you can go to La Palma. Why don't you just go to La Palma? Then we can go forward. In the meantime, if you don't decide, we're going to stop funding you." And that's what happened. The Japanese—hard-over, hard-over, hard-over, on Hawaii. Several of the others were weak.

Then the Canadians grew ever more sensitive, quite appropriately, to the issues of indigenous people, because that mirrored what was going on in Canada, and came to the conclusion that they would not support constructing on Hawaii unless TMT had the consent of the indigenous people in Hawaii, which is an extremely difficult criteria to define. 100%? What does consent mean? Literally 100 or 200 people can stop you on that road and generate thousands around the world by social media. So what does consent mean? You could have a very high fraction of Native Hawaiians consenting, greeting you, and still not succeed.

We tried everything. Before I left, I participated in Ho'oponopono, which is a kind of marriage-counseling-like baring of your soul, face to face, with Native Hawaiian leaders, and opponents. There were several of these, half a dozen of these sessions, with several different TMT leaders, to try to see if we could get past being apart, and get to looking over to us. The idea of science and culture coexisting, which is what is always raised. On Mauna Kea, can science and culture coexist? But there's something defective in that image. Science is here; culture is here. You are apart. To be accepted in a community that is as militant and as intense as that, you need to be together. The Ho'oponopono was like marriage counseling, trying to bring two people together, trying to bring two parties together, and it failed.

I will say it really failed because the most militant Hawaiians participating in it—and I was there in the room quietly watching it—simply wouldn't accept it. They viewed even their most intimate kind of social communication as an attempt to undermine their opposition. I was trying to lead the board towards decisions over and over again, and I gave several talks where I used the myth of Sisyphus to describe my own attitude towards dealing with the board. I was very frank with them. They were incapable of making decisions, and they were not taking any of my advice. In fact, some of them were beginning to snipe at each other, and at me, and the other leaders of TMT.

By the middle of 2020, none of my four criteria were satisfied, and it was actually getting to my health. I was losing sleep. I couldn't keep rolling the rock up the hill and having it roll back down on my face. That's why I—I quit, actually. I'll say this. Out of decorum, civility, together with Diana Jergovic and so on, we agreed that it would be announced as my retirement. But if things had been going well in TMT, I will tell you that I had no intention of retiring. So I left. It was painful. It was couched as retirement. I actually enjoyed retirement once I was retired. But if they had been doing their job, or if there hadn't been a quagmire in front of us, I had no intention of retiring.

From what I know now, the leadership of TMT, the board members, are not in a different situation. They're waiting for Astro2020, but I do have enough communication and so on that I know that those I left behind are still dealing with the same external quagmire and internal quagmire.

ZIERLER: Announcing this as a retirement is certainly a noble gesture in helping TMT save face, but for your own prospects, your own well-being, because you didn't want to actually retire, how concerned were you that this might cut off potential next opportunities?

SANDERS: Oh, I wasn't concerned about that at all. Let me make it clear—the day that I announced I was leaving—it might have been the beginning of December or sometime in November—I think I told Ed Stone early in November, and then I announced to the board—the day I announced, that day, I wrote a note to the board, which there's no way you can read that and see that what I'm doing is retiring. In fact, I recited the four criteria of I have to like doing this, I have to think I can succeed, now and then I have to have some fun, and I have to feel that the support there is enough that I have some air cover. I told them that that wasn't there, and therefore I'm gone. The public announcement was that I was retiring.

ZIERLER: But you presented it as a fait accompli? You did not allow them to come back to you and say, "You know what? All right. We're going to do this, this, and this"?

SANDERS: No, no, no. I was done. In fact, the note that I wrote to Ed Stone early in I think November, when I told him that, was—because I had been saying, to the board and to him, that if this continues, I'm not going to stay. So they knew that. The note I wrote to Ed said, "It's no longer a question of whether I'm leaving. It's now a question only of when. I'd like to talk to you about what succession period you need, if any." There was no negotiation. I finally got to the point where I felt that there wasn't any way they could behave that made it possible for me to succeed and to contribute.

One of the questions you asked me was did I feel that there was someone else who could do this? I did come to the conclusion that my attempt to lead the board or to show the way, so that they could perhaps take that way, was no longer effective. I did say maybe they can find someone who will match them better, which is a little bit different than saying that someone could lead them in a different way.

The guy who is acting in my stead, Fengchuan Liu who was my deputy, is a first-rate project manager, very good technically, very energetic, and he's doing a good job, but he's doing it in limbo. He's acting and he's doing it in a period of stasis while everyone is waiting for the decadal survey, and in a period where the project is spending the money it has and not getting any new money. It's going to run out of money at some point, and it's winding down some activities. It's trying to keep alive and also keep making progress. And they are making progress in some technical areas. He has a very, very hard job. The board is going to have to decide what to do with it—to make him the project manager or search for someone else, or wind down the project, if there isn't a way forward.

But I'm out of that, and fundamentally it came to the point where I had to quit because of—I'll say it—my health. I couldn't take the constant stress of being Mr. Sisyphus. Every board meeting was more painful to watch. You're a historian; maybe you want to go interview some people and try to understand the process of that board. You could start with Diana Jergovic who maybe you've talked with her. She has had a particularly good vantage point. She is a particularly experienced and wise person, so she can give you her views.

ZIERLER: In this interesting historical interlude before the decadal drops, the question is, will I be writing a history as a postmortem or as an unbelievable surprise success story?

SANDERS: That's your mystery to solve as a historian. As far as did I worry that if I quit I would hurt my next job, I didn't. I'm 75 years old. I don't know if I told you this story, but when I was an undergraduate in maybe 1965 at Columbia, I.I. Rabi, a Nobel Prize winner, had his retirement party, and he talked about the stages in the career of a scientist of becoming, being, and signifying. Rabi had won the Nobel Prize in 1944. He was the chairman of the President's Science Advisory Council or something. He was clearly signifying when he retired. I wouldn't say that I'm signifying at my stage of a career, although the panel I chaired yesterday was to recommend how to go forward in the future for the gravitational wave field. People thought of me, and they made me the chair. Well, that must mean I'm signifying, because people think of me when they think of one of these hard problems. What's the way forward for the next 20 years? That kind of thing.

I've always felt that in my career, I was always in the "becoming"—not the "being" stage. So the Super Collider, then to LIGO, then to TMT—each one was a new field, and I had to learn the new field and show my cred. I've spent maybe more than 60 years in the "becoming" phase of I.I. Rabi, and so on. But I finally was at the point, when I decided to leave, couched as retirement, that I didn't feel like I had to do anything anymore. I was satisfied with what I had gotten done. I was pleased that I had a chance to be a leader in LIGO, and that it had been so successful. A chance to contribute to a place like Caltech, because for 26 years at Caltech, I was helping to lead a thrust that Caltech wanted to succeed at. That was important. Both LIGO and TMT were things that the president and the trustees were aware of and they wanted to do it, and I helped make one of them successful, and I think brought the other one to the threshold of success, within my bailiwick. So I'm proud of that. I didn't need to do any more.

I wanted to stay involved with some consulting. I was asked to chair a review in May by NSF of another different billion-dollar class project. Just doing one or two of those reviews a year, do a little consulting, that's fine. The rest of the time, I was flying airplanes with the Caltech Flying Club. I had outside interests that I was doing. Simons Observatory came along, and it just fit right.

ZIERLER: Before we move on from Caltech, one thing I'm curious about in comparing and contrasting LIGO and TMT is the relative value and role that JPL played in both projects.

SANDERS: Let me say that in both projects, JPL played—and I don't mean this as a criticism—a minor role, in the sense that if you count heads and dollars spent, they were a small fraction of each project. But they played crucial roles, so that might be called a major role, in certain areas. The most important area that JPL played in LIGO, and some people might say it's a peripheral role, but we had support in quality assurance, mission assurance, from JPL, which was crucial at times. Trying to build things that you were going to put into the world's best vacuum system, and they had to work, and they had to work right, required quality assurance and mission assurance, the kind of skill that you don't normally get at a place like Caltech where people will tinker something to success. Whereas JPL, they can't tinker something to success. That was crucial. We had some things like internal optical baffles in our 16 kilometers of beam tube that had a black glass coating that began to peel off. What will we do? JPL was crucial in getting us through these crises and saving millions of dollars in retrofitting things. But also making sure that things that were made were quality. So I think mission assurance, quality assurance, they were a critical resource there. That's a small part of the project, but on the day we had these problems and they got us through it, they were really very important.

In TMT, again, they played a minor role in the sense of the number of people and the number of dollars, but an absolutely major role that was closer to the heart of the technical challenge in TMT. The technical challenge was we wanted to build a telescope that wasn't just a bucket that collected light, so-called seeing-limited thing, but it was diffraction-limited, in other words all 492 segments acted like they were one mirror. They were aligned so well and phased so well with respect to the wavelength of the light that they acted like one surface, so that you got the diffraction-limited resolution, the sharpness, of a 30-meter aperture. That technology was developed for Keck, a smaller telescope, with only 36 segments, and the control laws, how you would sense where the mirror segments were and what commands you would give to them so that they would phase up and act like a single mirror, well within—the spatial differences were well within the wavelength of light—was pioneered for Keck and led by Jerry Nelson and Terry Mast from Santa Cruz, Gary Chanan from UC Irvine, and then several people—Mitch Troy and others—from JPL.

By the time we started TMT, we had all of those people, but as time went along, one guy retired, Jerry passed away, Terry passed away. The heart of all of that effort—alignment and phasing of the primary mirror—was at JPL. The telescope doesn't work without that, and the core intellectual nugget was there at JPL. A real challenge for JPL. JPL was a place with a whole bunch of talented scientists and engineers, and missions come and missions go. They come along, they're urgent, they're challenging, and you throw a bunch of really smart people at them, and you get them done, and then the next mission comes along. Occasionally, there's valleys between the mountains of demand in them. It's very hard to keep the people you really need for as long as TMT has kept—16 years. Because there was demands on those people to go onto other perhaps more urgent from the standpoint of the director of JPL. Other missions. Nevertheless, we were able to keep the core intellectual expertise going forward with us, and working on this crucial area.

I think that has been a crucial contribution of JPL—how to make the 30-meter diameter telescope a diffraction-limited, meaning very sharp, telescope. They are the repository of the expertise, and in fact they helped train our competitors at the European Southern Observatory building the European ELT. We did joint tests together and exchanged all of our data. Right now, you could say the European ELT has learned, in smaller test beds, how to do this, and they will come on and benefit from JPL's contribution. So JPL, very important to TMT.

ZIERLER: Before you started to think deeply about the Simons Observatory, I'm curious what you knew about Jim Simons and how that might have influenced your decisions.

SANDERS: I knew very little, surprisingly little. I knew that he had led what we call a hedge fund, an investment thing, and I knew that he had figured out how to do trading algorithmically, without particular market research on this stock or that stock or that bond. I didn't know the details of it all, but I knew he was a very wealthy guy, a very smart guy, and that he had figured out how to make a lot of money over a long period of time. I knew that he had set up a foundation. But I surprisingly did not know much about him.

ZIERLER: Coming from all of the bureaucratic and cultural and administrative complexities of the TMT, was there something alluring about a mega-rich guy who loved science, the simplicity in that?

SANDERS: Well, remember that all the years I worked on TMT, I felt like I was trying to deliver this to Gordon Moore, who was a Caltech and UC benefactor. Even though we had international partners and I was one of the people who pushed to have international partners—I felt that was essential to the success of TMT, and that TMT would be a global asset that should be accessible by international partners—I always felt that I was doing this for the lead benefactor, Gordon Moore. He wanted it. He was interested in the science, and he was interested in some level, I'll say, in promoting the success of Caltech. I thought that was important. I was very clear, and I've always used the language—there are the owners, and then there are people who execute, and I was leading the group of people that were executing TMT, but I looked to the owners. To me, the key owner was the president of Caltech and the president of UC, and their benefactor was Gordon Moore. So I already had that experience.

When the proposal was made to me to look into Simons Observatory, it was made clear that almost all of the funding for Simons Observatory came from Jim Simons's foundation. Then I learned a little bit more about him and understood how much he had done in mathematics himself, and how much he supported science. Simons Foundation is a very impressive thing that supports a rather broad set of sciences, especially from the computational viewpoint, not surprising for a mathematician. But what was told to me was, "He wants to see the science from Simons Observatory done by a certain birthday of his"—85th birthday, 86th birthday.

It looked like the project was stretching out, and advisory panels for a couple years had been telling them that, "You need to bring in the kind of leadership expertise that can make this somewhat more deterministic." It took a while for them to decide that they were willing to do it. Academics don't usually ask for that. The early history of LIGO is another example of that. Why, in the end, were Barry and I brought in? When they finally realized that they couldn't get by just having an academic approach.

So couple of years, they had had strong advice from people who really understand big projects to the Simons Foundation to do this, and the team had not taken that advice and acted on it. They finally, during 2020, had started a search, and the person who contacted me and suggested that I think about it saw that the search wasn't getting where it wanted to get. They knew me, so—"Gary, why don't you take a look at this? This might be a good fit." And they were right. I think they were right.

ZIERLER: Who reached out? Who made the offer?

SANDERS: A guy named Spencer Curtis from a company called BCF, which is a company that provides cost and schedule and system engineering staffing to big projects. It was a company that I've used in the Super Collider project, their precursor people, before they formed a company, and then they became a company, and the company changed names. At the moment, it's BCF. They were supplying, I don't know, a dozen people or so to TMT, and they supplied a number of people to LIGO, and they knew me. They also supplied to many other projects—DOE and NSF projects, and European projects, and I frequently came in as a reviewer, or chairing a review panel of those projects. I was well known to them. I guess Spencer thought, "Gee, Gary's retired. My gosh. Maybe he's interested in this." So it worked.

ZIERLER: Obviously the Simons Observatory has a whole history preceding your tenure with them, but I wonder if you could talk a little bit about what you've learned since—how the Simons Observatory developed, why it picked the site that it did, and what some of the science goals are of the Simons Observatory.

SANDERS: There's a long history of looking at the microwave background from the cosmos from the period after the Big Bang. It was discovered in 1964 by Penzias and Wilson who were working for Bell Labs and were working on trying to understand how to communicate better with satellites and what the noises were, radio frequency noises and so on, and they saw this static in their antennas and didn't quite understand what it was. It was in every direction. Happened to be talking to the folks at Princeton—Peebles, Dicke, Wilkinson, folks like that. I think Peebles came down for a seminar at Bell Labs, came up from Princeton to Bells Labs in Holmdel, New Jersey, and they had a meeting of the minds. "Oh, this static? I think I know what it is." And they ended up publishing papers announcing the discovery of this, and that it was the remnant radiation from the first light from the Big Bang. About 380,000 years after the Big Bang, the universe had cooled enough so that electrons could bind to protons and light could actually travel a bit. And we see that light. It's about three degrees Kelvin temperatures because of the expansion and cooling of the universe.

This was the light from the early universe, the earliest light, from the horizon of the universe as it rushes away from us, and it tells us a lot. Is it the same light in every direction? I look there, I look back, it's the same. Why would it be exactly the same? Is it isotropic—in every direction you see exactly the same? Or is it anisotropic, different brightness and so on? And is that an indication that matter is more dense there, or was, or there? Maybe that has to do with the clumping that allowed things to form. So this is important stuff.

There have been a number of measurements of that over the years. Balloons, satellites. COBE satellite, the Wilkinson Microwave Anisotropy Probe, WMAP. There have been things from balloons, but also telescopes, looking at this cosmic microwave background in Antarctica, which is a great site. It's dry. It's high. And high up in the mountains in Chile, 17,000 feet, 5,000 meters or more. So there have been successive generations that have gotten better and better at measuring the cosmic microwave background and have learned a lot of things.

But one of the goals is to understand whether that light, for example, measuring not just the intensity but the polarization, and does that light show the effects of gravitational waves from before that bright moment? Close to the very earliest instance of the beginning of the universe, the inflationary period where, I don't know, about ten to the minus 36 seconds after the Big Bang, everything goes whoompf! And gravitational waves from that very early era may have an influence on that light. Can you detect that? That's one of the goals. I'm trying to talk about this in layman terms.

There have been several generations of these instruments. On the ground, in Chile and in Antarctica, a couple of generations, and there were a number of groups that were prominent in fielding these things. The Atacama Cosmology Telescope, Lyman Page, Princeton, Carlstrom with the South Pole Telescope, Chicago. There's a number of these different groups. The story that's told—I wasn't there, but it's in Brian Keating's book on Losing the Nobel Prize—was that a meeting in, I don't know, 2014, 2015, 2016, he was there with Jim Simons at some scientific meeting, and Simons was aware that there were a number of university groups, each proposing, each working on I guess you would call it the second generation of these things and talking about what to do in the future. Simons says, "Why don't you get them together? Make something where all these disparate teams, the leading teams, come together and build an observatory to go after this stuff." I'm simplifying the discussion. So, that happened. Simons obviously was interested in funding it.

Brian and others worked on it. Brian had been part of the BICEP collaboration, which had, including Caltech, mistakenly claimed to have seen this effect of the gravitational waves I think in 2012 and had to withdraw it. That was in the BICEP2, the second version of the BICEP thing at the South Pole. Brian and others got the groups from Princeton, Penn, Berkeley, and UC San Diego to join together, and the Simons Foundation gave money to UCSD with the intention of providing some awards to these others, to design and build the Simons Observatory.

The goal was, get to the heart of it. Get to the heart of inflation, and a long list of other scientific goals, with that set of telescopes. So one large six-and-a-half-meter thing, and three smaller ones, at 17,000 feet in Chile. At the same time, others at the South Pole—there was a next generation South Pole Telescope 3G, I think is the name, for a competing—called it third generation, ground-based, cosmic microwave background thing. There's a bunch of I would call second generation ones on the same mountain in Chile, at 17,000 feet. There's Atacama Cosmology Telescope. There's a Simons Array, which is an earlier, smaller project that Jim Simons funded nearby on the same mountaintop. There's something called POLARBEAR. There's something called CLASS. There's a cottage industry of little observatories there. But Simons Observatory was intended to be the real third generation, the next generation, and go after the really important science questions.

It got started 2016, 2017. I believe Simons committed $40 million to the price of the project. It was envisioned as a five-year project. Over the years, it became an eight-year project with a budget that was approaching$90 million to $100 million. There's where the advisory panel for a couple years was saying, "You need to make this more of a project and change the way you're approaching this thing, and measure your performance and understand the costs better, the schedule better, and how to make decisions." That ultimately led to the suggestion of me coming along. Interestingly, in parallel with this, a larger group of people are talking about the fourth generation. In 2014, there was a high-energy physics process called the P5 process. It's like their decadal survey. They gave very high marks to a first-generation thrust in cosmic microwave background, and this was from the perspective of the high-energy physicists, including the Department of Energy, not the NSF or not private. It was called CMB-S4, stage four. Guess what? About 60% of my colleagues at Simons Observatory are part of that. Guess where it's supposed to be built? On the same mountain. Well, it's supposed to be built partly in the South Pole and partly in Chile on the very same mountain, a neighbor to Simons Observatory. Simons Observatory is both competing with, and trying to scoop the key science before CMB-S4 would get built, but also be a technology test bed for CMB-S4. Many of the leaders of Simons Observatory will be part of CMB-S4, and they too, CMB-S4, are waiting for the decadal survey outcome, and DOE has committed some money, like$20 million, to development, and NSF several million dollars. That project is headquartered at Berkeley and Chicago but it includes a number of my colleagues. What Simons Observatory's relation is to it isn't clear. They are hoping to both get some of the science done quicker, faster, better, cheaper, but also become part of CMB-S4, and different members of the Simons Observatory have slightly different view of it. I view it as an evolution into the really bigger project.

It's interesting for me to watch this field now, but what I've had to do is learn as much as I need to at any given moment of the technology of the field, refresh my memory, and expand my understanding of the science of the field, and then also help these folks become more deterministic in carrying out Simons Observatory.

ZIERLER: At this stage in your career, obviously you have developed laser-sharp focus on what projects are going to work and what are not. Of course, the last thing you wanted to do was join a quagmire, as you say.

SANDERS: That's right. When I said January 6, someone called me about asking whether I was interested in project director for another big project, it was CMB-S4. I didn't say that. There are others who were approached as well. I declined because they weren't funded. There's a decade of getting it funded and going to Washington and going through decadal surveys, and at the same time trying to build a team up and keep them alive while the funding—I wasn't up for that. Simons Observatory is funded! The sponsor was, in effect, saying, "Tell me, Gary, how much it really will cost, and then presumably we'll support it." It was me in a position where I could actually make something that was already going successful, or more likely to be successful. I don't want to be egotistical about it, but my additional skills, expertise, and experience I think can improve the outcome here in the Simons Observatory project. That's very gratifying.

ZIERLER: Where is the project now? What's going on, on a daily basis, and what is the time scale, as you see it?

SANDERS: The goal is to get it finished by April of 2024, meaning it's doing science at that point. I think Jim Simons wants to see this finished by that time, and I think he's right, so I take that as an imperative. I believe it can be finished in that time. The four telescopes—three small ones and one large one—the first of the small telescopes is likely to be shipped in a couple or three months, to Chile. The large telescope, the guts of it, is likely to be shipped in 2022, although the mount for it probably won't come there until maybe six or eight months later. But in 2022, the big telescope and the first of the three small telescopes will be in Chile and the site should be ready for them.

The site is already under construction. Some of the foundations have been poured. The platforms for these telescopes, the so-called ground screens for them. A building is partly built. It had to stop for the Chilean winter, which was during our summer. Just starting up this week construction there. My goal is to have the site ready for the arrival of these telescopes in the Spring of 2022, and first science from the large telescope and the first small telescope in 2023, and the whole thing done in 2024. So, I'd say it's 50% to 60% complete now, and I'm trying to put into place the practices, systems, estimates, and performance measurement tools, and the management focus, to get this done on that schedule.

One of the problems with a project that's dominated by four academic groups coming together, each of whom in their own university is working in an academic style—faculty, postdocs, and graduate students; where are the engineers? There's very few engineers on this project. You asked me about JPL. TMT and LIGO had lots of engineers on the staff! This is a very academic skilled project, and one of the things I'm doing is adding some engineers for the final phase of the project, because there is some professionalization of things that needs to be done. But there, it's very easy for them to say, "Gee, I'm going to put these sensors in, but if I wait another month or two, I'll have those sensors, and they're better." That's a dangerous mistake when you've got a milestone coming which is called "Get this thing on a ship to Chile." So one of the things I'm trying to do is develop not just a chart that shows the focus, but the perspective, the lifestyle, of focusing on the next milestone that we have to achieve, rather than the discursive style of academics. It's being well accepted, I think. People understand that they need to do this. They also understand that when I was approached, I said I would only do this if I was actually working for Jim Simons and the Simons Foundation. I don't work for UCSD or Princeton or Penn. I'm actually working for the Simons Foundation. So I also represent the sponsor.

ZIERLER: You're an employee of the Simons Foundation?

SANDERS: Yeah, I'm actually a full-time consultant. It's complicated because they're all in New York and I'm in California.

ZIERLER: We talked about the relationship between the Simons Observatory and other land-based observatories. In what ways is the Simons Observatory working in a complementary nature with space-based telescopes?

SANDERS: There's data that has been taken by Planck, and certainly data will be analyzed by people who will look at all kinds of data, but the focus in Simons Observatory is to be able to access a lot of the really key questions from the ground, without having to go to space. I would say it's mostly a ground-based thrust to get at the heart of the science.

ZIERLER: Given, as we talked in earlier discussions, the existential threat that U.S. astronomy is facing if the TMT falls apart, do you see looking into the future that the prevalence of billionaires who are interested in science, is that a way forward beyond the NSF, in making sure that the United States remains a player in this area?

SANDERS: No. When the citizens of Boston saw a comet in 1835 or 1836, they decided they wanted to build a telescope, and they build what they called the Giant Refractor. They did it with private contributions from 90 wealthy people. From then on, all the telescopes that mattered in the U.S. until 1957 or so were privately funded. The Great Refractor, of course Hale's work for Yerkes in Wisconsin, the 40-inch refractor, and then he came to Pasadena and did the 60-inch, the 100-inch, started the 200-inch—all private. Keck was private. It was only in 1957 when NSF formed and started to think about astronomy that we began to see publicly funded, ground based astronomy. I'm ignoring space-based. So the tradition in the United States is that private funders have carried leadership in astronomy for a century or more, 125 years or so. The scale of what you need to do now is such that while I suppose a Gordon Moore could just write a check and build TMT—but they also understand the ethical and moral value of their money, and that maybe it needs to be spread more widely. I think these assets have now become so expensive they should be publicly funded, and they in fact should be internationally funded. The U.S. could take a lead in something, but they ought to have international partners. That's not to say that fantastic science isn't done by medium and small and individual bench-top facilities, but some science needs to be done by really large—the billion-dollar class facilities, those need to be publicly funded.

The U.S.'s leadership for 125 years up until today—Keck—has been privately funded. I think that era is over. I think that the private funders can start things. They have agility. They have mental focus. They can make decisions more easily. But I think the really big facilities are going to need public funding in the future. I think that if the U.S. doesn't built TMT, as I was quoted in The New York Times in March of 2020, it will be like the U.S. not building the Super Collider, and the U.S. will—and it may be inevitable anyway, given the time scale to build TMT and the size of the TMT with respect to the 39-meter the Europeans are building—the U.S. will become a second class practitioner of ground-based optical and infrared astronomy, and we'll have to journey to the European telescope or other telescopes, or building specialty telescopes, like the survey telescope, Rubin Observatory.

I think the threat is even worse than that. I do believe it has to be publicly funded. I think TMT is a tipping point for whether the U.S. will maintain leadership. But I also think that ground-based telescopes are built on sensitive places, and the rise of the sense of self-determination and aspirations of indigenous people are going to make it harder and harder to build on one mountain after another. I think the likelihood of continuing the wonderful program on Mauna Kea is diminishing. I think it's really under threat. Will there be world-class telescopes, existing ones, in 2035, after the lease expires in 2033? I don't think anyone knows.

But the legal path forward, if you try to plot a legal path forward—forget the culture and politics—just the time it takes to do the legal steps and get the votes in the courts and in the legislatures, and the decisions by the administrators who have to create the next disposition of land, whether it's a lease or something else, tells me that the existing presence of astronomy on Mauna Kea is under great threat. I know that there have been people in the astronomy community and in the NSF who have asked themselves, what other mountains might there be, for example in the continental U.S., where we could use them for astronomy in the future, where we might not have indigenous people issues? People are looking for ways forward, and I think it's a very difficult exercise. I'm worried about U.S. and Northern Hemisphere—because the U.S. leads in Northern Hemisphere astronomy. I'm worried about it more broadly than TMT.

ZIERLER: Projecting ahead, best case scenario, if Simons Observatory does everything that it wants to do, what will we know about the universe or better understand that we don't currently know?

SANDERS: It would be wonderful to see the influence of gravitational waves on the light, the first light from the far horizon, to show that it does come from—that it's a signature of this inflation mechanism, where the universe expanded really fast and got almost perfectly flat or uniform, a big pillar of the kinds of thinking in cosmology. It would be really nice to be able to see that signature. Or to demonstrate that the inflation model is wrong and the data leads us to different conclusions. To me, that's the most important thing.

There are other questions. I think Jim Simons is known in mathematics for something that I don't understand completely, the Chern-Simons mechanism, which might tell us something about—oh, we'll call it the optical homogeneity of space. Is the vacuum homogeneous? There are some really profound questions. But to me, I would like the Simons Observatory to get the first confident signature of inflation or an alternative. I'd really like that.

ZIERLER: Because you think that inflation is a testable proposition?

SANDERS: All the calculations, all the models tell you that if you do this, to this precision, you have a chance to see this, and if you see this, it's a sign of inflation. No one can say whether inflation is the right mechanism. It's the same thing with LIGO. We were pretty sure about general relativity, but we didn't have much evidence for the emission of gravitational waves by sources that we could detect. We did have the Hulse-Taylor thing where they looked at the spin-down, the decay of the orbit of a binary pulsar system, and saw that it was decaying in a way that showed that the emission of energy from the system was precisely consistent with the emission of gravitational waves. So we had confidence that gravitational waves exist, but would there be sources either of sufficient strength or sufficient quantity, within the accessible volume of the universe, that we could probe where we could actually detect them? We had no idea.

There was one or two candidates for relativistic binary inspirals, and estimates of the event rates were very, very uncertain. It turned out that what we saw wasn't in those estimates. So the same question. Do I believe in inflation? Maybe. But I do believe that the Simons Observatory has a really good chance to see a signature of inflation. To me, that's as exciting as I felt when I thought we had a really good chance with LIGO, whether it was Initial or Advanced LIGO, to detect emission of gravitational waves. There was no certainty there.

ZIERLER: I can only imagine how excited Alan Guth is about the Simons Observatory.

SANDERS: I'm sure he's excited about it. It's not the only thing looking for it. But yes, wouldn't it be nice—I suppose; I don't know. There are podcasts with him—Brian is running the podcast series. I think he has interviewed him. You probably can go watch those podcasts and see if he comments on it. But I cannot imagine that the person who came up with this idea or led in the exposition of this idea wouldn't be very satisfied to find someone actually detecting it.

ZIERLER: I'm sure for you there must be a certain poetry in connecting LIGO and gravitational waves to your current work.

SANDERS: I even said it yesterday at this Dawn gravitational wave conference that I spoke at. When someone asked me about Simons, I said, "This science is just as exciting as what we set out to do in LIGO." I've been very lucky. Yeah, man, really amazing. Very lucky to have the chance to be part of the group of people trying to go after these pieces of science. When I got into science, and we talked about it earlier in these interviews—I knew I wanted to be a physical scientist when I was a little kid—it was a romantic sense. When I think about inflation and I think about detecting gravitational waves and mapping the universe with these giant dark massive violent things, it's just romantically exciting.

ZIERLER: Do you have your own timeline? Do you have an idea of when you'll actually figure out when to retire for real?

SANDERS: I'm committed for three or four years to get Simons Observatory done, but I'm perfectly happy to continue helping. Because there are one or two proposals for upgrades. There is a plan for the operations. Remember my four criteria. If they're glad to have me, I think I can succeed, I'm having some fun, and I've got some air cover for now and then when I screw up—if those are still there and I'm still healthy, just keep on doing it.

ZIERLER: Now that we've worked up to the present, and we've even extrapolated into the future, for the last part of our talk I want to ask a few broadly retrospective questions to wrap it all up. As a first point, I've been incredibly privileged—I've interviewed over 500 eminent physicists, and I've never come across anybody with a career trajectory quite like yours. So it bears asking a few specific questions about how you understand your education, the development of your expertise as a student, and how that might be of value in all of the different ways that you've taken your career. Let's start first with experimental particle physics. As an experimentalist, what do you see as the basic value in all of the projects that you've been involved in? Sort of your entre to the field—why as an experimentalist have you been able to do all these different things, all over the world, in physics?

SANDERS: Every time I've come to the threshold of doing something, getting involved in a particular experiment or a line of research, it always comes back to this—I call it romantic. So someone says, "Let's—" When I went to work at Sam Ting's group, he was trying to test quantum electrodynamics at very high energy, which means very short wavelengths of small distances, because there had been some experimental results that it broke down. I thought, "Quantum electrodynamics? That's really important stuff! I really want to get involved in this." My thesis actually wasn't on that, but it was the same detector, the same data. We were doing things. So it always came to, "Is this really important?"

Then later on, actually about the time Ting was discovering the charm quark, the J particle that he called it, which was a bound state of a charm and anti-charm quark, I was working with a group at Princeton. I was an assistant professor, working at Brookhaven and Fermilab to try to understand the production of leptons, muons, and electron pairs, from collisions in those accelerators, because there was something going on there. There was some mechanism that was making new particles. So that was very exciting to me. Then when he found the J particle, we understood that we were in the first stages of understanding how to measure the interaction of strong particles in the nucleus, what we now call quantum chromodynamics. That was very exciting. Mapping out how quarks interact, even though you couldn't get them out. Those were the days when we were understanding confinement, that quarks could act like they were free inside a nucleon, but you couldn't produce them and get them out free, because when you did that, you just created new quarks, which made particles. The folks at Princeton—Wilczek and Zee and others—were inventing that theory. So trying to get at the heart of quantum chromodynamics.

Then later, trying to look for forbidden decays of particles, which would violate conservation laws. Then later, looking for the Higgs particle at the Super Collider or at CERN. Determining how many different kinds of neutrinos there were—these were all parts of fleshing out this set of building blocks of matter. They were all very exciting to me. Simple, point-like things that were the building blocks of matter. The leptons and the hadrons, the Standard Model of physics, this was all very, very exciting. I wasn't interested at all in doing experiments that were measuring some details, or "This is a little bit better" or serial publication. It was always trying to go at the heart of things. That's why, when I was called and invited to work on LIGO, it was like a tenth of a second to figure out that I was interested. Because "Oh my god, look at that science." The romance just got in the way of thinking about moving from one state to another, and so on. So it has always been the visceral psychotherapy of the thing looking in front of me. "Oh, that's exciting; now let's figure out how to do it."

Within high-energy physics, sometimes I worked at hadron accelerators. Sometimes I worked at electron accelerators, colliding beams, fixed target accelerators. Which meant the technology was different every time. What I had to do with my fingers, and my colleagues and my postdocs and so on, was different, because it was motivated by the scientific question. It eventually led me out of high-energy physics to gravitational waves, to optical infrared, and now into the CMB. So the trajectory has been strange, because I didn't follow the traditional thing of becoming a postdoc, assistant professor, and becoming a faculty member. I didn't get tenure at Princeton and wouldn't presumably have gotten it. No one ever denied me tenure there but I didn't expect to get it. Princeton in those days gave tenure to about one in ten of its assistant professors.

But I was very excited to go to the Los Alamos labs, which was a step outside of academia, because there was a new accelerator being built and I had a chance to look at these forbidden decays of leptons. Can you violate electron number and muon number? That would have meant that there's some kind of massive particle that we can't detect yet. So I was attracted by the science, and my family and I, we moved to Los Alamos.

I had a few chances to get back into the traditional academic career path, because I was attracted a few times to faculty positions at other universities, but I ended up staying at Los Alamos for a long time. One of the things that attracted me to staying at a national lab, which is outside of the traditional academic career—though there were excellent scientists there, and I missed teaching there—was the resources that were available. If you wanted to go machine tantalum, or titanium, it was just a walk across the street. You could do just about anything you wanted to do at a place like Los Alamos, or find just about any kind of expert. Not always the case in a university, even with our great national lab system. That always made me effective. I felt effective in moving forward.

When I came to Caltech it was again, not as an academic. By that time, I had gotten a reputation for someone who not only can build things and do experimental science and analyze some data and run a Monte Carlo, but someone who could see how to steer a project. So I ended up in a non-traditional career path from what you might think at the beginning, which is the beginning of progressing from assistant professor to a faculty member and then picking a line of research, many of whom stay in one line of research, and some of whom move around. I ended up always following the scientific opportunity that fell in front of me, and then taking an increasingly management role.

It's a non-traditional path, but I feel like the opportunities I've had to contribute to science are very satisfying, really satisfying. It's not the usual path. I think that's what you meant by you're talking to me and I haven't followed the classical path. I always tell people, "Find who you are, and be that."

ZIERLER: It's not just that it's a non-traditional path; it's also an extraordinarily eclectic path. If you look at, from, Los Alamos, SSC, LIGO, TMT, Simons Observatory, these are all different kinds of projects. It really runs the gamut of physics is what I'm saying.

SANDERS: Yes. One of the things it says about me is I tend—even though when I was a younger scientist and I was designing a Cherenkov counter, or writing a Monte Carlo code, or analyzing data and seeing mass plots come out from the spectrometer, there, you're working on every little detail. But I think I found along the way—this was while I was at Los Alamos—that actually what I was better at was standing back and looking at the whole thing and seeing where it was going.

I will say also this: one of the things I learned early on was really to appreciate the people who work for you and how they can get the details done. Then someone comes along and congratulates you for your success: "Wow." I learned how to be very satisfied working in a team, and not being the expert on this piece or that piece or that piece, but that I was actually pretty good at looking at where the ship was sailing. That's where I've ended up. I am not the expert on any piece of TMT or LIGO, although broadly I know a lot about both of them. But I was focused on where is the ship sailing, and is it sailing at the right speed and in the right direction, and how can I make it sail better. That's what I'm trying to do with Simons Observatory.

ZIERLER: Because of the historical chronology, where we are now, I certainly don't want to ask a question that sounds like a premortem for the TMT, because as we both acknowledged, it would be great if you're wrong and somehow this does go through. If you are correct, though, it would be really interesting to get your take, comparing and contrasting the interpersonal frustrations of both the SSC and the TMT, if the TMT fails like the SSC did, and what has been lost for physics and science generally by having these two extraordinarily important, expensive, and ongoing collaborations essentially stop, never to be rekindled.

SANDERS: I've already told you that what I've always been attracted to is a scientific problem that was romantically exciting to me, which meant it was a really hard, important problem. When you teach your kids to ski, you always say to them sooner or later, "If you're not falling down, you're not learning." If you look at my career—think of Super Collider, LIGO, TMT—god, that's three projects. People say I did a pretty good job on all three of them, but [laughs] two of them didn't happen. One of them really didn't happen, and the other one we hope will happen but I don't see a way forward. So why the hell is anyone congratulating me? My attitude is, we tried something really hard and really important, and sometimes it doesn't go.

Interestingly, one of the things I've learned, one of the things on the panel that I chaired yesterday for the gravitational wave, another member of the panel Jim Yeck pointed out, that many science projects don't succeed not for the science, not for the technology, but for the cultural, political, and community consensus and the rate at which it's developed, and the way it's developed or not developed.

So it was a demise that was social and political, and the scientific community didn't understand that arrogance and the nobility of your task aren't enough to carry you through. You have to make community with people and become one with them. They have to be allies. It didn't happen. LIGO almost died, again because academic leadership wouldn't go along with what the government wanted in terms of assurance and risk management, and in the end found Barry, and Barry found me, who I had worked with on the Super Collider. By the way, I think our part of the Super Collider project, our detector, was going rather well, but we watched all this going on around us, and Barry and I concluded this thing is not likely to go forward. So we could see it. But our part was going well enough that we didn't feel particularly under stress the way I did later on in TMT.

LIGO, once the task was clear that we had to organize this thing and satisfy the NSF that we were going to spend the money wisely and get the thing done, with the support of Caltech—the president at Caltech met me on the first day and made it clear how important this was to Caltech—that was a much more success-oriented setting for it. Caltech and MIT—the MIT groups anyway, not the MIT administration—it was a success-oriented approach, and it succeeded. TMT until it got into the quagmire of the indigenous people in Hawaii was going pretty well, and at that point, the quagmire became internal as well. Again, it's social, political, and cultural. Technically, the TMT was doing really well. So I've learned.

I said this yesterday at this meeting on the next generation of gravitational wave detectors—and others said it—Jim Yeck, who was on my panel, who has led a bunch of projects and has also been in the agencies—you've got to start on day one developing the social, political, cultural connections, community, agreements. Work with the site communities, the politicians in Washington, the members of advisory panels. Not to convince them, not to sell to them, not to be apart from them and communicate, but to develop a meeting of the minds and trust. Develop a sense of community. And that's the limit. The bigger these projects get, the more social and political they get. The technical stuff ends up being the easy part. We know how to do that. We can write the equations. We can order the parts, prototype it, make it work. Even if it seems impossible.

The next-generation gravitational wave detector is going to use a 300-plus-kilogram mass, and it will measure its position to the quantum limit, the limit of the Heisenberg uncertainty principle. Any physicist will tell you that's absolutely mind-blowing. But they will do that. The hard part is where are you going to find a place in the United States where you can build two 40-kilometer-long arms and not have opposition from local communities? And you have to start that on day one, even before you know which site it is. That's the hard part.

ZIERLER: It's an important point, as you indicate, that there was nothing preordained that LIGO had to be an enormous success story as opposed to SSC and hopefully not TMT. With that wide angle, being involved in these major collaborations where you've seen success and failure and wherever we're going with TMT, what was the secret sauce? What can be gleaned from LIGO as future major collaborations are developed?

SANDERS: The science has to be compelling. You've got to build community endorsement and priority. You've got to build support for it, the project. Then you've got to build a team that loves the project, owns the mission, wants to get it done, so that even when it's passing through a really bad storm, people are focused on what they're doing, because they really want to do it. One of the things I would say for these successful projects is you've really got to build a team and a community where everyone feels like they're glad to be there, lucky to be there, and really focused on moving forward. I don't know if I've answered your question, but I think those are the ingredients. You start outside by building scientific community support, sponsor support, and then you've got to build a team that just loves the task, respects each other, and is focused. Even when things are going badly, they're just focused on plowing forward to get the thing done.

ZIERLER: You grew up at the height of the American century, as historians call the 20th century, from Sputnik as a kid, to coming of age in physics as a graduate student during a really fundamental revolutionary time in terms of new particles being discovered, new understandings in physics. To take that and to fast forward or extrapolate to where we are now and some of the real existential concerns you've expressed about the future of astronomy in the United States and all of the confusions, what are some of the things where obviously there's still fundamental understanding in physics to be had? What are some of the lessons that we can learn from an early portion of your life that might be useful for the kinds of physics that are necessary now and going forward?

SANDERS: That's interesting. You're asking me a question, and every question you've asked me, it hasn't taken me a long time to think about it and answer. I have more uncertainty about the answer to that question than anything you've raised. Here we are, at the end of a pandemic—at the moment, at the end of a pandemic; it's probably going to go on for quite a while in various ways, because the virus has got nothing else to do but mutate. But the world has been saved, or is in the process of being saved, by science, and yet the public perception, veneration, value towards science is probably more rocky—I won't say it's low, because a lot of people respect science—it's more rocky and controversial than ever in my life. We all see that. I'm amazed at how even during the Trump administration, which was fundamentally anti-science, and during the growth of what we're in now in which institutions are not respected, expertise is not respected, science is not respected, in our country, Congress has been in a bipartisan way quite supportive of science. We still have that. I don't know whether it is going to be there five years from now. Are we just measuring a moment in time along the slope of erosion of the respect for science, and we're going to be in a very bad place, a place of myth and tribe, five years from now, where science is struggling? I hope not, but I just don't have the confidence. I think that's at the heart of your question.

At the moment, we're talking about space missions. We're talking about virology. I served on a panel of the American Academy of Arts and Sciences over the last couple years that has produced a couple of documents on big science, internationally, and the reasons to do it, and the reasons the U.S. should do it, and do it in an international context, and the reasons why globally it's extremely important. So there we were, in the American Academy of Arts and Sciences, projecting into the future and trying to write documents that people would read and be wise about. Should we do big science, and should we do it internationally, for the United States? The U.S. congressmen would read it and say, "Why should we collaborate with those guys?"

What struck me was that I grew up, as you started this question, in the era of the blossoming of the physical sciences, and the physical sciences grew to big sciences, and other fields weren't. But now there's big science across the board in every field. Atlases of brain data that are expensive to maintain and generate and absorb data and make the quality checks on the data which become a global asset—very distributed data products that have become big science projects in very different fields from everything I grew up in. Big science right now is everywhere, in every field of science. If one looked at those reports, one could see that it's everywhere. We're making the case in those reports for international collaboration and the social value of carrying these things out and what will redound to economic well-being. Not just intellectual curiosity; economic well-being, national security, health, the quality of life, the quality of the environment and so on. And yet what we're seeing in the United States, and maybe in other parts of the world, is a lack of respect for expertise and science.

I sat there helping to edit and write these reports with the staff at the American Academy and my colleagues on the panel and wondering whether we were writing a road map for the last war. The world ahead of us is going to be different and people are going to read this thing and say, "Why did they write this?" But I believe every word we wrote. I believe it's the right advice, that the American Academy put out. I just feel uncertain about the way forward. It's at a time when we need the value of science in all those areas—intellectual curiosity, economic well-being, health, national security and so on, climate change—we need it even more. We've also learned the power of science. We can actually do things. Imagine, in a period of a year, vaccines have turned the curve around on this just—it's unprecedented. It's just amazing. Yet the respect has gone down, down, down. I don't know what the slope is and how it's going to continue. So I'm a little mystified.

ZIERLER: Last question to wrap it all up. You have not pursued an academic path in your career, and that has prevented you from probably interacting with more students than you otherwise would have. In light of your trajectory, in light of all of the things that you've been involved in, for graduate students, even undergraduates today who obviously hope that they're looking upon a new American century with the same kinds of opportunities that you were so fortunate to have when you were coming of age, what are some of the pieces of advice you would give them, in terms of areas to focus on, in terms of how to work with people, in terms of establishing long-range plans versus keeping things open and letting yourself free to pursue any kind of opportunity? What are some of the most important things you would want to tell young people in the field today?

SANDERS: My answer is actually going to be quite simple and I've already given it to you earlier. I will say that on the day that I decided to leave the Princeton faculty and go to Los Alamos, I went to see the chair of the department, who was Val Fitch at the time. Val said, "It looks like a good opportunity but I'm really sorry to see you go, because among other things, you're a really good teacher." I really loved teaching, and I knew that I was going to a place where I was going to give that up. What I said to him was, "I think I'm a good teacher and I think I communicate excitement to my students, but the excitement comes from the fact that I just came out of the lab, and I'm doing things that are really exciting, and it bleeds over into my teaching. I'm going to a place where I'm excited to do the experimental work. So yes, I'm really going to miss teaching, but the excitement comes first, in some sense." That was what I said. I really loved teaching and I do regret, if there's any regret in my career, that I gave up the opportunity to do teaching.

I have lectured a lot. For a dozen years, the NSF had me come and lecture a weeklong series on managing big science projects and looking at the case studies of other projects. I've given a lot of lectures more like public lectures. I gave a public lecture at the opera house in Aspen to the town of Aspen and so on. So I certainly had opportunities, but they're not a substitute for teaching the young people who you know you're going to give the field to. So that's a regret, but I've had a lot of fun without teaching.

That's my advice. You love this field of science, you're a graduate student in it? Just work on it. When the next thing comes along, if it's exciting, work on it. But always be conscious that what you're trying to do is find yourself. Don't make a model and force yourself to fit into it. Because sooner or later, you're either going to be unhappy or you're going to walk away from that and go find yourself. So you might as well say, "Who am I, and let me find myself." In the end, what you end up doing is the stuff that comes easy to you, even though it may not be easy. That's my advice.

ZIERLER: Gary, on that note, it has been tremendous fun, a great pleasure, and such a wealth of historical insight and perspective that you shared with me over the course of your career. I'm so glad we were able to do this. I'd like to thank you so much.

[End]

Ed. Note: After the release of the National Academy's Astro2020 Decadal Report, Dr. Sanders took the opportunity to share additional thoughts on the report, which offered recommendations that were different than what he predicted. In the following discussion, Sanders reflects on his prediction and considers the path forward for TMT.

DAVID ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It is Friday, December 10th, 2021. Once again, I am so happy to be back with Dr. Gary Sanders. Gary, great to see you again.

GARY SANDERS: Great to see you again.

ZIERLER: What I'd like to do, just for the researchers who will access this as a historical resource, just to explain, we had completed our oral history discussions, and in the interim, the Astro2020 decadal report came out, and it said a lot of things that I think were a surprise to you relative to what you thought it was going to say. Those comments were captured in our discussion previously. Let's just jump in at that point about what you thought it was going to say, what that meant for the stakes of U.S. leadership in ground-based astronomy, and where we are now, circa December 2021.

SANDERS: Thanks for the opportunity to add some remarks and thoughts to the historical record now that a particular instance of history has taken place, which is the release of Astro2020. I've been aware that this interview, along with the interviews I did with Shirley Cohen in I think 1998, which are an oral history, are part of the Caltech Heritage Project, but also record for history things that happened and things that I've done and that others have done, such as in LIGO and the Thirty Meter Telescope and so on. This set of interviews more or less centers around the Thirty Meter Telescope. I think we were aware that we did not know the fate of the Thirty Meter Telescope at this point, so in the future, someone might read my thoughts, my words, in the context of a postmortem if TMT were not built, or as part of the successful record of TMT being built, and what happened and how it got there. But an intermediate marker in the flow of history is this Astro2020 report. I made a response to a question that you put to me, which is what did I think was going to be in the report? There's a range of things that they could have said. They could have said that TMT and its partner, the GMT, and the US-ELT proposal, is the highest priority, and by golly, it should be built. Or, they could have said, the science isn't as interesting, and it doesn't compete with CMB-S4 and ngVLA and the next generation gravitational waves and these other things that came before it in the context of large projects. They could have said something anywhere in between there. They did, for example, in 2010, where the subpanel on optical and infrared astronomy gave TMT the highest ranking, and then the overall steering committee downgraded TMT in its recommendations because they felt that there were other initiatives—LSST, known as the Rubin Observatory, was more technically ready. A conclusion that I dispute, but that is the record of history.

At any rate, you asked me what I thought was going to happen. I said I didn't think they were going to give a strong recommendation for TMT because of the interaction with the fate of indigenous peoples and the interests of indigenous peoples, having attended a number of the hearings that provided input to the panelists in the decadal survey effort and seeing how much presence was given to the voices of indigenous people. I sat in meetings of the State of the Profession—I believe it's called—Subpanel, of Astro2020, which normally comments on, "Is there enough funding for graduate students and postdocs? Is there enough effort and progress in equity, diversity, and inclusion? How are professors treating graduate students and postdocs? Is there enough grant money for them?" Normally they deal with those kinds of issues. But there was a very strong voice at the table from the indigenous people and how astronomy was harming them and continuing to harm them. They gave quite a bit of prominence. In fact, one of the main instances of that input was that they had a meeting in Honolulu. I think it was the American Astronomical Association, and there were meetings that were held in conjunction with it. It was clear that the panel was giving a lot of attention, listening to.

It was also noted that the Canadian Long-Range Plan, which is the Canadian analog to Astro2020, basically came out with a statement prior to Astro2020 in their own view of recommendations for the future within Canada that things like TMT should not be built amongst indigenous communities without the consent of the indigenous communities. I think we talked about consent and how difficult that is to define. So I saw the panel process giving a great deal of attention to it, and I had my own experience from TMT in Hawaii, and watching the rise of the expression of the feelings of indigenous people and the rise of attention to their pleas, as kind of a background or boundary conditions to all of this. To me, it was almost inseparable to consider the future of astronomy in a place like Mauna Kea without giving due attention to the role and influence of indigenous peoples, so I predicted that Astro2020 would have difficulty giving a strong recommendation for TMT in light of this rising tide of sensitivity to indigenous people. I even mentioned that there is concern that you won't be able to do ground-based astronomy in a lot of the mountains. Perhaps U.S. astronomy would have to find other sites, or if TMT was not built and U.S. supremacy in optical and infrared astronomy faded, U.S. astronomers would be traveling to Chile to participate in the European Extremely Large Telescope. or perhaps in GMT, a partner of TMT, in the US-ELT proposal. But I also said that I thought that GMT being a smaller telescope of a design that's not my favorite and adjacent to a 39-meter, where it's a 21- to 24-meter telescope being adjacent to a 39-meter European telescope, the astronomy done with GMT would be second-rate, if that were the only outlet for American astronomers. I didn't predict an untrammeled high priority for TMT and its partner GMT.

It turns out I was wrong, and really quite wrong. I've reflected on why, and what the lessons to be learned are, and what it means now to have this recommendation. I'm sad to say that I think even given the actual recommendation, I think the prospects for TMT to be built in Hawaii are very dim. I think in some sense, Astro2020 didn't deal with it. Let me talk a little bit about Astro2020 and try to give my post-Astro2020 reflection on the way in which Astro2020 works, and what it is as an institution. I, in making my mistake, in my prediction, failed to consider a number of things that are intrinsic to this process of decadal surveys in astronomy.

ZIERLER: To anchor our conversation, one aspect of historical import that you were certainly sensitive to was the potential parallels between the fall of the SSC and the potential fall of the US-ELT program. How do you think Astro2020 dealt with the concept of leadership in ground-based astronomy in generational terms? It didn't refer explicitly to the SSC, but how much do you think that was part of the background in just how strongly the decadal supported, without getting into any of the specifics, which we can get into, but just said very strongly, "The US-ELT program must be supported. It must go forward"?

SANDERS: Right. First, let me draw a distinction in your comparison between SSC and the possible demise of TMT, should that happen. The SSC went down because of poor management, enormous growth in the budget that eroded political support, and erosion of political support within the high-energy physics community which competed for resources for other things it wanted to do. That's not what's going on at all with TMT. The analogy that one should draw with SSC, should TMT not be built, is the one that I voiced at the National Academy hearing February 25th or 26th, 2020, when I said I mourned the loss of the U.S. loss of leadership in high-energy physics when the SSC went down, and I worry that that will happen if TMT and GMT are not built. We will cede leadership to the Europeans. That analogy I think I still believe is operative, and I worry, really, that it's going to happen. It was described later in March in The New York Times. That theme was described in an article, and I was quoted. It's an important theme that I contributed to the dialogue. Maybe others contributed to it, Matt Mountain and others. Dave Silva. But that one got notice at the hearings. I still worry about it. Reading the report, while there's vague reference to things like that, it's not a prominent theme.

I think the committee did an honest job in reaching its recommendations to recommend an aspirational picture of the next decade for U.S. astronomy. I think they just did an honest job, but clearly they had to be well aware of this. To come back to my remarks about the decadal survey, the decadal survey has gone on for decades. I think it probably started around 1970. It has become a venerated and respected institution used at the White House, Congress, and in the scientific fields to guide initiatives, funding, stewardship of the field. I did not give adequate weight in my prediction as to what was going to happen to the role of the decadal survey. In retrospect, I feel that probably the people leading the steering committee of the—which actually finalizes the recommendations of Astro2020—realized that they were going to write down something that was very important and guide the field, and that their primary responsibility was to do that. I don't know if they were nuanced enough or sophisticated enough to realize that the cultural issues, the indigenous people issues, were covered by other processes, such as the National Environmental Policy Act, National Historic Preservation Act, and other political processes. But in retrospect, I realized they really were very sensitive to what it was they could contribute.

There is a record over the decades of decadal surveys producing recommendations that sometimes weren't very effective. For example, some decadal surveys have said, "You should do this, if the federal budget is this big. And if it's a little bit smaller, you should not do that. And if it's even smaller then, then you should not do that and that." In other words, they gave programmatic recommendations. I think in this case, either through guidance from the sponsoring institutions or from retrospective wisdom, they decided no, what they should do is write down what should be done to have the best U.S. astronomy program and give ranks. They also didn't do what previous decadal surveys often did—I think always did, but I'll just say often did—which was separate out large projects, mid-scale projects, then smaller things, grants programs and so on, and make recommendations that were separate in each one of those levels of scale for projects. They just wrote down what they thought was the first, then they wrote down what they thought was the next priority. In fact, they picked two and tied, and said why, in terms of science, and so on, and discussed it fully. So they took a rather straightforward view that we are stewards of the advice to guide the next decade or more, because many of these projects take much more than a decade, or more, of astronomy, and they stuck to that. They gave a lot of weight to it.

I think that was one of the reasons, reading the report, that they didn't spend a lot of time and deal with particularities which have to be dealt with by the agencies—the programmatic issues, cultural issues, environmental issues, funding issues, the order in which things are done, the funding pace with respect to the technical pace of the projects and so on. They got advice from the agencies that said, "Write your aspirational recommendations and let us deal with the details." I think that was a very important perspective. I think historically, it was followed more in this process than it had been in some of the previous processes, where previous decadal surveys had been more prescriptive in their recommendations.

The second thing I want to say, and I could never have predicted this—I gave too much weight to the presence and role of the input from indigenous peoples and not enough weight to what it was that the decadal survey probably felt they had the responsibility to do. There was a second perspective that I think determined the extent to which the role of indigenous people issues, especially with respect to Mauna Kea, would play in the recommendations. That was there was another I'll call it indigenous people issue that they took up. I don't know whether one would say that the citizens of Puerto Rico are indigenous people, but they certainly are citizens of a place that's part of the United States but in many views could be said is given second-class status. That was particularly clear during the Trump administration when they were not treated the same way that the state of Texas or Connecticut would have been given in similar disasters.

In Puerto Rico, they had a major astronomical facility, Arecibo. Everyone in popular culture knows Arecibo because it was in a James Bond film with a giant chases up over the receivers and so on of the radio antenna, over this giant concrete-looking depression in the ground, which was the antenna. But it collapsed. It collapsed during the period of in which Astro2020 was carrying out its process. The people in Puerto Rico clamored very forcefully and effectively that Arecibo either be replaced or rebuilt, or that some other significant astronomy capability be maintained at Arecibo, because it was something that was valuable to them. They cherished it. It was an element of their economy and community that was extremely important.

So there's the decadal survey folks dealing with Hawaii, in which native people are clamoring against astronomy development, and Puerto Rico, in which native people are clamoring for the continuation of astronomy development. When I read the report, my own reaction is they've done an absolutely masterful job of steering a path right down the middle, highlighting the sensitivity that astronomy should play to local native people and host community people's issues, without taking a side in one way or the other. They had the advantage of having a pro- and an anti- [perspective] presented to them at the very same time. That made it easier. I'm not accusing them of being weak or cowardly; I think they did their job extremely well. But it certainly made it easy for them to say, "Look at the perspective here, pro and anti. We should just stick to what we do. What is the scientific merit of the things that have been presented to us?"

ZIERLER: On that point, to focus on the nuances of how you were wrong, I think in our original discussion, you were not sanguine about the prospects of TMT because you were focused, or you had the operating assumption, that the decadal would look specifically at TMT in Hawaii. But as you know, and which is very notable in the decadal, that the report Astro2020 is rather agnostic about the siting of TMT with regard to whether it's Hawaii or whether it's the Canary Islands. Let's talk a little bit about—

SANDERS: That's an example of them doing what I think they were given as guidance, which is, "Tell us what your aspirational view of the best science is but leave the details to us and the agencies." That's one of those things, because the site selection in the federal process, legally and formally, is the NEPA process. It's not their process, not Astro2020's process.

ZIERLER: Let's read between the lines. Astronomers, of course, are going to tell you that the astronomy is going to be better. The observational quality on Mauna Kea is going to be better by the order of 5% or 10% or however these things are measured, than La Palma. What do you make of the fact that the report makes no mention—if we can put aside the regulatory issues and the politics and all of that, how do we read between the lines where the report pointedly, I would say, makes no distinction between the observational quality offered either in Hawaii or the Canary Islands for TMT?

SANDERS: I may have misread, or I may not remember it in detail enough, but we told them the kind of 5% or 10% thing that you just quoted, about the difference in science. That we can do essentially all the science, some of it will take a little bit longer. The report was more neutral than that. I think you're characterizing it right. If you look in that report for language that favors one or the other, you can't find it. Maybe someone can find a sentence that I haven't found, but I couldn't find anything that tips it one way or another. They were talking in their recommendation about the intrinsic scientific reach of a thing like US-ELT if it's put at a good site, and no further. They made no comment about the—they had a lot of input on technical readiness and on costs from this Aerospace Corporation TRACE process. There could have been language in there that commented on the designs or which one might be more effective. They stayed away from all of it. They took the high road. In retrospect, I think they did it right. They didn't get into the weeds, which they are not really competent to get into. They did the right level. I'm surprised that they didn't say something about the site, even a glancing comment.

ZIERLER: What does that tell us about what Astro2020 might be telegraphing to the NSF? Because of course, the big political hurdle here is—there's one hurdle of building this in Hawaii with regard to the objections of many of the native peoples in Hawaii. But there's an additional hurdle of building in the Canary Islands, where the NSF would essentially have to fund something not on American soil. So in being agnostic, in not tipping its hand toward which site being better, what might the decadal be telegraphing either to Congress or the NSF?

ZIERLER: Now let's turn to the issue of consent. You'll find the word "consent" in the appendix. Consent does not appear in the main body to the report. How might we read between the lines of what Astro2020 is offering guidance on, in terms of threading that needle? Keeping Mauna Kea as a possibility but also emphasizing that the political and cultural concerns of the native peoples of Hawaii must be reached, without ever using the word consent. What's the takeaway there?

The other thing I want to say about consent is, look, they didn't really deal with it, as you pointed out. It's not in the main body of the report. It certainly was presented in the inputs. However, that issue is going to come up in what goes forward, using the decadal survey as a point of departure.

ZIERLER: Did they not deal with it because it cannot be dealt with?

SANDERS: My guess is that they did what I said earlier—they dealt with their charge. Their charge was to assess the science and to express as clearly as possible the aspirational view of the best science, and to leave the details to the agencies. That's my guess. It's the agencies that have to deal with it. For example, NSF has been engaging in somewhere between 100 and 200 conversations with people in Hawaii to learn of their concerns and to scope the issues. There have been press releases or public statements made about that, that have been quoted since the decadal survey, in the press, as I recall. But now, if the NSF wants to take this recommendation and move forward with it, they are going to have to deal with it through the National Environmental Policy Act and the National Historic Preservation Act, Section 106. They're going to have to deal with it. It's going to come up in the future.

Now, the word "consent"—I've said no one really knows what that is. You could have 95% of the Native Hawaiians in Hawaii sign a document that say, "We consent." I still don't think it would be possible for TMT to be built, because the remaining 5% can go chain themselves at the base of the Mauna Kea access road, and then the police authorities, county of Hawaii, state, the governor, the mayor, are going to have to deal with it. The decadal survey will not create the political impetus for them to get those people out of the way and make it possible for TMT to be built. So I think the idea of consent, you can try to quantify it, you can try to describe it—as much as it is close to the moral high ground and the right perspective, it's not a useful word.

I recently read the Cosmic Explorer Horizon Study. This is a document that NSF supported the preparation of for the next generation gravitational wave project. It dealt with this issue of consent in a way that I thought was better than any document that I've read in astronomy. Cosmic Explorer is a third generation proposed gravitational wave thing, much bigger than LIGO. LIGO has four-kilometer arms, two sites. These are 40-kilometer arms, much bigger. Two of them would be built in the United States. You don't know where they are to be built in this horizon study. The study describes the design possibilities, the tradeoff studies, and what the requirements for the site would be, but then it gives a very detailed description of how to address, communicate with host communities and indigenous people. Those are two different sets of words. They might overlap to be the same in some locations. Where in the United States would you put these two 40-kilometer—we're talking about an 80-kilometers-long system bent at a right angle, in two places in the United States. You can't decide on where they're going to be and have a design and go to Congress and say, "Now we're going to start talking with the local people." You can't do that. So they quite properly say that on day one of the study going forward of Cosmic Explorer, they've got to go talk to the communities and start dealing with them and get them, in effect, to join the proposal. This is very hard, because you haven't picked the sites yet. There's a process you have to go through that you pick the sites and then you go to the communities and they say, "Why didn't you come talk to us? We hate you." Or you go to a whole bunch of communities in parallel, which is very hard, and none of them, having been picked, are willing to bend and give you the support you need to generate the kind of partnership you want.

They use the word "integration." They want the proposal for Cosmic Explorer in each of these two places, the proposal to the NSF, to be an integrated proposal by the host community and the scientific proponents. If it's a Caltech or an MIT or a LIGO laboratory or some other institution proposing it, they want that proposal to be authored and signed by the host community, and that includes indigenous people. That I think is a better definition of the word "consent." The local community is clearly signing the proposal and joining in and integrating. They use the word "integrating." I don't know how they're going to do it, because you've got to pick the site, but you don't pick it with the flip of a coin. On the other hand, you can't wait until three quarters of the way through the process when you finally know which sites work. There's a lot of politics involved.

I'm telling you this story because I think the word "integrating" the host community and the proponents is the right definition. Are the local host communities and indigenous people, if there are indigenous people, willing to sign the proposal and join it, in advocating it, to Congress, to the Executive Branch, and so on? That's a really hard thing to achieve, both pragmatically in terms of when you start that integration process, because you don't know it on day one when you haven't picked the site. Then how do you achieve it? I think my colleagues in TMT, dealing with Hawaii, want to be thinking about—I haven't talked to them—integrating the proposal. That's a better definition. The proposal to the NSF should be signed by a broad array of host community groups. Not just the governor, not just the mayor, but the real community. I don't know how to achieve that. But my view of it is, it's not going to be feasible for TMT to be built in Hawaii. I think the opposition to it, based on historical sense, and the fervent nature of the opposition by the militant opponents, is so strong that the political and legal system won't be able to provide a path forward. So I don't think the outcome for TMT is likely to be different. Again, I hope I'm wrong. You can then interview me again.

ZIERLER: Let's move on to the timing of site selection. As you know, the decadal sets 2023 as the deadline for TMT. Obviously not GMT; site selection is a done deal for GMT. But in 2023, the Decadal's directive to TMT is, "Pick your site, and demonstrate that you have a viable plan for the NSF." In the world of reality, how viable is it that TMT can demonstrate to NSF, "We have a plan in Hawaii. This is viable. You should fund us on that basis, from 2023 moving forward"? How might we read between the lines of a deadline that's not tomorrow but it's also not five years from now, either?

They have no guidance from the decadal survey on which way to go. They are aware of how difficult it is to build in Hawaii. There has been no sign at all that I know of—and if they had had any contacts with folks in the leadership in the Canary Islands about the possibility of building in the Canary Islands, even someone who is now outside and detached from the process like me would know about it, because those things are instantly carried in the Spanish press. One thing I learned is that any meeting by a TMT leader with the leadership of La Palma, the leadership of the Canary Islands, anything like that, it's in the press the next day. It's a very open society. And no, we haven't seen any sign of that. So I think they're committed to Hawaii. We'll see.

In the end, a decision is to be made by NSF through the NEPA process. That's where you write down the preferred alternative, Hawaii, and then the other alternatives, and the no-action alternative. The whole NEPA process of environmental impact statements is carried out to assess the impacts of those alternatives, the mitigations of those alternatives, the cumulative impacts, and then the rationale for a decision. Now, 2023 is mentioned in the decadal survey. It's an advisory statement. The agency will certainly pay heed to it, I believe, but it won't be bound by it. Washington, the Congress doesn't operate under regular order anymore, and the executive agencies have their own challenges and their own time scales. They've been told by the decadal survey, in the case of the NSF, a whole bunch of things to support. US-ELT, CMB-S4, ngVLA, all got very high marks, and there were words in there about how they should be supported. It's a big bill for the NSF, so for the NSF to follow the advice, first of all they have to generate interest in having a bigger budget and taking on bigger projects, which traditionally they haven't done. They now have to take on billion-dollar-plus projects, and they have to be enthusiastic about it to raise that money in the Congress, and there hasn't been any sign of that yet. One other thing that was in the recommendations that you haven't mentioned—I'm sure you're aware of it, because you got that 2023—is they said if you support one or both of these two telescopes, you probably should take on an $800 million role and no more. ZIERLER: I was going to get to that. That's the next thing. SANDERS: Both projects used that number early on in their presentations, but I know enough about both projects to know about they really need more. The cost—I think the decadal survey talks about maybe$5.1 billion for the combined cost of the two projects? Probably using the Aerospace Corporation and the TRACE process. Half of that number is not very different from what I understood our cost was in TMT. So they're not wrong. Then for them to cap the total of $5.1 billion at$1.6 billion for the two, or 800 for each, was a conscious decision made, somehow, in the decadal survey, not to get more deeply involved financially, and that means more deeply involved in terms of the number of nights the NSF-supported community owns. Interesting, that they took that view. That must have been a sense of trying to gauge how much the NSF budget could grow, and how much had to be spent on these other things. Again, I'm just guessing in that. But I was surprised they capped it at \$800 million.

ZIERLER: Gary, is your sense that the way the Decadal phrased its funding decisions, does that put TMT and GMT in direct competition, and if one falters, it's a winner-take-all scenario?

SANDERS: I'm not even sure that came out of the wording, but it's alive and well in the wording. I think despite the fact that TMT and GMT earnestly have partnered in this, and I also think it's the right vision to present to the U.S. astronomy community—two telescopes, partial ownership, in both hemispheres, with the capability of the whole sky, twice as many nights, and a diversity of instrumentation—my gosh, that's—and technological diversity—I think that's a wonderful package and the decadal survey bought that argument. But everyone understood that the NSF might decide to just go with one of them, for budgetary reasons, for scientific reasons. I didn't see in the decadal survey any reason scientifically to go with one or the other. I don't think I missed that. I don't think there's anything in there that says, "This one, if you have to choose one, pick that one." There's nothing like that anywhere in there.

ZIERLER: Is the fact that La Palma is so alive and well as a possibility, what might that tell us about what Astro2020 is signaling about the importance of having a northern-based US-ELT project?

SANDERS: You said that right. You could read their recommendations as just saying, "We give the highest priority to partial ownership of two telescopes, one in each hemisphere." Period. "Of this type. With adaptive optics, and the 20- to 30-meter aperture" and so on. I think in the end, when the real world comes in and presents its complexity to the recommendations, that's kind of the raw recommendation. As I said earlier, I think the decadal survey makes it easier to get support for building in the Canary Islands.

ZIERLER: On that point, the marginal difference between the observational opportunities in Hawaii versus Canary, how do you compare that to the observational possibilities of no northern hemisphere ELT project and just having two ELTs, a GMT and the European essentially as next-door neighbors both in the southern hemisphere? How do you compare those differences?

SANDERS: I think they're very, very different. I think, as I said earlier, if the only outcome of this was GMT being built in Chile but not very far from the 39-meter telescope—its diameter is about 24 meters but its light-collecting area is about 21 meters because of the big gaps between its mirrors. So light collection plus the diameter, which tells you something about the resolution, the sharpness, of the telescope, is inferior to a filled aperture finely segmented 39-meter telescope. So the 39-meter telescope that the Europeans are building is a much more capable instrument, in most ways. There's a few things that are a little more difficult to do and some aspects of adaptive optics. But if I had to choose one or the other as advantageous, the 39-meter is unbeatable. To have the U.S. outlet be a second-class telescope nearby in the southern hemisphere is as very poor outcome. It just can't even be compared, I think, to having a telescope in the northern hemisphere. Now, if you had only TMT, if it were the only one built of the TMT and GMT, and you had ELT and TMT as the two telescopes, that's a far more advantageous scientific situation for the world community, forget the U.S. community.

ZIERLER: All of that kind of gets to the punchline, then, which is, given how the decadal is agnostic in looking at Hawaii versus the Canary Islands, and given, as you say, the TMT prospects in Hawaii are really not any necessarily better as a result of the decadal's recommendations, to what extent is the report signaling or can you read between the lines that it's actually really pulling for the Canary Islands, and it's doing all that it can to give TMT as much political and economic cover so that the NSF actually funds something of this magnitude not on American soil?

SANDERS: You may be very insightful and seeing it right. When I read the report, I couldn't find anything in it that said, "Go build in the Canary Islands." However, my own reaction instantly after reading it was, "Oh my god, this is a clear ticket to build in the Canary Islands." I will tell you that in the days after the release of the report, the emails I got from people around the community were overwhelmingly, "My god, this is a license to go build in the Canary Islands. Why doesn't the TMT leadership immediately make that decision?" As far as I know, they haven't. The project manager is living in Hilo, and the public statements by the TMT board are very few and completely neutral. To me, and to many people who corresponded with me without being asked, this was an open invitation to go jump on La Palma and move forward.

ZIERLER: Knowing what you know about the TMT partners, will they move with alacrity? Will they understand? Or at least if your read is correct, do you think they'll read it in the right way, recognize that 2023 is not happening in Hawaii, and move accordingly?

SANDERS: I think they won't. I've said earlier in this series of interviews that they have a divergent set of views, and reaching consensus, let alone unanimity, has been frustratingly elusive. I have no indication that that is changing. Based on my reading and my judgment, I don't see that emerging. I think there's sufficient diversity among their viewpoints and political stances that net motion in any direction is elusive. I think it may be, if we end up seeing that TMT isn't built, that people are doing the postmortem, that indecision is what undermines TMT. I've often said that not making a decision is a decision, and I think that's what's likely going on right now, though I haven't sat in a TMT board meeting or talked to anyone directly who has been in those board meetings. But people don't change. We're talking about six institutions represented around the table by a number of people, two or three from each one of those institutions. I witnessed years of the process and discourse, and I don't think the decadal survey is a reason for them to change the way they reach decisions.

ZIERLER: Let's even be more specific here. The Canadians obviously have major concerns about building in Hawaii, so presumably they would be delighted about the prospects of building in the Canaries. Whereas the Japanese are all-in for Hawaii, right? Who are the other players? How might these internal dynamics change or not as a result of what the report said?

SANDERS: I think I said earlier in these interviews that I think India is prepared, and frustratingly prepared, to go to the Canary Islands. I think they said for years, in front of me at board meetings, "Our government wants to know why you just don't pick the Canary Islands and go?" And so strong in those feelings that there was anger and a discontinuation of the cash funding by the Indians, for years. I think that is probably not changed by the decadal survey. So you've got Japan overwhelmingly, although perhaps not 100% but overwhelmingly, focused on Hawaii. Canada, I think, overwhelmingly focused on not harming indigenous people, which makes Canary Islands acceptable to them, and they've said that, in their Long Range Plan, that it is acceptable as an alternate, with very carefully written words. And India, for the Canary Islands. And who did I leave out here? China, whose role is very complex and hard to assess in this. China has traditionally supported large scientific projects only on its own soil and with the recent evolution of its geopolitical stance, this is likely to be even more focused in a China-centric manner. So I don't think China can push this one way or another. And formal discussions and relations between the US and China are really the only way to lead to Chinese participation at either site. This is increasingly challenging, but TMT could be part of a peaceful joint activity between these two powers amidst a growing confrontational stance. Caltech and UC, the last time I had contact with folks at Caltech and the leadership of Caltech, they wanted the project to go forward, and if Canary Islands was the way to get the project to go forward, go forward. I think they understood that the Canary Islands was the right choice but that the way to the Canary Islands, given all of the other perspectives and politics, was through Hawaii. Hawaii had to fail to open the way to the Canary Islands. Perhaps the decadal impetus revives that viewpoint. There you see the issues. I don't see that those things have changed much.

ZIERLER: What institutional flexibility does Caltech have, to the extent that the stakes for Caltech in terms of its long-enjoyed leadership in ground-based astronomy, if TMT fails to come to fruition, what does this mean for Caltech, and what might it do between now and 2023 to make sure that the scenario you're painting, that TMT remained mired in its hope that it will be built in Hawaii and that ultimately it will come to nothing, what will that mean for Caltech, and what can Caltech do to avert that scenario?

SANDERS: Speak up and push very hard for what I think Caltech—and I'm not one of them, but I'm going to guess that the president of Caltech and the trustees would see that the decadal survey increases the prospects for federal funding strongly, and that the way forward is likely to be the Canary Islands. So I'm going to guess—again with no input from any one of those folks; the last time I spoke to them was in 2019, to the trustees for example, and things have changed—but my guess is the decadal survey means that the trustees would favor moving forward.

I think I told you that when I was invited by Barry Barish while I was working at Los Alamos to work on LIGO and come to Caltech, my first thought was to do it, yes, and that Caltech is one of the only places in the world you could imagine doing something as wacky and grand as LIGO. It's the place to build the world's most amazing observatories that move the whole field together. It had been like that for a century. Here we are in 2021 where it's 120 years of Caltech leadership in ground-based astronomy, in many, many ways, but mostly in the optical and then optical and infrared later, and with LIGO. What a shame. I mean, I said mourning U.S. loss of leadership in optical and infrared like the SSC; I would also mourn, as someone who worked 26, 27 years at Caltech, I'd really mourn Caltech's loss of that position. The bleeding-edge smart people at Caltech are the ones who took those best facilities and made them the leaders. You can take the best facility in the world and give it to a bunch of good astronomers, and you'll get a certain good outcome, but the combination of Caltech's what I would call bleeding-edge smart people, and the best facilities, wow, that has carried us for 120 years. What a shame to lose that. What a shame to lose that.

ZIERLER: And the way we don't is if it's full steam ahead in La Palma, is what you're saying?

SANDERS: The way to go forward is for Caltech to speak up and say, "Full steam ahead in La Palma. Let's go to the NSF and figure out how to do this" and presumably to carry along their colleagues at UC, who I think ought to see the same thing. They participated in part of that leadership with Keck, for example. UC is a little more difficult because it's a gigantic, diverse, multi-campus institution, so it's not quite the same as having a meeting of the Caltech trustees who can just make a decision. Caltech has an agility. In addition to the bleeding-edge smart people, Caltech has an agility that the UC doesn't have. But they could work with their colleagues at UC who are also—the UC campuses are full of people who do not want to impact indigenous people. So there's a strong reason for UC to work with Caltech, and Caltech to work with UC, and it really is a great partnership. Then you've got the Moore Foundation. The Moore Foundation wants to support Caltech and UC, and is very sensitive—their own programs, they work a lot with indigenous people. To me, the private component of this should overwhelmingly be pushing for the Canary Islands. I don't know that it will happen, and I don't know that Caltech and UC aren't a bit burnt out. Leadership has changed.

I also have to say something else. One of the things that Caltech has done so well over the many, many decades is to always be on top of the—I'll call it the bleeding edge of science. I think part of the bleeding edge of science today is astronomy and astrophysics and cosmology. That's why I continue to work in it, now on the cosmology end. But there's a hell of a lot of other things, like the quantum computing, and the AI, and a lot of biological medical things. Caltech is just out there. So it may be that also, maybe, there's a historic thrust in the aspirations of Caltech that moves it in other directions. I think the scientific basis for Caltech continuing to lead in ground-based astronomy is still there. I think it competes with any of these other new thrusts in science. But I don't know what's on the mind of the leaders of Caltech who may be seeing more clearly than I—that is their job, by the way—what is the science we should be at 30 years from now, 50 years from now. Caltech is so good at that.

ZIERLER: On that point, just to put a bow on this discussion, we've been talking almost exclusively in the realm of culture and politics and funding. Let's just end remembering the importance of the astronomy. Hopefully the TMT will be built. Realistically, it would be great if it happens in Hawaii in a way that that works for everybody, but realistically, it's much more feasible that it will actually go through in the Canary Islands. If it does go through, what does that mean? What's so exciting in astronomy, in cosmology, in astrophysics, what can the TMT do that hasn't been done before?

SANDERS: First of all, the right place to get the answer to that question is to read the decadal survey report. They are the high priests and priestesses of the field and they have written it down. But we are in an amazingly—just as a comparative layman in this field compared to that combined corporate voice of the decadal survey, what do we know about the universe, and what is the rate at which we're learning new things? It's amazing how little we know about the universe and how quickly we're learning things.

I worked for decades in high-energy physics and contributed to the building of what we call the Standard Model, and it turns out the Standard Model, everything we worked on, was only a few percent of what's in the universe. We don't understand dark matter. We don't understand dark energy. We don't understand what happened in the very short instance after the Big Bang. The field that I've now moved into, cosmic microwave background, we're looking at the first light from the horizon of the expanding observable universe, 380,000 years after the Big Bang, and trying to find the imprint from gravitational waves that occurred 10-35, 10-36 seconds after the Big Bang from this inflation mechanism, which may or may not be true. In other words, profound ignorance. Was the Big Bang the beginning of time? Is there a t=0? Or was time before t=0? Are we an observable universe or are there many other universes? So the level of ignorance that we have about the really important questions is profound, despite the fact that in my lifetime, we have learned a lot.

Then if you look at, in every five-year or ten-year period, what we're learning, like the detection of gravitational waves and the observation of a whole bunch of different kinds of systems that we do not understand, that shouldn't have been there in our conventional wisdom—just to pick on that. Then there are so many other things in astronomy, astrophysics, and particle physics. How do you make really big black holes? No one knew how to do that, but now they're beginning to think that really big black holes may just be because you made black holes and then the universe expanded and they got bigger. Whole new ways of thinking about the universe. So, the decadal survey said, "You want to understand this stuff? You want to make progress into our profound ignorance? Build US-ELT. Build CMB-S4. Build ngVLA. Build the next generation gravitational wave thing." They got it right. That's my answer.

ZIERLER: Let's hope that TMT gets it right, also.

SANDERS: I certainly hope so.

ZIERLER: I'm so glad we were able to have this follow-on conversation. Let's follow up. Let's see where we are in 2023.

SANDERS: Okay!

[End]