Raymond Jeanloz

Raymond Jeanloz

Professor of Earth and Planetary Science, University of California, Berkeley

By David Zierler

August 2, 2022

DAVID ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It is Tuesday, August 2, 2022. I'm delighted to be here with Professor Raymond Jeanloz. Raymond, it's great to be with you. Thank you so much for joining me today.

RAYMOND JEANLOZ: Thank you. I'm really delighted to be able to talk with you.

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

JEANLOZ: I'm a Professor in the Department of Earth and Planetary Science at University of California, Berkeley. As it happens, I'm also a Professor in the Astronomy Department, and I have a faculty appointment in our Institute of International Studies. In addition to that, I also have an appointment at the Hoover Institution at Stanford University.

ZIERLER: Let's unpack that. First of all, the appointment in astronomy. To what extent is that about the fact that your interests in geophysics are not strictly terrestrial, that you have interests in other planets as well?

JEANLOZ: Absolutely. I think my engagement in our Astronomy Department, quite frankly, was triggered by my involvement more in teaching than in research, initially. I developed a very large course, mainly for non-scientists. As is often the case, astronomy classes are not only designed for science majors. When I say science, of course, I mean natural sciences. But a chair or the department several years ago decided that because of that teaching engagement – I'd created some courses that were jointly run by our two departments – that they wanted me more involved in the astronomy department. As it happened, at about that time, the revolution was starting to happen in astronomy with the discovery of extrasolar system planets, so perhaps that played a role as well. But increasingly, astronomy was embracing planetary science as part of the spectrum of astronomy, rather than either you do astronomy and astrophysics, or you do planetary and Earth science. There was really more of a sense of unification, and I certainly appreciated that, and welcomed and supported this kind of bridging between the departments. I'm not the only one with those kinds of joint appointments around here. Colleagues from astronomy have entered into my department, EPS, and vice versa. I think that's maybe one of the features we have on the Berkeley campus.

ZIERLER: Just to get a sense chronologically, what was your point of entree into the world of international affairs and nuclear security issues?

JEANLOZ: The honest answer is, one thing led to another. It was incremental. I've been here at Berkeley since 1982, and in the mid- to late 1980s, I was getting quite involved in the overlap between science and policy, starting with, for example, science education. I was quite interested in how we could improve science education and improve the impact of what we do in the natural sciences upon the broader public. That was not a very big focus at that time compared to what it is now. Of course, there were superstars like Carl Sagan promoting this idea, but I was quite enthusiastic about reaching out to the public, first through science education, and then through aspects of policy. I also got involved in what are now called decadal studies. I was involved in one of the first ones done for the Earth sciences back in the 1980s.

And with that, I became involved in the National Academies, the National Research Council, some of their committees and the Board on Earth Sciences. Increasingly, that got me into the world of national and international security, as one of the applications of science in general, and even of geophysics. For example, one of the special roles that seismology has played is in monitoring for nuclear explosions around the world–nowadays, we find that seismology provides a monitoring of many, many human activities as well as many non-seismological phenomena around the world. This is a wonderful blossoming for that field scientifically, but also in terms of its social impact. That drew me in, and by the mid-1990s, I was spending much more time getting engaged at the interface between science and the security areas. I have been doing that for about 30 years now, more consciously focused on security, advising the US government primarily.

ZIERLER: Berkeley's such a big place, and you have so many affiliations there. What role does the Hoover Institution play for you, your responsibilities, your interests that you can't get more locally on the Berkeley campus?

JEANLOZ: Hoover's kind of a special place. I got drawn into the Hoover Institute, I'd say, for one reason that has been a theme throughout my career, including in my later career, which is, I had mentors. I had people who were reaching out to me and helping me enter into new areas or explore different topics, or I was advising them, or they were prompting me. I was not shy in responding to a senior leader telling me, "Here's something you should really look at," or, "I'd like to know the answer to that." And the people who specifically drove me into the Hoover Institute were Sidney Drell, a longstanding physics colleague at Stanford, and through him, George Shultz, a former secretary of state. And I became quite involved in their projects, including the so-called Gang of Four project in the early 2000s, to try to think about what it would take to have a world free of nuclear weapons. I'm happy to elaborate on that, but I just want to say that it was a very thoughtful effort led by highly experienced people, George Shultz, Henry Kissinger, Bill Perry, former Secretaries of State and Defense, and Sam Nunn, former Senator.

Very thoughtful about not just being Pollyanna-ish, but really thinking of what it would take to contain and control this incredibly powerful technology that is the nuclear technology. Of course, Sid Drell passed away several years ago, and more recently, George Shultz, but I had established some working relationships with a number of individuals, and they find my participation to still be interesting to them; from my point of view, I learn a lot from interacting with them. Most of the Hoover Institute is not technically oriented, so we're talking about political scientists, economists, people with policy expertise, senior retired military officers. I learn a lot from those very different communities, so I welcome that opportunity. As long as they're willing to invite me to participate in their activities, I'm happy to contribute and I get a lot out of it.

ZIERLER: The optimism around ridding the world of nuclear weapons perhaps reached its crescendo during the Obama Administration. Nowadays, with the crisis in Ukraine, concerns over Chinese designs on Taiwan, speaking for yourself, but also getting a sense from the peers you work with on these issues, is that more of a pipe dream, or would you say the optimism is still warranted?

JEANLOZ: I'd say the optimism is as warranted as ever. The actual process has historically been cyclic. We go through periods of crisis. Of course, during the Cold War, the Cuban Missile Crisis stands out as an important one, but there were other crises as well. There are also crises in confidence, times at which one or another nation decides it has to pull back and rearm itself or advance its armaments. These are cyclic processes.

For me, the underlying optimism is: we still have to keep on talking with each other. These are enormously powerful technologies. They're almost in a different universe as technologies; as technical people, it means something to say the power that nuclear explosive technologies have is on the order of a millionfold or 10-millionfold that of conventional chemical processes and explosives.

And we need, as scientific, technical, engineering people, to understand what that implies, what the consequences could or would be, and therefore, how we might mitigate and control those consequences, including the social and political consequences that might lead to the terrible use of some of these technologies.

You could ask the same question about biotechnologies that are also potentially very, very powerful in their own way. Not in the sense of physical destruction, but in other ways; and certainly in terms of the possible casualties, biological weapons are also horrific to contemplate. Nuclear technology is not alone in our acknowledging that we humans have gotten to a point of creating technologies that are very powerful, and the question is, are we emotionally, intellectually, socially strong enough to control those technologies we've created? How can you not be optimistic? The alternatives are really not something to be contemplated.

ZIERLER: Turning to your main area of expertise, in geophysics, what have been some of the commonalities of all the things you've pursued in your career? What aspect of geophysics has been central to your agenda?

JEANLOZ: Mostly, I'm interested in the properties of materials, planetary materials, to be sure. Planetary materials -- rocks, ices and the like -- are complicated things, so we often have to first understand more simple versions of materials: simple salts, metals, ceramics and oxides.

Then, the emphasis has been on understanding these material properties at very high pressures and temperatures, the conditions that exist deep inside planets. One of the themes has been that we want to understand the properties that control what makes up planets, how they evolve and change over time based on understanding what's happening deep inside them. In many instances, the chemical and physical properties are quite different from those at ambient conditions.

There are huge disciplines of chemistry, materials science, and condensed matter physics, and so on that tend to document materials at human ambient conditions, and we're passionate about trying to understand how those properties might change systematically as one goes to the more extreme conditions existing deep inside terrestrial (Earth-like) planets, giant planets, and even in the transition between planets and stars; so substellar objects, brown dwarfs, things like that.

ZIERLER: In what ways has your research agenda treated our knowledge of Earth and other planets as a two-way street? In other words, what we now understand about Earth, we can extrapolate to other planets, and vice versa.

JEANLOZ: Necessarily, we know so much more about Earth that we apply that knowledge and insight to other planets, in particular, the so-called terrestrial or rocky planets. Unfortunately, that can also be a flawed logic. Here, the best term I know of is actually one from the policy and security world, which is the phrase "mirror imaging." In other words, you imagine that some other nation, society, or perhaps even an adversary, thinks the way you do. It's a crude analogy, but we have to be very careful in thinking about other planets as being similar to Earth rather than appreciating that planets can be very different from each other.

Of course, the comeuppance for much of the community came with the discovery of extrasolar planets and realizing that our Solar System is not typical, as far as we can tell now. All the theories about planet formation and what planets ought to be like were very strongly based on, and biased by, our knowledge of the Solar System.

And then, we learned that most other planetary systems look really quite different, and we're trying, as a broad community, to parse out and understand this. Much of that, I have to admit, is only indirectly related to my own research, how planets actually form. Where we come in is, as a planet starts accumulating: the birthing of a planet is a violent process, with impacts and more.

This is something we actually start entering into and making measurements on materials, the kinds of high-density, high-pressure plasmas that are created at high temperatures as materials slam into each other, and fundamentally, offering much, maybe even most, of the energy source that then drives the subsequent geological evolution of a planet. It's kind of amazing to think that when we see volcanic eruptions and sense earthquakes here on Earth, to some significant degree, we're looking at the action, the geological activity that is still a consequence of that energy that was put into the planet 4.5 billion years ago as it was accumulated. I'm quite passionate about trying to understand those processes, including, in the case of Earth, the giant impact that led to the formation of the Moon, that basically splashed the Moon out of the earth.

ZIERLER: We all learned in grade school that our Sun is just a regular star, so wouldn't it follow that our Solar System would not be particularly special? What are some of the things we're seeing observationally that tell us otherwise?

JEANLOZ: We're really trying to parse what's typical and what's not, including recognizing that planetary systems change as a function of time. But of course, even from some of the earliest observations on extrasolar systems, the observations of planets very close to their stars, compared to what we see with Mercury, Venus and Earth, we have nothing like planets that orbit our Sun in a matter of a day or two or a few days, so that's one difference. Another difference is, large planets, like Jupiter and Saturn, that are quite close to their stars.

Early on, people were very skittish about interpreting those observations, because the nature of the observations tended to make it easier to identify and measure high rapidity, high-periodicity orbits, and orbits of heavier planets around a star. With the improvements in technology, it's been, I think, very conclusively shown that the sampling was not as biased as was at first feared. It's kind of amazing the quite different configurations we see in most extrasolar planetary systems, with close-in large planets and very close-in planets orbiting at very high periodicity.

ZIERLER: Given the fact that Earth has a biosphere, which makes it unique, as far as we can tell, what does that tell us about how unique earth's interior is relative to other planets? Or is the biosphere not considered to be a relevant factor here?

JEANLOZ: I have to say, on this one, I'm a bit of a skeptic and a cynic. As far as I can tell, biospheres may exist in a wide variety of environments. Let me give you an example of something that's a little bit of a pet peeve of mine. Astronomers and planetary scientists often refer to the habitable zone as being that region which is far enough away from the star that liquid water could be present at the planetary surface without boiling away, and not so far away from the star that the water is frozen as ice.

Why am I a little bit skeptical? Don't get me wrong, I use that concept, and it's based on trying to make sense of what observations are available. But the habitable zone is really a very pale reflection of the true range of conditions under which life not only can but probably does initiate and evolve. I'll give you an example. Even the icy moons, such as Europa or Enceladus, which are icy on the surface, harbor oceans underneath the ice layer, and those are very plausible environments for life. Subsurface life, but very plausible environments for something we would label as life.

Similarly, if you have volcanic activity, that can locally provide enough warmth to really stimulate life–and actually, we see something like that here on Earth, where we have the black smokers in the ocean basins that show an incredibly rich set of ecosystems in terms of diversity of organisms and genomic evolution. I'm actually quite enthusiastic about the possibility of life existing under a much broader range of environmental conditions than we normally think of.

In that sense, I kind of decouple the work I do on the long-term interior evolution of the planet from whether or not it can harbor life. But surely, the presence of an atmosphere, possibly of oceans or icy regions, can play a very important role in determining a biosphere and how life originates. My working hypothesis is that life originates quickly and often.

ZIERLER: A technical question. Absent our ability for direct observation of planetary interiors, being able to drill down far greater depths than 10 kilometers or whatever the limit is right now, can you explain the observational methods that we use so that we have a degree of confidence that this is not just a simulation, that we're seeing the real deal?

JEANLOZ: My community would challenge what you mean by direct observation because yes, grabbing a sample and looking at it is, in some sense, a direct observation, but so is probing the interior of a planet using acoustic seismic waves. In fact, you can come up with a conceptual argument that it's almost the better way to do things. With our eyes, we have a limited range of wavelengths with which we can look at things. With seismology, at least for Earth, there's a very broad range of frequencies or wavelengths, many orders of magnitude compared to the narrow window we have for our eyeballs. Better than that, we can see two kinds of waves. Light is just transverse waves corresponding to shear waves in seismology, but seismology can also look at pressure waves. There's actually a great richness that comes out of seismology in terms of studying Earth's interior, and now the interior of Mars, and hopefully, with time, other planetary interiors.

We even have some hope for the possibility of observing the elastic oscillations, seismic oscillations of large planets with the beautiful work that's been done in so-called helioseismology on the oscillations of the Sun, and there's hope in the community that at some point it'll be possible to also see the oscillations of the giant planets. Things are quite complicated, there are lots of winds, currents, and things that need to be looked at. But that's a very exciting domain in terms of understanding the materials, and also the dynamics of planetary interiors.

I'd be remiss if I didn't mention the other important process that is characteristic of planetary interiors, which is the creation or sustainment of a magnetic field. The magnetic field for Earth, the magnetic field for the planets in general, the internal magnetic field originates deep inside the planet in the stirring of electrically conductive fluid. For Earth, it's the iron-rich core; in the cases of Jupiter and Saturn, it's the metallic form of hydrogen or hydrogen-helium mixtures, as is the case also for the Sun.

And this is where my area comes in because we normally think of hydrogen as being a transparent gas, but at the conditions existing inside the giant planets, it's no longer a gas, it's a fluid. And indeed, it's a fluid metal. It's more like mercury in that it's electrically conductive, it's shiny, it's reflective, and we're quite enthusiastic about determining the properties of metallic hydrogen because at some level, it's actually the most abundant material in our Solar System. For example, it's what makes up the bulk of the interiors of Jupiter, Saturn and the Sun, and is also present in other giant planets. To varying degrees, it may even be present inside Earth as an alloy constituent. But we're very interested in the properties of metallic hydrogen for these planetary astronomical applications, and also because of the fundamental physics and chemistry that's involved.

ZIERLER: For all of your interests beyond Earth, ground-based telescopes, space-based telescopes, spacecraft themselves, I wonder if you can provide an overview of how each of these different instruments is important for the questions you're after.

JEANLOZ: The revolution in astronomy has happened in all three areas. It's really quite amazing. Ground-based telescopes are still at the cutting edge. Even though you might think, "They'll just be replaced by space telescopes that don't have to peer through the atmosphere," brilliant minds keep on coming up with new things that can be done. One area I'm very enthusiastic about, not in my own direct research, but I keep an eye on it, is the use of ground-based telescopes to monitor how the sky changes with time. I mean how specific astronomical or astrophysical objects are changing, so it's kind of time-dependent astronomy, and trying to understand how well we can get snapshots of processes. Of course, one version of that is also the discovery of extrasolar planets.

Two and a half decades ago, ground-based astronomy helped revolutionize that. And even now, there are observations that can be made on the ground that are too demanding to do in space. The other way to look at it is, you first try something very sophisticated and challenging on the ground, some new type of spectrometer or detector, and once that's proven out, then you take it to space.

The Hubble Telescope, I think appropriately, drew enormous public attention, only to be superseded. The general public may not quite realize it, but the scientific community is still reeling with the discoveries made with the Hubble Telescope, and it's not just pretty pictures that the public can enjoy, but a terrific set of scientific contributions. Many of the other space-based observations, the Kepler mission, for example, and of course, now, the James Webb Telescope. We're all super excited about these developments. Finally, the rovers, the landers, the kinds of instrumentation that have been taken to asteroids, to comets and to Mars: this is absolutely phenomenal. I hope to be able to see more samples actually return from these objects.

The cynic in me recognizes that very often, when we've gone to other places and picked up samples, it's only to then recognize that we already had those samples. We went to the Moon and didn't realize that some of the meteorites we had in our museum were actually lunar material. We've gone to Mars, and we've not yet returned samples, but our understanding is that we already have samples from Mars and from asteroids, including some specific asteroids we think we can recognize.

That said, it's still hugely important for us to go out there, catch bits of comet dust, stardust, as they say, but also the debris that's out there, including in these asteroidal objects, which are really the remnants left over from the formation of our own planetary system. By studying these, we can get a sense of the original materials that made up our planet, then people like me can come along and say, "Yeah, but, for example, Earth's core may or may not be exactly like the kinds of natural analogs we see in asteroids." And we want to understand those differences that may have taken place over geological time. As our own core has evolved, it's changed in temperature, possibly in chemical composition, it's unraveling itself. We're quite interested in those dynamics.

ZIERLER: This has been a great tour of some of the big questions you've pursued over your career. Let's do some personal history. We'll go back to Amherst College first. Were you interested in geophysics even as an undergraduate?

JEANLOZ: Essentially, no. I have to qualify that. Amherst is where I got my bachelor's degree, but it was actually the third college I went to. In fact, I even took what would nowadays be called a gap period. I intended it to be a year, it turned out to only be about six or seven months. But I mention this because one rushes through middle and high school, then off to college, and it served me, in my opinion, very well to have a little bit of a time period where I was starting to think, "What do I really want to do?"

To make a long story short, when I did come to Amherst, I'd come to the conclusion that I was interested in the sciences, and I happened to choose geology or Earth sciences because I also loved the outdoors. I was doing a lot of mountaineering and hiking, so it seemed like a natural way to get into the sciences. I'd had a little bit of science in high school, but quite frankly, I didn't have that much scientific training. I got a degree in geology at Amherst, and the teachers there were terrific. I got a fair amount of math.

But I'll just be blunt, I had a poor science background compared to many of my peers getting degrees in the sciences. That was one of the key reasons why I came to Caltech. I wanted to shore up my technical background in the sciences. And that was a rousing success for me. I can't speak for Caltech, but it was a terrific experience coming to Caltech and being immersed in what I still think of as kind of monastery of science. I was immersed in coursework and research. And I really learned an enormous amount, I had to beef up my physics, my chemistry backgrounds. I was surrounded by other graduate students who had been physics majors, chemistry majors, biology majors. That served me really well. I'm not sure they got as much out of me as I got out of them, but it was a terrific experience. And in that sense, Amherst prepared me very well.

When I say my science training was mediocre, it wasn't their fault. In college, I was primarily interested in comparative literature and music, a little bit of anthropology. It was only toward the end that I focused on science. Graduate school was really to get my science going.

ZIERLER: It begs the question, intellectually and geographically, you were a long way off from Caltech as an undergraduate. Was it a professor? Did you do your own research? Were you aware of Caltech's reputation? How did the Seismo Lab get on your radar?

JEANLOZ: It really was the reputation of Caltech and the Seismo Lab. The department at Caltech really stood out as a premiere research environment, and I knew that Caltech had the highest of standards for education. I liked the small size. All of the schools I went to in college were quite small. Actually, the very first college I went to was in Eastern California, and I guess it was one of the smallest accredited colleges in the United States. But anyway, I was coming back to California in that limited sense. In fact, I'd been introduced to some geology in Eastern California when I was in my first two years of college. I came back to Caltech because of the reputation in the sciences in general, and Earth sciences in particular at the Seismo Lab was just off-the-scale excellent.

ZIERLER: When you arrived, was it still in a moment of transition? Was the Seismo Lab still up in the hills, or had it already moved to campus?

JEANLOZ: It had just moved to campus, and I benefitted from the fact that–due to the gap period I took, I finished my bachelor's degree in December rather than the normal June. Had I come to Caltech a bit earlier, I might've been caught up in that transition. As it happened, when I arrived, that transition was already complete, so I was very lucky that way. And second, I was lucky because I didn't quite fit into the normal schedule of courses. I was able, in my opinion, to have a little bit more flexibility with the courses and activities I undertook. Because I came in mid-year. I was kind of an oddball, at least for that reason, if not for others as well. But that served me well. I suspect my mentors and professors may have found that I was kind of a pain in the neck from that point of view, but I'd like to think that wasn't an issue or a problem.

ZIERLER: How much of your time was specific to the Seismo Lab, and how much of it was, as you mentioned, playing catch-up in GPS more generally?

JEANLOZ: I had quite good geology training, so from the geology point of view, I'd done summer work, working with the USGS and also on an NSF-sponsored research project. I had a bit of experience in doing field-related geology. I really needed beefing up in physics, chemistry, and math. Some of that, I did through courses, but quite frankly, a lot of that, I did on my own.

At the time, I had the view as an undergraduate student, and also in high school, that the teaching of science, physical science in particular, was not very good in the United States. I'm sorry to say, I'm not sure that my opinion is that much better these days: one of the reasons I've been very passionate about trying to contribute to science education. I thought at the time that it was one of these go, no-go decisions. To be considered a serious science student, you'd have to put up with all kinds of crazy demands–you're supposed to work super hard, and it's okay that this homework took you 20 hours to do.

We're not trying to abuse science students or students in general. In many cases, we're trying to entice students to learn a little bit about science without the idea being that they have to become science majors or professionals, or else they're not worthy of the topics. Quite the opposite. We'd like to inform citizens so that they have a better understanding of the technology in which we're all immersed in our modern society.

I'm speaking in gross generalizations. I was very lucky to have fantastic professors and teachers at every level, high school, multiple colleges, Caltech. But I was informed by the concern that more often than not, I might take a class and after a lecture or two, realize, "This is way more work than the reward. I'm willing to work hard, but not if it's gratuitous." One thing I realized at the time was that the most efficient way to learn something is to have a good mentor, a senior person you can sit down with who says, "Here's how it works." And that's the objective, I think, in good classes. The idea is for the professor to try and communicate that to as many people as possible.

It doesn't always work because people are at different levels, and describing things one way works for some, but not others. I acknowledge that. In fact, one of the features of some of the work I've done in teaching is to try and provide alternative ways to come to a conclusion and understand something. That's what was hard for me to find in the normal courses at the time. On the other hand, I found mentors, professors who were willing to sit down with me. And one of the benefits of Caltech because it was small is, I found it was possible to go knock on doors and say, "I don't understand this. Can you help explain it?" And that was a huge benefit for me. In a weird way, I'm now realizing that I really benefitted from the fact that I wasn't all that successful in coursework. I got pretty good grades when I finished in college and all that, but it was a struggle, and it was more self-taught material and going to mentors that became a huge theme for me throughout my career. Any success I've had really comes from those individuals who have helped me and the fact that, in a way, I had to turn to alternative mechanisms rather than the courses we professors think are the best way to communicate with students.

ZIERLER: Given that at Caltech, initially, there was so much for you to learn and so many professors to work with, what was the process of narrowing your interests, choosing a thesis advisor, choosing a dissertation topic?

JEANLOZ: Very often, it's a combination of the subject itself being interesting, something catches your attention, catches your eye; and, inevitably, personal style also plays a role. I want to be careful how I say this, but I quickly identified a mentor and supporter, my thesis advisor, Tom Ahrens, where we found a mutual compatibility that really worked. He reached out and provided support right from the beginning when I was at Caltech, so he really identified me rather than the other way around. I found him to be a very good person to work with. We had similar working styles. I was probably working like a fanatic, as I think he was at the time. [Laugh] He was not very popular with students because he would be in his office on a Sunday morning or a Saturday afternoon or evening, and a lot of students felt, "I've got a life. I've got other things I want to do." I was at a phase in my life, and maybe I'm still in it, where I was really committed to learning stuff. If I wasn't in the lab or my office working on something, doing an analysis or collecting data, more likely than not, I was at home reading through a textbook or something. And that kind of resonated. I have to admit, that working style played a role. And that's informed me as a professor and advisor over the years.

I'm very honest with graduate students who are getting started in stating: "It almost matters less what you or the research group is working on than the working style. If you resonate with that group, if they support you, if they provide an environment you feel really good working in." I really had that. My advisor was not alone, I found out I had several people I could turn to. In fact, I remember the director of the lab, Don Anderson, was a longstanding friend and colleague over the years. I viewed him also as another great mentor. I could knock on his door and ask for his advice.

These people, I realized later on, had also introduced me to the fact that they were busy doing things outside their research. They were busy in Washington DC, they were involved with the space program, they were involved in advising the government, and I'm sure that also had an influence on me and my interest in reaching out to the policy implications of science.

ZIERLER: Was JPL a resource for you at all during graduate school?

JEANLOZ: Not directly. It could've been, but I was very involved with the shockwave laboratory in the sub-basement of South Mudd, and that was a unique facility. It had just been set up, and it was a unique facility in academia. In fact, it's still the case that there are very few of these kinds of shockwave facilities. It's not that there was a deficiency at JPL, there was just such an overabundant richness on the campus, and at the time with the new Seismo Lab, that I didn't really have much time to go out to JPL. I went there a few times, but most of my activities were really at the level of understanding basic material properties. The comment I made earlier that we aspire to learn about complicated materials like minerals, feldspar or quartz, stuff like that, but to get there, you have to start off with measuring the properties of gold, platinum, silver, or sodium chloride, and so on.

We were really in the throes of doing some basic experimental work, trying to understand the role of impact on changing rocks as they get impacted on a planetary surface. This was as the Apollo program was winding down, and all those rocks had been brought back. Essentially every one of those rocks has been subjected to a whole range of impacts, from large-scale to micro-meteorites. Then, we were also interested intrinsically in the properties of materials at high pressures and how that might apply to understanding the interiors of planets, the cores, deep mantles. There was kind of this dual use. One is planetary impact, and the other was planetary interiors. And that still remains a theme of interest.

ZIERLER: Intellectually, as you were getting ready to focus on your dissertation topic, what were some of the bigger questions in the field at the time, and how did you see your research developing to be responsive to some of those questions?

JEANLOZ: We were trying to understand some of the basic properties of the deep mantle of the Earth, the core of the Earth, the kinds of materials that are present there. Already, I was collecting some data. But I was also analyzing other people's data to try to understand the properties of, for example, Earth's core, based on what one can infer from the properties of iron at very high pressures and temperatures. I was happy to take other people's results and try and interpret them.

In the case of my own experiments, I was also really interested in impact metamorphism, how rocks get changed upon impact. I did some studies to try and understand what you might think of as how to interpret the textures and changes one observes in rocks that have been subjected to impact. Impact on Earth, by the way, as much as lunar rocks.

I might mention that this was the heyday of Gene Shoemaker, another professor in the Division, documenting how many craters are still observable on Earth. Many of them have been deformed, eroded or transformed over time because of Earth's geological processes, but he was really bringing home how much Earth's surface still has a record of ancient impacts. In combination with the lunar samples and lunar program that documented the impacts on the Moon, I was quite intrigued in trying to see, for example, if we could take a rock and say something about the size of the impact, the velocity or magnitude. It turns out we can say some things, but there are a lot of complications and modeling involved.

At that time, I was also branching out into some new experimental techniques. I mentioned dynamic compression in the shock-wave lab, basically shooting a bullet at a sample. That was one of the specialties at Caltech. At the same time, there was another development in the field, which was the development of so-called diamond-anvil cells, basically squeezing on a tiny speck of material between the points of two diamonds. And that technology was just coming online.

As a graduate student, I was really fascinated by that. I went to the leading experts in the field, in Washington DC, and spent some time learning those techniques, collaborating, and putting together a few early studies while I was a graduate student. I was very lucky to have mentors and professors at Caltech who provided the intellectual and financial support, who said, "Go for it. We can redirect our grant money to include these new technologies." I was able to start combining the kinds of measurements that can be obtained. Under impact, you not only compress materials but heat them up, whereas when you squeeze a material between the tips of two diamonds, you don't heat it unless you separately put the diamonds in an oven or use a laser to heat the sample. These were technical differences we could use to combine the data from both types of experiments to say more about material properties, and that became a theme, especially after I left Caltech. I've continued to use both of those technologies.

ZIERLER: Can you talk a little bit about the interplay of theory and observation for your thesis research?

JEANLOZ: At the time, theory was very limited. I'd say by comparison now, first principles theory, quantum mechanics has become really an important working tool in the planetary and geophysical sciences, just as it has in materials science, condensed-matter physics, and chemistry. It's been a real revolution where for many years, even well into the first decade or more of my career, the theoreticians doing first principle calculations were still trying to develop their techniques, improve them, improve the approximations. It's quantum mechanics, but in practice, many approximations have to be made in solving for material properties. At the time, we were trying to provide experimental data that would help to test theoretical calculations, improve those calculations, extend them. At some level, we're still doing that, but there was a real change starting somewhere between 20 and 30 years ago.

People doing theory now come to us and say, "I can predict that you'll see the following if you do the experiment." In the 1980s, and well into the 90s, it was the other way around. You'd do an experiment, make a measurement, and the theoreticians would come running after you, saying, "Look, I was able to reproduce your experimental measurement. I get the same answer, more or less." We'd say, "Yeah, but that's not very useful. I needed that before I did the experiment." Now, it's the other way around. They come to us and say, "I can not only calculate the properties for many more materials than you can measure, I can calculate them at conditions that are really hard for you to get to, and I can calculate properties that are really hard for you to measure." It's the other way around.

Theoreticians come to us. They help us design experiments, help to interpret the measurements, help us to extrapolate the measurements to properties we may not be able to measure, and extrapolate to conditions we might not be able to get to. There's been a wonderful intermingling of the communities, and from my point of view, it's been a fantastic development over the years. I've been part of that, I've benefitted from that, and we've certainly supported having that blending between theory and experiment. In my group, we've done a certain amount of theory over the years, just enough to keep us in tune with the theoreticians. Otherwise, we work with people doing full-time theory just as we work with people who do full-time technical laboratory work, and we try to provide a bridge between the communities.

ZIERLER: You mentioned the importance of modeling during graduate school. It's going to sound like a long time ago, but what did the computers look like, and how did you use them?

JEANLOZ: At the time, I did almost everything with a hand calculator. I remember when the first megabyte of memory was brought in. It was a big deal. [Laugh] Quite frankly, it was a transition period where, if I'd stayed on a little bit longer, what I was developing would've clearly gone over into being more computerized. I'll give you an example. We used to collect the records from shock experiments on photographic film. I think I was one of the first, at least at Caltech, to go over to the Astronomy Department, where they'd already discovered when they had photographic plates, they wanted to digitize them because then, you can analyze them on the computer. I actually used a digitizer of photographic plates in the Astronomy Department and digitized these records so they could then be processed numerically, digitally.

That was a big breakthrough. The actual analysis I did was pretty much by a programmable calculator, I guess a precursor of a laptop. A little bit after I left, everything was becoming more automated. Rather than doing things by hand, one would start processing the data using routines that, quite frankly, decades later, we're still working to develop community-wide. Every graduate student develops their own routines, but making it a user-friendly community program takes a huge amount of effort and coordination across the community. We're getting there. Certainly, we see this in many fields, seismology included. It's also happening in high-pressure research. But it's just to acknowledge that first deriving the equations and showing that you can apply them to the data is a big effort. Doing the first studies is a big effort. But making all of that really accessible to the community is also a lot of effort and requires community coordination, which fortunately, we have.

ZIERLER: Did your research involve any field work, or was data coming in remotely?

JEANLOZ: I did some research in my first year and a half or so that included a field project in Southern California. But I never went back into the field. Ironically, even though I entered the sciences through Earth sciences because I liked the outdoors, I think I discovered I really enjoyed the outdoors for fun. Less so for work. If you're doing things like geological mapping or sampling, it's like, "You've got to go up to that peak or ridge, or down to that valley, because you've got to see what's there, collect some samples," and that made me less enthusiastic than being able to hike wherever I wanted to. I think it was mostly the fact that I found the lab work really fascinating. I'd had a pretty strong background in thermodynamics, I was learning about topics like geodynamics, fluid dynamics that determines the thermal evolution of planets. I was really thrilled to learn about these more theoretical indoor types of approaches and concepts. I kind of got distracted from the field component altogether.

ZIERLER: When did you know you had enough to defend?

JEANLOZ: I was just publishing papers as a graduate student. I was starting to give talks at conferences, but I was also starting to give talks in departments, and departments were starting to indicate an interest in whether I'd be interested in a faculty appointment. Again, hindsight gets distorted over time, so I don't want to read too much into this, but I was very passionate about research, about the academic career. I was interested in teaching. I must say, my recollection was that teaching was not one of the great emphases for the faculty at Caltech. There were some great teachers, don't get me wrong, but it's not like in the modern time. Certainly, nowadays, at any high-level university, everyone is expected to contribute to the educational mission at least as much as to the scholarly research mission. But I was quite passionate on the teaching end as well. In fact, I even started doing some teaching when I was in high school. But the short story was that I was starting to get interest from various universities. There was talk of a possible job offer if I finished my thesis, so I took a bunch of papers and strung them together. I'd been very, very lucky to have such supportive faculty around me who just cheered me on, at least as far as I know.

ZIERLER: Who was on your thesis committee?

JEANLOZ: I know Don Anderson was a longstanding advisor. George Rossman was also one of my advisors. I know he advised one of my orals proposals, and he was a big influence on me. The chemistry and spectroscopy background he had was something quite new to me, so I learned a lot from him. He had to bring me up to speed on some things that I'm sure were incredibly introductory, and he was actually a very effective teacher, and I very much appreciated working with him.

Tom Ahrens was my main advisor. Lee Silver was the person who mentored the fieldwork I did. I also got advice over the years from Gerry Wasserburg, who I remember as a very busy guy, not only in the lab, but doing a lot of work in Washington and the like. So I'm not sure how much of an advisor he was officially, but I certainly got a lot out of talking with him. Ironically, over the subsequent years, after I left Caltech, I saw Gerry in a number of academic environments, where we had very good interactions. Same with Tom Ahrens and Don Anderson. These were colleagues who I would run into and were very good mentors, even beyond the PhD.

ZIERLER: After you graduated, what opportunities were available to you? What did you want to do next?

JEANLOZ: I was in a place where I was able to go into a faculty position right away. When people look at me funny like, "How's that even possible?" I say it was a place and time where what I was doing was in a brand-new field. It was kind of self-identifying as mineral physics or the physics and chemistry of minerals. At the time, it wasn't even condensed-matter physics, the research areas were a combination of solid-state physics, metallurgy, ceramics. These were the fields of materials science and physics. Working at the interface between those fields was exciting. I benefitted enormously from talking with materials scientists, including at Caltech, UCLA, and elsewhere.

The difference in what we were doing with planetary materials was looking at really ugly, complicated materials, complicated crystal structures, but also there was always this tension in the community, and we still have it. Do you try to work on the purest, best sample that you can get? Or do you work on a dirty actual sample that might have all sorts of impurities and imperfections? The answer, of course, is you have to do both.

You have to see what you can determine on the very pure, exquisite, high-quality artificial samples with which you can try and establish reproducible properties But you also want to make measurements on the natural versions, hopefully not too far-removed, to see if any of those impurities, defects, and minor elements make any difference. Sometimes they make a huge difference, and in many cases, they don't make any difference. It's really important for us to disentangle that, and it's been one of the themes in my career that in my lab, we're very proud to often work on very dirty samples, while the rest of the community kind of holds their nose and says, "We would never touch those kinds of irreproducible samples."

And I totally understand that. We need all of the above. Anyway, I was very lucky that I was able to get a faculty appointment right away. In fact, as a graduate student, when I knew this prospect was coming together, it motivated me to wrap up my thesis. And I seem to remember I wrote an NSF proposal while I was a graduate student, and I was able to submit it through my new university department to actually get some funding pretty quickly, right when I started as an assistant professor. It was a very lucky time. Nowadays, when people ask me, "What should I do?" I say, "Consider at least one possibility is to create a new field." [Laugh] A crude analogy is, instead of trying to compete with all the other concert pianists out there, play a very unknown musical instrument, and become the world's expert at that.

ZIERLER: This is as much an educational culture question as anything else, but when you joined the faculty at Harvard, were you made to understand or was it understood itself that prospects for promotion for assistant professors were really nonexistent at that point?

JEANLOZ: My experience at Harvard was off-scale fantastic. It was absolutely wonderful. To answer your question, no. I always felt very welcome, I had wonderful collaborations with people in chemistry, with people in materials science, what's now the Division of Applied Science at Harvard. They had a materials research center, and I participated in its activities. In chemistry, they had a group doing first-principles calculations with an absolutely charismatic professor, who has since switched fields: Roy Gordon, a terrific colleague. And he had come in as an assistant professor and gotten tenure. In my opinion, he's a brilliant person, so just because he managed to do it doesn't mean that I would manage to do it.

But to be honest, I always felt extremely well-supported intellectually by the department. It's not only that I had no complaints, I thought it was a wonderful environment in which to work, to set up a lab, and to thrive. It was a very traditional department, very traditional university. The flavor, style, culture was, of course, quite different from Caltech. But I'd grown up in the Boston area, so I was familiar with the seasons, and I very much enjoyed living close to the campus and being there. And I have nothing but really positive recollections. And I felt that way at the time.

ZIERLER: What aspects of your time at Harvard were a continuation of what you were pursuing at Caltech, and what was brand new, just by virtue of being in a new environment?

JEANLOZ: I consciously moved away from the shockwave experiments. That requires a very big laboratory and lots of funding. Quite frankly, I kind of felt sorry for how hard Tom Ahrens had to work to maintain the funding to sustain that lab. I decided to go in a different direction, which was to use the relatively newer technology of diamond-anvil cells, very miniaturized.

Actually, this also reflects on personal style. Even though I'd been in a lab, where you have big bags of propellant, big samples, big diagnostics, I actually kind of liked the miniaturized world of diamond-anvil cells. A lot of technology was becoming miniaturized at the time. A lot of detectors were making it possible to study samples in tiny specks, synchrotrons were becoming available for doing X-ray diffraction and spectroscopy. A lot of technologies were becoming available to emphasize small samples.

I developed a small-scale lab for diamond-anvil research at Harvard, consciously moving away from shockwave experiments. But it's not that I abandoned the science. I was still interested in the science of shock waves, and either through collaboration or maintaining communication with Caltech or other labs that did this kind of thing, I maintained an interest.

Ironically, I didn't know it at the time, but my senior colleague at Harvard, Francis Birch, had been one of the pioneers in developing shockwave experiments. And I didn't fully understand or appreciate this because his effort in this area was during the Manhattan Project during World War II, and he talked, I'd say, not at all about his war years or experience. In many regards, he was considered kind of the father of geophysics or the greatest geophysicist in the US for the 20th century, a fantastic individual. Very quiet, very reserved New Englander. He was always very, very nice to me. He had actually been a visiting professor at Caltech for maybe six months or so, so I'd known him a tiny bit as a graduate student, but I didn't really get to know him.

When I moved to Harvard, he had the office next-door, so I got to know him a bit. He was very charming, always incredibly friendly and supportive to me. He gave me some problems to work on, some of which I'm still working on. Very generous in that sense. But he did not tell me anything about his war years. I think I was aware that he worked at Los Alamos in the Manhattan Project, but I knew nothing about what he had done. It was only later on that I realized that a lot of what I had worked on as a graduate student, for example, shockwave experiments, really came out of the Manhattan Project-related research. I say this because I'm just a little bit sorry that had I known more what questions to ask, he might've been more forthcoming. I have to say, though, I asked enough questions that I knew he was just not willing to talk about his war experience. And I respected that. I was not going to press him on it. Of course, when he died, a lot of this history became available, I think because it became declassified.

ZIERLER: Tell me about the decision in 1982 to move to Berkeley.

JEANLOZ: Basically, I got a fantastic offer to move to the West Coast. I mentioned I grew up in Boston. Wonderful city. I lived in Cambridge, I could walk to work. It was wonderful. But even as a kid, I never liked hot and muggy summers. I can't stand Washington DC, New York, or Boston kinds of summers. When an opportunity came to move to Berkeley, the physical and intellectual climate was really terrific, with a wonderful offer made in terms of startup funds and setting up a lab. I saw opportunities for being able to collaborate in California with Caltech. It would be easier with Lawrence Livermore National Laboratory, where they did shock experiments, and I could pursue that collaboration.

But to be quite honest, Harvard was a great place. When this opportunity came up, there was a little bit of negotiation, but I felt there were real opportunities here. I'll also make another comment, I don't mean to be rude or anything, but the department here in Berkeley, in my view, had historically been one of the top departments but was not in good shape academically.

Its reputation was, in my view, plummeting. When I was being interviewed, another colleague was being interviewed, and we both compared notes. We came to the same conclusion, that weirdly, there were great opportunities to go someplace that was no longer the best in the world if it was embedded in a broader institution that was very top-quality. That was a conscious decision. It was a risk, but it's paid off fantastically.

The University has been incredibly supportive of developments in this Department. That colleague of mine is still here and just retired recently. We found we had a lot of opportunities for enhancing the impact of the department we're in because we're embedded in a larger university that has terrific capabilities, high standards, and all that. It was an opportunity to go to what was considered not the best department in the world anymore. Caltech, I think, was widely considered the best or one of the best. We aspired not so much to compete, but we all aspire to be top caliber in all of our education and scholarly work.

ZIERLER: Given that you saw your recruitment as part of a rebuilding of the department, did that influence your research at all, the kinds of questions you wanted to pursue when you joined the faculty?

JEANLOZ: Yeah, at that point, I was becoming a little more strategic. My first couple years, it was: set up a lab, and get some measurements done to establish some credibility in the new environment. I'd done enough of that, and I'd also done some theoretical and modeling work. Inevitably, as an experimentalist, when you're setting up a lab, it can take a year or more to get things going before you're up and running, maybe even longer sometimes. I did a fair amount of modeling analysis of other people's data and some other kinds of modeling. When I came to Berkeley, I was a little more strategic in realizing I had to think on a decade timescale. I had some plans. The main material that makes up the interior of our planet had been discovered. It's a mineral called bridgmanite now, the perovskite-structured, high-pressure phase of one of the minerals we see near Earth's surface.

And I was determined to study its properties and document its stability to very high pressures and so on. I was not the first to work on this, and I was not the discoverer of this phase, but I was determined to make sure we made some key measurements on that material. And we succeeded in doing that in the first five, six years I was here. I set up a lab, and we got those kinds of measurements made. And also measurements on iron, but the measurements on iron allowed me to renew collaborations with Caltech.

Our measurements on, for example, the melting of iron were done very collaboratively with the shockwave lab at Caltech, and we put out some results that were controversial at the time. They're less controversial now, but it's still an active area of study, and we were off and running. I do think I was a little bit more strategic. I felt I didn't need to perform with such an immediate kind of timescale for documenting results. I could think more on a decadal timescale, and that was a great opportunity.

ZIERLER: Was there a specific space mission or technological advance that propelled you into space science, beyond-Earth kinds of studies when you were at Berkeley?

JEANLOZ: I would say I was really focused, actually, on terrestrial planets and geophysics up until the mid-90s. It was really with the discovery of extrasolar planets that I became very excited about other planetary applications. Also, by that time, I'd become a little bit more enthusiastic about studying hydrogen and hydrogen-helium mixtures. I should mention that there was already a very active area of research, including with diamond-anvil cells and with shockwaves, on hydrogen at high pressures. The search for the metallic state of monatomic hydrogen has been going on for 80-plus years. We're not even sure we've managed to make it yet. There are some indications that it's been made, but it's still very controversial and hasn't been reproduced.

But long story short, I kind of stayed away from that area because it was a very competitive, specialized field. You needed a lot of specialized low-temperature technology and so on. With time, I became more involved in that community through shock experiments. I could collaborate. I eased myself into that community, looking at the materials making up the giant planets like hydrogen and helium. Quite frankly, it was a combination of that technology becoming more available and applicable, and the extrasolar planets that led to me realizing, "We're really going to have a huge amount of new information about planets in general, and we need to know better about a wide variety of compositions, ices, gases, rocks, metals, and so on, what the possible permutations are for planetary interiors."

ZIERLER: In the 1980s, while the Cold War was still happening, were you involved at all in nuclear weapons verification and things like that, or that came after?

JEANLOZ: I was aware of it, but I was not involved directly. I was aware, for example, that many of the graduate students in seismology at Caltech but also Berkeley were supported by the Air Force, basically, for research related to monitoring nuclear explosions. Actually, that program generated phenomenal capabilities and exquisite modeling and simulation, quantitative modeling of explosive movement. Because an explosion is a relatively simple source that can be modeled very exquisitely. And that same modeling could be applied to earthquakes, which are much more complicated rumbling, frictional stuttering, and so on. It was a terrific development from that point of view, from the modeling and simulation point of view. Terrific development of seismic networks around the world for monitoring purposes, now being used for Earth structure and monitoring of earthquakes. I observed that more on the sidelines, getting to know the seismologists, trying to interpret some of the broader data that applied, for example, to the core and the mantle.

But I was not so directly involved. It was really only in the mid-90s I became more involved with the nuclear weapons kinds of technologies. I should say, I did benefit from the fact that by then, I'd had 10 to 15 years' worth of collaborations with people at the Lawrence Livermore National Laboratory and Los Alamos National Laboratory. I was aware they had their mission-oriented programmatic work related to nuclear weapons. I was not at all involved in any of that. But I was aware that the same technologies I was using, gas guns for shock experiments, diamond-anvil cells to study materials at high pressures, somehow were relevant to the nuclear weapons technologies, and that seismology was involved with monitoring. Then, I got drawn in more from the advisory side to learn more about these techniques and how to advise policymakers about them.

ZIERLER: A chicken-and-the-egg question. When you were appointed professor of astronomy in 1998, how much of that was you were already doing work in that area, and you got kind of pulled into the department, and how much of it was that they saw what you were doing was really relevant to astronomy at that point?

JEANLOZ: I think the way they viewed me was more as contributing to their educational mission. It was through the teaching of big courses. Back in 1998, not just here in Berkeley but in most astronomy and astrophysics departments around the world, the planetary side was not very strongly emphasized. Usually, like in GPS at Caltech, planetary was associated more with Earth science and geology than astronomy and astrophysics, and I think that was more the norm. That has changed quite a bit, and to a large degree, because students have been knocking on the door, saying, "I'm really interested in extrasolar planets," so there's been a bridging between astronomy and geoscience, which I think has been good for both sides. And I think I happened to be in the right place at the right time. I was teaching courses using planetary science to teach concepts of science and technology to non-scientists, and I think my colleagues in astronomy were supportive of that.

I have to give credit, again, to Carl Sagan, who was a big positive influence in astronomy and the sciences in general. He really set a standard that I think still exists to date in astronomy for putting effort into public communication and education, broadly speaking. It's worthwhile, it's valuable, it's really important in all science, and he highlighted that in astronomy. I think there was a receptiveness there.

Quite frankly, some of the best teachers on this Campus are also in the Astronomy Department. Of course, I feel not only honored but challenged to try and match or emulate some of these superstar teachers. With time, though, I have to say, I have had research collaborations and graduate students in that Department, and those have involved some of my own materials-oriented research, bringing materials into the astronomical sciences, and I've always felt very welcomed by that community.

ZIERLER: If you can provide some historical perspective, nowadays, as you well know, there's so much excitement in exoplanet research coming from a variety of disciplines. From that first discovery 25, 30 years ago, was your sense that everybody knew that this was the tip of the iceberg? Or were people concerned that it was really just a one-off, and there wouldn't be this rich 5,000-planets-later kind of development that we've seen?

JEANLOZ: I think there was hope that there would be many discovered, dozens or hundreds. I don't recall imagining there would be thousands or tens of thousands, which is where we're headed now. But we were painfully aware that those first observations were very challenging. And certainly, by the time of the Kepler mission, the perspective had completely changed to, more or less, every star's got a planet around it and that kind of thing.

The original work raised the possibility that many more planets and a diversity of planets would be observed. You may recall that the very first evidence for a planet was really for a planet orbiting a dead star. There was the question of whether we'd see planetary systems in the mid or early life of a star or only after a system had evolved to its death. But that quickly changed with the brilliant observations made using the various doppler-based methods documenting that, indeed, one can start really documenting that there are many extrasolar systems. All of a sudden, we went from that hope for a few dozen to hundreds, then thousands observed.

ZIERLER: With all of the interest in both techno-signatures and bio-signatures, do you see a specific geophysics area of expertise that will help contribute to that all-important question about the potential for life beyond Earth?

JEANLOZ: Yeah, I think so. But I'm going to disappoint you because I'm going to disentangle two different things. I think the potential for life is very rich. The possibilities are high. As I said, my working hypothesis is that there's plenty of life out there. It starts early and often wherever it can. It's a hypothesis, and it's, in principle, falsifiable. That's different from what many people focus on when they say life. They think of "intelligent" life, or life that can communicate with us. That part is still, I'd say, very much in the realm of speculation, whether or not we would find evidence of other technological entities out there that could communicate with us. My enthusiasm for lifeforms being potentially present in a lot of places is just a recognition that we humans are just a weird end-member of–and I don't mean the most advanced, we're just the tip of a twig on a tiny branch on a bigger limb on the Tree of Life.

Much of that life can reside under very unusual circumstances, very demanding conditions, and under a great variety of conditions. When you think of life as we know it, it's mostly microbial, microorganism; not macro-organisms, like plants and animals we can see. From that point of view, I think there's a lot of potential for life being out there.

Looked at from that point of view, yes, we will have to be looking for bio-signatures. These might be spectroscopic indicators for certain molecules in atmospheres that we might be able to convince ourselves are more likely the result of biological or life processes than inorganic processes we might otherwise expect. And that really comes down to some combination of geochemistry and geophysics, but also combined with astronomical observations of the spectra of atmospheres, the kind of data that's just now beginning to come to fruition empirically.

ZIERLER: Because you've had a front-row seat to the processes, I wonder if you can talk a little bit about the role of the National Academy in formulating science policy in the United States.

JEANLOZ: Our National Academy of Sciences is a rather unusual organization. As far as I can tell, it's widely misunderstood, including by most of its members. It's really got a role to play in helping to inform the nation. It was established by Congress to advise the US government; that's its role. Ironically, it was designed to be an independent organization, not part of the government.

Nowadays, we talk about things like conflict of interest, thinking it's a modern concept, but this goes way back in our own history, including to the time of the Civil War, when the National Academy was set up. There was already the understanding that if you want solid, reliable advice, the best way to do that is to bring in an entity that is independent, that doesn't have an axe to grind or favoritism involved. By the way, ironically, there's also another small implication. All the work that, in general, we in the scientific community do for or within the Academy, or on its behalf, we do as volunteers. We're labeled as volunteers. And that was already embedded, again, when Congress commissioned it. They said, "We want people who are not getting paid."

I make this point because if you look around the world, there are not that many governments that benefit from having strong technical input that is also independent. I think this plays a very important role in our society and has great potential, looking to the future. In some cases, the academies are completely honorific, and have nothing to do with advising their governments or serving society, or the interface between science and society, except to the degree they think it's interesting. Maybe those academies are more to promote science and its appreciation. In other cases, there are advisory bodies around the world, but often, in other nations, quite frankly, the advisors are insiders. It's networked. Maybe they're even consultants being paid for their advice. There's nothing necessarily wrong with that, and we also have plenty of consultants to government. I'm just saying that the business model we have for the National Academy in the United States is rather unusual and, I think, serves us very well. It's not for me to say what other countries should do, but it does serve us well.

And I include in that not only advising on science and science policy, but other important domains like science and technical education for the public, including for the public that aren't going to become scientists or technical people, but also security, military advice on national defense, and so on. There are some countries where, for example, national defense and academia have a huge gap between them. They're pulled apart by social, cultural, or historical tradition, and I think we've benefitted a lot in the United States by bringing in academics from the outside with technical expertise, but who also ask questions such as: "Why are we doing this? Why are we doing it this way? Is this the right thing to be doing?" Policy, like science, is a human activity. It's not always perfect. In fact, in many cases, it's quite imperfect. We grope around, trying to find the best solutions.

But we can address current questions like, "Should we be collaborating with scientists in Russia, given the war that, from our understanding, is a war that was created by the Russian Federation? What's the moral thing to do from a policy point of view, long-term?" By the way, we would all like to think that at some point, there will be an opportunity for bringing about a peaceful resolution. How do you have a peaceful resolution if you don't have any channels of communication? There are issues like that.

I should also note, by the way, that immediately on the 24th of February, some of our most distinguished long-standing colleagues in the Russian scientific community stood up and very publicly said, "This is wrong. This is not us." Do we abandon those people, including, quite frankly, those in the intellectual community who can look to the outside? They know they're facing the potential of 15 years of prison just for calling the war into question. What's the right way for us to reach out and be supportive without undermining them, making them vulnerable, without facilitating the technology being put to bad use by the Russian Federation?

Not everyone in the scientific community in Russia has been against the war. In fact, there are some who have been vocally in support of the war that many of us consider to be absolutely wrong. Meanwhile, what do we do to support our colleagues in Ukraine and the surrounding European Union? These are big questions. I, as an individual, don't have the answers, but I'm happy to contribute, if I can, to some of the discussions about how to think about these things and find the right balance, so we don't just chop off all possibility of communication, but on the other hand, so we're not inadvertently facilitating an effort that many of us consider to be an absolutely wrong war imposed on a smaller neighboring state.

ZIERLER: Tell me about the Miller Institute at Berkeley and some of the value for you when you had an affiliation there.

JEANLOZ: The Miller Institute was made possible by an economist, not a natural scientist, with, at the time, a small endowment, a few million dollars in the mid 1950s. That money was very explicitly assigned to supporting basic research in science. And the argument of Professor Miller, a professor in what is now our business school, was that the applied areas of engineering and science, as well as other applied areas, get plenty of support from the government, industry, and society in general, but basic fundamental science, he felt, needed support because that would provide, if you will, the feedstock for future innovation and for applied technological developments we would all benefit from. He set aside this money; and that endowment, over the years, grew into a fairly substantial amount of money that has allowed our University to support scholars from the outside, post-doctoral fellows, visiting professors from the outside, and also given a bit of support for faculty on the inside who are doing basic research in science.

What I thought was wonderful about the Institute is that it was cross-disciplinary right from the start. Every aspect of science was involved, from astronomy and astrophysics to mathematics and zoology. The Institute's relatively small. Typically, there are maybe two dozen post-doctoral fellows. They get a three-year appointment, so maybe a dozen get appointed at a time, then some stay for a second or third year. There might be a dozen other members. It's only three-dozen people or so. What, to me, was important and interesting was the ability to talk across disciplines. I believe the first person to be a Miller post-doctoral fellow was, in fact, Carl Sagan.

When I became associated with the Institute, I thought there was a little bit of a tendency, and it's something that's very common in many departments, to have the attitude of, "The best way to deal with the endowment is to get the specialists in each area to identify the very best people in their specialty."

We kind of turned that logic on its head. We said, "We're really looking for people who are not only excellent at what they do, but can also communicate across the disciplines." You have to be willing and able to communicate. There are some people who want to do it but aren't very good at it, and there are some people who are very good at speaking, but they don't have very much to offer. You're looking for this magical combination of people with really interesting accomplishments, but also who can talk about them across the disciplines. We thought this was important, especially for the more senior members. I mentioned there are Miller professors and visiting professors. It was very important for that cadre to be in a place to mentor the post-doctoral fellows, who are just entering into the field.

A mark of our success is, actually, we find that the Miller post-doctoral fellows, especially those who have been here for six months or a year, really get it. They really understand how important it is to be able to communicate to someone in a different discipline, or maybe even someone who's not a scientist, in 30 seconds, in three minutes, in a short period of time.

"Here's what I do, here's why you care about it." Often, it's now the visiting professors, very eminent people who come in, and they're learning something. For the first time, they're put on the spot of not, "You're famous so-and-so, so I'm going to listen to you." It's like, "You tell me why I should be listening to you past the first 30 seconds." We're not adversarial, but through example, the Miller post-doctoral fellows have learned to communicate their material very effectively. And we've noticed some very senior people pick it up and go, "This is very interesting." We've been proud of that development of consciously being cross-disciplinary.

Some people have compared and contrasted us with the Society of Fellows at Harvard University, and I think actually the Society of Fellows has a similar kind of model, but there's a big difference. I'm not sure who's better off, but we have the easier task. The Society of Fellows cuts across many disciplines. The Miller Institute is really focused on science. There are benefits and drawbacks to both. You don't have the opportunity for a younger person to interact with the likes of a John Kenneth Galbraith, or a very famous author or historian. In that sense, we're narrower.

On the other hand, I think, especially for a first step toward broadening one's education and ability to communicate, we find it easier, and possibly more effective, to have a focus on the natural sciences. It's hard enough getting a biologist to be able to explain to an astrophysicist and statistical mechanic in physics what they're doing. We have a narrower domain, and we think that's already a big contribution. But don't get me wrong, these are great efforts on all sides, and I see them as complementary, in a sense. I was very lucky to be associated with the Institute.

We did start a program where once a year, we get together for a couple of days and have cross-disciplinary discussions. We've been doing this for approaching 25 years. And for comparison, I was part of a similar effort to have a cross-disciplinary conference in the United States, set up by a different organization, but it lasted only three years. I realized that it's very hard to make these things work. You have to have just the right audience and interaction. It's a combination of social interaction as well as willingness to take a risk.

You're literally asking people who are top-notch in their fields to be willing to ask a "stupid" question, to realize, "No matter what I ask, I'm not making a fool of myself. I'm just trying to learn." I have to say, this is something I learned from my advisor. Tom Ahrens was noted for asking questions about things he just didn't understand, no matter how introductory it was. Very much, I think, in my life, I've felt like the important thing is to communicate. There's no such thing as a dumb question. Of course, we may be ignorant about some basic things, or worse, we may have forgotten things we're trying to reconstruct. Maybe I'm asking a question about something I might've even discovered years ago. But the point is, it's okay to ask a question, and it's not a reflection of not caring or being stupid, but rather being interested. The Miller Institute has been a wonderful environment in which to develop that kind of theme.

ZIERLER: You're saying a mark of a truly great professor like Tom Ahrens is that they don't let their ego get in the way. When they're ignorant about something, they're not afraid to show it.

JEANLOZ: Just ask a "dumb" question. Ego is a very funny thing. It's very easy for us to think about ego as "the ego that fills a room" or suffocates everyone around them. Ego gets a bad rap, and for reasons like what you're alluding to, keeps people from asking the questions that would educate them and help them contribute more. On the other hand, ego is also what drives people to be excellent. There's this funny balance between ego being some of the fuel that powers much of innovation because there's someone who's really willing to work hard and try to become super rich, super famous, or super impactful, what have you. That's a form of ego. But you're absolutely right, ego can also get in the way.

ZIERLER: To bring our conversation up to the present, the last 10 years, specifically in light of your appointment at the Hoover Institute, just a time-management question. With all of your involvement in national policy and international affairs, how do you carve out the time for the science, to remain at the cutting edge of the field, to stay on top of the literature, to give your students the attention they need?

JEANLOZ: I have to admit, first of all, as a more senior scientist, I'm not keeping up. The literature is exploding in richness. Sadly, this means that for many students and younger colleagues, they tend to narrow their domain because that's the only way they can keep up within their own area. All I can recall for you is Richard Feynman's statement that he used to read the Physical Review from cover to cover whenever it came out, and now, there just wouldn't be the time in the day to do even some small fraction of that.

Part of the answer is, actually, the technology we're using right now. I can use video conferencing to talk with colleagues. I'll quote a colleague of mine who was in DC at the time, but he also has an appointment at the Hoover Institute. I said, "Next time you're in the Bay Area, please come and visit." He chuckled and said, "The reality is that it's so easy to have a video call, even across the Bay Area, why not do that?" That has revolutionized our ability to interact, also scientifically, across our research collaborations and teams, and in the international discussions we have. Actually, in the international realm, it's really been revolutionary because it's made it possible to speak with people quite often for shorter periods of time, but you can catch up and have question-and-answer cycles that are much more rapid. That's been part of the answer, but another part is that I'm not keeping up as well as I wish.

ZIERLER: To give a sense, to bring our conversation right up to the present day circa August 2022, what are you working on currently, both in the science and the policy realms?

JEANLOZ: I've been involved for more than two decades with a group within the Academy that talks with international security specialists or national defense specialists in other countries, specifically longstanding dialogs with colleagues in the Russian Federation, China, South Asia, but also many other parallel efforts. Right now, I'm part of an absolutely fantastic team of retired senior policymakers in the US, retired senior military officers, and a number of senior scientists – ­most of us not retired – talking about national and international security, arms control and so on. In the case of the Russian Federation, our group used to meet with our Russian counterparts every year or year and a half. We now video conference with each other every two weeks.

Our Chinese colleagues, similarly, we'd see them every year and a half. It's been historically very difficult for the Chinese to come into the United States because of certain visa restrictions on senior military and government officials, so we'd tend to go to China. Now, instead of seeing them every year and a half or two years, we see them every several weeks remotely. Of course, with COVID, we had to do that.

Ironically, this is one of the silver linings of COVID. COVID has been devastating around the world, to public health, mortality, and economies, but one of the silver linings is, it's gotten us very used to communicating remotely as human beings, but also in our intellectual endeavors and professions. We've been able to have discussions with counterparts to talk about developments in nuclear weapons policy and cybersecurity, the military use of both cyber intrusion and also autonomous systems: what kinds of weapons there are, could be, or should be that are partly or fully automated.

We can talk about space security because nowadays, almost everything we do goes through space, including our cyber infrastructure, the internet, and so on. What happens in space now is no longer determined by just a few powerful nations, like during the Cold War, where it was mostly the US, the Soviet Union, and to a limited degree, a few other nations. Now, space is everyone, including the business community. It's a very different kind of domain.

Of course, terrorism: these are very pressing topics. In some cases, in my opinion, we learn a lot, for example, from talking with our colleagues in India or Israel. They sadly have a lot more experience per capita with terrorism than we do in the United States. We're fortunate in this regard. We learn when we talk to communities that have to deal with countering terrorism, mitigating the effects, trying to avoid catastrophic terrorism.

Of course, we're talking also with our major counterparts, in Russia and China in particular, about how to avoid and reduce crisis. Our role is really to try and step in and create or maintain conversations, channels of communication, especially where our governments cannot do so.

Right now, for example, the US government has great difficulty in talking with the Russian Federation. We have sanctions against, for example, government-to-government collaborations in many areas of science and technology, where there used to be collaborations up until a few months ago. That's now being terminated because of the concern that those collaborations are helping to sustain and support the Russian war effort in Ukraine, and that's not something we want to do. The counter to that, of course, as you no doubt have heard, a few days ago, the Russian Federation said they will pull out of their collaboration with the International Space Station, and possibly with all space collaboration. Many of us feel that this is unfortunate because every channel of communication that gets broken increases the chances for miscommunication and misunderstanding between our countries.

We don't have to like each other necessarily, but we have very powerful technologies in both of our countries and in other countries as well, so we have to learn how to live with each other and how to avoid crisis that would trigger the catastrophic use of those powerful technologies.

Crisis prevention, strategic stability, these kinds of things are very much at the heart of what we're trying to sustain through backchannel discussions. They're behind closed doors, we don't advertise them, we don't talk to the media, but we do talk very much with our government. We work on behalf of the United States people and the United States government, so we're in very close communication with our government. I'm truly fortunate to be working with a team of people who have been at very senior levels in our government, in international organizations like NATO, and senior positions in our militaries; and they have a deep understanding of how essential it is to prevent crises rather than allowing them to erupt, then trying to deal with them. Once a crisis takes over, the timescales are so short and mistakes are so consequential that the results are very, very unpredictable.

ZIERLER: For the last part of our talk, now that we've come right up to the present, I'd like to ask one retrospective question, then we'll end looking to the future. Looking back over the course of your career, it's remarkably eclectic, both within and beyond science. To what extent, for graduate students today, looking to chart their future careers, is the path you pursued advisable? Does it make sense nowadays to do what you were able to do in the 1970s at the dawn of not one, not two, but maybe three brand new fields?

JEANLOZ: I feel very lucky, and I think one should recognize that no matter how hard one works, luck always plays some role. There are people who are smarter than me, more capable than me, work harder than me, better than me in any and every way, and in one case or another, may not have been lucky. In some cases, not lucky to live long enough, not lucky to have good enough health. Or maybe their family's circumstances. It's a matter of recognizing, appreciating, and leveraging one's good fortunes.

If anyone is interested in this interface between science and policy, or in general, in cross-disciplinary kinds of interactions, in the end, my best advice to people, is, first and foremost, you have to have depth in at least one thing. I'm not a big fan of cross-disciplinary education at an early stage, cross-disciplinary undergraduate degrees, for example. Don't get me wrong, I totally encourage students, graduate students, or post-docs to develop their broader interests.

But it's really essential for them to have deep expertise in at least one thing, so they can bring something to the table as they're starting to work across disciplines with other people. I've found too many people who have very broad interests and blossom in a cross-disciplinary way early on, but never create enough depth to make the contributions worthwhile to others. That's a tradeoff we all have to make. And we take risks. I will say, in the policy arena, it's very different from academia, and specifically science. I know what it takes with some reasonable assurance, to have it be appreciated. I can be proud of some body of scientific work, even if it doesn't get broad notice or big recognition, and know I did something special.

I'll contrast that with the policy arena. As soon as you start working with, let alone becoming, a policymaker, especially if you have to be elected, I harken back to the Roman expression, "You live by the sword, and you die by the sword." For those who go into policy, everything you've been working on can be upended at a moment's notice.

An election can go a certain way, a policymaker can retire or disappear. For reasons that have nothing to do with the quality of your work or what you've done, you can really lose out. I feel very lucky, and maybe this explains why I've stood more on the academic end. I'd rather be the advisor, happy to help in whatever way I can. But I also respect those people who have gone into the fray and are elected or appointed to a high office, trying to make a difference, but knowing that what they've done can be overturned right away.

I work with two people who were the lead negotiators for two major arms control treaties, for example. Both of those treaties may disappear as a result of recent events. You can almost say their life's work could be upended. It's got nothing to do with them. In fact, almost worse, it's because of the quality of work that they did. And by the way, the collaboration they generated on both sides, due to current political cycles, is what's being rejected by certain entities.

I'm not trying to point fingers exclusively at the Russian Federation or China. We're seeing tendencies within the United States to also upend a lot of the longstanding approaches we've used. This is part of the human condition. You asked how I can be optimistic, and my answer is, because we recognize there's cyclicity, and we have to be there to try and support the things that are now being perhaps undervalued or put down by some people coming into power. And we're going to keep on saying, "No, this is a very valuable contribution," and we can only hope there will be a future generation that will say, "Hey, I heard you, and I'm impacted by that comment and the contribution that you and your generation made. We're going to pick it up and run with it." That's the best I can hope for.

ZIERLER: Last question, looking to the future. Extrapolating from all you've accomplished, what's the frontier for you for however long you want to remain active? What haven't you done that you want to?

JEANLOZ: I'm just starting a sabbatical year, going through old notes, and trying to work on some technical analyses that have been put on the back burner due to one deadline or another. Basically, I'm trying to catch up on science, but I should start off by saying I have graduate students and other people I want to be able to pay a bit more attention to. We've got some really fantastic experiments we're planning to do over the coming year, in or associated with my lab. Also, I have a large collaboration, a big international team that I'm associated with, trying to do experiments at the National Ignition Facility at Livermore. That's more like "big science," where many dozens of people are involved with those efforts.

Finally, I do hope to be able to document a little bit more completely some of the policy-related material I've engaged with. I'm increasingly being asked to give lectures in areas of national and international security, so I'm trying to develop some of those lectures a little more extensively. If I'm really lucky, I'll be able to write some of this up, either as articles or otherwise. But I think there are a lot of opportunities. We're continuing with our outreach to counterparts in international security around the world, and I'm trying to see if I can't capture some of these policy-related activities in a set of lectures or writings that might be useful to others.

ZIERLER: Lots to keep you busy, no doubt. Raymond, this has been a terrific and wide-ranging conversation. I want to thank you so much.

JEANLOZ: Thank you, I really appreciate it.

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