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Julia Greer

Julia R. Greer

Ruben and Donna Mettler Professor of Materials Science, Mechanics, and Medical Engineering, and Fletcher Jones Foundation Director of the Kavli Nanoscience Institute, Caltech

By David Zierler, Director of the Caltech Heritage Project
December 21, 2022, January 30, February 23, March 1, 13, 2023

DAVID ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It is Wednesday, December 21st, 2022. I am delighted to be here with Professor Julia R. Greer. Julia, thank you so much for having me in your office. I really appreciate it.

JULIA R. GREER: Thank you for coming, and thank you for inviting me to participate.

ZIERLER: Wonderful. Julia, to start, would you please tell me your titles and affiliations here at Caltech, because I know you have many.

GREER: I am a professor of all things that begin with an M.

ZIERLER: OK. [laugh]

GREER: [laugh] I'm a Professor of Materials Science, Mechanics, and Medical Engineering. I'm also a musician and a mom, so it all fits this whole M—

ZIERLER: The five M's, I love it.

GREER: —the M theme, yes, absolutely.

ZIERLER: Do you still direct the Kavli Nanoscience Institute?

GREER: Yes. I have a few titles. I'm an endowed chair professor. I've got the Ruben and Donna Mettler Chair Professorship of all those things that begin with an M, as well as the Fletcher Jones Director of the Kavli Nanoscience Institute. I guess it's an endowed position.

ZIERLER: Is there also an affiliation with the Chen Institute?

GREER: No. I have had funding and students that are involved in multiple centers on campus, like the Chen Neuroscience Center. We had a grant from them, and so we had collaboration and research in that space, as well as the Resnick. I'm very involved in the Resnick Sustainability Institute. I used to be on the board of directors—but I think they changed that structure—as well as the Rosen Bioengineering Center, and the KISS, Keck Institute for Space Studies. I've been involved in—

ZIERLER: You're all over the place. [laugh]

GREER: —a lot of centers on campus. It's great. That's what Caltech is. That's one of Caltech's strengths is that it's so small yet it's so impactful that it's very easy to form collaborations, and to be interdisciplinary, and to participate in all these centers and activities and thrusts that you normally may not even consider.

ZIERLER: Exactly. Julia, let's stay on the titles for just a second. Ruben and Donna Mettler, have you met the Mettlers? Do you know their connection to either your research or to Caltech?

GREER: What I know is that the person who held this chair before was Bill Johnson. He's a great colleague of mine, and maybe you did a—

ZIERLER: Not yet.

GREER: —stint with him.

ZIERLER: He's emeritus now?

GREER: He's emeritus now. I was awarded this chair two years before I could tell anyone because Bill Johnson hadn't yet retired. From what I understand, Ruben Mettler was the CEO of TRW. I think he might not be alive anymore. I don't think so. It's he and his wife that endowed this position specifically for a professor of materials science, possibly with a focus on mechanical properties. That's what Bill Johnson did. He's a pioneer and a giant in the field of metallic glasses. Since there's a finite number of endowed positions, I had to wait for them to retire for them to offer this chair to me.

ZIERLER: Now, with the Nanoscience Institute, there's two benefactor names in there. Of course, there's Fletcher Jones, and there's Kavli. Let's start first with Fletcher Jones. What is the Fletcher Jones Foundation?

GREER: The Fletcher Jones [laugh] Foundation is a smaller participant. I think they probably contributed a bit to the endowment of the KNI. We call it KNI, the Kavli Nanoscience Center. But it is the Kavli Foundation that provided the initial endowment to get matched, I believe, by the Moore Foundation together. Then smaller entities came in to help out along the way. I think that the Fletcher Jones Foundation founded the directorship position, the small contribution, whereas the Kavli Foundation oversees the center, and contributes a major, major part of its operations.

ZIERLER: Now, the Kavli Foundation, they do astrophysics. They do all kinds of things.

GREER: And neuroscience.

ZIERLER: Is this part of a larger Kavli family of science? Are you connected with other Kavli Institutes?

GREER: Very much. We are very much connected with them. You're right, there's astrophysics, there's neuroscience, and nanoscience. There are 17 or 18 centers, I think, around the world now. Cynthia Friend is now the director of the Kavli Foundation. I haven't yet met her in person, but she's coming here in February. She took over, and there's going to be a 20th anniversary event or series of events next year. We're planning this big celebration. Our Kavli Institute has been already functioning for 20 years, which is hard to believe. We're very connected. There're assemblies in New York City, where all the center directors go. For the most part, most of the center directors know each other. The Kavli Foundation itself hosts this assembly at the end of May, usually, where all the directors meet each other, and they come to visit all the institutes.

ZIERLER: As director, how much of an administrative burden is that in any given week? Is it a lot? Are you able to compartmentalize it?

GREER: It's a lot. It's a big job. I am super lucky because I have a terrific team. I have an executive director, Tiffany Kimoto, and the director of technical operations, Guy DeRose. Without those two, I wouldn't be able to do this job. They're instrumental in running this. But it is a big job. It requires technical expertise, of course, because it's a big clean room. Guy DeRose is running this big clean room operation. I understand all this on the technical level. When the piece of equipment goes down, or when we need to bring in a new capability or something like that, together with the executive function, where we connect with the Kavli Foundation, or we organize events, there are initiatives who participate in a series of bigger initiatives from both an academic standpoint as well as being liaisons to the Foundation as well. It's a lot. [laugh] It's a big job.

ZIERLER: Does being director influence your research, the kinds of things you're interested in doing?

GREER: I wouldn't say that, no. I compartmentalize that. It's a wonderful enterprise to run and, if anything, my management skills have improved tremendously since taking that over. I've learned one particular thing, for example, that it's important to elevate people; that people do better not by being reprimanded but by being placed in greater responsibility positions, and just explaining that, and praising them in front of their peers. I use those approaches to run my research group, but it hasn't influenced the types of problems that I tackle because that's very personal. I think each faculty member at Caltech really passionately cares about what we ultimately do and where that's going. That's in part where our creativity takes us. One of the reasons why I rollerblade everywhere is it's my thinking time. It's when I don't belong to my students or to my kids, because I am very needed [laugh] everywhere.

ZIERLER: You can't be caught? [laugh]

GREER: You can't be caught. When I rollerblade, it's really creating that space to really think through some of the research questions that I may want to pursue, or just reasoning through a particular direction and carving that out. That's such a personal thing that I think knowing about what people do in the Kavli Institute is very interesting to me, but I wouldn't say it influences. It's more like it's broadening my sense of what's out there, but it doesn't influence.

ZIERLER: We've covered administrative titles. Now, let's go to discipline titles. Between what you have in the title, the things that you work on, your educational trajectory, what aspects of your research agenda are more on the engineering side, and what are more on the fundamental science, the basic research side?

GREER: That's such a great question. I really love being a scientist.

ZIERLER: That's what you are, first and foremost, a scientist?

GREER: I think so, very much so. I really love the sense of discovery. The most rewarding experience to me, from the research perspective, is very much the scientific discovery, and uncovering something that hasn't been known before, and then trying to explain it, trying to uncover some phenomenon, or observing some phenomenon, then making sure that it's real. When you're doing research, you're exploring, and so you don't really know what's correct. You have to double-check and triple-check that the data you're collecting is in fact meaningful, and then trying to explain it, trying to understand the mechanism that underlies a particular phenomenon. That's really satisfying to me.

Then what we very often do in my group—and this is largely driven by students and somewhat by the funding agencies—is that now that we have this phenomenon, and we know how to explain it, what do we do with it. How do we make use of it? That's where the engineering part couples into the scientific part very naturally. There's a clear synergy between the two, because in materials science, ultimately, the whole world's made of materials. What we do a lot in our research is we start with some very basic concept, either a molecular construct of some material that we chemically synthesize or at the atomic level microstructure, and then we build up that very basic atomic level microstructure into a material. We do that through a series of processes. Once it's a material, and it behaves like a material, and it has certain properties, then it's neat to be able to see where you can push the boundaries of what's possible today. The engineering concept comes from making use of the phenomenon that we uncovered. I think, first and foremost, scientist and then an engineer by—I don't want to say by necessity but by curiosity. [laugh]

ZIERLER: In what ways do your engineering sensibilities or skills supercharge the discovery? How does it make the discovery, learning how nature works, more efficient for you to have that skill set?

GREER: When you try to emulate something that occurs in nature, and when you try to build something that doesn't occur, it brings up a different set of thinking parameters. How to make something work, you have to build it, you have to make a part, and then you have to make that part work. Very often, we formulate a hypothesis. I think it should work like this if you stimulate it like that. I think that something should curl to the left if you pull on it really fast, or it should curl to the right if you do it very slowly. Now that you know this, you force yourself into that thinking space where you say, "Where would that be useful?" Then you say, "Something that morphs, like an airplane wing, for example, it could morph into a particular shape during turbulence, and then it can unmorph when it's laminar flow.

An example that I really like—we haven't made this yet, but I would like to make this—say you're wearing a shirt right now. This is a pretty lightweight shirt, and it's not very cold. But then if you, say, go to Boston or to New York, it's going to be really cold. We can build intelligence into the material itself, where it'll be triggered by, oh, the temperature outside is much, much colder, so it'll reconfigure the textile in your shirt such that it's as warm as a jacket, without changing anything else, so you wouldn't have to change. Then, conversely, you would go to Hawaii, and then the shirt would be too hot, and it would reconfigure itself to make it be porous. The idea behind it—this is something we're very much thinking about—is how to build intelligence into material design at the fundamental level. This is a very exciting area of research for us, and we're just starting to uncover it.

ZIERLER: Intelligence like artificial intelligence?

GREER: Like this, what I just described, like being able to make decisions based on the environment. There's definitely a lot of artificial intelligence that we are now starting to explore. I don't know if you've interviewed this Professor Anima—

ZIERLER: Not yet.

GREER: —Anima Anandkumar.

ZIERLER: I'm going to get to her. [laugh] She's amazing.

GREER: She's a great friend, and she's awesome, and we're starting to collaborate specifically on this. How can we teach AI or, rather, how can we utilize AI to teach our materials as they're being built into a part to make that decision, "Oh, I'm going to be a good part, I'm going to be a bad part, or I'm being shaped like this, but I really should be going in this other direction," so incorporating that decision-making capability right as the part is being printed?

ZIERLER: Does that mean incorporating computation itself into the materials? How is a material otherwise capable of making decisions?

GREER: Yeah, because we're making it. Additive manufacturing is a process where you're creating a part. You start with some chemical resin, and then it's being shaped into a 3D architecture, into a 3D part. That's what I mean by that. You start with something that's just chemically synthesized, and then we're using various 3D printing techniques to shape it into something that ultimately will serve a particular purpose. During that process of being shaped, we want the part to either use images as it's being shaped to make the decision for where to go next. Say you're making a flower, and you made one petal too crooked, and then the flower itself decides, "This is too crooked. I'm going to be a rocket instead or something else." But being triggered, as the part is being printed, being able to make the final call, "Am I going to be a good part or a bad part, or am I going to be something else from what I set out to be?"

ZIERLER: You already mentioned the love of discovery. What about motivations for applied science, applications, translations of discovery into things that make society, make human lives better?

GREER: I touched upon that. Are you looking for specific examples?

ZIERLER: When you're specifically motivated by a societal need, and you push your science in that direction, what are some examples of that?

GREER: I would say sustainability's a really big one. We've been really working in batteries for some time now, trying to get to the independent energy storage. But, ultimately, now we're much more excited about decarbonization, removing the CO2 out of the processes that can be used to create steel, for example. This is something we're starting to work on. We have a collaboration with Harry Atwater and Karthish Manthiram on decarbonization of ammonia production. There's something like four major, major industries that take up like 99% of all the CO2 emissions in the world. One of them is cement. Another one is ammonia. I forget what the other two are, but these two are really, really big. Oh, steel, sorry. Cement, steel, ammonia, and there's one more. For the steel production, what we've been doing is developing ways to 3D print metal parts using a certain chemistry. It's entirely hydrogel-based. "Hydrogel" means it's water-based, so it's a lot less toxic than what you would normally use to produce steel. But now, when you produce these big vats, like in a big plant producing steel, the CO2 that's being emitted, there's just tremendous volumes of it. You can look to other processes, like electrochemical production or photochemical production, and I think the ammonia synthesis that we're pursuing in that collaboration, I think it's relying on the photoinitiated reaction to split water. Once you split water, you can sequester the hydrogens that are being released. They can sequester the oxygen so that CO2 won't form. That's one approach. But the way we are doing it is by 3D printing, you only make what you need. When you utilize this additive manufacturing approach, you already are not wasting that much material because you are only making what you need to be making. Because it's a small part, for the most, you can capture the CO2 that's being produced, without even this electrolysis or any kind of alternative prosthesis. Even during the regular thermal treatment, you can capture the CO2 in the furnace where you're doing your secondary thermal treatment. Once you've captured it, you can reuse it or you can release it somewhere. But the point is that it's not being emitted into the atmosphere. That's something we're very much interested in is how do you make these additive manufacturing processes much more green? That's a big societal need, so that's one.

Then we've been working quite a bit in the biomedical space, making scaffolds for skin replacements, for example, or for any kind of a tissue replacement. How can you make a much more integrable scaffold that's for bone, for example, for bone regeneration or like for skin, so they don't have to take a piece of skin from elsewhere on your body, and then put it somewhere else so that scar tissue wouldn't form, etc.? The idea would be we create these 3D architectures where you can populate the cells onto it, and then the cells would form tissue, for example, and so understanding what is it that cells like or don't like. Instead of using a hearing aid, you can just make the cochlea bone, and directly put it in the ear, so looking into ways of how we can help the body or how we can make artificial things but that can be used directly in the body eventually? That would be a huge advancement. Another pursuit is we're developing lightweight armor or lightweight impact protection.

ZIERLER: Better than Kevlar?

GREER: Much better than Kevlar, yeah. The idea would be so that our military personnel or any kind of protection personnel wouldn't have to wear these super heavy bulletproof or impact-resistant jackets and vests, and run with them when it's really hot outside. The idea would be to replace those with a much, much lighter, much, much more impact-resistant material, because it's really very weighty. In fact, I had this amazing experience where we went to all the military bases and all kinds of military operations from Fort Benning to Edwards Air Force Base and many others. We shot guns with the Marines, and we got to participate in a lot of these military exercises, and it's very impressive. We had to put on all that gear, and it's very, very heavy. When you're in Atlanta, and it's 180 degrees and 100% humidity, you could faint, and soldiers really do. It's a very uncomfortable thing to deal with.

ZIERLER: Because these technologies are very commercially exciting, where are you operating as a consultant, have you thought about your own entrepreneurial venture, or is it just about coming up with the ideas, and letting other people run with it? How do you deal with all of that?

GREER: That's a good question. We started a little company—it's called nFugue—with my colleague, Andrei Faraon, who's just my neighbor right there. That's specifically to produce nano-architected sheets. That pertains directly to the lightweight armor. That would be a commercial operation; at least we're hoping for it. The idea would be that instead of making very tiny samples—everything we work on is nanoscale and microscale—but nFugue is printing them as sheets. You would have like a two-inch by two-inch sheet, and then you can start making these platelets, and incorporate them into the vest, for example. They can also serve as filters. Right now, microplastics is a big problem in the world. How do we make filters that can capture microplastics? Filters are on our minds, now that we're able to make nano-architected membranes effectively that can be chemically functionalized. nFugue would be the enabler to be able to do that, to produce the nano-architected sheets of paper effectively, so that's one. Then we produce quite a lot of patents. I know we've licensed a lot of them. I know people are really using them, so that's been exciting. I do consult just as an individual to whoever reaches out. But from the research perspective—founding nFugue was one big step, and then everything else—it's through IP and through partnerships. That translational work usually comes through collaborations and partnerships with others.

ZIERLER: Do you feel like you've been at Caltech long enough where you've seen this evolution towards ventures where professors want to do things like that? Has it become more common even since your time on the faculty?

GREER: I hope not. I want to say no. I think we don't like that, for the most part. I'm saying "we" generically here. But I know many people went to the—

ZIERLER: The Institute culture, you mean?

GREER: The Institute culture is very much not like that. I know that several people left for other universities and then they came back, and it was specifically because there was so much pressure to be entrepreneurial. I'm quite happy doing [laugh] fundamental research, and I think a lot of my colleagues share that passion for discovery, and passion for doing the experiments, and passion for uncovering something, much more so than being translational. I know many people, especially in, say, medical engineering. That's a new department, and it's a lot more translational-oriented because it's device-centric. Of course, when you're building devices, they're specific to targeting something, or to actuating something, or to enabling something. People who work on devices, I can see that they would be a lot more maybe entrepreneurially oriented. But I think that the fundamental culture of Caltech is fundamental science, and I think that's something that drives us, and I think that that's something that unites us. Getting that bug out of our sys…there are other universities. There's one very well-known university up north, where the pendulum has really swung in the entrepreneurial direction. Now, everybody wants to leave. I know a lot of faculty members have a lot of friends there who are really asking, "How can we get to Caltech? We don't want to do this." I think that being entrepreneurial is a great thing. If you think you invented some awesome technology that can really help people, that's awesome. All the power to you. But it shouldn't be expected. It shouldn't be an expectation, in my opinion. It should be something that you are passionate about that drives you, and you go after that. It's not a university culture, necessarily, but it's something that you care about passionately.

ZIERLER: It does raise the question, of all the things that you could have created companies for, why this one? Was it, like you said, because you made this discovery, and you can just go with it?

GREER: No. That's also a very good question. We didn't want to start a company, but our investors convinced us to. It's an interesting thing. I didn't want to start a company, and my partner also didn't want to start a company. But we wanted to develop this technology. I guess where I lose interest is when we've developed the technology, I don't have much interest in seeing it be made into a product.

ZIERLER: You don't want to do sales and marketing—

GREER: Definitely not.

ZIERLER: —and all of that stuff. [laugh]

GREER: I would love for other people to do it, and I would love to explain it to them or to be the scientific advisor, and to hand them the technology, but I'm not motivated by the problems associated with making product. I worked at Intel for three and a half years, so I know what it's like to make products. Definitely I can see how many people consider that to be cool, but that's not for me.

ZIERLER: Julia, let's go to some history of technology questions now. What have been some of the technological advances in the lab, computationally, that have really revolutionized the kinds of things that you're able to do, since even graduate school?

GREER: Computationally?

ZIERLER: Computationally or—

GREER: We're mostly an experimental lab, so we do computations to support our data, but we're not a computational lab.

ZIERLER: In terms of technology, in terms of maybe microscopy or anything else that just allows you to do the things that you do now that might not have been possible 20 or 30 years ago—

GREER: Absolutely.

ZIERLER: —what kinds of technologies have come online?

GREER: What kinds of technologies? There's two that directly come to mind. Imaging, for sure. Microscopy has come such a long way. When I was in grad school 20 years ago—it was a little less than 20 years ago—18 years ago, the focused ion beam was this incredible tool. [laugh] I did my PhD between 2 a.m. and 6 a.m. a lot of the days on that tool that's called FIB.

ZIERLER: Just because that's when you can get the time?

GREER: Because that was the only time I could get the time. It's called the focused ion beam, and it allows you to carve out micro and nano things out of whatever it is that you want, out of metals, out of polymers but mostly metals. You can carve out like a nano chair or a micro object by removing atoms. You start with a cube of something, and then you remove atoms and material all around it to shape it into exactly what you want. It's a very powerful technique. It uses ion microscopy and electron microscopy so you can visualize what you're making. But it was such a new thing when I was in grad school. There was one FIB for the entire university. I remember, 2 a.m. to 6 a.m. is a rough shift, I remember saying, "Someday I will have my own FIB. I'm so fed up with this." I have my own FIB now, I've had it for a while, and it was a huge thing.

ZIERLER: Is it the same technology, or is the FIB itself improved?

GREER: No, it's much more advanced. That's what I'm saying. It's much more advanced.

ZIERLER: In what ways? How has it improved?

GREER: The resolution has come tremendously a long way. You can really resolve things down to the nanometer level. This is true for all microscopy, for scanning electron microscopy or SEMs, and transmission electron microscopy and TEMs, and FIBs, the focused ion beam. That technology has come so far, and so the kinds of materials that we're able to image, the quality of the images that you create, and the quality of the shapes that you make is tremendous. That's one. The second one is additive manufacturing. That's huge. We're using this process called two-photon lithography, or TPL. It allows you to shape whatever you want. That's not subtractive. You don't start with a chunk, and subtract out the material you don't want. Instead, you add up. You start with nothing, and then you build it up. That's called additive manufacturing. That didn't even exist. Two-photon lithography didn't even exist when I was in grad school, and that's ultimately what we're doing. All these images that you see in my office, all of these—

ZIERLER: What was the breakthrough that allowed additive manufacturing to come online?

GREER: 3D printing, so just recognizing that when light interacts with photosensitive chemistries and resins, it provides a sufficient amount of power to crosslink that resin, and so that hardens it, ultimately. You can imagine now you have this voxel that's a very intense light pattern, and you can raster that voxel in three-dimensional space, and the material hardens where it's traveled, and it remains liquid where it hasn't. That's how I can write a nano you or a nano body or a nano rollerblade using that technology by recognizing that if you have a lower power laser than what we're used to—like the UV lasers is what has typically been used for semiconductor processing. But now for 3D, you have this voxel with a lower power laser, but there are exactly two photons per femtosecond pulse. That provides a sufficient amount of power to crosslink the polymer. Each one of these things has existed, like the patterns of light, the crosslinking of polymers, and the 2D lithography, but I think combining all three of these concepts into recognizing that you can make 3D shapes was a big breakthrough. 3D printing didn't used to be a thing. When I was in grad school, nobody was doing 3D printing. But now not only can you just have a 3D printer in your kitchen or in your garage, at every elementary school, you now have a 3D printer. They're much bigger. But that whole concept of using a liquid precursor to solidify it into a particular shape, I think that is a major breakthrough. It enables us to really think of materials in a very different light. What we work on is adding that extra level of organization into material design.

Ultimately, all materials are made of atoms. The way the atoms are arranged, the way they've come to their equilibrium positions, very much defines how materials are going to behave, and what properties they have. We've been slaves to this coupling for always. Every materials science book will show you this is how you make steel. This is how you make cement. This is the atomic level microstructure that forms, and these are the properties. In fact, there's this quintessential materials science triangle. It's called structure, properties, processing. You process, and all three vertices are interconnected. How you process defines the properties, how your process defines the structure, and then the structure and the properties are linked together. They've always been coupled, and that's why everything is so heavy. All the bridges are heavy, all the buildings are heavy because materials that are strong, that we know that their microstructure leads them to be strong, they're also very, very heavy. What we set out to do was to decouple these phenomena as much as we could, and that's where the architecture comes through. That's an entirely new direction that I started, after tenure actually. The idea is that you can build these intricate architectures that are bigger than atomic-level scale, but they're smaller than what a human eye can see, so they're nanoscale. What makes them be nano-architected is these kinds of intricate three-dimensional lattices or patterns that you can build into the material. Now, the largest dimension in these materials is just the width or the thickness of one of these individual nanoscale building blocks, yet the overall material is as big as room or a brick or something like that. It makes it be very lightweight. It makes it be full of air, but then you can still elicit the properties that you want. That's that extra organization that we build into materials that allows us to play around with it. There's just so much to uncover that it's fun. [laugh]

ZIERLER: Julia, I loved looking at your academic lineage outside—

GREER: Oh yes.

ZIERLER: —and all the centuries back it goes. It begs the question, how many generations back do you think you can go where the professor, the scientist would see what you're doing, materials science at the nanoscale level, and it would be recognizable to them? How many generations back do you think you can go for that?

GREER: Maybe two or three. Definitely my advisor, definitely his advisor, and possibly his advisor. [laugh] Do you notice I'm the only woman on that academic trail? [laugh]

ZIERLER: I did notice.

GREER: There are some, I think, since that time.

ZIERLER: Two or three generations ago, what would be the dividing point? What did the fourth-generation—?

GREER: Microscopy.

ZIERLER: It's microscopy?

GREER: I would say it's microscopy. Richard Feynman—what was it—150th anniversary from there's plenty of room at the bottom or something like that. One hundred and fifty years ago, they didn't have the microscopes. They only had the optical microscopes, which are limited by the wavelength of that light, of that visible light. You really can't resolve features that are much smaller than maybe a micron, and that's one-millionth of a meter. But now we're operating with nanoscale resolution. All of these scanning probe microscopy, scanning tunneling microscopy, transmission electron microscopy, there are all these much more advanced techniques where you can observe the behavior of individual atoms, and understand them, and visualize them so much better. I think it's the development of microscopy, at least in materials science for sure, that has enabled so much progress in terms of understanding material behavior at these very small-length scales. It turns out it's different.

Physicists have been doing quantum science for centuries. They've been doing electron-based studies for a long time. But you can't see them, for the most part. They either come through the data or they're theoretical, for the most part. These experiments are usually done at close to zero kelvin, and they're very tedious to set up, and they take many, many years. But what we do is we make some material, and we take it to the scanning electron microscope, and we look at it right away. Right away, we can see features that are 100 nanometers or below that every day. That used to be such a big adventure, and now it's something that we do every day. Then we can base decisions for what to do next based on what we see. We can deduce and do this iterative human learning—not machine learning—based on what we've made. About three generations ago, I think, is when people started really delving into microscopy.

ZIERLER: A technique that does go back very far, of course, is crystallography. Is that relevant for your work at all?

GREER: Very relevant, because crystallography implies periodicity, and implies a perfect lattice. But, of course, materials are just like people. It's the defects that make them interesting.

ZIERLER: [laugh] That's great.

GREER: We're very interested in the behavior of defects, and so crystallography is the number one branch of materials science—and kudos to you for recognizing that. X-rays are used a lot to understand the crystal structure, but they can't explain everything, and they're particularly not effective to recognize defects. You can even go into the synchrotron, like massive X-ray sources, and understand quite a bit about the construct, the crystal structure of a particular metal or particular crystal. But you wouldn't be able to identify things like dislocations, for example, or point defects. For that, you need to have transmission electronic microscopy. That's where the TEM comes into play quite a bit. I did that a lot for my PhD, and I do that a lot still now. The amount of information you can get out of the crystal graphic diffraction experiments, for example, is very valuable.

ZIERLER: In running an experimental lab, are there theories from materials science, physics, chemistry that are important for your work that might provide an intellectual framework to figure out what you're seeing?

GREER: One hundred percent, yes, absolutely.

ZIERLER: [laugh]

GREER: The chemistry, the materials science, the physics, all of that is a foundation of what forms the material, and we use that every day.

ZIERLER: What are some of the theories that are so important for your work?

GREER: The names of theories?


GREER: There's Hall-Petch. That tells you about how the stress of a material depends on the grain size. Knowing the grain size in metals or in crystals is very important. There's so much dislocation theory. I teach a class on dislocation theory, understanding everything about how dislocations move.

ZIERLER: What is dislocation?

GREER: What's a dislocation? It's a disregistry. When you have a crystal lattice, all the atomic planes are perfectly aligned. Think of Ping-Pong balls, and now connect them with toothpicks. You can create these stacks of crystal. Imagine that each Ping-Pong ball is an atom, and say they're equally distant from each other. They're connected into these planes, like egg cartons. The planes can stack up into ABC, ABC, ABC stacking, for example. You can see ABC and then A, and so by the time you get from one A to the next A, they're going to be exactly one on top of each other. Then it's the next ABC, and then it's the next A. That's what defines a crystal. So there's a lot of periodicity. In any crystal and lattice, there's always a three-dimensional degree of periodicity. There can be more symmetry or less symmetry but, at the end of the day, it's still periodic. What a dislocation is, is when you either take out an extra plane of atoms or insert an extra plane of atoms that doesn't belong there, and it terminates somewhere. Those kinds of dislocations are what enables metals to be deformable. The reason why we can bend a paperclip is because you're multiplying the number of dislocations inside. If every crystal were perfect, it would take a tremendous amount of force to bend, and then it would just break. The reason why we're able to deform metals, and to shape them into anything is because of the existence and motion of these dislocations. They're defects. They're like ribbons or like little elastic bands within a crystal. We are very excited about dislocations. We really like dislocations. [laugh] I teach a whole class in dislocations. There are a lot of theories. The entire dislocation theory is something that we use quite a bit to understand what formed them, what kind of dislocations they are. There are different categories. There are screw dislocations, edge dislocations. how they interact with one another, how their elastic fields—we use elasticity theory a lot. A lot of continuum mechanics type theory, linear elastic fracture mechanics, for example, and all the Hooke's law, like a lot of theories.

ZIERLER: A lot of theories.

GREER: Yeah, a lot of theories.

ZIERLER: [laugh]

GREER: Then in chemistry, we use a lot of synthesis, like organic synthesis, and so there's clip chemistry. There are a lot of theories as well that dictate how a certain polymer—like polymerization theories—like how a certain polymer should be made or what it depends on. We work with a lot of theoretical collaborators.

ZIERLER: That's what I wanted to ask. In physics, for example, there's a very clear divide between the experimentalists and the theorists. Do you serve as your own theorist, or do you always go to the theoreticians?

GREER: We do both. Our theories are phenomenological. The theories that we come up with is we look at the data. We do the experiments with a certain underlying hypothesis, and that hypothesis is always based on some theory, or we're trying to debunk a theory, for example, or somebody proposed a theory that we're trying to—what happens in theory a lot, at least in materials science, is that somebody puts some theory out there. It sounds good, but you don't really have a way to either prove it or refute it because it's not clear how you would go, because how would you disprove it? It's not like we set out a goal to debunk a theory, but it has happened several times where a theoretical paper would come out, and they would predict a certain thing. Then we would do an experiment that would inadvertently either support that theory or would debunk that theory. It's really exhilarating to do that. It's not really our goal, usually, but it's just something that happens along the way.

We almost always have one or more theoreticians, colleagues that are working with us on a specific project because, at some point, you can't really know only based on the experiments what's happening at the molecular level or at the atomic level. When we make a new material—right now, we're working on this very unique class of materials that's called MPEC, or metal-polyelectrolyte complexes—the idea is that you have a polymer. Usually, when you create a polymer, and you process a polymer into whatever—like any polymer part like a wind turbine or a screen or a flowerpot or like the sole of your shoe—the bonds in that polymer are set. They're usually called crosslinked. They're either thermally set or through light activations. But that polymer is not going to change its properties, unless you heat it up to some ridiculous temperature. But, for the most part, they're set. These bonds are very strong, and they're called covalent bonds. Now, in these MPECs, there're very interesting materials. There's still the polymer bond, and there are ions in there, but they're not covalent, and so they form and reform. It's like this free will, free love kind of a thing. These bonds can form, they cannot form, and they can choose how to form, and they have tremendous properties. You can extend them by more than 1,000%. Then you can cut them, and they'll self-heal. Then if you put a different metal ion, you wouldn't be able to deform it or to stretch it. If you put like nickel or calcium in there, for example, you can stretch it, stretch it, stretch it by 1,000%, and if you put iron or aluminum, you can hardly stretch it, and it will crumple—the same material. Trying to understand this, we did the experiments, we stumbled upon this. We didn't know that it was going to be different—it's called valency—based on a divalent versus trivalent metal ion. But we discovered this, and then we said, "This is weird. Maybe we didn't do the experiment correctly." We repeated it many times. Now we're discovering that this is very much a real phenomenon that exactly the same polymer, when you put trivalent metal ions like iron and aluminum, it behaves one way, and when you put divalent metal ions like nickel and copper, it behaves entirely differently.

We patented that, for example. We just submitted the invention disclosure. You can really do a lot with it, because you can dictate at the molecular level what your material properties are going to be. At some point, we didn't know. We don't know how to explain that, and so we reached out to our collaborator here, Zhen-Gang Wang. He's a very well-known theoretician in chemical engineering, who's working specifically on polymers. We reached out to him, and then we said, "We don't know what's going on. Somehow the metal ions are coordinating differently with the polymers, and we need help." We're working with them very intensely. They love this problem, and so they're discovering so much more. They're discovering their stress relaxation, their dynamic bond formation. There's just so many more questions that arose by partnering up with the theoreticians, and so it's a big project now. This happens a lot. We would discover something. We wouldn't mean to discover it. It would just happen. We would do all the validating experiments to confirm it. We would develop our own hypothesis for what we think is happening, and then we would go to the theoreticians, and they would give us a million more questions to consider. But it's really fun.

ZIERLER: Julia, question on your interests in sustainability as it relates to this amazing gift that the Resnicks recently gave to Caltech. Answering for yourself or just your general sense of the faculty at Caltech, are a lot of faculty members just interested in sustainability, and the Resnick Institute now has a centralizing force on this extant research, or because there's this Resnick Institute, more people are getting involved in sustainability than they might otherwise have been, had the Resnicks not had this amazing, generous gift? What is your sense of that dynamic?

GREER: Absolutely. I think there are multiple categories of people. There's some people who genuinely have always worked in sustainability. Many chemistry research thrusts directly feed into sustainability research, just by its very nature, trying to decarbonize the materials, for example, or trying to come up with syntheses that are more green, and things like that. But then there all these gray areas, for example, mechanical engineers who are working on lighter vehicles. That is a sustainability problem, because the payload that's required, the amount of fuel that's required, it's not the most obvious connection to sustainability, but it's still sustainability. Then you can think of photovoltaics, like solar energy, very much a sustainability problem. All of that research went into that as well. Turbulence and flow, developing airplanes that are going to use less fuel, not through making materials lighter but through more efficient wing design, that's also sustainability. I think that maybe what we're doing is we're redefining what sustainability means, and maybe expanding it from the most obvious pursuits, which are generally chemical synthesis, catalysis. How do you improve catalysis? How do you improve certain synthesis? How do you make things in a more green way, spreading all the way into alternative energy sources like batteries, for example, and of course photovoltaics, and making much lighter materials, making much more efficient flow models, wind turbines? Each one of these problems is complex, and it requires this multidisciplinary involvement, even in the photovoltaics world. One thing is to make a device.

But now with the Resnick Sustainability Institute, the problems are being enhanced by the translational aspect too. They want us to make something that's a real product, and so there's a new building that's being erected here. It's all going to be dedicated to translational research, and to applying all of these discoveries and phenomena that we were just discussing to real products, and to eventually being commercialized. The Resnicks are very interested in commercialization in the translational aspect of that. I think that two phenomena happened. One of them is that many more problems that used to be only tangentially related to sustainability became defined as sustainability. That's one. Recycling, sorry, that was another really big one, again, a chemistry problem. Recyclability, how do you get a polymer, and then decompose it either back to its original monomers or to much smaller molecules that you're able to do something with to recycle or to reuse them somehow? Polymer recyclability is a big direction as well. Redefining and maybe enhancing the scope of what sustainability means is one, and then also being able to think about these problems from a much more translational perspective than only basic.

ZIERLER: Now, for you in your interest in improving batteries, does that predate the Resnick gift, or was the Resnick gift the kind of thing where you thought you could get involved in this area?

GREER: It's a little bit of both. We are very student driven, student interest driven. I keep on trying to get out of batteries. [laugh]

ZIERLER: [laugh]

GREER: But starting with maybe 10 years, I don't even remember my first battery student, when the new grad students come in, they often have ideas for what they want to work on. This is pervasive throughout Caltech. When a brilliant grad student walks in, and says, "I really want to work on X"—in my case, this happens a lot that they really want to work on batteries, or on energy storage, on sustainability problems—I need to figure out a way to support them, unless they have their own funding. But, more often than not, if they join my group or somebody's group, that advisor has to pay for them. That funding has to come from somewhere. It's generally the student's interest that drives our thinking, to which funding agency we're going to apply. The Resnick has these internal competitions, which of course are so much easier than the external ones. It became natural to submit a proposal on batteries like, for example, to create an all solid state battery, so we don't have to deal with these liquid electrolytes that are flammable and dangerous and unsafe and all that. We got that particular grant. We've had a few Resnick grants. It's a chicken and an egg in multiple ways, but it ultimately begins with a student. If a student comes in, and they're interested in doing particular battery-related research or sustainability-related research, it forces us, the faculty members, to apply for funding in that space if we like the student. The Resnick just provided this, and provides still, this amazing opportunity for internal funding, and so it coupled together.

ZIERLER: Julia, two last questions for today's talk. One is on science communication. TED Talks, interacting with journalists, appearing in the media, do you do that because you're good at it, or you do it because it's fun? Do you do it because it's necessary, or is it some kind of all of the above? You're very comfortable in that space, that's obvious, so I wonder what your motivations are.

GREER: [laugh] I was about to make a snide remark. Of course, I'm very good at it.

ZIERLER: [laugh]

GREER: No, I'm just kidding. I think it's necessary. I think there's a huge gap between what the society sees in general, and what they think of science and scientists, and what is actually happening. I think that the more accessible you make the science, and the more human you bring to it, the more credibility I think we can attain, first of all, and the more inspiring we can be to the younger people to consider this. The TED Talks make it possible for me to tell my friends who are not in scientific fields to be like, "Oh, you should watch my TED Talk, and then you can understand what we do," because right now, it's this big unknown. It's like, "Oh, there's Caltech, and it's a university, and people there are really smart," and that's about it. [laugh] I can explain to you what I do if you could just focus for 15 minutes, if you could just listen to this TED talk, or if you could give me a chance to explain this to you. What happens very often is that people get inspired when you explain it without being irritated, without being—it's annoying—but without having that condescending persona. Putting that aside, people actually—

ZIERLER: Just being a real person?

GREER: Just being a real person, it's inspiring. Hearing someone describe the kinds of problems that we work on, and what remains unknown, and how we tackle these things, it makes it more accessible.

ZIERLER: Is there an added dimension as a woman to maybe reach girls, younger women who might say, "Oh, maybe I can go into that field"?

GREER: "Maybe I can go there." I'm going to tell you a little bit of a story that happened. One of my closest friends here is Frances Arnold, and of course she's a Nobel laureate. I have two daughters, and so my two girls, we hang out with her all the time. Then she got the Nobel Prize, and then I asked them did that make the Nobel Prize more attainable or did that make Frances more unattainable?

ZIERLER: That's great.

GREER: The friendship has definitely changed, no matter what. We're still very close friends, but that definitely—

ZIERLER: The Nobel changes people, it sounds like.

GREER: The Nobel really changes people. It was an adjustment, I think, for all of us. I think this is an important question to consider. We carry the responsibility. I'm not a Nobel laureate yet.

ZIERLER: [laugh]

GREER: But, nevertheless, I think we carry the responsibility of doing science right, and that means explaining it to the community, and that means carrying it forward in the most untainted way that we can. We can't let it be corrupt, because if you corrupt something that's so data-driven and that's so reasoned, we've got nothing. Explaining that, and explaining maybe in a way that is inspiring maybe to younger girls but just to people just to show that science is not bulletproof. It's not the way we teach our kids that there are answers at the end of the book. Math works that way, for sure. There's the right answer, and then everything else is wrong. But science really doesn't.

ZIERLER: It just opens up a new portal?

GREER: Right. A good scientific project is when you start out with maybe one question that may be a little bit abstract, and after doing a few experiments or after dabbling in that for a little while, it brings up a plethora of additional questions where you hadn't even anticipated. That's called exploration. That's how science works. Making mistakes is something that's par for the course. Pursuing these things, and not being afraid of going into it, I think that's very much Caltech culture. When there's pressure to be entrepreneurial, you are not giving yourself this chance to explore, because failure is not a thing these days. Our kids are growing up in the world where they're constantly judged. They're constantly judged on Facebook—they don't use Facebook—on Instagram. Old people use Facebook.

ZIERLER: [laugh]

GREER: On every social media outlet, they're being judged by their peers in every way, and so they're terrified of failure. I asked my grad students—we just went on a retreat—usually, I take my students on a retreat, and propose three questions before we go. Then when we go, we do this big hike in the mountains, and it's this beautiful, beautiful place in nature. Then everybody sits down, and there's a safe sharing space. What happens on a retreat stays in the retreat. Everybody comes and answers these three questions. It was amazing. People are willing to go there, people are willing to share, and what comes right through is that they're very fragile. They're incredibly afraid of failure. These are brilliant Caltech students. These are students who have nothing to worry about in life, yet they're so afraid. They're afraid that I'm going to think they're stupid, and they're afraid of failure. I can't stress it enough.

ZIERLER: You see that generationally?


ZIERLER: Do you not see that in your own undergraduate experience?

GREER: Not at all. We were all making mistakes, and we were all there for each other. There was no fear. At least I don't remember being afraid, and I don't remember feeling like being a woman was something different. I remember we were just all there together, learning and failing and getting bad grades together sometimes [laugh], and getting really good grades sometimes, and learning. It was so natural. But now, especially when they say, "We're afraid that you're going to think we're stupid," and I'm like, "I'm your biggest advocate. I'm the person who trains you academically to then go into the world, so that fear factor has to be removed. I'm not there to judge whether you're stupid or not. I'm here to train you, so I need to see your data, and we need to talk about this data, like colleagues." But that inherent sense of failure is pervasive, and it's very much generational. This is new, even in the last three, four, five years, and COVID really didn't help. I definitely see the difference between the COVID students who had to start anything, like either start school online, start college online, start grad school online, they're afraid. They're afraid to try things. They're afraid to be creative. For the most part, they're afraid of people. They had to reintegrate. Adaptation into the social world didn't come as easily to them. I definitely see that, unfortunately.

ZIERLER: Between COVID and fear of failure, these are both big problems for science.

GREER: They really are, and being able to explain, being able to interact with humans, just talking about it, and having a conversation. Another thing I very much discussed with my students is I can't be right 100% of the time, so you have to tell me. You have to say, "I don't agree with this," or we need to have situational conflicts that don't translate into personal conflict but a disagreement that is taken up on the whiteboard, or that's taken up in a group meeting, and we may have a heated discussion, but you can't not argue.

ZIERLER: Yes. [laugh]

GREER: You can't not have disagreements. You can't just be subservient, and that culture of subservience, that's an enemy [laugh] of science.

ZIERLER: Finally, Julia, last question. Your music, do you wall that off from your scientific life? Do you integrate it? Is it part of how you see the world? Are these sort of like two separate areas of your life?

GREER: Very much integrated. I just played a concert at my first-grader's elementary school, two concerts today. My day is not complete if I don't practice. It's a huge part of who I am, and it's a huge part of my scientific thinking. I don't know. It brings everything to being OK. It's a stressful job.

ZIERLER: Absolutely.

GREER: I'm sure you hear this [laugh] from everyone.

ZIERLER: Of course.

GREER: It takes time to process, and we all are being taught, "Oh, you need to create space to process and to absorb all this information." But what parent, what working parent has the luxury of processing or having time for self-reflection?

ZIERLER: You have to get on your rollerblades. [laugh]

GREER: I know, I have to get on my rollerblades to think about research.

ZIERLER: [laugh]

GREER: But when I practice piano, that's when it all gets organized, and that's when everything starts off with this very high entropy state where there's just like Ping-Pong balls everywhere. It's like these are the 83,000 things that happened to me today, and they're all in this disarray. Then when I practice piano, it self-organizes into something that I can process.

ZIERLER: That translates to better science for you?

GREER: That translates into much better science for me, because things are not chaotic. Every day is chaotic, with so much happening, and the expectation that we can just process it all. [laugh] My favorite part is when a student walks in, and just picks up right where they left off.

ZIERLER: Yeah. [laugh]

GREER: I'm like, "Of course I know all 20 of your projects in intimate detail," and I don't. When I practice piano, whatever sense that music creates, whatever it is, everything falls into an equilibrium configuration in my brain when I practice. [laugh] They're integrated through the brain.

ZIERLER: Julia, this has been an awesome conversation.

GREER: [laugh]

ZIERLER: I want to thank you so much. Next time, we'll go all the way back, learn about your parents, grandparents even. We'll build the story from there.


[End of Recording]

ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It is Monday, January 30th, 2023. I'm delighted to be back with Professor Julia Greer. It's so nice to be with you. Thank you so much for joining me today.

GREER: It's great to see you again, and I'm looking forward to our conversation.

ZIERLER: Thank you so much. Julia, today we're going to go all the way back to the beginning, trace your family's roots in Moscow in Russia. First, I want to ask a very topical question. I know last time we spoke, before I hit record, you expressed some feelings of just discomfort with being Russian, given what's happening in the world right now. I wonder what are you feeling these days? What's difficult for you, and what perhaps opportunity or responsibility do you have to get out the message that what Russia is doing right now is not necessarily representative of all people who are Russian or who come from Russia? I wonder if you can just reflect on all of those things.

GREER: This is a great question, and I really appreciate how you put it. It really does go back to how I was growing up. I grew up in a very intelligent family, and we really valued books, and reading, and culture, and going to concerts, and getting to know people with similar intellectual standards. The country where I grew up, to me, was never aggressive or unfair or awful, which are all the things that I feel it is being right now. Instead, it was this mecca of really smart and creative people, who were genuinely caring, and genuinely committed to the advancement of science, and advancement of goodwill, and doing the best for their kids. I was a kid there, of course, and I went to a math high school, and I had all these amazing opportunities to go to themed camps, and to go to the theater, and to go to the symphony. I went to this Gnessin School of Music, which is this conservatory level type of music school. The discrepancy between the world where I grew up, which was so inspiring in many ways, and what Russia is doing now to Ukraine is horrific to me. I am ashamed to be Russian right now. I can't believe how not representative of my world that country is being right now.

ZIERLER: You want to emphasize its Pushkin not Putin?

GREER: Pushkin not Putin—

ZIERLER: [laugh]

GREER: —that's a great way to put it. Also, my family is not communist, of course, in any way, shape, or form. We're also not religious. We grew up in this interesting niche of intelligentsia that was very scientific. My dad is an applied mathematician, my mom has a master's in mechanical engineering, and the people that we hung out with were from that same breed. Everybody knew poetry. Everybody read Dostoevsky. You just were like this—I don't want to say aristocratic but certainly in a very educated community. I think that's the values that I was brought up with, and I thought all Russian people were like that. [laugh] I guess it's a little bit naïve, but I just felt like I could trust this person because they're Russian, so they must have the same values. It was very eye-opening. I think my parents just did a really good job of sheltering me from the real world because, to this day, I hear that "we moved to the United States for you so that [laugh] you wouldn't have to stand in line for the washing machine, to get one." I think my hat's off to my parents for protecting me from the ugliness that obviously is inherent to that culture.

ZIERLER: The community of intelligentsia that your parents were part of, do they still exist but they've been muzzled, or do they really no longer exist anymore in Russia?

GREER: That's a great question. I don't know anything about Russia anymore. We left when I was 15, and that was the end of it.

ZIERLER: You're sort of frozen? Your memories, your understanding of Russia is sort of frozen in time?

GREER: As a teenager, yeah. I read about it now, just like any American would or any person would, and I learn about it, but I don't feel connected to it in any way. We went to visit my 94-year-old grandma, and I took my girls, my two daughters to visit. I didn't experience any pangs of nostalgia or anything like that. I went to visit my grandma. I love grandma, of course. I had anticipated that I would get nostalgic, or I would say, "This is where my childhood was." But it was like visiting another European country. It was nice that I could speak the language very well, and to see all these places, but it didn't elicit an emotional response. It was more like, "Here's the Red Square. I used to come here as a kid to watch the parade." Then it's like, "There are tanks and military that go here." I think that the perception that we have of various events, and being able to put events into perspective as an adult is very different from what a child's mind is doing. When I look at all this horrific stuff that is happening in Russia right now, I think all the intelligentsia pockets have left. I think they left for the US. They left for Israel. They left for someplace where they wouldn't be destroyed. I think fewer and fewer people that can think for themselves remain in Russia also because of the fever. They don't treat people with their own ideas very well. I think in many ways, it's a huge shame, and this I feel in the scientific way. There are such brilliant people there, but they have no resources. We have a lot of Russian students here, and they do great at classes. They do amazing things. They excel. Then when they come to equipment, they don't really know how to do things with equipment because you have to do a lot of hands-on stuff. [laugh] I think part of the reason why the Russian people are so brilliant is because they have no equipment, so they have to make do with their brain. [laugh]

ZIERLER: That's right. [laugh]

GREER: When I went to give a talk at the Moscow State University, I remember just telling them about their experiments, and they were like, "How can you do this?" I'm like, "We write grants, and then we sometimes get these grants, and then we buy equipment, and then we can do these things." The money in Russian science is definitely in their brain power, and not so much in the experimental facilities. That was an eye-opening experience for me because it's like where does it go from there? They theorize all this stuff, and they come up with brilliant ideas and brilliant advancements, but then what do you do with it? You have to leave. You have to go to Europe. You have to go to the US to make it happen.

ZIERLER: I don't know if you've ever talked to Alex Varshavsky about any of this, but this is exactly his story.

GREER: What did he say?

ZIERLER: That he had no equipment, and he had all of these brilliant ideas in biology, but he had barely anything to work with. When he came to MIT, it was like Candy Land.

GREER: Candy Land, it's like a kid in a toy—yeah. This is not a story about Russia, but if I could just tell you the story—

ZIERLER: Please, please.

GREER: —because it's relevant. I did my PhD at Stanford. There was this new at the time piece equipment that's called FIB or the focused ion beam. Focused ion beam stands for FIB. I was kind of young, so I was pretty low on the totem pole, and so I had to do a lot of my experiments between 2 a.m. and 6 a.m., which is pretty tiring, even for a grad student who stays up all night long. It wears you out. I just remember being in there one day, and being like, "Someday I'm going to have my own FIB, and I won't have to do this at 2 in the morning." It's amazing because I got to Caltech, and after a few years, I got my own FIB. I have my own FIB now, and it's such a testament to the land of opportunity. You really can build yourself here, and get to places, and earn the things that you set out to earn by working hard or by whatever it is. Certainly, there's a lot of luck that's involved. But you're not going to be stuck as a scientist. You're not going to be in a situation where you can't realize your science or your ideas because somebody doesn't like your ideas, or because somebody tells you what to do, or because you don't have equipment.

ZIERLER: Your parents being urban intelligentsia in Moscow, does that go back previous generations? Is that also true of your grandparents or even their parents?

GREER: I'm glad that you asked. My mom and dad have very different pedigrees, and have very different family cultures. My dad's side of the family is very much in the intelligentsia world. My grandpa could recite any poem, any Pushkin, any Lermontov. He was extremely well read. He just only recently died. Grandma and Grandpa on Dad's side were professors of chemistry at the Moscow State University, so my dad grew up in a very intelligent family, and maybe not so warm and emotional but definitely very intelligent. Their parents, I think they were Polish Jews. I don't know how they ended up in Moscow. But there was intelligence and being well-read, and those were the values that they grew up with.

Then my mom's side of the family is less sort of book smart, but much more street smart. They were survivors. My grandpa fought in the Second World War, and he was one of the officers. Then my grandma, of course, was with him, and they had three kids, and my mom's one of them. They're extremely kind people, and just very warm people, and they were definitely the nurturing type. When my mom and dad met, they came from two very different worlds, and then they seeded their own community. People in Russia form friendships for life. This is one thing I definitely observed. The friendships in Russia are so much more long-lasting and powerful and permanent than anything I've experienced in the US. I have terrific friends and they're amazing, but there's something very human about the bond you would form with other Russian people. Even to this day, I still talk to my high school friends from Russia.

ZIERLER: Maybe it's because life is more difficult? You need those friendships.

GREER: I think you're right. I think people rely on each other. They don't have therapists that they can go to [laugh], or maybe they do.

ZIERLER: [laugh]

GREER: But friendships were above all else. Once you have a friend, you help him. It's your responsibility to take care of each other. I think that fostered a really strong sense of community. That was a very positive part of my upbringing, and I model my family in many ways this way too. We have a lot of friends, and we always have people come over. Just warm relationships, and learning how to show someone that you're there for them, and you've got each other's back, that was big. That was big in Russia. My parents have been telling me to this day, they're like, "All of our friendships are permanent." Because I said something like [laugh], "Oh, you stayed with those people. Are you guys still friends?" [laugh] They're like, "All of our friendships are permanent." My parents moved to the States when they were younger than I am now, and I can't imagine. I tell my kids sometimes, "Can you imagine completely leaving all this behind, your friends, your language, your lifestyle, and us moving to another country where you don't speak the language, you don't know anybody yet, and being thrown into a new high school, and you just go and learn it all? That's what happened to me." I think in many ways, immigrants are survivors, and we persevere. [laugh]

ZIERLER: Tell me about your parents' work, starting with your mother. What did she do?

GREER: In Moscow, she worked the night shift. I don't know what she did, to be honest, but she worked for the port transportation, like port authority transportation. But she was an engineer, so I don't know exactly her job function, but she was an engineer. Then my dad was an applied mathematician, and so he worked at the Moscow Academy of Sciences, I think, or at some institute for a while. But then when things got tough, like in the '90s, and he had to support our whole family when my brother was born, my mom stopped working, as is very typical for all the moms in Russia. My dad started getting more towards the business side of things in the computer science world. Of course, it's all so corrupt. Business culture was not established there, and everything was corrupt, and it was so dangerous. So that he could support us, we became that stereotypical family where the mom stayed home with the kids, and the dad was working. He was still an applied mathematician. He was developing a lot of models that would predict ecological processes, like ecology of animal population, and population control, basically models of population growth, and population properties, which is funny because now he's doing risk management at GE, or he has been doing financial—he had to completely reinvent himself.

Fun fact: my mom's brother, my uncle—my grandparents had three kids: my mom and the two brothers. One of them had moved to the States in the '80s. This was like an exile kind of a thing. That was way before the iron curtain had been lifted. We got the refugee status in '92, and that's when there was a mass exodus to Israel and to the US. We're not Jewish technically, so we weren't welcome in Israel. But we came to the US, and that worked out pretty well. But he had defected in the '80s, and so that's why we moved to Rochester, New York, which is where my high school happened, because my uncle was there. My uncle and my dad had a bit of a misunderstanding because my dad asked him, "Is it necessary to have a PhD for me to find a job in the US?" Here's this dad who is the breadwinner, and he's expected to support his family, and he's bringing all of us there. He's going to need to be employed. Obviously, he's going to have to find a job. He had everything he needed to get a PhD except he just didn't defend, like, except defending the diploma. He asked my uncle, "Is it necessary for me to have a PhD to have a job?" My uncle who doesn't have a PhD, and is not in that world, said, "No. You're going to be overqualified. You don't need this." Biggest mistake, so there was a huge falling out after that because once we moved, my dad found that he is in fact overqualified for all the positions where he ought to be, but without a PhD degree, they won't hire him. He was underemployed for a while, basically for the entire time that I was in high school until I went to college. We went to college at the same time because I went to MIT, and he went to the University of Rochester to their business school. At the age of 40-something, he got his business degree, and completely orthogonalized his career. He went from being a pure applied mathematician to being a risk analysis financial person. He just recently retired, so he's alive and doing well. But he had an extremely successful career in risk modeling at GE. I guess he got to apply his applied math skills anyways. But it was a pretty depressing period I think for him to be working for some…he worked for Sabin Metal Corporation. It's this factory that makes metal parts. He's like, "What am I doing here? This is not…"


GREER: That was rough, especially the transition from being in this sort of intelligentsia world in Russia where you were respected for the very literary world and the very intelligent world to be plopped down to just like the normal folk. That was a big culture shock for him.

ZIERLER: What neighborhood did you grow up in, in Moscow?

GREER: How do I describe it? Do you know neighborhoods in Moscow?

ZIERLER: If people wanted to—

GREER: Not in the center.

ZIERLER: —visit your childhood home, where would they go?

GREER: It was close to the university, so far away from downtown. My high school was close to the university. There's the Moscow State University, which is a big landmark. My high school was right next to it. You could just walk there. Then we lived like a 15-minute bus ride towards the outskirts of Moscow.

ZIERLER: Did you feel any deprivations of communism growing up, breadlines, lack of goods, those kinds of things?

GREER: This is, I guess, a little bit of a soul-searching question. I don't remember it being that way at all. Honestly, I had the best childhood. Maybe I was just so self-absorbed as a teenager in a big city, and I had great friends. I went to a math high school, and I was also in this conservatory school of music, so there wasn't much time to be aware of my surroundings. [laugh] But I definitely went to the store, and there were definitely huge lines, in the bread store especially.

ZIERLER: Maybe it didn't feel unnatural to you though?

GREER: It just didn't feel weird because it was such a part of my reality. My reality was that when you go to the store, there's a line. What's the big deal? What we definitely never had was any shortage of anything. But I think we were just brought up to be grateful for whatever we had. It wasn't a big deal. I don't remember feeling deprived. I guess that's probably the bottom line. That's the accurate way to describe it. Even though there were breadlines, and even though there were lines in the cheese—I guess there was the dairy. There's the vegetable store, the dairy store, and the bakery, all categorized like that. We would take the bus everywhere, take the metro everywhere. I had my grandparents, and I had my friends, and we went to the circus, and to the theater, everywhere. I had a great childhood. Now that I think back on it, maybe it wasn't so great, or maybe all of those things, which totally were normal to me, were in fact the indications that it was not such a great place to live [laugh], politically unstable, economically stable. But, to me, I never felt deprived. But, then again, I got a new pair of shoes for my piano recital, and that was a big celebration moment. Now when our kids need shoes, we just get them shoes. For me, I had to wait until my piano recital to get the new pair of shoes. But, again, everybody else did too, so it wasn't a big deal.

ZIERLER: Did you feel the Cold War when you were a kid, the Soviet invasion of Afghanistan, the missiles in Europe, NATO, those kinds of things? Did that register at all with you?

GREER: That is a great question. Yes, but the way we were taught it was definitely not true to reality, and the way that we were taught the Second World War, which was the Great Patriotic War to us. No, we were brainwashed, even in my math school, which was the highly intelligent school, and everything. It wasn't very political, or maybe they were trying to not stress. We were focused on math and literature and whatever else we were learning. It was very manipulative. It was taught in a way that was not presented in a multifaceted way, like we would here, or at least in the progressive states, where multiple opinions are taken into account, and you get the information not just from a single source. I knew that there was a huge divide between the Western world and Russia. There was the iron curtain and all this. But I had an uncle in the US. Every once in a while, we'd get a care package, and I would get a beautiful dress. It was like this ball gown that was so amazing. I didn't know these people, but I was like, "Oh, I got this awesome gift or some toys or whatever." Gum was a big thing. I think it was just like there's this enigmatic place called the United States of America, and we can't go there. But they have Hollywood, and they have all these amazing palm trees, and stuff like that. It was more of a magical like the Wizard of Oz kind of thing, without knowing the horrific things that our country at that time was doing.

ZIERLER: What about Glasnost and Perestroika?

GREER: Oh, that was huge.

ZIERLER: Did you feel that?

GREER: Big time.

ZIERLER: Did that change things?

GREER: We left right around when that happened. Gorbachev was in power, and Glasnost and Perestroika were awesome. All of our friends, my parents' friends were of course very supportive of it. I think we left right after Yeltsin got on the tank. It was the big coup in '92. I was in the Baltics, Estonia. I would say I was in Estonia with friend, and my parents were in Moscow, and the whole coup was happening. They brought me back very quickly, and [laugh] then we left for the US. But Glasnost and Perestroika story were big. That's when they had Samantha Smith and Katya Lycheva, the two girls who did the exchange. They went and brought the goodwill, brought all this gum. I remember, she was my idol, Samantha Smith. Everybody knew Samantha Smith, and everybody loved her. Katya Lycheva was her equivalent from Russia. That was all happening during the Gorbachev era. I definitely felt it. Everybody was a lot happier. Everybody was just like, "Oh, we're finally making progress. This is going to be a civilized society one day." But, again, I was a teenager, so all of that stuff was happening in the background.

ZIERLER: But for your dad's professional prospects, the collapse of the Soviet Union was not good for him?


ZIERLER: He was working at the university, and then he had to do other things, as you were saying.

GREER: I see. I think that happened before. He was working at the Institute of Sciences, the Academy of Sciences or some kind. He felt like he needed more money, so he started doing more business work, so got more money, so it was a good thing.

ZIERLER: It was a good thing?

GREER: It was a good thing for us. We had our own computer when a lot of families didn't. We had our own car, so that was a good thing.

ZIERLER: Now, growing up, did you always love math and science? Was that sort of your strengths, your academic interests?

GREER: Yeah, I think so. It was just like what was expect…I guess it was easy. Math was easy, and it just came very naturally to me. Then I guess, at some point, I pissed off all the teachers in a normal school, and they told my parents, "If she's such a know-it-all, you should put her in a special school," and so my parents put me in a special school. There were all these denominations of different high schools in Moscow. I went to a math high school where it was very progressive. We would go on these backpacking trips, and we would sing in front of a fire with a guitar. I guess everybody was just really smart, and we were all nerding out together, and it was a great life. Math was my thing, and I'm competitive. We had this core group of friends, these five girls, and it was a good time.

ZIERLER: There was nothing gendered about math and science? It was not perceived to be like for the boys?

GREER: It was so not a thing. That's very weird to me.

ZIERLER: When you came here, you saw that?

GREER: When I came here, I was like, "What is going on here?" I was so used to just being part of—because it was mostly girls in my friend group, of course. All of my friends got into the university, into the Moscow State University. My best friend left for Israel, and I left for the US in the middle of our last year. I would've gotten the silver medal, not the gold. My friend beat me out to the gold medal, but I would've gotten the salutatorian medal. Something interesting then happened when we moved to the US. Because I went to a math high school, I had already done all my calculus and all that stuff. That was 10th grade. In 11th grade, we were going almost from multivariable calc. When we landed in Rochester, and I went to Penfield High School, there was not a math class for me to take. I didn't speak any English. I took some other language at school, but English was not something that I could use. But I really spoke math and piano, and so they put me in this calculus BC class, and I'm like, "I don't understand why you guys think it's so hard. Come on." [laugh] I learned English by speaking to all these kids who didn't know how to do math. [laugh] I was being trained in a pretty professional way to be a pianist. I was just practicing in the auditorium one time, and this little woman walks in. She said something to me, I don't know what she said, but I imagine it was something like, "Who are you, where do you come from, and why do you play piano?" or something like that. It turns out that was the director of their high school symphony. She basically adopted me, and she took me to the Eastman School of Music, and we got me a scholarship. I started taking lessons there, and she would take me there. It was very kind. We were hosted by the Jewish Community Center or the Jewish Family Federation, maybe, of Rochester, New York—something like. They were our sponsors because my mom's brother was there, and it was through his wife, so my aunt's work. I was a junior, and I had taken every math course that the high school had offered. [laugh] My dad would take me to the RIT, Rochester Institute of Technology, to take all the other math classes. I took multivariable calc and differential equations before I graduated from high school, so I didn't have to take any math in college. [laugh] But it wasn't hard. [laugh] I guess it just wasn't. I thought that was normal. In fact, my mom likes to say, "You're not unusual. I don't know why you would think that." I'm like, "OK, I'm not unusual. This is great."

ZIERLER: Now, your parents told you they were leaving the country for you? They were explicit about that?

GREER: Unfortunately, yes, not for my brother but for me. I'm like, "That's a lot of pressure, Mom." [laugh]

ZIERLER: Because of your academic prospects?

GREER: In retrospect, I think probably they saw maybe some potential in me a little bit, and I suspect that they just didn't want me to grow up in the horrific country that can't get their political or economic [laugh] situation worked out. They just didn't want me to have the kind of future, like, to be the non-working mom, and raising the family, and not make use of any of the skills that I developed. They told me, "We're moving for you." I'm like, "Thanks." [laugh]

ZIERLER: How did you feel about that?

GREER: A lot of pressure.

ZIERLER: Did you feel excited? Were you nervous? All of the above?

GREER: All of the above. I think it's great that I'm a little bit naïve or I was a little bit naïve, because I wasn't able to fully comprehend what was happening. I was just excited, like, "Hey, we're going to go see McDonald's." When the first McDonald's came to Moscow, it was like the opening of a new adventure center. Everybody skipped school. We all skipped school, and we all went to stand in the line. This is why lines are not a thing, like, not a big deal there, because the line was like two hours long, but who cares? You just chat with your friends. We just stood in line to get the, whatever, strawberry milkshake and a Big Mac. I'm a vegetarian, so I don't even remember what I ate at that time. But it was a big event, and everybody went. It was a big thing. Then I was like, "We're going to America. They have Hollywood, and they have McDonald's, and we can drink soda." When we landed in JFK, those are the things I focused on. I wasn't focused on it being like a life-changing journey [laugh], and we're never going back.

ZIERLER: How did you socially adjust in high school? Did you make friends? Were you by yourself? How did that work out?

GREER: That was hard. That was definitely very hard, and I really missed my friends. Being 16 and 15 is already rough.

ZIERLER: Sure. [laugh]

GREER: [laugh] I was the middle of my junior year where all the cliques are formed, all of that stuff is already set, and you're the new kid who doesn't speak any English. That was not good.

ZIERLER: No other Russian kids? There wasn't a larger community there?

GREER: I don't know. That's the thing. My parents didn't let me interact with the Russian kids. They wanted me to fully integrate, and I was happy to not do that as well. They're like, "If we're moving to the US, for you to have a productive career and all this"—

ZIERLER: Jump in?

GREER: —"you should really just integrate," I think. They didn't give my number to any of the Russian boys. There definitely was a Russian community. What am I talking about? There definitely was a Russian community. I just didn't know them. I went to a normal American high school. The way I made friends was through math. It was through tutoring these kids who didn't understand calculus, and so they wanted help, and so I would speak English in return. Little by little, I got connected with a few smarter kids and the nerds, and then I played in the band. Little by little, I became a part of that already awkward—now looking at it—awkward group of high school students who are all very successful now. I had friends, but that didn't happen until probably senior year. At first, I just didn't know. My dad and I would walk from school. They had school buses, but we would walk back from my high school. He would come to pick me up, and we would walk back. My brother had a very different experience. He came in elementary school, so he just fully integrated very quickly. But I was already in high school. I remember there was the senior prom, and I didn't know what that was all about.

ZIERLER: When it was time to think about colleges, were you already on the fast track to looking at the best schools?

GREER: Also, another funny experience. I look back at all this, thinking like, "What was I thinking?" I was only going to MIT. I didn't know that there were other colleges like this. It really helps sometimes to have the blinders on. [laugh] When we lived in Moscow, and I went to my math high school, there was this camp, the American Russian math camp. I don't even know what it was. Maybe it wasn't a math camp. It was like just some camp for smart kids. It was an awesome summer. I don't know how I got there.

ZIERLER: American? It was like a cultural exchange?

GREER: Yeah, both the Americans and the Russians kids were all together in some awesome camp in nature. It was probably like a week—I don't remember—but probably a week long. I had an American roommate, and I was like, "Wow, what kind of creature is she?"

ZIERLER: [laugh]

GREER: We thought they were so exotic. They thought we were exotic. It was the first encounter. I'm like, "Oh, these are the Americans." It was this amazing, amazing opportunity. That was the first time I heard English. That was the first time that I was like, "Oh, there are all these different people. This is so exciting." We didn't just do math. It was some kind of an academic camp.

ZIERLER: You heard about MIT here?

GREER: At the end of the program, each delegation was supposed to make a presentation about their colleges. We did the Moscow State University, and I guess there's another one like the Caltech of Moscow called PhysTech, so probably that's what we did. But all I saw from their side, I was like, "There's MIT. I'm going there." I just saw their presentation, and I was like, "Yeah," and that was that. [laugh] Then we moved to the US. Come senior year, and I need to study for the SATs, and that was a process because, again, did I mention how I didn't speak any English?

ZIERLER: [laugh]

GREER: The verbal part, they're like, "If you don't know the word, think of its connotations. Is it positive or negative?" I'm like, "I have no connotation with the word "amalgamate."

ZIERLER: [laugh]

GREER: Just amalgamate, I don't know what that means.

ZIERLER: [laugh]

GREER: I just had to brute force through it. The math, on the other hand, was quite trivial. Math, I was like, "Are you kidding me? This is what I have to do?" Yeah, I was going to MIT. [laugh] Then my aunt, the same aunt who invited us, I guess, she was like, "You're never going to get into MIT? It's impossible. It's the best engineering school in the country. There's no way you are going to get into MIT." I was like, "OK, way to put me down." But I got in, so I went to MIT. It just all happened.

ZIERLER: What about the piano? Was that—?

GREER: Hold on, I just want to finish a little bit. I had a guidance counselor. The guidance counselor [laugh] at some point said, "You should probably have a backup school because getting into MIT is really hard." I also applied to Cornell [laugh] as my backup school.

ZIERLER: [laugh]

GREER: [laugh] I don't know. I think just luck, very lucky, through some of it. I think that piano is what got me in, in some ways, because I guess I'm a pretty good pianist.

ZIERLER: My question about piano was, were you so fully focused on math at that point that a musical career was not a consideration like going to Eastman or Juilliard or Berklee or something like that?

GREER: Oh, hugely so. In fact, halfway through college, I was ready, I packed my bag, and I was going to run away to Juilliard, for sure.

ZIERLER: You were?

GREER: Oh, it's still my career. It's still a part. I still perform, and I've always performed. I went to San Francisco Conservatory, and I had a scholarship for advanced music performance at MIT. No, it still is a huge part of my life, and it was even more so.

ZIERLER: You went to MIT on the basis that you could continue with the piano? That was part of?

GREER: For sure, yes, and they had a contract with New England Conservatory professors there who gave us lessons for free. That was part of the scholarship. This other friend of mine, Grant and I were the only two sophomores to be admitted to that scholarship program. In the freshman world, there's the freshman program, and a few kids were there. But for sophomore, it was like the elite and, somehow, we got really lucky, and we got admitted to that. It was huge. We were required to perform at the Museum of Fine Arts, and at the MIT Lincoln Lab, and on campus, and give recitals. There were huge expectations there, so it was a huge part. In high school, too, that was why I didn't get depressed as much as I should have. I played Rhapsody in Blue with the Brighton High School Symphony Orchestra.

ZIERLER: What you lacked in English, you made up for communicating in math and music?

GREER: In math and music, so the "M." It's funny because I'm still the professor of all things that begin with an "M." It's medical, materials, and mechanical, and it was math and music. Now I'm a mom, too. It's the "M." There's something magical.

ZIERLER: This is a great place. We'll pick up next time. When you got into MIT, and you had your plan, do you feel like at that point you had achieved what your parents had hoped in uprooting the family and coming to America? Was that it right there?

GREER: Wow. You ask really profound questions. No, in fact, I don't think they still think that I'm good enough.

ZIERLER: [laugh]

GREER: Definitely, no. In fact, I don't think I ever got the like, "We're so proud of you for everything you've accomplished. This is exactly what we envisioned for you." No. Maybe it's like the Russian parents don't do that kind of thing. Every once in a while, I get the like, "We're so proud of you," but it's not—no.

ZIERLER: There's always more to achieve.

GREER: No, it's not like that. It's more like, "You're not doing things right." It was always criticizing, like, maybe not so much of the accomplishment but of the pathway that I took to get there. They didn't like that I rode varsity crew in college. They certainly, I think, didn't think that I was raising my kids right. It's just every part of my career ladder or whatever, somehow, I wasn't doing it right. That felt a lot more than like where you've accomplished, no, absolutely not. When I got into MIT, it was more like, "OK"—


GREER: —"keep going, next." [laugh]

ZIERLER: [laugh]

GREER: Yeah, exactly. [laugh]

ZIERLER: Clearly, you've put that to positive effect though, for whatever psychological effect it's had on you.

GREER: Yeah. I can't imagine being as gutsy as I was. I can't imagine people being—because now I teach, of course. I run a research group, and I'm on the opposite end. I'm that professor now, where students come in, and I don't see people as gutsy as I was back then. I was unafraid. I don't know why. It wasn't a thing. I was just doing what I was supposed to do. Some things came easy. [laugh] Now that I've told you how easy math was, let me tell you how my AP literature class went—

ZIERLER: [laugh]

GREER: —because reading The Great Gatsby, I was like, "I can't understand a word. I don't know what this is." Reading Hemingway, all of this stuff, especially participation in government, that would be my "favorite," in quotation marks, class. I was like, "I don't understand why people participate in government. What is that? Why do I need to know this?" Everything that wasn't math or music was just a complete mystery to me. I persevered. I figured it out. [laugh] I think I was just so unafraid of failure or so unafraid that just my whole life, it was like, "This is the next challenge, and I'm going to do it." I wish I could get a little bit of that back, and I wish that all the students now could have a little bit of that, more of that. Everybody's so afraid. They're like snowflakes.

I told my students, I was like, "You're so fragile. You're like snowflakes because you're so afraid of being judged, of failure." They told me offline, "We're so worried that you're going to think that we're stupid." I'm like, "Then why are you in grad school if you're worried that I think—first of all, then don't be stupid or don't do things that are stupid. If you really think that, I'm your advocate. I am here to help you, and I'm part of your academic training. There's no merit for saying, 'Oh, we're worried you're going'—it's not about what I think of you. It's about doing things, and caring about them." I wish more people were like—I think I had that. I think I had that. I think I was totally like, "I love doing this, or I'm feeling this right now, and I'm going to go with that, and I'm tackling these challenges the best that I can, and I'm just going to do it." I definitely pushed to the limits. I pushed myself really hard in every way, and learned where my limits were, which worked pretty far. [laugh]

ZIERLER: It's probably a two-way street in terms of your innate fearlessness, and the expectations that your parents had. Your fearlessness is probably not purely a manifestation of their expectations. They probably saw your capabilities and fearlessness, and adjusted their expectations accordingly, to some degree.

GREER: That's fair. I think that this is a quintessential problem of children and parents is that they have a certain model that I ought to fit into, like a certain mold, and I just really didn't, and I still don't. It was like overshot. I wasn't this elegant, very feminine, whatever, little girl, which I think is what they envisioned for me. I was an awkward, loud, doesn't fit into, whatever, the elegant category, teenager or young adult, I guess, at all. I went after what I wanted to. The thing I'm not doing as a parent now is that I have learned to accept the choices that my kids make for them. It wouldn't be my choice, and I would maybe not approve of this choice for me. But I've learned to really accept those choices that they make for them. My parents never really did that. They would judge my choices because they didn't work for them. I distinctly remember how excited I was. I was like, "I made it on the varsity crew team." My mom was like, "I don't approve of you doing this. You have a bad back. How can you be in this?" and whatever, all that stuff. I'm like, "I can't even share my enthusiasm with you?" I would be like, "I have a boyfriend." She'd be like, "All right. That's great." It's just all of the things that I really was excited about, I had to do on my own because there wasn't the reciprocation.

ZIERLER: Your parents wanted you to integrate, and here you are—

GREER: Boy, did I integrate, yeah. [laugh]

ZIERLER: —you've become an American parent. [laugh]

GREER: Oh, definitely, yeah. It's an interesting dynamic to see this. Right now, my dad hates Russia so much that he won't he won't buy anything Russian. He supports Ukraine, of course, and so he won't buy anything Russian. He's very much like the stoic Russian dude who is not supposed to feel any emotion. That's him. That's my dad.

ZIERLER: Next time, we'll pick up life at MIT. We'll go from there.

GREER: Sure.


[End of Recording]

ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It is Thursday, February 23rd of 2023. I am delighted to be back with Professor Julia Greer. Julia, as always, great to be with you. Thank you for having me.

GREER: Thank you for coming again. It's always so much fun.

ZIERLER: Awesome. Today we're going to pick up the beginning of your undergraduate career. You proved your aunt wrong. You got into MIT. That was the place for you. Just in terms of your own identity, when you started at MIT, did you feel American at that point? Were you enough assimilated that that was not an additional challenge on top of all of the challenges that a freshman at MIT would experience?

GREER: For the first time, I didn't feel like an outsider, because when you go to high school, you're the only one that's an immigrant. There weren't that many immigrants in Upstate New York. It was pretty homogeneous. [laugh] It was pretty homogeneously white, and it was pretty American. Then I went to MIT, and there are all kinds of people from all over the world, from all over the place, and I was like, "This is so great. I don't need to be the odd one out anymore." It's not so much that I felt American, but it was very much like I felt accepted. I felt like this is finally the place for me. I don't stand out in any way. I'm just one of all these people. It was quite empowering.

ZIERLER: Did you think it was going to be mathematics at first that you were going to focus on?

GREER: No. This is a funny part about my upbringing. I went to a math high school in Russia, which means that it was pretty advanced math-wise. When we moved to the States, and I was a junior, I had already taken BC calc, so there was nothing that the high school could offer me. I took college-level classes at RIT. My dad was [laugh] at Rochester Institute of Technology. My dad was freezing, walking around in the Rochester winter, doing laps around the building while I was doing my math class at RIT, because I couldn't drive yet. I was 15 or 16, and I wasn't able to drive yet. I took everything. I took multivariable calc and differential equations and linear algebra, I think. I took [laugh] all the classes that were required for any college. I didn't have to take any math classes in MIT at all. I did just for fun. But when I got there, I was like, "I don't know what to major in." Math is not all that interesting anyway—not interesting, but I felt like I'd already taken all the math requirements, so what else is there to do? I also really liked chemistry very much, and so a bunch of my friends said, "You should do chemical engineering." I was like, "Great." I'd made some friends, and they were like, "Chem-E is the way to go," so I went chemi, chemical engineering, so no math. [laugh]

ZIERLER: Right to Chem-E from—

GREER: Right to Chem-E. [laugh]

ZIERLER: —from the beginning?

GREER: Yeah.

ZIERLER: That worked for you?

GREER: Yeah.

ZIERLER: What did you like about it?

GREER: I don't, because I switched to materials science. [laugh]

ZIERLER: How soon after?

GREER: No, in grad school. [laugh]

ZIERLER: Oh, in grad school?

GREER: Yeah. No, I got my bachelor's degree in chemical engineering, but I'd had it with liquids and gases. I like solids a lot better. Chem-E is all about liquids and gases and all these dimensionless numbers. But in materials science, it's solids, so I feel a lot more grounded in my solid world now. I switched at Stanford.

ZIERLER: What was your experience like as a student at MIT?

GREER: That's a loaded question. It was a very multifaceted experience. [laugh] The freshman year was great. I loved freshman year, I loved being independent, and I loved making all the friends. I was on the piano scholarship too, so I made a lot of friends with music, and I got a lot of opportunities to play. I was finding my way. I was 17, so I was young. I was finding my way, being both exhilarated by all this freedom but also unprepared for life. It was a big transformation. Making friends really helped. I learned how to play trumpet. Do you want to hear a funny story about this?

ZIERLER: Please.

GREER: It's a really funny story. [laugh] When I was in high school, I started dating this boy Toby, and he played the trumpet. I didn't. I was a pianist. I don't play trumpet. I play the trumpet very badly now. But that was not my thing. [laugh] MIT had this women's preview weekend. On April 23rd of whatever year—'93, I guess—they flew all the women and minorities to visit campus before everybody else arrived. Here I was. "Oh my gosh, MIT, this is so great." That's where I made a few friends before I even started. This girl, a super enthusiastic girl who's already a student there, comes up to me as part of this weekend, and she says, "Hi, my name is whatever. Do you play any instruments?" [laugh] I was like, "Yeah, I play piano and trumpet." Then I was like, "What the hell?"

ZIERLER: [laugh]

GREER: "Why did this come out?" It just came out. She could care less that I was a pianist. She just immediately latched onto the trumpet, and she's like, "You play the trumpet? This is so awesome. I play in a concert band. You should come join the concert band." The more she talked, the more terrified I got, because I was like, "She's going to remember me. She's going to seek me out when I get there. I don't know how to play the trumpet, but she's going to come and recruit me." I went back home, and I was like, "Toby, you need to teach me how to play the trumpet right now."

ZIERLER: [laugh]

GREER: In three months—that was in April—from April to August, I learned how to play the trumpet because I was terrified that this girl, who I'm sure had graduated and had forgotten all about me, was going to find me, and make me play in band. [laugh] I came to MIT fully knowing how to play a whole bunch of little tunes. I got my own trumpet. I did all that, and I played in the concert band, and that's where I eventually met my husband. [laugh]

ZIERLER: Oh wow.

GREER: [laugh] I was the worst chair, and he was the second-to-worst chair. We were both pretty bad.

ZIERLER: At MIT you met?

GREER: At MIT, yeah, not at that time. Eventually, he became my husband.


GREER: It was a funny story about playing the trumpet. [laugh]

ZIERLER: Did you feel at home at MIT just in terms of being surrounded by students who love science?

GREER: I felt at home at MIT because everyone was just accepted. Everyone was a nerd. It wasn't even so much that they loved science; it's just like everybody thought in the same way. Especially now, I so appreciate how much I took that for granted. Everyone was really smart, and everyone thought in the way that logic made sense. Hanging out with people was just really a rewarding experience. It was really hard though, so halfway through, I decided I was going to run away to Juilliard because it was too hard. I felt like everyone was smarter than me. It was tough, so at some point, I was like, "Forget this whole thing. I'm just going to go play piano [laugh] at Juilliard," packed my bags, and went to the Greyhound station. [laugh] Got pretty far. By senior year, everything changed.

ZIERLER: Did someone talk you out of it, or you talked yourself out of it?

GREER: I talked myself out of it. I was like, "This is just a stumble in the road. It's going to be OK." I went back. I really loved it. I did so much. I did theater. I did the Circle K. I was eventually the president of Circle K organizations, this community service organization. I played in the band. I played in orchestra. I was on this piano scholarship. I had great friends. I rowed varsity crew. I was a rower. I tried a lot of things. I don't know. It was awesome. It was a great place. I cross-registered with Harvard, because we could. I took a philosophy class that I slept through every single one of them. I also took a bartending class, which was a lot more—

ZIERLER: [laugh]

GREER: —entertaining. I took graduate-level classes. I did projects. We bonded so much. I explored Boston. That's where rollerblading, is in Boston too with my best friend. Remember when malls were a thing?


GREER: We went to a mall, CambridgeSide Galleria, and found this random sports store there, and I was like, "This is it. I'm going to get this." She's like, "Do you even know how to rollerblade?" I was like, "No, but I'm going to figure it out." I put on my Rollerblades [laugh], and rollerbladed all the way back to my dorm. It was good times. Thinking back to it, I felt so unafraid. The world we live in now is so horrific, with the war in Ukraine, and the school shootings, and all this horrible stuff that's happening in our world now, and that we are so aware of it. I just felt like being at MIT, I was not a part of any of that. It was that small world that was so awesome with great people, with amazing activities. It was great.

ZIERLER: Now, playing the piano, was that more an outlet, or was that an educational experience where you furthered your training?

GREER: It was very intense. That scholarship program cut no corners. We got lectured all the time. "You guys are the crème de la crème. What kind of performance is this?" We got yelled at a lot, because we were underprepared. MIT's tough. You spend a lot of time on problem sets, and a lot of time on studying, and a lot of time doing schoolwork. Practicing piano was a huge second priority but the second priority nevertheless, so we were never up to snuff, and so we got yelled at a lot [laugh] by our professors. At the end of the day, I had to do a senior recital, like a full-on solo senior recital. We had to go play at the MIT Lincoln Labs. We had to go play at the MFA, Museum of Fine Arts. It was a lot of demands. It was very intense; not an outlet.

ZIERLER: What kind of music did you focus on as a college student? What were your favorite composers?

GREER: All classical.

ZIERLER: All classical.

GREER: All classical, very rigorous classical upbringing, so Brahms, Rachmaninoff, Schumann, Beethoven. I still to this day play the Schumann piece that I learned back then. That was a part of my recital. Still, that's my one go-to piece whenever people ask me to perform, which happens a lot. That's my go-to piece.

ZIERLER: Were there professors that you became close with at MIT?

GREER: Definitely. Their professors were just as quirky as the kids, so it was neat. I had a chemical engineering professor, Mike Mohr, who died, but he was awesome. There was a Take Your Professor to Lunch day, where the undergrads would choose the most popular professor, and we'd go with him. MIT really knows how to do undergrad education. They really made it fun, and they really made it interesting. There was Professor Bertozzi, this big, jolly physics guy who was totally Italian, who just brought this little Italian mafia feel into his physics classes. I definitely did, definitely with my music teachers too, with my music professors. That was a big part. I minored in music.

ZIERLER: Right. What did you do during the summers? Did you stay in Cambridge?

GREER: I did research. They have these REU programs, research experience for undergrads, through NSF. I did one in Virginia Tech—that was my last one, I think—one at the University of Rochester, back home—two in Rochester: one at the University of Rochester, and one at RIT in Virginia. I think that's it. How many summers are there in freshman?

ZIERLER: There's three summers.

GREER: Yeah, there's only three summers, so those are the ones.

ZIERLER: When did you figure out that you wanted to go to graduate school? What was that process like? Was there a professor who said, "You've got to go to graduate school"? Was there somebody in particular who encouraged you?

GREER: If I really think about this, the imposter syndrome is pretty strong, I think, just in me for sure but also just in my group of friends. My best friend went to med school, and I never thought I'd be good enough to go to grad school. There was just no way. I didn't think I was going to get in anywhere. But it just happened to be that in my last year, things always happened at the end. In my last year, I took a graduate polymer science course. It was within Chem-E but it was a graduate-level class, and it was the first time that I took a graduate-level class. I did really well in that class, and I really liked it, and I was like, "Maybe this is it. Maybe I can do polymer science." I really wanted to go to Berkeley in chemical engineering. I don't know why. That was my dream because I'd never been to California yet. I was dating this boy, who moved to Berkeley to do grad school, and I went to visit him, and I think I just loved the Golden Gate Park so much. I just loved San Francisco, and loved the Golden Gate Park that I really wanted to go to Berkeley. I remember that. I didn't get into Berkeley, but I got into everywhere else, especially to the University of Delaware. That has a great polymer science program—


GREER: —specifically for polymer science. I think that the grad school thing was just more to prove to myself that maybe I'd get in. I didn't think I was going to get in anywhere but I did, and the only place that I wanted to go to—Berkeley—I didn't get into that. I didn't want to go to Stanford. [laugh] What happened was that I decided to do the gap year, and I really wanted to come to California. Then this guy, the other guy who played the trumpet, he went to Berkeley in Chem-E, and I was super mad. This guy had like a 4.0 from MIT, straight A's, got into a Chem-E program at Berkeley, and I was like, "That schmuck."

ZIERLER: [laugh]

GREER: I want to go to Berkeley for Chem-E. I didn't get in. But I also moved to the Bay Area independently of him. He went to Berkeley. I moved to the Bay Area to work at Intel. I got an internship at Intel for an entire year, and it was the best year of my life. It was so awesome. I decided I was going to go to Delaware to do my PhD in polymer science, but I deferred it for a year. This is something you can do in grad school. I went and visited all the places that I got into, and I really liked Delaware, and so I just deferred it.

ZIERLER: Was it all polymer science programs except for Chem-E at Berkeley that you applied to?

GREER: No. It was only one, the opposite. It was only one program that wasn't Chem-E.


GREER: It was one polymer science program at Delaware. Everything else was Chem-E, Stanford Chem-E, everything Chem-E. That year that I worked at Intel was a little bit pivotal in multiple ways, but one of them was that the projects that I worked on at Intel were all solid metal films and thin films and transistors and semiconductors, and I was like, "This is so awesome." I really shifted towards materials, and the project that I had there was in collaboration with a professor at Stanford. Now, this professor wasn't really a professor. He's an adjunct professor, but I didn't know. I was really young.

ZIERLER: Sure. You don't know those distinctions.

GREER: Yeah, we don't know any of those distinctions. We don't understand what is an adjunct. We don't understand grad school at all. I was particularly young because I started college at 17, so I was 21. I'm pretty young in every way. That project was in collaboration with Stanford, and so I got to go to Stanford every week, and I was like, "This is so great. This is totally awesome. Too bad I'm going to Delaware." In May of that year, the boy—his name is Frank—was like, "Hey, I really like you. You should really stay here." Of course, I loved my life in the Bay Area. I had my best friend. I had my awesome friend group. Who wouldn't love California, and especially the Bay Area?

I became the social director of the entire group of interns. We went everywhere. We went hiking. We went scuba diving. We just did boating, kayaking, everything. It was the best year of my life. I realized that I really liked materials science. He said, "Why don't you not go to Delaware? You should really stay here." I applied to Stanford again, I guess, from the previous year. I wrote to them, and I said, "I applied to Stanford's Chem-E department last year, and you guys were generous enough to admit me. I'm not at all interested in Chem-E, but is there [laugh] any way I could get into materials science?" They transferred my application, and they admitted me to materials science. But who applies to grad school in May? You apply to grad school in December or in January. Right now, in February, we already selected all the grad students, so from February to May. I applied to grad school in May, and they were like, "We'll admit you but only into the master's program. [laugh] We can't admit you into the PhD program because we don't have any more fellowships." As you know, that's the most important—


GREER: Now, as a professor—

ZIERLER: You understand?

GREER: —I understand that we've given away all the fellowships. I got in, and I went to that same adjunct professor, and I said, "You know how we've been working on this project with Intel, how about I do this same project for you, or how about we work on this project still together with me being a grad student, your grad student?" Now, I should mention that professor is an adjunct faculty member which, again, I didn't know at the time. I was like, "We're just doing research. This is really great." I took classes. I ditched Delaware twice at that point, so I think I'm a persona non grata in the state of Delaware. [laugh]

ZIERLER: [laugh]

GREER: Frank and I got engaged, so that worked out really well for us at that time. I was taking all the classes in materials science, so I completely switched from liquids and gases in Chem-E to solids and atoms, and that was really hard. Switching from one major in undergrad to an entirely different major in grad school was hard.

ZIERLER: Let's go back to Intel. What was the project you were working on there? What was it?

GREER: It was stresses in thin films. You have a microprocessor, and the microprocessor has some transistors in it, and then it also has contacts through metal wires for how that transistor communicates with the rest of the microprocessors. There's a lot of steps which require you deposit a thin film, and then you pattern it into lines, and you pattern it into the so-called vias and contacts. I was studying the effect of how the stresses, the mechanical stresses that build in thin films affect their electronic properties.

ZIERLER: Did you ever think about staying at Intel, just pursuing a career there, and not going to graduate school?

GREER: Funny. If you allow me to continue with the story—

ZIERLER: Please.

GREER: —you'll find out. Because I was an intern, there was a discrete termination date. I was in a particular program. I was in an internship program and, in fact, I had to finagle my way to stay an extra six months. I wasn't in school anymore. The internship program that they had was for undergraduate researchers for only six months, and I was neither one of those because I had graduated already from MIT, and it was my gap year, and I really wanted to stay there for a whole year. I had to go pull some strings, and convince them. Now, because there was a certain termination date, I had to figure out what to do, and I definitely wanted to get a PhD for sure. I went to Stanford but got only in the master's program. Then the professor who was chair of the department at that time said, "Oh, it's no big deal to transfer from the master's program to the PhD program." Such a huge lie but I didn't know that at the time. I was working with this adjunct guy. I was taking all the classes with all of my classmates, preparing for qualifying exams and all that. One day, I come to work—it was in 2000—and the guy, the professor guy says, "You know what, Julia? Intel cut my funding." I was like, "Yeah, OK, that's really nice. What are we going to do today?" I didn't know what that meant. He was like, "No, I don't think you understand. I can't support you anymore." I was like, "What do you mean you can't support me anymore?" He's like, "I don't have any more funding for this project and, in general, I think you're a bad scientist. Women shouldn't get PhDs, and you're a bad scientist."


GREER: We were building this amazing diffractometer. This other grad student and I, we were building this X-ray diffractometer that was so special and so awesome, and we built it from scratch. I learned so much. I learned everything from soldering the little motherboard circuits and logic on these little PCB green boards, like motherboards, to constructing this furnace, to operating an X-ray source to like everything—we built everything from scratch—to writing code in Fortran. We built all this stuff for him, and then he was like, "I think you're a bad scientist, and you should just like forget it."

ZIERLER: Was this your first encounter with this caveman perspective of women in science?

GREER: Yeah, it really was. It really was. It was an amazing whiplash. I was Julia Rosolovsky at that time. If I were the Julia Greer that I am today, I'd probably punch the guy out. But, at that point, I was like, "Yeah, he's right, I'm a bad scientist," so I went and cried for a while. Then I went home. We lived in San Francisco. I was like, "Frank, this guy thinks I'm a bad scientist." Oh, because he was an adjunct, there was no one to champion my case to stay in grad school. If I had worked for a real professor, that person would've stood up for me, presumably, because I did a great job. Looking at it now, even objectively, just looking at what we had accomplished in that amount of time, we built it an incredible instrument from scratch. Most grad students don't do that. We really did a great job, this other guy Matt and I.

ZIERLER: What were the science objectives of the instrument?

GREER: To measure the stresses in thin films. You measure the lattice spacing using X-rays. If your film is strained, you're going to get a bigger lattice constant as a function of temperature. We built even a furnace with a Beryllium window so that the X-rays could go through it. It was very precise. Usually, these kinds of experiments, you can only do in the synchrotron. We built a diffractometer that is able to measure the lattice spacing in these copper films or whatever metal films without having to go to the synchrotron at different temperatures. We really saw the evolution of lattice spacing as a function of temperature and how it all played out. It was awesome. It was an awesome project, and I'm so disappointed that nothing ever came out of it. We didn't even get a paper out. Somebody got a thesis out of it, I think, somebody who worked on it before. But we were so close. All we needed to do was take some data using this technique. We would've really published it. But then the guy was like a dinosaur. He was pretty old. Frank is in his PhD program at Berkeley. Here I am, about to master out, and I made him promise. I was like, "Look, I will go work at Intel because that's where I see myself. My future is going to be at Intel. I'm going to go work at Intel, and I'll support us," because we lived in San Francisco; not cheap, not a cheap place. "We'll live like that on the promise that I will get to go and finish my PhD after you are done." That was our agreement. That is exactly what happened.

I did work at Intel for two and a half years as a real person; not as an intern. They took me back. It was a different department. But they took me back. Then what happened was that when he finished, he had always wanted to be a professor, so he started applying, I guess, at the end of his PhD. Nothing really took. I never ever wanted to be a professor. I was working at Intel. I'm happy at Intel. But then because we had this deal, I was like, "I'm going to apply to grad school again." Because I had taken all these classes at Stanford, I was ready for a qualifying exam. It made sense to go back to Stanford if they were to accept me. Same thing happened: I got in, and then they're like, "But we don't have a fellowship for you, so you're going to have to find an advisor who can support you." I went to the visiting day, which is silly because I already knew. My cohort, the people in my cohort, were fifth-years now, because I did the masters with them, and then I worked for two and a half years. They're all either ready to graduate or have already graduated, but I stayed friends with them for the most part. I'm looking for an advisor, so I talked to a bunch of people.

There was this one very famous professor, Bill Nix. There is one very famous professor, Bill Nix, who is in all three National Academies; a super amazing guy; so famous that there was just no chance. I talked to some of his students, and they're like, "There's no way you can get into his group," and so I didn't even talk to him at visiting day. I wasn't even there. I went back to my little job at Intel in one day. [laugh] I was like, "Man, this is really stressful. I can't find an advisor, and without an advisor, I don't have anyone to support me. How am I going to do this?" Frank, at that point, started working at Novellus, which is a semiconductor company. All of a sudden, I get an email—guess from whom—from Bill Nix himself [laugh], the amazing Bill Nix. It said something like, "Hey, Julia, congratulations. I saw that you got into Stanford. I have this project that's fully funded. It's on the mechanical properties of materials, so I don't know if that's interesting to you. But if you might possibly be interested in this project, why don't you come down, and we'll chat?" I was like, "Oh my God."


GREER: I was like, "I will bring coffee to you." I was like, "The great Bill Nix emailed me." I could care less about what my project was about, because I'm like, "I'll just bring your slippers and coffee every day if I could be in your group because this is unfathomable." That's how it happened, and I completely had to shift my focus again towards mechanical behavior of materials, and so that's how I got into Stanford, and then it was all backwards from there. I don't know if you're ready for that next part of the story.

ZIERLER: No. What were you doing at Intel the second time? Was it the same work? You said you went to a new group.

GREER: Not at all. No.

ZIERLER: What was it?

GREER: Working at Intel the second time is what solidified my desire to go to grad school. I was working in something called IMO, Intel Mask Operations. To make a microprocessor, you have to transfer patterns and light. You shine light through a mask, through a pattern, and then you transfer that pattern into something that's called a photoresist, and then you etch away the parts that didn't get exposed, depending if it's positive or negative, or did get exposed, but you transfer the pattern that's written on a mask, like a snowflake or a pattern or any feature into parts that eventually become microprocessors. I was in charge of a bunch of masks but in charge of their design, in charge of their making, in charge of their going to the right fab and all that. I was the integration engineer.

ZIERLER: Did you appreciate the Caltech-Intel connections, Gordon Moore, Carver Mead? Did you recognize any of that when you were working there?

GREER: Not at all.

ZIERLER: Not at all.

GREER: I knew about Gordon Moore. I met Andy Grove, who was the CEO at that time, and Bill Nix's friend, Craig Barrett, who eventually became the CEO of Intel. I met them both but, no, no connection at all.

ZIERLER: Did you meet Ted Jenkins?

GREER: Eventually, I did.

ZIERLER: Eventually?

GREER: Yeah.

ZIERLER: But not then?

GREER: Not then, no.

ZIERLER: Now, you said this experience convinced you you wanted to go to graduate school.

GREER: Yeah.

ZIERLER: Why? What about it?

GREER: When you work at a company, they only care that you make things work. They don't really care why they don't.

ZIERLER: It's not fundamental research?

GREER: Not only is it not fundamental research, but there's no bandwidth for even asking. It's not curiosity-driven. It's product-driven. It's very product-driven. There would be situations where something didn't work, and there would be a SWAT team, and you would go and figure out, "Did you do this? Did you do that? Did you do that?" Then you figure out what it is, and you just move on. Intellectually speaking, it was a little bit unsatisfying. It was very fast-paced, very intense but not all that interesting by the second year, to be honest. Also, it's probably because of my job. I was an integration engineer, so I didn't go deeply. I wasn't responsible for etch. I wasn't responsible for deposition. I wasn't responsible for laser writer. I wasn't responsible for a particular area, which possibly would've been a lot more interesting. I was responsible for the overall process, and so, at some point, I felt like I was this glorified organizer of other people. It felt really cool at first because I was like, "Wow, I'm the youngest one here, and everybody listens to me." But then, at some point, I was like, "What am I doing? What's interesting about this," and there wasn't.

ZIERLER: Now, this was right around the time of the dot-com crash.

GREER: That's right.

ZIERLER: Did you feel that at Intel? Did that reverberate?

GREER: Very much so, yeah. There was the dot-com crash. Y2K happened. I got my master's degree in 2000, in the spring of 2000. That was Y2K, and then I started at Intel, and then the dot-com crash happened. Luckily, we bought a house in San Francisco [laugh], so that was really nice. When we first started, they had all these great events. There were little dinner cruises, and the interns all had a car. Get this. When I was an intern at Intel, every intern got a rental car with no questions asked. If you didn't like your car for whatever reason, you just would go and return it, and get another one. They gave every intern—I think it was a car per two. Every two interns got a free car. I was like, "This is absurd." They had all these parties, like really great. When I was there as a real person, there were no more parties, there were no more free events, but you could tell. You could really tell. Things got a lot more intense, and a lot less freebies.

ZIERLER: Do you have any idea how you got on Bill's radar? How did he know about you?

GREER: Bill Nix?


GREER: I took classes from him, because remember I was a Stanford student for a while. Even though I didn't work in his group, he—

ZIERLER: He knew who you were?

GREER: He taught all the classes that I'm teaching now. I'm teaching both classes that he taught. He knew who I was, of course. It's not such a big program. I smile a lot, so I'm a happy person.

ZIERLER: [laugh]

GREER: He's like, "I remember your smiley face." He remembered me. I must have made an impression. [laugh] I don't know why.

ZIERLER: What was that like when you met him and discussed the project?

GREER: I fell off my chair. Literally, I was sitting at Intel, or standing—I had a stand-up desk, just like I do here—typing away, doing something, and I just lost it. I was like, "Oh my god."

ZIERLER: That was really your ticket? That was your way back in?

GREER: Pivotal. He was the first person who really believed in me. Up to this point, there was a lot of people not so much believing in me. It's like you can't get into MIT. You can't do this. You can't do that. You can't get into grad school. I didn't get into Chem-E Berkeley. A lot of aspects of my life were facilitating this imposter syndrome. They were like, "You're right, you're not good enough, or you're a bad scientist," up to that point. I just believed them. I was like, "I'm not so good." Bill Nix was the first professional person who was like, "You're not so bad." [laugh] Do you see how well that worked out? [laugh]

ZIERLER: Tell me about the project once you signed on.

GREER: A funny story. Up to that point, I'd only worked on electronic materials, and transistors, and Intel-relevant things. Here's Bill Nix, who could care less about devices and about anything translational. He's very fundamental, like the stresses on thin films, and mechanical properties of materials, so very different. He said, "There's this new instrument here called the focused ion beam, FIB, and I was thinking that you could make little tiny nanopillars out of something. Go figure out that instrument." I was like, "OK, I'm going to go figure out this instrument, nanopillars, sure." [laugh] I spent a lot of time getting intimately familiar with my friend, the FIB, and because I was [laugh] so young, my shift was from 2 a.m. until 6 a.m. I was the lowest on the totem pole, of course. It was really late at night, and I was super tired, and I was getting to know that FIB, and then there's the nanoindenter, and I made the gold nanopillars. At that point, I remember I went to him, and I was like, "Why am I making the nanopillars? What are we measuring here?" He said, "There is some work that suggests that"—in every textbook, you will learn—I'm just telling you this—in every textbook, we learn that if you take a brick, and you measure its strength—we call that yield strength but basically strength—it's one thing. Say you break the brick in two, it's still going to have the same strength. Say you break the brick in four, it's going to have the same strength. This particular material property called the yield strength, or strength or fracture strength or toughness or anything like that, is a material property that's independent of size. It doesn't matter how big the brick is—it could be huge, it could be small—it will break at the same strength. It turns out that when you make things at the nanoscale, it's all upside down, and it becomes very much dependent on size, with smaller being stronger. This is not something that anybody could have anticipated or anybody knew about. His previous student, Mike, hinted at that. He did some experiments, not with nanopillars but with small-ish, micron-size pillars, and showed that the strength is higher in those small ones. But it was just one-off, one experiment, so maybe he was wrong.

I think that the point of Bill Nix pointing me to making the nanopillars was to probe whether that's real or not. Here I was. I came as a clean slate. I didn't know any of that research. I didn't speak mechanical properties. I was working in electronic materials. I managed to make the nanopillars, and managed to test them, figured out all that stuff, and, boy, were they stronger. I worked with gold. Gold is typically a very malleable metal, very soft, very easy to deform. But when you make it at 200 nanometers—so it's one 10,000th of your hair in diameter—it becomes as strong as steel. We were like, "Is this real? Is this really happening?" I passed my qualifying exam. I did all the things that the PhD students are supposed to do. But I had taken most of my classes before, so I didn't have to take them over for the most part, so I could focus on research. In my third year summer, I think, I got to go to a conference, and I got to show this research. I didn't think much of it, just like that it was interesting. Then at some point, he's like, "We should really write this up." I was like, "All right, let's publish a paper. I don't know anything about publishing papers." [laugh] I wrote up this paper, and it got accepted right away. I was like, "Easy-peasy."

ZIERLER: [laugh]

GREER: Everybody does that. Everybody has that experience. You write a paper, and it just gets accepted.

ZIERLER: Where did you submit?

GREER: Acta Materialia, which is the flagship materials journal. We should've submitted it to Science, and eventually we did submit something to Science, and there was some controversy and whatever. But that paper to this day is considered to be pretty seminal. It gets cited once a week since that time, since 2004, I guess—I think it came out in 2005—but since 2000. I was a third-year grad student. It came out in 2005. If you look at the number of citations, it's once per week, so it's 52 times a year, at least.

ZIERLER: I want to go back to the FIB instrument. What did it look like? How do you work with it?

GREER: It's awesome. I was a little bit like Scarlett O'Hara because I was so fed up with doing the 2 a.m. to 6 a.m. shift that I was like, "Someday I'm going to have my own FIB."

ZIERLER: There you go.

GREER: "I will never be fibbing at night again." What do you know? I have my own FIB, and I love the FIB. It's my favorite instrument. What does it look like? It looks like a big vacuum chamber with a whole bunch of things in it. There's an ion source, and an electron source, and there's this thing that lifts things up.

ZIERLER: How is the ion source created? Where does it come from?

GREER: Gallium. They're gallium ions. A big vacuum chamber, and then there's this liquid metal ion source of gallium, and it shoots gallium ions at the material and it etches it away. You can make like a nano toilet or nano anything, nanopillars. The big vacuum chamber with a thing underneath, and a whole bunch of things sticking out of ports.

ZIERLER: Is there safety considerations? You could just use it without protective equipment?

GREER: Oh, yeah, because it's in a vacuum. Everything is in a vacuum chamber. You have to vent the chamber, and then you go pfff, move it out. You have to wear gloves, of course. You put your tiny little sample on the sample holder into the stage, and then you go pfff, and then you pump it down to vacuum. Then you see it.

ZIERLER: Why gold?

GREER: Why did I work with gold?


GREER: It's a pretty standard metal that doesn't form an oxide. I could have worked with platinum too. But all the other ones like copper and aluminum and nickel and all the other—it was important to work with an FCC metal, with a so-called face-centered cubic metal. There are very few that don't form an oxide, and they're all very expensive, so gold and platinum.

ZIERLER: You found that the yield strength goes up, the thinner the material is?

GREER: It not only goes up; it goes up in a power law fashion. It goes up as whatever the strength is to the power of m. It's not linear. It's very much going—

ZIERLER: Why does it do that?

GREER: Because in nanostructures, the defects behave very differently. When you're dealing with a big bulk crystal, all of your defects, which are affectionately known as dislocations—which is the class that I teach, from which I just came—they operate collectively, in concert. There's this textbook law that I just taught called Taylor Relation, which says that the stress is proportional to the square root of the dislocation density. The greater the dislocation density, the greater the strength. What we discovered is that at the nanoscale, it's the opposite because the dislocation density drops down so low that you now have a scarcity of dislocations, or we called it dislocation starvation. You starve your crystal of dislocations, but dislocations are your units of plasticity.

The reason why we're able to bend a paperclip is because we're moving these dislocations around, and they accommodate that shape change. If our world were ideal, everything would just break. Everything would be extremely strong, but then they would just break. Nothing would be deformable. The dislocations enable metals to be deformable. Typically, in typical metals, you're constantly multiplying them, which is the process that's called cold working or strain hardening. By the virtue of multiplying your dislocations, you get materials to be stronger. In our pillars, we ran out. Because they were so small, and there was always a surface available next to the dislocations, the dislocations ran out. Once you start deforming them, they would run out of the crystal. Now you have a crystal that's perfect. It doesn't have enough dislocations in it to accommodate further deformation. But we're still deforming it, and as we're still deforming it, then dislocations have to come from somewhere; otherwise we won't be able to deform it. They had to be nucleated. To nucleate something to form something requires a tremendously larger amount of energy than to move something. We were in this dislocation starvation regime where we had to nucleate to produce new dislocations, which is what required the much greater force.

ZIERLER: Why the term "nucleate"? Why does nucleate create these new dislocations?

GREER: That's just a very typical scientific term. Nucleating something means forming it. It's just a typical term. When something nucleates, in the atomic jargon, you nucleate things. Everything nucleates. A particle nucleates. Dislocation nucleates. Nucleation and growth is something you learn about. It's a materials science term.

ZIERLER: What is the actual mode of action of a FIB device? Does it break? Does it split? Does it fry?

GREER: The FIB carves.

ZIERLER: Carves.

GREER: The FIB carves a structure. Imagine a butter cow at a county fair. You carve it out. Imagine you have butter, and then you carve it out. It's a subtractive process. You start with a chunk, and then you etch away all the things you don't want.

ZIERLER: Like a CNC machine?

GREER: Like a what?

ZIERLER: A CNC machine.

GREER: What's a CNC?

ZIERLER: It's a rotating blade, and you put a block of wood, and it carves whatever shape you want.

GREER: Yeah, kind of like that, or a knife with butter. You carve out exactly the shape that you want out of just a chunk.

ZIERLER: But to measure the strength or the resistance of the deformation, why not just—?

GREER: That was a different instrument.

ZIERLER: That's a different instrument?

GREER: That's a different instrument. That's called a nanoindenter.

ZIERLER: Got it.

GREER: I should've mentioned that a little more explicitly; two instruments that I worked with. Bill Nix was known, at that point, on the mechanical behavior of thin films. He won a medal on that. He is very well known in the mechanical deformation of thin films. But this is entirely new because now we're dealing with nano. A thin film is a two-dimensional object, which behaves very differently. It hints at the behavior of what a standalone nanostructure could do, but there was no way to infer it. I was the first person in his group to work on these nanopillars that are very different. But to probe them mechanically, you can use the same instrument. That's called the nanoindenter. But what a nanoindenter does is it's a sharp diamond tip, and you drive it into your thin film. It was developed specifically for thin films and for bulk metals. As you deform your metal underneath, you can get its elastic properties and even get some information about its hardness. That's a plastic property. But it doesn't allow you to measure stresses or strains, which are the key parameters in any mechanical behavior. People were obsessed with nanoindentation, and it was two of his former students that developed this technique. It was something that was used by a lot of his students, and I didn't want to be the n-plus first. And he specifically told me that he didn't want me to be the n-plus first person working on nanoindentation, because there's very little left to break new ground. I was doing an entirely—

ZIERLER: Meaning he was sensitive for your career prospects? This was going to be your calling card?

GREER: In retrospect, possibly. I don't know. I honestly don't know because nobody knew what was going to come out of it. It was an entirely untapped territory. I don't think he was so much looking out for my career. I think it was more like he was ready. He didn't want another student working on the same set of problems. That's how I would treat my students now too. Say there's this process that we developed, and somebody new comes in. It's not so much that I'm looking out for their career because I will make sure that their career does well, but it's just there's so little space left for doing something truly innovative in something that you've already been doing for a long time that you find a person, and you're like, "Why don't you go try this because you're young, and you can, and I can afford for you to spend a year trying something new?" I think it was more like that, more like an exploratory type thing.

ZIERLER: Now, did you know from when he introduced you to this project that this would be your thesis research?

GREER: No. He just told me, "Go learn with him." I was like, "OK. Never heard of the FIB before, I don't know what it does, but I'm going to go figure it out." No, there was very little guidance.

ZIERLER: The paper made a splash immediately?

GREER: The paper made a huge splash. I got invited to all kinds of conferences. I won all kinds of awards. It was amazing. Then what happened after that was even more amazing. I was a third-year grad student; very young. I got the little MRS Gold Award, this one, for that research, and it was a big deal. We couldn't have predicted how big of a splash that was going to be.

ZIERLER: Bill was as surprised as anyone?

GREER: Exactly. Bill was more—we call him boss. The boss was more surprised. I probably lengthened his career by about a decade—

ZIERLER: [laugh]

GREER: —just by doing these ridiculous—they were challenging experiments, and no one had done them before, except for that guy Mike. But he worked with a much bigger length scale. No one had done the nano things, and so because of that, there was some competition, and these German people were trying to shoot us down. There was some drama, anyway. What happened was that I went to present this research. Do you know who Harry Atwater is?

ZIERLER: Of course.

GREER: I did my little award talk at the MRS, and this dude—this dude right here—came up to me after that, and then he said, "I would like to invite you to present this research at a German castle, at this amazing castle in Germany. We're inviting you, so we'll pay for everything." I was like, "What?"

ZIERLER: [laugh]

GREER: Usually, you invite the advisor. You can't invite a grad student. I was like, "What the heck is all this about?" I was like, "Is this legit?" It seemed legit. Then there was this workshop called Lazarian, and I guess he was impressed with my—I don't know why, but he invited me. I went to Bill Nix, to the boss, and I was like, "Boss, you're not going to believe this. I got invited to give this talk, and it's in an old German castle. What do you think I should do? What do you make of this?" He's like, "Let me look at the list of participants." He's looking at the list, and he's like, "Harry Atwater, I know that guy. He's your guy. Stick with him." I was like, "Who's Harry Atwater? I have no idea about any of this." We went. This is the picture from there. Here's Harry Atwater, and that's me being a little grad student.

ZIERLER: Where was Harry at that point?

GREER: Here.

ZIERLER: He was at Caltech?

GREER: I think so. Yes, he was definitely at Caltech.


GREER: Now, I should mention one more thing. I had a friend named Christine in grad school at Stanford, who left Stanford to go to Caltech. The only things I knew about Caltech was that Einstein was here, and Richard Feynman—I really loved all those books: Surely, You're Joking, Mr. Feynman, and that's it—and then my friend Christine, who went to Caltech. Now, we weren't close friends or anything like that, so all I knew just through the grapevine was that she worked for somebody, but then that somebody went to Harvard. Her advisor went to Harvard for a little while, and then he came back, but she stayed at Caltech, or something like that. I just knew something about that. It's totally independent. Here I am at this Lazarian workshop with all these men, [laugh] a lot of men. I needed to leave a little earlier, and I asked at some point, "Is anyone going back to the airport on this day because I can't stay longer?" This guy, Harry Atwater, whom I hadn't met before is like, "I'm going to go to the airport a little bit earlier too. Do you want to come with me?" I was like, "Are you a Harry Atwater?"

ZIERLER: [laugh]

GREER: I was like, "Oh my god. My boss told me I should stick with you." We're on the freeway, on the autobahn, and this guy is a driving maniac. He's going so fast, and I just got really nervous because I'm alone. I'm really young.

ZIERLER: What's happening? [laugh]

GREER: What's happening? I'm a third-year grad student, and this guy's driving really fast. Also, he wasn't talking to me very much. We weren't bonding or anything like that. We were just chatting in a forced way. He's growing 150 kilometers per hour. It was very fast, and I was so nervous. When I get nervous, I start talking a lot, even more, and so I just was like, "Oh, you're Harry Atwater. You're a professor at Caltech. Oh my god. I don't know anything about Caltech, except I know I have this friend, and she worked for this crazy advisor who was at Caltech, and then he went to Harvard, and then I guess he didn't like Harvard, and then he went back to Caltech, and I don't know what that was all about." At that point, there's dead silence in the car, and that was the first time that he turned around and looked at me, and goes, "That was me."

ZIERLER: [laugh]

GREER: I was like, "Oh, shit. You can just let me out here. I'll just walk to the airport. It's OK. I don't need to get to the airport."

ZIERLER: [laugh]

GREER: I was so embarrassed I had the temerity to offend the great Harry Atwater without even knowing this. What do you know? We get to the airport, and he ditches me. He goes to the United Club, of course. Again, I'm like, "Oh, I'm going to fly back home to San Fran." A few weeks later, the boss walks into my office, and he goes, "Hey, Julia, Caltech called." I was like, "Great." He goes, "They want to [laugh] interview you for a faculty position."

ZIERLER: Oh, wow.

GREER: And I was like, "What? What are you talking about?" He's like, "No [laugh], they really do." There was a professor here, Sossina Haile. I don't know if you know her.


GREER: She's at Northwestern now.


GREER: I guess I must have impressed Harry Atwater so much [laugh] by being so rude to him. They had a search here. He must have told Sossina about me, and so I met her at the MRS, and she was the search chair, which I didn't know about. But they called the boss, and they're like, "What's Julia thinking?" He's like, "What do you mean? She hasn't graduated. She hasn't defended her dissertation, and she hasn't even looked for her postdocs yet. She's very green." They're like, "We want to interview her." I was like, "You are kidding me. This must be some kind of a joke." I was completely unprepared. I submitted this package, which I knew nothing, like so young, like a third-year grad student. Here I was at Caltech. I'm like, "I'm just going to enjoy myself because there's no way I'm going to get this job." [laugh] I called Sossina, and I was like, "You guys want to interview me?" She's like, "Yeah. Why don't you come and give your talk, prepare this." I was like, "Do you have any advice for what I should do?" She said, "You're never going to get this job." Maybe not in so many words, but I got that message loud and clear. She said, "You have to demonstrate the same level of maturity as people who've had several years of postdoc already under their belt, so it's very unlikely that you would even get this position. But why don't you come and tell us about your full science?" I was like, "Message received." I'm never going to get this job. It's going to be just a fun trip. I wasn't even nervous.

ZIERLER: Low stakes?

GREER: Exactly. I was like, "This is never going to happen. This is not real." Also [laugh], I was in the process of preparing to play a solo with the Redwood Symphony, the Brahms' Second Piano Concerto, which is a big piece. My mind was somewhere else. I was getting ready to defend, but all that stuff was happening at the same time as I was preparing this big concerto concert. It was an intense period in my life. I came, I had a great time, I met some amazing people here, I told them all about my nanopillars research, and they were really excited. I was like, "Yeah, this is a cool project. It's about dislocations, and nanopillars. I'm so excited about it too." It was just not scary. It was fun, and so I had a great time here. I went back home, and then two weeks later, the boss walks in again. He goes, "Hey, Julia, MIT called. [laugh] They would like to interview you for a faculty position." But this time I knew what I was getting myself into, and so I was like, "All right." I put together the same pack. I knew what was going on, and I was like, "Maybe this research is exciting, like, people really think that there's something to it." That happened, and then I started interviewing for my postdoc positions, and [laugh] then I defended. It was totally backwards.

[unrelated conversation]

ZIERLER: Now you were ready for a proper faculty presentation at MIT.

GREER: Right.

ZIERLER: How did that go, and what were your experiences like comparing MIT and Caltech?

GREER: Very different. Caltech was so fun. Everybody at Caltech seemed happy. They had pictures of their children, pictures of their families. They were fun people. Also, it was California, so it was sunny and happy, and I just got a really good vibe here. MIT, for me, it was a very nostalgic experience, because my—

ZIERLER: Undergrad.

GREER: —whole undergrad, the formative years, that's when I truly became an American, really. It was a lot of personal growth. There was a lot of assimilation. There was a lot of integrating.

ZIERLER: But you were also seeing it at a very different time in your life.

GREER: Right. But it brought back all these memories. It was very surreal being interviewed for a faculty position there, and having all these professors, who used to be my professors, be colleagues as I was a third-year grad student. It was strange. It was a great experience. I was more like in awe, and I was a bit more nervous. It was a powerful experience. Caltech's experience wasn't powerful. It was more fun. I don't have another better way to describe it. It was really just going and talking about my work to a bunch of people that cared about it, and it was fun. I didn't feel scared. I didn't feel any pressure. I didn't feel nervous. It was just a great scientific conversation, or many great scientific conversations. But at MIT, it was scary, and it was what a faculty interview—you would imagine it to be like. It was intense and scary. I think I did pretty well, at the end of the day, but it was very different.

ZIERLER: Did you feel like you were being seriously considered for both, or that it was more like there's no way?

GREER: Not at Caltech, but I very much felt that way at MIT. At Caltech, I knew I wasn't going to get this job. I really went in with that attitude because of what Sossina told me. Fun fact: Sossina had a four-year-old son, who is now in my group and in my class.

ZIERLER: Oh, that's awesome.

GREER: It is so heartwarming.

ZIERLER: That's awesome.

GREER: I still can't get over it, because this is the kid I babysat when he was four years old when I first got here, and now he's a Caltech student, and he's in my lab. He's working in my lab. This is crazy.

ZIERLER: You said, at the same time, you're also applying for postdocs.

GREER: Yeah, because that's what they do. This is what a lot of faculty searches now do. They like to snatch the talent—we're doing this right now—from grad school, straight from grad school, and then just send them to do a postdoc so that they could mature. I did that. I did everything backwards. I got my faculty position first, then I interviewed for my postdocs, got my postdoc position, and then I defended. [laugh] Most people do it the opposite. Most people defend first, then get a postdoc, then get a faculty position.

ZIERLER: Where did you get offers?

GREER: Those two.

ZIERLER: Caltech and MIT?

GREER: Yeah. I didn't interview anywhere else.

ZIERLER: Caltech, at the end of the day, gave you an offer?

GREER: They were so quick. They gave me an offer two weeks after. MIT took a long time.

ZIERLER: Do you think that the advice that you received was incorrect, that your prospects were better, or did you display the level of maturity that you were told you needed to display? It has to be one or the other.

GREER: I think I really charmed them, honestly. I think I just was so excited about my research, genuinely very excited about my research, with no reservations, and I think it really showed. I'm a pretty dynamic person, so I think I really was like, "Look, this nanopillar stuff is really elegant, and you can learn so much. Look, this is defying every theory in every textbook that we teach. This is big. Look, we can apply it to this, and we can apply it to that." I met with all these people, and I connected with everyone on some level, so I think that I charmed them, honestly. [laugh]

ZIERLER: Yeah. Who were some of the faculty that you interacted with on that faculty visit?

GREER: Definitely Harry, Bill Johnson.

ZIERLER: Did you have a better experience with him at that point?

GREER: A much better experience with him.

ZIERLER: [laugh]

GREER: He's my friend. He's one of my favorite people here. I love Harry. He's definitely one of my favorite people here. Sossina, Bill Johnson, Brent Fultz, Kaushik Bhattacharya, Ravi Ravichandran, Rob Phillips, Julia Kornfield.

ZIERLER: Ares Rosakis? Was he part of that?

GREER: No, Ares wasn't a part of—at least I don't think I met him at that time. Chiara, I think I met Chiara Daraio—or maybe not during my search.

ZIERLER: It was a pretty easy decision between Caltech and MIT for you?

GREER: So easy. Oh my god, it was a no-brainer. I told people I didn't want to change my driver's license, but it was not that at all.

ZIERLER: [laugh]

GREER: I felt like I belonged here.

ZIERLER: They said, "Come, defend, postdoc, and then joined the faculty."

GREER: Exactly. Richard Murray was the division chair at that time. He called, and he's like, "We'd like to make you an offer." Then at that point, I had to grow up really quickly because they're like, "What equipment do you want? What kind of lab do you want?" I was like, "Oh my god." Again, I'm a third-year grad student. Let's not forget. I was really unprepared for life at that point, and so I had a pretty rough experience as a postdoc. They said, "We would like to make you an offer. This is very exciting. We think that you're bringing an entirely new research direction here." I was like, "Oh, thank you." But I said, "I would like to go do a postdoc." They didn't have the FIB. Sorry, they had the FIB, but it wasn't in a clean room. They were still building the Kavli Nanoscience Institute, which I now direct. But, at that time, they were just building it, and so it wasn't ready. I was like, "I don't want my tenure clock to be ticking while they're building the facilities, while they're building stuff, because it's just going to waste my time." I said, "I'd like to go do a postdoc." They said, "We would also like you to go do a postdoc because you're too green." That's what Bill Nix had told them. They're like, "What's Julia thinking?" He's like, "I'm thinking that she's too green," and I was. I did an almost two-year postdoc, and they waited.

ZIERLER: Where did you do your postdoc?

GREER: At PARC Palo Alto Research Center, where the mouse was invented, and ethernet.


GREER: I was at Xerox PARC.

ZIERLER: What did you do while you were there?

GREER: Oh my god.

ZIERLER: Did they have a FIB?

GREER: No, I worked on an entirely different thing. I worked on thin film electronics, thin film transistors on compliant substrates. I worked on something completely unrelated to my current research.

ZIERLER: But this was much more fundamental in the work you were doing at Intel?

GREER: No, it was like halfway. It wasn't much more fundamental. It was much more like what I was doing at Intel, but they were making innovative products, so it was somewhere in between. It's a wholly-owned subsidiary of Xerox. I was put on a project that was fun and more fundamental in nature, but they were making devices, so much less fundamental than grad school but more fundamental than Intel.

ZIERLER: Now, the thesis defense, was that almost an afterthought?

GREER: Yeah.

ZIERLER: Was it more hurried than it otherwise would've been?

GREER: It was a thing I had to do before I played, or I was really focused on my Brahm's concerto. My parents flew out. Honestly, I don't remember my thesis defense very well.

ZIERLER: Yeah, it's a blur.

GREER: Yeah, it's a blur. My parents came out, and I don't remember my defense very well. It was a big deal, I'm sure, but my mind was somewhere else. I was really focusing on the Brahms.

ZIERLER: Was Bill useful? You said you had to grow up really fast. What do you need for the lab? Was he a resource for you in that regard, or you figured it out on your own?

GREER: He wasn't a resource for figuring out the start-up. He is still my go-to person for every kind of advice, and I love him and respect him tremendously. But I think for setting up the lab, I didn't go to him. I went to some younger people who were doing work—

ZIERLER: They're closer to the research?

GREER: —closer to the research, and that were closer to my age, obviously, just because he hadn't gone through this process of negotiating for 45 years or 50 years. He had just retired, so he was very much sunsetting his career. I talked to some people who were much more relevant to that time.

ZIERLER: Did you feel for the postdoc you were really just biding your time until the FIB was ready?

GREER: I went through a little bit of a crisis in my postdoc. I think it was too much. I think all of that intensity, like the way I'm describing it now, it's fun.

ZIERLER: A lot happened real fast?

GREER: A lot happened real fast, and I got pregnant, and I really wanted to have a kid, and we were going through some really rough times. It was a lot. The Brahms' concerto was too much, and the defense was too much. Getting a faculty offer when you're 26 years old was crazy. It was too much. I definitely had some kind of a mental breakdown I think when I was there. I was not eating and not doing so well, so I took it easy. I learned a lot. I took it easy. Thank god that I had this offer because I don't think it would've materialized had I not.

ZIERLER: Now, was there a two-body problem, or you knew that you were just both going to come down here?

GREER: They were awesome. They created a job for him at JPL. He has a PhD from Berkeley, and he's a pretty smart guy. When we first came, Caltech said, "We don't do two-body problems. We don't accommodate spouses." I was like, "What are we going to do?" They said, "Let's see if we can come up with something at JPL." It took so long for me to do my postdoc, like almost two years, that in that amount of time, they made him an offer from JPL in his own right. But it's good to have had that time.

ZIERLER: Absolutely.

GREER: I moved by myself, four months pregnant, by myself. But he came a month or a couple of months later.

ZIERLER: Was the postdoc useful for when you wanted to get going at Caltech, or not really?

GREER: It was, it really was; maybe not in terms of the research but in terms of growing up, in terms of becoming more independent, in terms of making decisions, in terms of how do I plan my lab? What am I going to do? Who am I going to hire? What am I going to do? All of a sudden, the financial aspect of things was never a part of my grad school. It just wasn't something I had ever experienced. I don't really involve my students in proposal writing even now; sometimes only when it's a cool idea. But the financial, I feel like that's for grown-ups. As a grad student, I was never a part of it. At PARC, I got a little bit of a preview for what it's like to write a proposal. I [laugh] remember I worked on my career proposal for six months. Most PIs work on their proposals for three weeks. I had six months. I really planned it. I was like, "I'm going to totally write this," and I got it [laugh], so it was great. But I spent a lot of time learning how to write proposals. It was a self-care postdoc. [laugh]

ZIERLER: Last question for today. We'll pick up next time. You joined the faculty at Caltech. This long period of time where you're waiting for the FIB gave you probably an opportunity to think about what are you going to do when you become a faculty member?

GREER: A hundred percent.

ZIERLER: How strategic were you, from day one? Did you have a really good idea of what you wanted to accomplish, or did you recognize Caltech being Caltech, it's all about meeting people, and going to the Ath, and going to seminars, and figuring out what's fun? What was your sense of how to manage all of that as a brand new faculty member?

GREER: It was overwhelming. It was all of the above, everything. This is a really well-posed question. It's all of that. I didn't know. Caltech has really changed and, in general, academia has really changed. We didn't have mentors. We now have a mandatory mentorship program, so I'm mentoring a younger faculty member. We didn't have anyone like that. For next time, save a story. There's a story that came with how I was brought here, because I traveled a few times. I traveled from Stanford to come here to attend the opening of the KNI, the Kavli, or to attend a graduate admissions meeting, or something like that. There were discrete events where I would come in, and do something, and then I would fly back. I want to say it was strategic because I really carefully thought about what I wanted to do, and everything was on my side in the sense that it was a new field that I founded. When we first started doing the nanopillars research, it was very new. It was a new game in town. By the time I got here, there was not a single materials conference without a full symposium dedicated to it, and I started that. It was really a testament to that research being really meaningful, and people recognize that. Even with all the fighting and all this stuff, people knew that we were first, the first ones. There's a little bit of who was really first, but people knew that we started that field.

It was lucky that because it was such a new, young field, there was a lot to be discovered. There was enough place under the sun for everyone. As part of my strategy, I knew which way I wanted to move, and I knew what I wanted to do. There's an army of Germans that have just a ton of people and a ton of resources that just reproduce whatever you do a hundred times. I learned very quickly that to stay ahead of the game, I couldn't just continue to do the n-plus one thing, so I never did that. I would always seek out new ways, new collaborations, and that's where the postdoc came in very handy. I'm so glad I learned about the thin films because I scored some kind of a collaborative proposal that got funded doing electronic properties. I was like, "Hey, look at that. I know about electronic properties of graphene." It was about graphene. I would've never learned about graphene had I not done that postdoc, and measured transistors, and understood what that meant. Mobility, I was like, "What is mobility?" It was great. It was useful.

ZIERLER: Despite the personal crisis, it really was good for you?

GREER: Despite the personal crisis, it was a great place for me. It was very nurturing. I met amazing people. One of the people I met there is now the chair of the materials science department at Stanford now. I made great friends. I had a good time. It was a break, because it was escalating at such a fast rate that it was just too much. I think had I not been myself, something would've broken down. But I did it. I pulled off the Brahms. I pulled off the faculty position. [laugh] I pulled off the defense. It worked out. I had a beautiful baby girl—

ZIERLER: Five months later.

GREER: —five months later. It was intense.


GREER: Yeah. [laugh]

ZIERLER: We'll pick up next time—

GREER: Sounds good.

ZIERLER: —starting life in Pasadena.

GREER: Yeah.

ZIERLER: OK. [laugh]

[End of Recording]

ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It's Wednesday, March 1st, 2023. I am delighted to be back with Professor Julia Greer. Julia, as always, thank you for having me in your office.

GREER: Thank you for coming and visiting us again. This is such a fun experience. ZIERLER: Awesome. Julia, today we are going to pick up right at that formative moment we left last time. You shared with me this obvious feeling that you had between MIT and Caltech. The faculty at Caltech were just having fun, and that resonated with you, and that made it a very easy decision. From day one, how did that culture of fun and adventurousness at Caltech inform the kind of Caltech professor you wanted to be, the way you wanted to build your lab, the way you wanted to build your group? Who was around that might be early collaborators for you? The question there is, you saw the fun, how did you activate that as you began your career at Caltech?

GREER: I should probably preface this by saying it wasn't an easy decision.


GREER: No, it wasn't.


GREER: I thought about it. MIT obviously has the allure of MIT.

ZIERLER: Definitely.

GREER: It was very scholarly, in a way, and the walls and the hallways were so—because I was an undergrad there, there was something very special. Intellectually, there was a lot of admiration that I had for the place. At Caltech, it wasn't so much that it was fun; it just felt human. It felt like I could belong there. People liked each other. People had a true sense of community. Collaborations were very easy, and everything was done on a human level. I really connected with that. I resonated with that. It wasn't like a big institutionalized something. People talked to me. I went to dinner with faculty. I walked somewhere with Harry Atwater, and we interacted. It was just a very interactive—sort of the original FaceTime—kind of thing. When I first arrived, it all seemed unreal there. I had my own lab. They were asking me questions like, "What color carpet do you want in your office?"—

ZIERLER: [laugh]

GREER: —as a third-year grad student. I'm like, "Wow, I get to choose my own carpet?"

ZIERLER: [laugh]

GREER: Then, "What color do you want to paint the walls in your lab?" I remember that question very well. I'm like, "I had never had to think about something like this. Seriously, you're asking me what color? Oh, let's do happy yellow and green [laugh], earth colors, something like that." I think that from the very early days, it was really forming the connections and the relationships. I feel like I know pretty much everyone on this campus now. I really took the time to get to know the people around me, to learn from them—to not collaborate. We are advised against collaborations. As a young faculty member, as an assistant professor, we are advised that to get tenured, you have to make your own mark on the world.


GREER: You don't want to be collaborating. First of all, definitely don't collaborate with senior people. Because I had a really famous advisor—and this is true for many of us—we have a very famous advisor, you have to really distinguish yourself. You have to really start doing things that are not going to be like what your advisor would be doing. But, naturally, since you had just graduated, your advisor is still very invested in that project, or in those thoughts. I had to spend a lot of time at Caltech, when I first started, thinking through where I was going to take this field, and that was the freedom.

ZIERLER: When you say "the field," what is the field? What was it called?

GREER: Nanoplasticity. I came here as a—

ZIERLER: That's the name of the game for you at that point, nanoplasticity?

GREER: Nanoplasticity, yeah. It's looking at the deformation of nanostructures, nanometals. We call them nanopillars. Remember the awesome instrument, the FIB, the focused ion beam?


GREER: We made a lot of the nanopillars and a lot of the nanosamples using the focused ion beam to get them to be nano, and then we studied their deformation. What are their mechanical properties? How do they deform? What are their strengths? What are the defects in them, and what is the behavior of these defects, and what kind of data do you get? That was my field. It was nanomechanics in many ways; nanoplasticity, specifically. What happens after the elastic bonds are broken? How do different metals, different crystals, different symmetries, different microstructures respond to that kind of an inquisition, I would say? That was my field, and I had to really have the academic freedom to think it through. I feel like at Caltech, you're given that freedom when you first come. Now, Caltech back then—this is 15 years ago now—was different. Of course, everyone will tell you that every decade is different. The one big difference between now and then, being an assistant professor, is that we didn't have mentors. We didn't have formal mentors, and we didn't have informal mentors. For a person like myself, it made me adopt some mentors to be mine on my own.

ZIERLER: The system that we have now is sort of indicative of what you wanted there to be that you sort of invented yourself?

GREER: We all did, all the assistant professors who came at that time.

ZIERLER: Maybe that's a generational thing.

GREER: It was a generational thing because we were expected to just be thrown—there's a saying that at MIT, they throw you in the water, and see if you can swim, and then they don't tenure half of you.


GREER: [laugh]

ZIERLER: That's not a humane way.

GREER: It's not a humane way. They hire a bunch of brilliant people, and then they throw them to the sharks, and then they're like, "Let's see if you can"—

ZIERLER: Because "brilliant" doesn't necessarily translate to being a successful leader of a research group.

GREER: That is a very well-put statement. Being brilliant doesn't mean that you have the maturity of management, or leadership, or setting up your own lab where instead of doing everything yourself, you now delegate these tasks to others, and you train your postdocs.

ZIERLER: You're being imaginative, and you're solving problems, and—

GREER: Oh, all the time—

ZIERLER: —all of the above.

GREER: —and you're planning all the time. You would have to be a parent to really figure out how to do all that, because you have to recognize that there's so much growing and so much learning to be done. The way Caltech does it is exactly the opposite. They will take forever to hire someone. I've been on so many searches where we didn't end up hiring anyone, or we just scrapped the whole search, or something didn't work out.

ZIERLER: Because you really need to fit to be made the offer.

GREER: You really need to be that person. Not only do you need to have the capability to eventually be the leader of your field that you're going to become a household name for some new phenomenon, but you have to be a good colleague that we all are going to embrace and help develop, and you have to just fit in. It's amazing how many people that didn't end up here are now at Stanford, at Harvard, at all kinds of very successful universities doing really great. It's not in any way a reflection on their research or on the quality of their proposed research. It's just it wouldn't be the right fit. We stand by every single person that we hired, with possibly some exceptions—but for the most part.

ZIERLER: It's a pretty good batting average.

GREER: It's a pretty good average, yeah, exactly. [laugh] They will take forever to hire the right person, but once they do, they really support them to get tenured. The tenure rate at Caltech is much, much higher than that at MIT, and anywhere in the Harvard and Yale and Duke and everywhere else, because we really take the time and the effort to hire somebody that we know will succeed. Because of that, I felt supported. I never felt like I needed to be cagey. We don't have too much overlapping discipline. I came as a nanomaterials person, and I was the only game in town. There weren't any—maybe a couple of people who also were maybe interested in nanomechanics but not as their main research thrust.

ZIERLER: Is this because this is sort of a growing field, and you're up and coming with it, or Caltech was just not involved in an area of research that was established? How do you see that distinction when you came?

GREER: It was both. It was all of the above, because there was a person here who was doing mechanical properties but of much, much larger systems. In every mechanical engineering but also in every materials science department, there must be somebody doing mechanical behavior. Somebody has to be studying mechanical properties of materials. There really wasn't anyone here, certainly not when I came in. There were some people in aero, there were some people in mechanical engineering who were doing mechanics but not mechanical behavior of materials, and so that intersection was kind of lacking at Caltech. They didn't have the right person.

ZIERLER: Probably that was one of the factors for your hire.

GREER: Probably, and that field was entirely new. I was in grad school. That field was just starting to become a field. It wasn't a field at that point. It was just like a set of experiments that everybody does.

ZIERLER: This idea that junior faculty should not collaborate, especially with senior faculty, because they need to figure it out on their own, was this communicated to you? Did you divine the tea leaves? How did you come to recognize the way of doing these things?

GREER: Academia is much bigger than just one university.

ZIERLER: Of course.

GREER: Here at Caltech, we're all kind of singularities here. That's very much a hallmark of Caltech. Everybody here represents a particular field, and the fields don't really overlap too much. Because of that, it leads to an atmosphere where you don't compete. There's no caginess so much. People share equipment. People share ideas. It gives you that freedom to think about your problems, or it gives you that freedom without being too stressed out that somebody's going to steal your idea. But, of course, the world of academia is much, much bigger, so a lot of it is hearsay. A lot of it is just talking to your mentors, talking to your senior colleagues, talking to people at conferences. I had a lot of senior mentors or just colleagues who would say things, and I would really listen to them. I really listened to my old advisor quite a lot. I listened to everyone.

The consensus was that if you're an assistant professor, you have to publish some things where you are the last author, you are the senior author, and there better not be another senior author, so that by tenure time, people can really evaluate your impact. Because if there are two senior authors, unless it's so clear who did what. For example, collaborating with theoreticians is no problem at all, because it's very clear they did the theory, you did the experiments, so no one's going to question who did what. But if you're collaborating with another senior colleague, either at Caltech or elsewhere, how can they tell what was your contribution, and who really was the intellectual power? We have had cases at Caltech where people didn't get tenured because of that, because there was a more senior overseer or participant than this. It was just a very easily open place of vulnerability where if somebody wanted to throw a rock, and say, "What did this person really accomplish?" Unless there's a very clear—

ZIERLER: That's a consideration on capacity for leadership; not the science. Probably the science was excellent. But if you can't stand on your own two feet, that's where the assessment is.

GREER: In many ways, that's fair. In some other ways, it's less fair because it's cultural. What I mean by that is that there are certain cultures where you have to be deferential to your senior colleague, whether they're right or wrong. Even if you have all that leadership potential and everything that it takes to be a successful person, you are so engrossed in your culture, in your own cultural origins where it's not so much a meritocracy but it's very much seniority driven, you are not allowed to disagree with somebody. If a senior person is pushing you into an administrative duty, or a senior person is asking you more and more and more to do all these favors or to do all this non-scientific stuff, for example, or leadership stuff, you can't say no, and so your science suffers. That is a huge consideration, the cultural background. This is why having mentors can be a double-edged sword. The mentor has to be not self-serving. The mentor has to put your career as a priority, and not take advantage of your exceptional skill of any kind. Now, if you're really good at organizing something, or if you're really good at running something, or if you don't ever say no to get another task, it's very easy to put that person in charge of graduate admissions or in charge of organizing the seminar series for the department, or in charge of some event because you know they'll do a really good job. If you're extra competent at something, of course you're going to get all of these tasks being assigned to you.

ZIERLER: I'm married to one of those people.

GREER: Exactly. See, the super moms and the super capable people, they immediately end up with so many action items because they execute. Imagine you're an assistant professor, and you should be only focused on getting tenured. You should be absolutely working on having impact in your field, going to conferences, communicating your science, publishing, publishing, publishing, all that. But now imagine that there's a more senior person who's telling you, "You did such a great job organizing this seminar. Do you mind running the seminar series for our department?" Of course, you're going to say yeah. You can't say no to a more senior person, so you're going to do that, and that takes a lot of time. Now, imagine you also have a child. Also, your tenure years are your child years. That's when you start a family. Then, in addition to it, you now have a baby, and you have to juggle all that. Then they come and they say, "We're really impressed with how the graduate students are really driven to your lab. You obviously have rapport with graduate students. Would you mind running our graduate admissions?" Before you know it, you're now tasked with these community service responsibilities in addition to being a parent, and somehow you still have to make tenure.

ZIERLER: You're saying one of the values of a mentor is knowing when to say no?

GREER: Yes. One of the values of a mentor is to say, "You have to set boundaries, and you have to recognize that the system is never going to demand less of you because they are empathetic." I'm mentoring somebody right now in that same way. Not only do you reserve the right to say no [laugh], to refuse service to anyone, but you should really establish a practice of doing so, so that you know what your boundaries are, because so much is demanded from you. The most important thing is that at tenure time, we're going to ask for letters from the world authorities in this area or in general in materials science to comment on whether this person is the true leader in the field. You're not going to be able to do that without being—

ZIERLER: Because that's the expectation at Caltech?

GREER: That is the expecta…yeah. At all other universities, when you get the NSF Career Award, people say, "Congratulations, this is so great." At Caltech, if you don't get the NSF Career Award, people ask, "What's wrong with you?" It's the expectation. [laugh] You don't celebrate somebody getting something. You're more like, "OK, moving on." It's expected. Our bar is very high, but we will support you all the way. We're giving you all the resources that you need. Now go do all that.

ZIERLER: I want superimpose—before we get to a more in-depth conversation on the mentorship part—for your own experiences, given a very famous advisor, and the fact that this research made a very big splash, I'm well-positioned to appreciate that lots of eminent scientists who went on to do great things didn't necessarily have a high-impact event like you did—to your surprise.

GREER: To my surprise, unbeknownst to me. [laugh]

ZIERLER: You're getting to go abroad. You're on the cover of this. You're speaking at that. I would say for sure less than 50% of faculty had that kind of—I can't speak off-the-cuff.

GREER: You're completely right.

ZIERLER: It's a unique experience, in the end.

GREER: It is a unique experience.

ZIERLER: Between the fact that you had this person as your advisor, and you had this unique experience of doing really significant research that resonated in the field, beyond what a normal dissertation experience would be like, how did that influence—to go back to the question of navigating your way, and figuring out what your research agenda is, and figuring out where you needed to be mentored but also figuring out the question we were talking about before I hit record, when do you drill down and continue with this, and when do you say, "This opens up this, this, and this"? How did you deal with all of that?

GREER: That's a really good thing to think about. I'll begin by saying I'm definitely unusual in that sense. I also kind of stand out from the crowd because I'm a pianist, so I've been invited a lot to play. I would go to a conference, and they would ask me, "Can you also perform?" I guess what happened to me that wasn't very hard for me, which could be harder for others, is to become visible. People became very aware of my name very quickly. I would go to the conferences, and people would be like, "That's Julia Greer," or, "That's the nanopillar lady." It's unusual to have a scientist play piano.

ZIERLER: If I could say also woman blondes—

GREER: Blonde woman in science, also unusual. There was just a lot of [laugh] a sufficient amount of unusualness about me in particular that made being visible not a challenge, shall we say? I got invited to places, and I would go and give talks, and I would publish, and I would do all that. Now, the advice I got was that you have to stay razor sharp with this nanopillar field until you get tenured, and then you can explore. I finally knew that I was ready to go out for tenure when I wanted to do so many other things, and I very much felt that.

ZIERLER: That was your gauge?

GREER: That was my gauge, and I didn't even know it. There was so much to do in the nanopillars field, still, there were so many ideas that it was pretty easy to pick. For example, the family of metals that we've focused on are called FCC, face-centered cubic metals. It's a particular type of symmetry in a crystal.

ZIERLER: Face-centered—?

GREER: Face-centered cubic, so FCC.

ZIERLER: What is centered about the face?

GREER: The atoms are in the face centers. Imagine a cube.


GREER: There are atoms at each vertex and also in each face center.

ZIERLER: Got you.

GREER: It's three pairs.

ZIERLER: Got you.

GREER: Gold and copper and nickel and all those metals that are very common have that crystal structure, and so we focused on those, and we thought we understood what was going on, and kind of figured it out. Nobody had even touched—there's this other cubic family of metals that are called BCC, body-centered. Now you have all the atoms in the vertices in one big—not big; same size but in the center; not in the face.

ZIERLER: A clump?

GREER: No, just an atom.

ZIERLER: But they're all centered, you said? They're not separated on the face.

GREER: Imagine a cube, and you have an atom at each vertex. In a FCC, you also have atoms at each face center.


GREER: In a body-centered, you only have it in the middle of the overall cube.

ZIERLER: Got it.

GREER: Only two atoms versus four.

ZIERLER: [laugh]

GREER: Four atoms in FCC, and two atoms in BCC.

ZIERLER: Remember I said scientists are people too? You might know more about this and everything, but you still have to count to four.

GREER: I totally did.

ZIERLER: [laugh]

GREER: Yeah, I still have to count because there's three hubs.

ZIERLER: [laugh]

GREER: Yes, exactly, six hubs. It's three and one-eighth of one, so that's one more.

ZIERLER: There you go.

GREER: Four versus two. Anyway, BCC are metals like molybdenum and tungsten and chrome and all these refractory-type metals. The defects in those kinds of metals behave very differently from the defects in the FCC ones, so that was like a hugely unexplored territory when I was doing a postdoc. My postdoc was all on thin film transistors and organic electronics, and remember I told you I went to a completely different field, so I was doing that. But then I had to maintain some presence. This was a very important thing. I already had my Caltech position waiting for me, but I couldn't be absent from the field for a couple of years. Even though I was working on something else, I felt like I couldn't afford to be not going to the nanopillar symposia and conferences, etc., because people would forget about me. I couldn't start my career.

ZIERLER: You're being strategic.

GREER: Strategic, yes. I started all that BCC work that no one had even attempted before, while I was doing a postdoc as sort of like the afterhours. I collaborated with a professor at Stanford. Stanford was very close to PARC, Palo Alto Research. Everything was in Palo Alto, so it was relatively easy to just go back to campus and to start on that. I kind of in parallel never got out of the nanopillars field, even though I was doing a postdoc. By the time I got here, I had it handed to me on a silver platter that we were almost done with that work. I still made a little bit—not a splash-splash, but it was a local splash within that field because we've entered into this other family of crystals. By that time, everybody, especially the Germans, who have armies of people to do all this stuff, they're like, "Hey, we can do this. We can use the FIB to make a whole bunch. We are not limited to just crystals. Let's do nanocrystals. Let's do polycrystals. Let's do this. Let's do nonmetals. Let's do all this." It just exploded, and everybody started doing all this stuff, and that's when I knew that I had to move on. As a young assistant professor, you can't compete with an army of 100 Germans who are all doing every possible crystal structure. The game was and still is, how do you stay ahead? Right now, everything we do is additive manufacturing, nanoarchitected materials. I've moved long way from the nanopillars. I still have maybe a couple of students working on that. But, for the most part, we don't work on nanopillars at all. The same thing is happening. We kind of started this field of nanoarchitected materials, and it made a big splash, and everybody started following it, and now everybody's doing it. We're moving forward. The game here at Caltech is that you can't beat anybody with the numbers. You have to beat them with the idea.

ZIERLER: You define the field, and then the field—

GREER: Then you get out.

ZIERLER: —gets rushed into, and you move on to the next one.

GREER: Once it becomes mainstream, it's no longer interesting. No assistant professor knows this. The assistant professor comes thinking, "This is it. This is my golden ticket." It's only when you realize this field is coming to maturity, and I want to do other things, and I want to try other things. I've always had this idea in the back of my mind, ever since I started doing nanopillars in grad school, what happens if you put them together? What happens if you architect them into—I have some pictures on the wall here. What happens if you take these nano building blocks, and build something out of them? The largest dimension within this new material is still going to be just the size of the nanopillars, so it's still nano-sized, but the overall material size could be as big as a brick or it could be like a balloon or something like that, something you can touch. When you zoom in, there's just so much empty space; empty, empty space. It's like an atom. It's like peeling apart an atom. There are some electrons, neutrons, etc., but they're very widely separated. That's kind of how nanoarchitected materials are because all the nanoscale building blocks are there, and they comprise this material, but it's 99% air. I've always wanted to explore that, but I was advised against. "Before tenure, don't try risky ideas because you don't know." I waited patiently until I got tenure [laugh], and then I really tried a lot of—

ZIERLER: Did you think from graduate school to postdoc to early faculty years, was this exclusively basic science? This is curiosity-driven science? Were you thinking at all about applications, start-ups, companies? Was that in your world at all?

GREER: Not in the slightest.

ZIERLER: Is that simply because this is so cutting-edge, we can't think about any of that stuff until we figure out what we're looking at?

GREER: It's just a much more mature thing. It's not for kindergartners. When you're in third and fourth grade, you can start thinking about projects having a theme. But when you're in kindergarten, you're learning how to use the scissors. We were just all learning how to use the scissors, and how to make shapes out with them.

ZIERLER: Questions about how entrepreneurial a place Caltech might be, when you were thinking—again, to go back to the matrix of considerations of MIT versus Caltech—Caltech's development as a culture of—

GREER: Fundamental.

ZIERLER: No, as a culture of when you have a great idea, you can think about applications. That was not on your radar at all as a brand new assistant professor? It was a non-issue to you because it wasn't relevant at the time. What kind of institution is Caltech, based on my applied interests? Because that's getting ahead of the game. You don't have those applied interests yet.

GREER: Honestly, it was the opposite. I was excited about it because I didn't have to think about the applications. Doing fundamental science is really fun, and discovering new phenomena is really fun, and that's what I wanted to do, and that's still what I want to do. I think that that's what attracted me to Caltech, because MIT is very entrepreneurial, and Stanford is really entrepreneurial. But it's not very interesting. To me, developing a product is a lot less. Maybe because I've worked at Intel, and I've worked with real product before that that's just not inspiring. But discovering new things, and trying to understand mechanisms, and trying to understand. Think about how fascinating this is. Atoms are arranged in a particular way. Atoms are doing whatever they're going to do, and we are making connections and inferences about those arrangements, how they influence some property of a table, for example, or a property of some material—that's fascinating—or that you can stretch something forever and ever by 1000%, and something else you can't. That all comes from the atomic and molecular nature in the microstructure. How everything behaves emanates from that. Fundamentally, it's really the atomic constructs that govern our entire world. That's a lot more interesting to me than, oh, can we additively manufacture a scaffold and put something in? I'm being facetious, of course. Right now, the applications are meaningful, and the applications are interesting, and I would care about whether it eventually becomes a real product. But it's still not as intellectually interesting.

ZIERLER: Now, to go back to your innate expectation that Caltech should have a mentor kind of program, which it did not by law or even by culture—

GREER: [laugh] Even by culture.

ZIERLER: —did you band together with other assistant faculty members, and say, "Let's do this?" How did you start to build that?

GREER: We most certainly nucleated a group together, for sure. All the assistant professors were so cohesive. It was like going to school again as first years, except now we were the first-year professors, and so we definitely all gelled together. The women in particular did. We had lunches together. We had women's dinners together. We really stuck together, and it was really awesome.

ZIERLER: This is among divisions? This is not just an EAS thing you're talking about?

GREER: Absolutely. It was all among divisions. It was women in EAS as well. It was just a lot. It was women in EAS lunches for sure with everybody from my class, like Azita and Chiara and Beverley. We were all absolutely going to these lunches together, as well as across Caltech. Absolutely, we would hang out together, and then as well as with all kinds of colleagues. The Caltech culture has been really nice in the sense that we have these faculty parties. There's a winter party. There's the welcome new faculty party at which I played. We had like the introduce all the new faculty, and also Julia's going to play, so I was featured there. Then we have the winter faculty party. We have the spring provost reception or something like that. Then by the time everybody has kids, everybody goes to the Athenaeum, to al fresco on Fridays, and everybody's kids roll. Our professional lives and our personal lives are very much intertwined and integrated together, so everybody knows each other, everybody who's a parent, anyway.

ZIERLER: You mentioned the women of EAS, the assistant professors that you came in with.

GREER: We all have babies at the same time too. [laugh]

ZIERLER: The lack of a mentor program at Caltech, do you think that's simply a function of this was a guys culture for very long, and maybe mentorship for male faculty members could be interpreted as a sign of weakness or something like that?

GREER: I totally think that.

ZIERLER: Do you think that there might be an element there?

GREER: I think so too, because I heard another colleague, a male colleague, talk about it after, and he said, "We've never needed mentors. Why would these guys need mentoring?" It was very much frowned upon almost. It was very much the philosophy of figuring it out is part of the game. If you don't get the whole professor gig, and if you don't figure it out on your own, then maybe this is not the right place for you. It was definitely a little bit not stigma, but there was definitely a little bit of the expectation. Why do you need a mentor? You're here, so figure it out. That's part of what you're supposed to prove to the world.

ZIERLER: The more recent language, of course, is diversity and equity and inclusivity. Nobody was talking about these words or not in the way that we do now.

GREER: Not at all, no.

ZIERLER: Looking back, if not with those particular words, do you feel like you were building a more inclusive campus community by thinking about mentorship and not being afraid to ask for help when you needed it? Did you see it in those terms at all?

GREER: Yeah, I really did. It was really helpful to connect with the friends, with the other women, and hearing them bring up issues, and talking to the older girlfriends too. I also got adopted by the women faculty who made it possible for us to have such a good life. They were here first. People like Melany Hunt and Pamela Bjorkman and Frances Arnold, they were here. They were the first women that were hired at Caltech, and they were the ones who had to go through so much to just [laugh] show them, first of all, that women are capable of being scientists. They paved the way for us.

ZIERLER: These are battle-hardened veterans.

GREER: Oh my god, totally.

ZIERLER: [laugh]

GREER: We came into a pretty cushy environment where it's OK to have kids, it's OK to have families, it's OK to be taking time off or whatever, to the point where they shifted tenure. There's a tenure culture, and every university now pretty much has it. You get a year added to your tenure per child that you have during tenure after two kids. Normally, you would go up for tenure after your fifth year, you submit your package, and then sixth year is when they make all these decisions and solicit letters and all that, and then you have the seventh year to leave if you need to. But they made it so that if you were to have a child during that time, you would submit your package by the end of your sixth year. If you were to have another child, it would be by the end of your seventh year. They give you an extra year to have a child. But that backfired a little bit because people who were ready to go at their normal—it's a little bit like assuming that it's a handicap, that having a child is a handicap on your career, and so of course you're going to need more time. But some of us were ready to go up for tenure when we did, and so then you had to—

ZIERLER: Some of us don't intend to have kids.

GREER: Some of us don't intend to have kids, and then of course you have to treat everyone the same way. Then the women would say, "But that's a much bigger burden on us and all that." At the end of the day, anyone who wanted to go up for tenure or who felt like they were ready to go up for tenure at their normal time had to request to go up early. Also then the bar gets higher. Why are you requesting to go early? It's not early; it's my normal time. I just was able to do it even though I had kids. That's where having a mentor would've been great, or knowing are you ready to go up for tenure or not? Am I doing OK? We have this thing called the mid-career evaluation where at the end of your third year, you are put through a mini tenure. They solicit letters but maybe only three or four, and you get evaluated on how you're doing, and it's a reappointment. Your initial appointment is for three years, assistant professor, and then you get this mid-career evaluation or something like that, and then you're given the green light to go forward and to be up for tenure. It's still a contract. It's still a three-year contract, and so that you have a chance to go up for tenure. At that midpoint evaluation, I got some feedback from my division chair, which said something like, "Keep doing what you're doing. You're doing fine." Then I got something like, "You might want to collaborate with some people."

ZIERLER: You're like, "Hey, I thought I wasn't supposed to collaborate."

GREER: I was like, "I thought I wasn't supposed to," exactly. That feedback is not very helpful. But this is where having a mentor, like now I would tell the—

ZIERLER: A mentor could tell you what's what.

GREER: Yeah, a mentor could tell you like, "They mean it. No, they don't mean it. What do you mean by this?" "They mean you can collaborate with some computational people so that you're not always doing all this without theory, or something like that." Anyways, there would've been a lot of value in just—for example, my friend Chiara Daraio, we started at the same time. I remember we were both in my office, and we had just learned that somebody didn't get tenured. This is very obscure at Caltech. You never know if somebody got tenured because you don't really celebrate. In some departments, it's wonderful. There's this great tradition. You do a celebration, and I've had that from my mechanical engineering affiliation. The materials science people didn't do anything, nothing, and they didn't really tell anyone. Say you're an assistant professor. That means that you're not invited to the tenure meetings. If you know that somebody goes up for tenure, you don't know if they got tenured or not. There's no announcement. There's nothing. How are you supposed to know if somebody succeeded or not? They're going to be around for a while. You can't just go up and ask them. They may not know themselves.

I remember Chiara and I were in this office together, and we had just learned that somebody didn't get tenured here, and we were just shivering because we were like, "Oh my god, if this person didn't get tenured, we have no chance." There were a lot of conversations like that. Having a mentor being there and explaining like, "Look, every circumstance is different, and I was in that meeting, and I understand why this happened. There's no formula. It doesn't correlate with how many high-impact papers you publish. It doesn't correlate with how much community service you do," and things like these. We had to just learn by living. It would be great if somebody could have just stepped in, and said, "You don't need to worry about this," or, "There's a reason. Everybody's an individual, and it's not going to apply to you," or something like that. It would've been great. I remember talking to Harry Atwater, and saying I was really very stressed out about tenure. Apparently, I passed it with a huge margin. Nobody tells you when enough is enough. That's just part of academia that you don't know when it's enough or if it's enough. I just remember talking to him, and saying, "I can't process what you're saying right now because I need to get tenured." He said, "I think that your time would be much better spent if you could focus on what you're going to do after tenure." I was like, "I can't think that far right now. I can't imagine."

ZIERLER: Although that was suggestive that it was a foregone—

GREER: It was very much a compliment, because he was saying, "You don't need to worry." But I couldn't process that. That year before tenure is very stressful for everybody, because people talk. You would go to a conference, and somebody would say, "I got a request to write a tenure letter for you." Then you're like, "Oh my god." All of a sudden, the power dynamics kicks in because this person has—

ZIERLER: Is assessing me; has the power.

GREER: —has the power to influence my future. I would get people saying, "What? You're not tenured yet?" That was the worst. It's a backhanded compliment because they feel like you should be but, no, I'm not yet. Should I be? It's a very stressful, very vulnerable year.

ZIERLER: Last question for today. We're bumping up on 5:20 already.

GREER: That's OK.

ZIERLER: When it was time to put your tenure package together, just for yourself, if you could shut out what everybody else was saying to you, one way or the other, what did you see as your contributions? Going back to that original question about drilling down in this one area of expertise, and then also seeing where you could use this as the launch point for what comes next, assuming there is a next, how did you put all that together in your own mind when tenure came up?

GREER: I will start by saying it felt like I didn't accomplish enough. I don't know how many women you've interviewed. [laugh] Maybe this is something that resonates with all of us. No matter what I'm about to tell you in a few sentences, it felt like I didn't accomplish enough. There wasn't enough words. It wasn't enough publications. There wasn't enough talk.

ZIERLER: There's the duality there.

GREER: That's right.

ZIERLER: There's the internal assessment of not doing enough, and then there's the external or other people thinking. I wonder if you could delineate that.

GREER: That was setting up the stage for that. Because of that, everyone who feels insecure overcompensates by really shouting themselves out because that's what I was supposed to do. My tenure package was supposed to be so impressive and so compelling that they would give me tenure. It's even more of an effort for somebody who feels like they didn't do enough, because you have to really exaggerate. You have to compensate for what you think all the shortcomings are. I had to really portray all my work and everything that we've done as something that's really revolutionary or monumental in some way, without being humble but letting the work speak for itself. When I went through that, it was a very interesting experience because it was like, wow, I've demonstrated a lot, and we really looked at these effects, and it's a sizable chunk of research that we've done that people are citing all the time and people consider to be meaningful and important. It was a reflection. It was definitely a process where I had to go from feeling like obviously this is not important, and obviously I didn't get enough awards, and I should have gotten this one, and I guess I got that one, but that's not enough, and all that stuff, and use that as a springboard to really objectively, as much as I could, evaluate how much I have accomplished. That internal struggle was an interesting experience. When I put it all together, it was like, wow, I've done a lot. I'm an extremely energetic person, so I have boundless energy.

ZIERLER: There's always more that you can do, almost?

GREER: There's always more that you can do it, and so it felt that way to me. I've organized symposia. I chaired conferences. Of course, we published a lot. I'd given so many seminars. I'd given this crazy Midwest mechanics lecture tour. At the end of the day, I was very visible in the community, and there was nothing wrong with my package, but it was impossible to see it from there.

ZIERLER: Was there a place for a mentor relationship to rebalance your own lack of certainty?

GREER: Oh my god, so much, hugely so. That would've been the time to have it, it's the most vulnerable year, and also because we all have to raise money. We all have to fight for funding. When you are really well known in the field, like I was in the nanopillars, I knew where to go. I knew who the program managers were. When proposals get reviewed, you generally are asked to review the research as well as the PI. All the feedback that came back was the PI is very well known in this field. The PI wrote the seminal paper. The PI has established this field. I never had to prove my—

ZIERLER: Give Julia what she wants. [laugh]

GREER: It was really not a problem to be evaluated as an impactful PI. But switching fields—and that's what many people do. Many people that you will interview will tell you that after tenure, they went to biology. They went to medical. They went to some other. You don't have that reputation yet. You haven't built it, so you still have to start young again. You have to learn, and you have to integrate yourself in the community. I saw all of that nanomechanics research that I was doing as a stepping stone towards moving into these architected materials. I really wanted to pursue these ideas. One nanopillar wasn't enough anymore. I wanted to have thousands of pillars, and to put them together into nano-Lego constructs, and start thinking of them as meta atoms. When you look at a material, and you zoom in, there are all these atoms, and they organize in particular domains and grains and things like that. I wanted to now use that. Think fractal. Think hierarchical. I wanted to use that as my building block, and build an extra level of organization into materials to create fake atoms in some ways, or fake lattices, to see how that would create an entirely new paradigm. It would shift the entire paradigm of how we think about materials, and that's exactly what we showed right after.

But that was a huge leap of faith. That was a huge risk. How in the world, how do you even conceive of an idea like that? It worked out. [laugh] For us, it worked out. But there was just no way to know that, and we needed to try, and I needed to inspire my students to try that, and so we did it. For about three weeks, we held the Guinness World Record on making the world's lightest material, until there were some graphene aerogel guys who blew us out of the water. We made ceramics that were super light, 99.9% error that recovered that you couldn't damage; that if you dropped them, nothing would shatter, so were like nano bricks but super lightweight, like weight that had the density of water. We really proved, we really showed that you can decouple this entire property space in materials, and make entirely unique materials.

ZIERLER: Last question for today. I'll phrase it like this. How much did you weigh the tenure decision as a larger statement of your capacities as a scientist? In other words, there's lots of people, even if it's as a self-protective mechanism, they say, "I believe in myself. I believe in my science. If I don't get tenure at Caltech, I know what I'm doing, and I'm going to take my lab somewhere else." How much did you coat yourself in that, and how much did you really nod and said—going back to that terrible advisor who said, "You're not a good scientist," how much did you equalize the tenure decision with your, quote, unquote, "worth as a scientist," however irrational that might have been?

GREER: You're really good at this.

ZIERLER: [laugh]

GREER: I was just going to bring up both of these. When I did get tenured, the first thing I did is I called the advisor Bill Nix, and I said, "I want to shove this piece of paper into that advisor's face. I want to show him that this is the bad scientist. I just got tenured at Caltech." He had the wisest thing to say. He said, "Don't bother, because he will figure out a way to make you feel bad. He will say, 'Oh, it's amazing to see how low the standards have gotten,' or something."

ZIERLER: Don't engage.

GREER: "He's not worth it. Don't engage." That was the first thing, but that was my first thing. It was such a huge self-approval. At that point, I've proven to the world that I'm the key leader in this field, and I just got tenured. We become full professors when we are tenured at Caltech. That's very unusual.

ZIERLER: You came in after they abolished the associate then?

GREER: There was no associate anymore, that's right, so we went straight from assistant to full. Everybody does that. We didn't even have that associate rank anymore. There were no more hoops for me to jump through. That was it. I so wanted to shove that in his face, and got the good, wise advice.

ZIERLER: The best revenge is living well.

GREER: Exactly, yes. The first half of your question was also very important, and I forgot what it was.

ZIERLER: The extent to which you applied a protective psychological coat, that if you didn't get tenure here, you're still a great scientist, and you can go somewhere else—

GREER: I'm still a great scientist, and I'm going to go to Iowa State.

ZIERLER: —or Stanford. It doesn't have to be Iowa State.

GREER: Somewhere else, yeah.

ZIERLER: Exactly.

GREER: I was saying these words to everybody. I was like, "I know I'm doing my best. I know I'm not cutting any corners, so if my best is not good enough for Caltech, I'm going to go somewhere else." That wasn't true, and I didn't believe it at all. I said that to try it out a few times [laugh] just to my mom and to friends. Then I was like, "No, if I don't get tenured at Caltech, I'm going to be done with academia. I won't be able to do that." I don't love science so much that I'm going to be able to live with that for the rest of my life as an academic, so I'm going to go back to Intel or somewhere. I wasn't going to stay in academia anymore, so I wasn't going to take my lab to Stanford or to Iowa State or anywhere else.

ZIERLER: Caltech or bust?

GREER: Caltech or no academia, that's exactly it. Either my best is sufficiently good here, and then I get to stay here, or I'm switching careers, and it's no problem. I can always be a pianist. [laugh]

ZIERLER: I take it though, in your current role as a mentor, that's probably not the advice—

GREER: Definitely not.

ZIERLER: —you give to others.

GREER: No, because that's wrong. That's just the really wrong thing. It's just a way to wind yourself up into this stress ball, and it's not productive and it's not healthy. That's the most important thing.

ZIERLER: Particularly when Harry Atwater is telling you to think about your post tenure. [laugh]

GREER: I didn't even process that until much, much later. [laugh] I'm like, "Oh, I think that's what he was telling me." That's exactly right. [laugh] My very first tenure case to which I was invited, after I got tenured and I was invited, it was my friend, and she didn't get tenured. Then there was another guy, whose wife was my friend, but he didn't get tenured. That was very painful. That was very painful for me too because I couldn't wait. I so wanted to be in that tenure decision room. How do they tenure people? What is this like? What is this process like? We all really want to be invited, and you can only be invited once you get tenure. I was so excited. I said, "I'm going to go"—

ZIERLER: While resisting the pressure to just be super nice, and tenure everybody?

GREER: Tenure everybody, right. That was very painful because it was my friend, and it was a woman, and she had that situation where her more senior mentor didn't protect her, and so a lot of our publications were with that senior mentor. I was like, "I hope you feel really bad about this situation because you should have protected her, and you didn't." In both cases, it was a senior mentor who I feel like screwed them, unbeknownst to them. I think they didn't mean badly, but they ultimately ended up screwing that person's career. That was hard. I'm really glad to see they both have very successful careers, and they both are doing really well. But I think that there's something very emotionally scarring about not getting tenured anywhere. I later learned, much later learned that the two previous people in my position in mechanical behavioral materials didn't get tenured here. I'm the third one, and I guess I'm the charm. The two people before me went to Iowa State [laugh], and then another one right before me also didn't get tenured. I didn't know that. I didn't know that this [laugh] position was cursed—probably for the better. But there's nothing wrong with not getting tenured, and shifting your career elsewhere. I consider that you just make a different choice.

ZIERLER: Again, to go back to an earlier point, in many ways, it's like a marriage. Sometimes it's not a good fit. It's not necessarily a statement of your capacities as a scientist.

GREER: That's exactly right. It's funny you should say that because I got divorced right in the year—

ZIERLER: [laugh]

GREER: —right after I got tenured.

ZIERLER: [laugh]

GREER: Absolutely, it's either the tenure—

ZIERLER: I wasn't leading you there. I didn't know that. [laugh]

GREER: [laugh] But it was either the tenure or the marriage that was going to survive.

ZIERLER: One or the other.

GREER: It's so funny. But it's exactly it. It's a relationship. It really is a relationship. You can choose to have a healthy relationship and work at it, and it takes a lot of perseverance, and then it works out, or you give up on the relationship. Then if that happens, then you move on. You just move on to another one, or you recognize that you're right. It's not a reflection on you or them. It's a reflection on it not being a good fit. Some people are not meant to be in academia. Honestly, it's not a good situation. I tell this to grad students all the time. Grad school is not for everyone. If you're not happy, and if you're not satisfied in a way that you could be in different ways to live, doing a different lifestyle, doing a different career—

ZIERLER: Doing great science.

GREER: —you only get to live once. It's your life. You're not proving anything to anyone by suffering. You're not making anybody happier or anybody better. It's just you. You're hurting yourself. God forbid if you have a family or whatever. Then they have to reap the benefits of you not being happy. There's no point in being a martyr. There's no point in suffering. The earlier you realize that, and set yourself free from all that, boy, it would've been so great to have a mentor. It just happens to be that I love this job, and I love working with students, and I am so grateful to Caltech for giving me all this, but that's not true for everyone. Having somebody have that healthy perspective, and explain that to you, and say, "Look, yes, you're driving yourself nuts, but it's because you want to. It's because you really care. Because if it's not for that reason, you shouldn't be here."

ZIERLER: On that note, we'll pick up next time.

GREER: [laugh]

ZIERLER: You weren't just satisfied with one pillar. Now it has to be many pillars.

GREER: It has to be many pillars.

ZIERLER: What happens then?

GREER: 83,000 pillars.

[End of Recording]

ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It is Monday, March 13th, 2023. I am delighted to be back once again with Professor Julia Greer. Julia, as always, wonderful to be with you. Thank you so much.

GREER: My pleasure. Thank you so much. [laugh] It's almost Pi Day.

ZIERLER: Oh, yeah, 3/14.

GREER: 3/14 tomorrow.

ZIERLER: That's so exciting.

GREER: At 1:59, everything should be happening at 1:59.

ZIERLER: Julia, first, thank you for showing me the wonderful elementary school kids who are having a blast in the lab over there—

GREER: [laugh]

ZIERLER: —and all of the future scientists you are producing here.

GREER: [laugh] Oh, yes—

ZIERLER: [laugh]

GREER: —[laugh] from young to the not so young.

ZIERLER: [laugh] Julia, we're going to pick up from our last discussion, the transition point. We talked about you're here as an assistant professor. You're hyper-focused. The expectation is you are going to be the recognized leader in this specific area that you specialized in, nanopillars, and at a certain point, you felt the freedom to branch out, to do things beyond what you were here to do. To frame that within the chronology, how do you look at that evolution in your research agenda against the backdrop of achieving tenure? Is that the same story? Are you approaching the tenure decision, and you want to be ready after getting tenure to branch out? Do you want to do it before getting tenure, because that's part of your tenure package? How did you think about all of those things in the 2011, '12, '13, that rough area there?

GREER: That's a great question. I'd like to point out first, my area wasn't nanopillars. [laugh] It was nanoplasticity.

ZIERLER: Nanoplasticity. I'm sorry.

GREER: [laugh] Nanopillars is the mechanism for how we got there.

ZIERLER: Yes. My apologies.

GREER: It was nanoplasticity, so that it's like an actual field. [laugh]


GREER: It's a great question because those years just immediately leading into tenure are quite stressful, I think, for everyone. No matter how prepared you are, and no matter how much you've accomplished, it never seems enough, because of course you're your worst judge or your harshest judge anyway. I think that the most organic way to tell that you're ready to go up for tenure is when you start getting a little bit bored with your area, and maybe growing outside of it, and maybe expanding it more. That's what started happening with me that this nanoplasticity, understanding the role of defects in these very small nanoscale structures, especially in crystals with different microstructures, it was still interesting. Even now, we're still working on some problems about that. But, honestly, it started becoming a little more mainstream and a little more routine than was interesting for me. My role is that as soon as something becomes mainstream, I've got to get out, and then it's not interesting anymore.

ZIERLER: Weren't you also saying that there was the arms race with the Germans?

GREER: With the Germans, yes, absolutely. There's always an arms race with the Germans. As soon as our group or any other group that's at the forefront of what they're doing publishes something, the Germans just come and say, "You work on this. You work on this. You work on this." They just have lots of people. They just have a lot of human resources to do these experiments. The only way to beat that sort of massive following would be to always stay a little bit ahead. I had always had this idea that these individual nanoscale building blocks or nanopillars or any other nanoshapes can be put together into these much more intricate three-dimensional architectures, and that will provide an extra layer of organization that's somewhere between the atomic layering and the structure that you're building. At the atomic level, we generally have atomic planes, and we have crystallographic planes. In a crystal, it could be a polycrystal, and so you would have different grains with atomic planes arranged in a certain way, or even at the molecular level. There's this notion of crystallinity. There's some kind of long-range order. Now, that's an organization that's created by the process that made that material.

Now, if you take that as its own building block, and organize it even further into something else, like into a lattice, into a three-dimensional cubic lattice, or an octet lattice or something like that, then each individual beam is now like a nanoscale building block, like a nanopillar, but now it's collective. Now he's bigger. He's bigger than himself. He's now part of a community [laugh] that's all organized in this very intricate way that can be periodic, just like the atoms are, or it doesn't have to be periodic. It could be anything you want. The degree of control that we would have over that architecture is much, much broader than what the atoms are allowed to do because that's entirely driven by physics and thermal treatment, etc. But we figured out a way where we can write them. We can write these three-dimensional constructs in a way that we control.

Now, you have this combination of the properties that are governed entirely by the atomic scale versus this extra level of organization that's very small. It's still at the nanoscale and at the micron scale but much bigger than the atomic scale. Then you construct them to be as big as a brick, and so it looks like a brick, but it's extremely light. It weighs something like a gram or something like that, and it sits on your hand, and it's also very mechanically stiff. That's something we didn't know about pre-tenure, or this is something that I wanted to explore, because the material itself is more than 99% air. It's all open space. There are these nanoscale building blocks that each have an individual property. The big question was, do the properties retain? Can we harness these beneficial properties that we discovered only at the nanoscale, and proliferate them onto much larger length scales or materials with macroscopic dimensions by utilizing this concept of architecture, by cleverly architecting these very tiny parts into a much more organized network, so to speak, so that we can still retain those properties? That was the big question. But I have an interesting tenure story to tell you.

ZIERLER: Let me just ask so I can clarify. When you start to get bored or you realize that you're not at the cutting edge—you're at the cutting edge of the field, but the field has come to you, is that the point where you say to yourself, "I'm now ready for tenure?" Is that a dual conversation that you're having?

GREER: Yeah.


GREER: Very much so. But the scope of that field has to be commensurate with the tenure scope. The reason why I say this is because it's very common that a small subfield—not small. For example, lithium-oxygen batteries used to be a very hot thing, and that was a subfield within the overall lithium-ion batteries community. Lithium-oxygen was popular for a few years, and then it fell out of favor, and it left. That wouldn't be enough for tenure. Getting out of that kind of a subfield, and moving on to other things, the scope would be a little bit limited. It would have to be a kind of a field that has a real following., like a field where many people are uncovering these kinds of problem. If there's a Gordon Conference organized on that topic, then you know that's like a real field. When you start feeling a little bit an antsy to not be pursuing problems, there's still thousands of problems to be addressed, but when they're no longer exciting, and you want to probe things outside, this whole concept that I just described about nanoarchitected materials is what I wanted to try, but I felt like I couldn't until tenure.

ZIERLER: Is this where the value of the faculty mentor comes in, where you can share those feelings, and superimpose them upon the tenure timing? Is that useful?

GREER: No. This is what I want to tell you the tenure story about.

ZIERLER: Here's the story.

GREER: That's not where the mentors are helpful. This is where your division chair should be helpful. The way tenure works is you have a tenure committee that is appointed by the division chair. That happens when the division chair feels like you're ready, and that is definitely something that's formalized in your first appointment letter. You're first hired for three years, with an opportunity to renew as an assistant professor. Then when you renew, it's another three years, and with a clear stipulation that by the end of that third year—

ZIERLER: Up or out.

GREER: —which is about fifth year, so at the end of your second year in the second period, you would submit your tenure package. You'll be evaluated for tenure, and then you have that one more year left. I think that's how it's constructed. Funny story. If you happen to have children during that tenure process, they grant you a year per child, up to two kids—so you can't mass produce—to add to your tenure.

ZIERLER: [laugh] Yeah.

GREER: Which is a double-edged sword.

ZIERLER: This is for men and women?

GREER: For men and women, so paternity leave, men and women equally, anyone who has a child. You can adopt a child, genetic kid, any kind of a child. If you happen to become a parent or a re-parent, I guess, again [laugh] during your tenure, they will automatically add a year to it, which means that if you are ready for tenure at your regular time, you would then have to apply early because you don't want any stick. The reason why they did this is mandatory. Now, it's not a choice. It's not an option. They automatically add a year to your assistant professorship so that you are not going to apply at the end of your fifth year. But if you have one kid, it will be at the end of your sixth year; if you have two kids, at the end of your seventh year.

ZIERLER: What if you have twins, and what if you have quadruplets?

GREER: Same.


GREER: Quadruplets doesn't count. Only two of those count. But, yes, it doesn't matter. It doesn't matter in what sequence you had them but a year per child. Say career-wise, you're ready to go up for tenure at your regular time. Technically, the mentors are helping you understand if you are working on the right kinds of problems, if you're doing well, if you're visible enough, etc., but they don't have any influence about when your tenure case should come up. If you feel like intellectually and career-wise, you're ready to go up at your normal, regular time, you have to make a special request to do that. That's tricky because you now have to go up early, and then the bar goes up, because anyone who goes up for tenure early, what do they think of themselves? Would the world think that they're ready and all that? It creates a whole big splash of cascading emotions.

I had to go through that process. It's an interesting thing. Adding a year per child for tenure is meant to be a gesture of like we understand that having children has a tremendous impact on your life, and so we want you to not be stressed. But instead it created the opposite stress. It created the stress that now people are like, "But I want to go up. I don't want to be tempered anymore." That was a little bit unpleasant. It's backfired, because they now made it so that there's no stigma. Some people choose to take it, some people didn't, and then the people who didn't were like, "Ha-ha, I could do it. Why didn't you do it?" They made it mandatory, and so then all of us who didn't utilize that had to go to our division. I went to my division chair, and I asked, "Do you think I'm ready? I think I would like to apply for tenure now." There are many reasons for why I want to be tenured, but I don't know if I'm ready. It created an even more stressful environment. When you're ready intellectually, it's when you get a little bit bored with your research. When you're ready administratively, it's whenever your appointment ends.

ZIERLER: How do you intellectually, through your students, when you came upon this nanoarchitected idea, where does it come from? Is that part of the process of being bored that you're casting about, or how do you jump into a new area?

GREER: How did I come up with that idea?


GREER: It was a DARPA program, and we had a collaboration with people from HRL and the University of Illinois, I think. I don't even remember. But HRL was a huge part of it. They were working on these trusses that look like this that you can see here, but they're truss architectures, not small, not microtrusses, just trusses.

ZIERLER: Like what supports a roof?

GREER: Yeah, but smaller than that—

ZIERLER: Right, of course.

GREER: —so mini trusses. They were working on that, and they invited me because they wanted to understand the mechanical properties of materials that they're making them out of a little better, and so I was part of the team. As we were working on that project, I envisioned, oh, this is a truss. We can make it into a tiny thing. I think one of the team members mentioned like, "Maybe you can make nanotruss." I was like, "Hey, there's an idea. Maybe I could make a nanotruss." I'd always had the idea that I would like to combine these nanopillars or nanoscale building blocks into something larger. Then there was the microtrusses into nanotrusses combination. It was the confluence of all of these hints being dropped that I really wanted to try. I think I put a student in it—in fact, I remember who it was—and just said, "Why don't we try this? Why don't we try to write something?"

The process that you use to write these is called two-photon lithography. The company that makes them is called Nanoscribe, and they were a very young company at that point. It was a spin-off from Karlsruhe. It's a German company. It was a spin-off from Professor Martin Wegener at KIT, Karlsruhe Institute of Technology. Then another Martin, whose last name I can't pronounce, started Nanoscribe. Then they invited me to come visit KIT and also Nanoscribe because we were already either using one or, somehow, we were already familiar with two-photon lithography. It was the best reception ever. I walked in, they were super nice to me, and they welcomed me just like royal treatment. They spelled out, they wrote in 3D, "Welcome Julia" using Nanoscribe, and then they made a little Statue of Liberty and everything. It was lovely, and I just really love that company. That meeting was really great, and I felt so inspired after. I said, "We've got to get one of these." We bought the second machine in the US with Harry Atwater together. They're not cheap. All of these instruments are very expensive. Apparently University of Nebraska had one, for some reason, and then there were no more in the US. We bought the second one, I believe, and that's still here.

ZIERLER: How much was it? Do you remember?

GREER: Close to a million.


GREER: Yeah, it's expensive. That's why I split it with Harry. Now we have our own. That one, we split with Harry, and we donated it to the Kavli Nanoscience Institute. Since then, I bought our own. My group uses it all the time. It's a great machine. It's a great company. We tried it. We use that machine. We love it. It's one of our favorites. [laugh] We tried it, and then we tried to coat it with different things. We tried to coat it with ceramics. That was a big-splash paper for us. It was a Science paper. When you write a three-dimensional architecture that's like an octet, for example, or an octahedron, and then you coat it with a very thin layer of maybe 10 nanometers or so of alumina—it's aluminum oxide—and then etch out the polymer, it ends up being like an Easter chocolate bunny that's all hollow on the inside. It was like that.

We made one that was 50 nanometers thick, which is very thin already, and then we made one that's 10 nanometers thick, which is five times thinner walls. Imagine your coffee mug with a severe case of osteoporosis. It's very brittle. Alumina is very brittle. It's that white material that furnaces used to be made of; very porous; very brittle. If you were to try to compress it, it'll just shatter, and it'll just crack everywhere. Then when you make it even thinner, when the walls are even thinner, it should crash even more readily, because now it's even that much more fragile. We discovered that when we do that, and we compress it, it just springs back like a sponge. That was a huge breakthrough to demonstrate the same material. The only thing that was different is the size reduction. That provided a lovely, really wonderful way to tie it all into my previous research. The whole point of nanopillars was that smaller was stronger. Anything that's smaller behaves differently. The hypothesis we wanted to probe was can you take all of these nanoscale properties, and proliferate them onto these larger scales, and that was our answer right there. Sure enough, the mere size reduction in this particular material elicited a diametrically opposite response. That was a big finding, and that served as the springboard for everything that came after. Does the geometry matter? Do the defects matter? What if we don't coat them? What if we coat it with something else? What if we make it monolithic? Then after that came all this chem. We do so much chemistry now. We used to be a fully nanomechanics lab, and now we're chemomechanics, and biomechanics, and bionano, and we do so much additive manufacturing in every realm, starting with chemical synthesis. It really grew like a flower.

ZIERLER: Julia, a previous point you made, now that we're talking about chem and bio, when you got here, the idea is you are discouraged from collaborating, especially with senior faculty. The whole point is you want to be able to show that you can do research on your own two feet, right?

GREER: Right.

ZIERLER: Once you become senior faculty, young senior faculty, however you call yourself after tenure, do the training wheels come off, and that's no longer a consideration?

GREER: Completely.

ZIERLER: How do you operationalize that? I'm sure you're chomping at the bit. You can't wait to collaborate and talk.

GREER: It really is very much like that. The training wheels come off. Not only do the training wheels come off but they send you off, and it's like you go bike wherever you want. While you're an assistant professor, there's a tremendous support network. Caltech itself is very supportive. They nominate you for all the awards. They put you forth. You don't have to serve in committees. It's great. They really protect you. Once you get tenured, you're on your own. No more funding. No more support. [laugh] You go off into the distance.

ZIERLER: You came after the associate position was abolished.

GREER: There was no associate. You went straight from assistant to full.

ZIERLER: You have none of the responsibilities with assistant, and then all of the responsibilities as a professor?

GREER: Yeah. We're the lowest paid full professors, I guess—

ZIERLER: [laugh]

GREER: —[laugh] because there's no more hoops to jump. No, it's been really great. In many ways, you're off on your own trajectory, trying to go somewhere, and there's so many budding collaborations, I think, that by the time you're close to tenure, you already are collaborating with people because you already are in a known entity, which is another hint that you are ready for the next step and you're ready to be tenured is when the collaborations just naturally happen. For example, collaborations where somebody is a theory colleague, and we do mostly experiments, that wouldn't ruffle anybody's feathers because it's very clear who did what. I'm known for my experimental work. I'm known for this. We have certainly collaborated. Even prior to tenure, we had collaborated with computational people, fully computational. That's not dangerous. It's dangerous to collaborate with your former advisor, or with a much more senior person who in general is just very well known in the field. I feel like I've collaborated with so many people that I feel like it will be hard to remember all of them. But one thing that I found through this whole process that I formed so many new, unusual and unexpected collaborations, and that's the most invigorating thing ever. We've collaborated with chemists, with real doctors, with computational people who do computational chemistry, like Tom Miller, one of the people you interviewed. We have a paper that's about to come out. We had one come out already before with Bob Grubbs, with so many people all over the world, not just at Caltech, in fact. Your wings are no longer clipped. You can really collaborate with whoever you want on whatever projects.

Now, of course, the downside to that is that you've got to raise money to support that research. That's probably what curtails some of the activities that you otherwise would do instead. Can you raise a sufficient amount of funding to pursue these ideas? The kinds of collaborations I've had have been extremely rewarding. We've collaborated with physicists and with chemists. They've been really educational for us because we all speak a different [laugh] jargon, different language, and so just coming to terms with what you're calling what has to happen prior. We have to find this common language. It's like budding. It's like you're this flower. You can make this analogy to a plant. You start out as a seed, and I guess you do well at erupting, and then they hire you into a faculty position, and all you're supposed to do is grow. No flowers. You just grow and grow and grow and grow and grow. [laugh] Then the bud comes up, and that's when you know that you're ready for tenure. Then once it blooms, it just blooms everywhere. That's like tenure and lovely life after. [laugh]

ZIERLER: Now, because collaborations are always a two-way street, sometimes you're going to them.

GREER: Actually, more than two.

ZIERLER: But sometimes you're initiating. You're going to somebody and saying, "Can we work together?" Sometimes someone's coming to you and saying, "Can we work together?" What is the commonality? The people who are coming to you from chemistry and biology and business, is there a unified theme of expertise from you that, no matter where they're coming from, they're coming to you because of this generally singular area, or not? You're more adaptable, and the thing that they want to collaborate with you might be very different than the thing that another person might want to collaborate with you, if that makes sense?

GREER: They're not mutually exclusive. It's both. It's all of the above. Our core expertise, for sure, is in nanomechanics and nanoarchitected materials and additive manufacturing. Maybe this is tooting my own horn, but I'm pretty sure we're a little bit of a household name. The Greer group, people know that this is what we do. If anyone has an idea to put together a team, a proposal team, where they need something very intricate to be built, it's very likely they will reach out, just because that's what we're known to be. But, having said that, the proposal calls and collaboration opportunities usually have their own agenda. For example, we have lots of collaborators in a battery team. For that particular team, it wouldn't be some expertise that we generally have. It wouldn't be for any of those three core expertise areas, but they really know how to handle battery materials, and they can figure out their basic mechanical properties, so they're a great person to have as a team member.

Our core expertise is not in electrochemistry and it's not in batteries, yet we've written so many papers on batteries [laugh], and I have so many students working on batteries, even though it's not our core expertise. That's like more in the second category. For any team whose central theme might be in electrochem, something that's unrelated to what we do, it's generally good to have a mechanical properties expert on the team, because ultimately you need to know something about your material. That would be more for your first option where they need a particular expertise, and we are known for that, and they'll reach out, versus where there's a team that's forming, and they have this idea, and they want to try some crazy new metamaterial, or something like that, that they would be like, "Let's reach out to Julia. They don't make these materials, but we've seen some images, and maybe that's something they can do." They would reach out even without knowing what they're reaching out for. [laugh] Then we would have this conversation, and then I would tell them, "This is what we can and can't"—this just happened very recently. There's a call for hypersonics. We've never worked on hypersonics before and, truth be told, I don't know very much about hypersonics, but they think that they could use our metamaterials. It's like, "Let's talk about this. [laugh] Let me tell you what we can and can't do." Everybody sees their own agenda, and the reasons for reaching out to somebody might be either for their core expertise or because they think that they could enable something that they need.

ZIERLER: What did all of this mean for your graduate students and your postdocs? Earlier, when your group was so focused, and now you're so eclectic, so diverse, what does that mean for, first of all, the size of your group but then also the kinds of graduate students or postdocs that are obviously a good match; that you see you're a great person? Did that archetype of student change once you broadened out or did it not?

GREER: Hugely so.

ZIERLER: It did?

GREER: That is such a good reflection point. It really did, because it used to be that the type of students who came all cared about nanomechanics in some way. Not only were we in the same community—their advisors, for example, and I would go to the same conferences, and their core expertise would be the same as mine, and when we read papers together, we knew who the people were. Even if they were too young to know who the people are, they had heard of them.

ZIERLER: It's a small world, you're saying?

GREER: It's a small world. Especially so now, but after tenure, once we started, once we took this additive manufacturing by storm, my students go to conferences like ACS. Our flagship conferences are the MRS and the TMS, so Materials Research Society, and the other materials conference. My students now go to ACS, American Chemical Society. They go to ECS, Electrochemical Society. We go to Gordon Conferences. We go to SPIE, which is an optics and nanophotonics type of conference. We go to such a strange and much broader range of conferences that otherwise my students would never be present in those. It's very different because of what their interests are, especially all the biomedical people. That's a big learning experience for me.

Once we started doing electrochemistry, and my students and I started being invited to these battery workshops, or to the Battery Gordon Conferences, that was a new learning. Then all these biomedical people came. That was a new learning. Then all these chemists came, and so now we're going to all these different conferences. Not only did it change the. landscape within my group but it enriched it. It really enriched it because not everybody was caring about the same kinds of problems. In some ways, it was a little bit frustrating because they didn't know as much mechanics. We have this gas diffusion electrode project. Many of my students now are working on these metallo-polyelectrolyte complexes, which are mostly chemistry and some mechanics. Mechanics almost became tangential, and then I was like, "Wait, no, we can't have that happen. We can't lose that expertise entirely." It was definitely a little bit of a panic mode. Once the pendulum shifted so much more towards these other projects, I needed to get back my nanopillars [laugh] because we had literally one person at some point who still remembered the nanopillars. I was like, "No, we can't lose the core expertise."

ZIERLER: That's your roots. You got to go back to your roots. [laugh]

GREER: It's my roots. You can't completely let go of the roots, exactly. [laugh] We do now, but that was a big change.

ZIERLER: In the way that you insist that the fun is in the basic science, the discovery, and the applications, do you get all of the satisfaction in being socially useful through your collaborators? In other words, wherever they take it, and whatever benefits that these products might have to society, is that where you offload your satisfaction in making things that are relevant? Is that how you think about that?

GREER: Yes. It's so rewarding. Say we published a paper, and then somebody really read that paper, cited it, maybe took our patent, and then made something out of it. There's no better reward. For me personally, there's no better reward than your legacy carrying through. We've now produced nine professors in the US universities. My students are now professors at Stanford, professors at MIT, at Duke, at Penn. That is the most rewarding part, so I guess my product is another faculty member at one of the really top-notch institutions. But the second level of that high-end pride is when something you did, some basic research that you did, or some concept, or even some more technologically relevant application became something and is being used, or when our patents are being—we have a lot of patents, so when our patents are being licensed. We started a little company too. That's not as satisfying at the moment. I guess this is a little bit natural for humans, but being invited to be part of the team is a really big satisfaction. It gives you like this, "Oh, they really think of me. They really know. They want me to be a part of their team. That's great." Being invited to be part of these seemingly random teams [laugh] because they thought of me, and they thought to invite me, that's very rewarding too.

ZIERLER: Julia, I can't help but ask, but the satisfaction when there's a patent that comes out of the basic research, if that patent goes on to be a hundred gajillion dollar idea, are you a little disappointed you weren't part of it from the beginning, not in terms of your research motivations but in terms of there's real money to be made that you're on the sidelines for?

GREER: No, but I'm not. We filed the patent at Caltech, and then the companies license it from us.

ZIERLER: You're not even concerned about that?

GREER: We have those, but the royalties will go to us.

ZIERLER: "Us" meaning Caltech?

GREER: No, they share it. Yes, to Caltech, but they share it. We as PIs get research funds.

ZIERLER: It's really the best of both worlds, you're saying?

GREER: It really is [laugh], yes. When we patent something from Caltech, and somebody licenses it, they add money to your account, which is what we want.

ZIERLER: Obviously there are more potential suitors that come to you than you accept, right?

GREER: I don't know.

ZIERLER: You have a hard time saying no? Is that what you're saying?

GREER: No. OTT deals with them.

ZIERLER: In general, when people come to you to collaborate—


ZIERLER: —there's certainly more people who want to work with you than there are hours in the day.

GREER: You flatter me. Yes, of course. No, it's true. That's the nature of the job.

ZIERLER: That's a numbers statement. What would be some of the commonalities? Without naming names, what's an easy yes for you to say for a collaboration, no matter where they're coming from, and what's an immediate no or a red flag, where you say, "Sorry, not interested"?

GREER: I asked that exact same question. I asked my PhD advisor for the invitations, because what started happening after tenure is—actually, even before—not after tenure. At some point, I started being invited to so many things. Let me preface this question about collaborations with the invitations. I got slammed with invitations to go give invited talks at so many conferences and so many seminars and so many events. I went to the World Economic Forum twice. I went to give a TEDx Talk. I went to give these talks at National Academies and things like that in all the seminars and all the conferences. It was just hugely taxing. If I said yes to every invitation that I got, I'd be traveling every day.

ZIERLER: You wouldn't be a researcher.

GREER: I also wouldn't be a parent. No parent can do that. I can't imagine doing this at all. I called up my PhD advisor, and I was like, "Boss, I need some advice. How do I say no?" Same question that you're asking me: "How do you know when to accept something and when to not?" He gave me very simple advice that I still follow. He says, "When it's a situation where they need you more than you need them, then you say no. If it's a real opportunity, then you say yes." That really put it in perspective because there's so many conferences that would love to use the name Julia Greer as a figurehead, or as a plenary talk. "Now it's a plenary talk delivered by Julia Greer." Then they know people are going to come. They're using me as a tool to recruit attendants. But I'm not that tool for you. When he said that, at first, I was like, "What is he talking about?" But that's how I treat collaborations. When it's very clear that whoever is inviting me to do this is not really interested in our development or in our intellectual contribution but more they needed—

ZIERLER: It's the shiny object.

GREER: Right. But they need it for whatever, for recognition, for maybe getting funding, for whatever their motivation is, if I can see through that, which I usually can, then I typically say no.

ZIERLER: Sadly, you're forced to be cynical?

GREER: Exactly, and we are forced to start with that. You assume that they need you more. For example, if it's the National Academies, I will definitely say yes, or those incredible once-in-a-lifetime opportunities, for sure, or the Kavli Prize, or something like that, that I've been invited to and have never gone. I also say yes to the distinguished seminars. If it's a named lecture somewhere that's something to take, that's a true recognition, because then you know the caliber of the people who are going to be there. First of all, I love doing seminars when they're students because, ultimately, that's our legacy. The reason to do all this research is so that you can pass it on to the younger people who take it even further. That's why having my students become professors is so extremely rewarding because they take that legacy in a much more interesting direction that I could even think of, and they succeed, and so it's like that passing on. Distinguished seminars bring in not only great faculty members so that I'll connect with colleagues but also very brilliant students. Those I typically say yes to. The red flags are all the invitations from, shall we say, certain geographical destinations [laugh], or when it's a conference that no one's heard of before. To a Gordon Conference, I would say yes, or when it's some conference that I'm not familiar with or something where it's too good to be true.

ZIERLER: You're not a ratings booster is what you saying? [laugh]

GREER: Exactly. I also say no to all the NSF panel reviews. I hate the NSF. They used to be the agency that used to fund science.

ZIERLER: Ooh, ouch.

GREER: Yeah, they're awful.

ZIERLER: Speaking of funders, when Kavli and Caltech started talking about maybe doing a nano endeavor here, were you part of those early conversations? Were you a point of connection at all?

GREER: No, it was before me. That was in 2003. We're celebrating 20 years next year, 2024. 2004 is when they started these conversations. I was a second-year grad student.

ZIERLER: OK, way before. [laugh]

GREER: Yeah, that was before. But they were building the KNI. The entity of the Kavli Nanoscience Institute had already been established. I came in 2007, and it was just a bare basement. It was so crazy. It was this sub-basement with exactly two pieces of equipment—maybe three—that had the focused ion beam that I needed so much, and the e-beam writer, and just bare walls, like walls and columns, like concrete everywhere. That was the clean room [laugh] at that time. I was definitely part of the early building stage, and then there was an interesting development that happened. The Kavli Foundation had a charter that no untenured faculty member could be on the board of directors. I didn't know about this, but there was a faculty board of directors. I guess they changed the charter or they modified the charter a little bit for me because they [laugh] really wanted me to be on the board. I was included in the board much before I was supposed to, and so I was very much in that decision-making body from probably 2010 or something. Now I'm the director of the Kavli. I had been there from 2010 to 2023, so for the last 13 years, which is longer than anyone else, really, other than the founding directors.

ZIERLER: That really speaks well of KNI that as a board member, you really get to see what's going on—

GREER: I really understand.

ZIERLER: —and you still wanted to become director.

GREER: I still have all the people complaining. I understand all the complaints. I didn't want to be a director. I was made director. That was voluntold. That was like a definite situation of [laugh] nobody asked me.

ZIERLER: Is there an end point? Is this sort of an ongoing responsibility?

GREER: No, it's every five years. I'm in the fourth year now. I'm enjoying it, and I think they like me, for the most part. It was the right leadership opportunity for me and, I would be OK to continue. I don't know. I don't think it's healthy for something to be run by the same director for more than five years. I think five years is a healthy amount of time, so we'll have to see what else is out there.

ZIERLER: Sure. Beyond nanoarchitected materials, is there another new initiative in your lab that is at that same level as nanoarchitected materials?

GREER: Yes, absolutely. We're working with this new, very unique class of materials called MPEC that's metallo-polyelectrolytes complexes. It's fascinating. It's an entirely new way to look at how a material forms. Usually when you 3D print something, there's this concept called crosslinking. You start with some monomers and a photoinitiator, and it's a huge cocktail. There are a bunch of other chemicals, a monomer. Most importantly, you need to build these chains, polymer chains, that then become crosslinked. That's what allows you to architect. That's what allows you to 3D print anything. You start with some liquid resin, you shine some light on it, and then you form this pattern, and you do it. The reason why that happens is because there's this photoinitiatable chemistry that starts the polymerization process. You go from monomers to polymers, and then they're set in their ways, and that's crosslinked. Now, these MPEC materials are very unique because none of the bonds that they form are covalent. It's not monogamous. It's a very open relationship-type thing. It's like, "Oh, I'm going to coordinate with you for now. But then, you know what, if I'm pulled in another direction, I'm just going to dissociate and, look, no strings attached,—literally." These polymers are self-healing. They're remarkable. You make something, then you cut it, and then you put them back, and all the bonds reform because they're like, "We never had any permanent bonds to begin with. Now you put us back together? Sure, we'll reform." Depending on the metal you put into it—aluminum versus nickel or zinc or calcium—you can stretch it by 2000%. You can make an artificial muscle out of this thing. If you put a different metal into it, it'll be much stronger or much more stiff, for example, but it won't be as stretchy. You can make actuators with them. They're all hydrogel-based, so they're water soluble. They can be put in diapers that can absorb a ton of water. These polymers, by the virtue of their very interesting and unique molecular construct, are able to exhibit properties that we hadn't even thought of before. This was remarkable. We had this little idea. We started synthesizing it. It kind of worked.

Then we had another student come in, and start doing the mechanical properties. She showed that, for example, strain rate, meaning how fast you deform something, really influences how they deform. If you take this little bilayer strip, and you pull on it really fast, it'll buckle to the right. If you take exactly the same strip, and you push on it very slowly, it'll buckle to the left every time, and there's a reason for it. Different strain rates lead to a left versus right buckling response. Then depending on how long you hold onto it, which is called a stress relaxation experiment, it'll curl up by a different amount when you release it. Say you hold it for an hour, it'll curl up a whole bunch. Say you hold it for one minute, it'll curl up a little bit, or the other way around. All of this chemistry fully translates into mechanics. Then we recruited some collaborators, some chemical engineering collaborators who helped, who are still working. This is becoming more and more exciting by the day. Now we have the mechanics theory collaborators. This team is now six people. We're studying its fracture properties and toughness properties. For example, usually stiffness and toughness are mutually exclusive. Something is either stiff and strong or tough. We're getting both. We don't understand why, but it's all about these bonds. We're very excited about these dynamic bonds, and making materials out of them.

ZIERLER: You're really learning much more science now, in a sense—

GREER: [laugh] Yeah.

ZIERLER: —than you were in graduate school or as an assistant professor?

GREER: I would say—

ZIERLER: How do you think of that?

GREER: That's a good question. I was learning much more deeply in one area. It was a very deep dive in grad school. In grad school, it was a very deep dive into a relatively new field, but I knew everything about nanoplasticity. I knew my dislocation theory. I knew everything that I needed to know in that one relatively narrow field. Now my learning is much broader so, because of that, of course, I can't go in as much depth. I still have that core expertise where I really understand the microstructure of metals and metallurgy and defects, and those are the classes that I teach. But all of this new chemistry, I learned through these projects. I know a lot more in the sense that I know a much broader set of topics, but I can't go in as much depth.

ZIERLER: Is that where your graduate students and postdocs come in? They're your access points?

GREER: Instrumental. They're my deep divers. I'm the boat [laugh] that delivers all the deep divers in. But I learn a ton from my students and from my postdocs, and I wouldn't have been able to do it. I learned so much about batteries because they were working on batteries. I never took electrochemistry. Absolutely, I wouldn't have accomplished any of this without my grad students.

ZIERLER: How much have you transferred your own graduate experience into the kind of mentor you are, the good parts?

GREER: I really did. I really think it's super important to show your students that you really believe in them. This is a touchy subject a little bit because we go on a retreat every year where we hash things out. That's where I usually pose about three questions for the group of the nature, like, what works, what doesn't. If you knew back then when you first started what you know today, what advice would you give to your younger self, or what advice would you give to me, so very provocative type questions. Then everybody goes up and shares. When we first did the retreat, I didn't think anyone was going to share. Everybody came up. They shared things about such private things, and whatever happens at the retreat stays at the retreat. I didn't know. It was an experiment. I didn't know if people were going to be willing to go there, and everybody did. It was a cathartic experience. Everybody shared. It's uncomfortable, because a lot of these things are not good, or they would say, "I felt lonely, I felt depressed"—especially during COVID, lots of people said that—"or I feel detached. I feel like I don't know what I'm doing. I feel like I'm not doing enough. I feel like I'm not getting enough feedback." All of those things, all the criticisms come through that.

My mentorship style is hugely influenced by that, and so I really try to respond to their needs. Some of them are ridiculous, but it's a good reflection point, maybe not so much my graduate student experience that influences it the most, only in the sense of being respected. I think the key learning that I took from there that I really impart onto my students is that respect is really important, and believing in them, showing them like, "Look, it's OK. I'm going to be harsh about your research if you're not doing well. If your results are not great, that's part of the academic training, but we're going to finish this. You're going to succeed. It's not a permanent thing." That's a huge thing. Then together with all the feedback from the retreat, we have office hours every Monday, so today we had them, where people just come for one-on-one attention, and they ask anything they want to ask.

ZIERLER: From those discussions, a previous comment you made, which was very interesting, the cultural divide when you got to Caltech, and your fellow cohort of junior professors, the cultural divide of you all wanted a mentor relationship and that, generationally, nobody knew what you were talking about, and you were supposed to be tough and stand on your own. Now that you're on the other side of that, on the young side of senior faculty—

GREER: Now I'm a mentor, yeah. [laugh]

ZIERLER: —what sort of generational divides are you now seeing, given that you have this relationship with your students where they can share their feelings with you? What are they expressing that you need them to express because you wouldn't see it yourself?

GREER: You have to set expectations very early on, and to align on expectations. I feel like what I've learned is that most conflicts arise from a mismatch of expectations. I think this is really important for any kind of mentor-mentee relationship is to talk about it, to say like, "This is what I expect. This is what you're supposed to do, or these are the different pathways that would help you succeed, and I expect that you are going to follow one of them". On the opposite side, it would be, "If you're my mentor, I expect to be meeting with you every quarter, or I expect this, or monthly check-ins or something like that." I think spelling out and really being open about what you expect from each other is really important for any relationship but especially for a mentor-mentee, because there's a little bit of a power differential. Whenever there's a power differential, the mentor has to be really careful not to override, not to overshadow, and not to overrule, overwrite, and be dismissive. On the mentee side, they have to exhibit their own initiative. It's on them to ask for help. It's on them to be a self-initiator. If you need something, you have to step up to the plate to recognize that that's what you need and to go ask for it.

ZIERLER: Julia, what does the best summer look like for you in terms of what you need personally, what you need as a scientist, as a scholar, and what you need as a mentor to students? What does the best summer look like?

GREER: I love going on mini sabbaticals for the whole summer. [laugh] I love being in Europe, Norway. This year, we're going to Cambridge. A few years back, we went to Norway. We went somewhere else. France, we went to France last year. I think that traveling internationally with my kids, taking the family, and going to a different place, and specifically to a different country, just to get rejuvenated so that we are in a different environment—we're not in this ridiculous Pasadena heat [laugh]—but also just to clear your mind, I find that I come back a better mentor and a better parent and a better teacher and a better colleague, just to cleanse the palate so to not be here. I think that the summers, definitely making it into somewhat a vacation as well—when you're bogged down with so many responsibilities, and you're stressed out, and you have to raise funding and all the stuff, you are pulled in so many different directions that it leaves very little room for creativity, other than to just rollerblade. I can think while I rollerblade. But it's very hard to think when I'm attending to daily needs of every student. I have more than 20 PhD students and postdocs and undergrads. Cleansing the palate by going somewhere internationally, and doing a mini sabbatical, for even half the summer is the best.

ZIERLER: Do you think not being born in the United States, having a dual culture—how can I say this?—it gives you a sense of the importance of culture in science, that it's important to see how the Norwegians do it or how the French do it? Are you sensitive to that or is that something that you want to get out of that experience as well?

GREER: A hundred percent, but I'll push it even further. It makes me feel [laugh] good about being an American because people in other countries, especially in Europe, they're bogged down by so much bureaucracy. They don't do science the way we do it. We are definitely the freedom country here, even academically speaking. It's very enriching to go to Asia as well—we spent a sabbatical in China as well—to go to Asia, to go to Europe, to go to countries that have a presence in the scientific world, and to compare or contrast of course, and to learn how they do it. But also it makes me feel really good about where we are because we're so much more in control of what we work on. We're so much more independent. We're so much more self-sustaining. We're autonomous.

At Caltech, each faculty member is responsible for what they're doing. Nobody's telling me what I'm supposed to work on, nobody. If I can get funding to work on problem X, I will work on problem X. If I decide I don't want to work on problem X, I don't. It gives you this tremendous degree of freedom and control. We're all control freaks, of course. It gives you that sense. But that's not how things are done in Europe ever. There's this always overseeing governing body that you have to always report to someone or something like that. The amount of freedom that you have as a scientist in all those other countries is curtailed a lot compared to us. But, at the same time, they're really good teammates. European scientists and Asian scientists work together much better than we do, just as a general statement.

ZIERLER: The rugged individualism of the United States? [laugh]

GREER: That's right, the rugged individualism shows itself in many different ways, but one of them is that they don't fight. There's no infighting, or it's not at least as visible as I can gain in three or four weeks. I see that the camaraderie is genuine, and they're all working together. But also because they're all working together, they don't have their own ideas as much, and they all represent the same idea that somebody else maybe has given them. It's like the collective versus discrete, a little bit. It's very interesting to compare and contrast.

ZIERLER: Moving our conversation closer to the present, when COVID hit, and everybody had to stay home, were there automated techniques that you could lean into to keep the lab going at all?

GREER: We never shut down, so I came into work every day. I'm considered essential in my office, of course. We had the 4/10 schedule, so we had cohort A, cohort B. We have some automated techniques so that you can monitor stuff from home. Of course, we shifted a lot of our efforts towards theory and trying to do things computationally. But everybody came in. We did the 4/10 schedule, as in you come in for four days, cohort A comes for four days, and then you take one day off, and then cohort B comes for four days, and you come back, and then they leave. It was like that. The trouble with that was that if you come in on one day, you're not going to come into lab for another 10 days.

ZIERLER: This is not how science is supposed to happen?

GREER: People wouldn't take risks. Of course that's not how science is supposed to work. Not only that but they would only do the experiments that they knew for sure would work. That cohort of grad students during that entire COVID period was very timid, and they're still timid, and it's hard for them to still integrate socially. This year, I had my TA ask me, "Are the office hours going to be on Zoom?" I'm like, "No, nothing is going to be on Zoom anymore. They're all going to be in person, you're all supposed to be here, and you have to come to class." But I remember very well teaching here. I had this computer and my iPad to write things, and I had the camera filming me, so it was all here. I was physically in the office while the kids were zooming at school. My students would come in, would all of course be wearing masks, and they would be doing experiments very far away from each other, because I also had to do the KNI, the Kavli. Luckily, the infrastructure that I have there—my technical director did all this. But in the clean room, you can't have a certain density of people. If you can't have a certain density of people, sometimes you just couldn't use an instrument because there'd be somebody else on another one. It was a nightmare. We were constantly asked for our plan. "Send me your COVID plan. Send me your people density."

[unrelated conversation]

ZIERLER: Julia, in what ways has your research group fully recovered from the pandemic, and where are you concerned that culturally or just ways of doing things remain, even if the pandemic is on the way out, and what causes you concern in that regard?

GREER: I was a lot more concerned last year. This year, I feel a lot more—

ZIERLER: I'll move over. [laugh] It's coming.

GREER: —[laugh] experienced, even though it's daylight savings. Now, I feel like we're completely back to normal—

ZIERLER: That's great to hear.

GREER: —how it's always been. Last year, I was a lot more concerned because there was quite a bit of depression. There was quite a bit of still not fully socially integrating. There was a lot of ambiguity because many conferences were offering the hybrid mode, or many events would be like, "You can either do it in person or you can do it virtually, but then if you do it virtually, you don't get the same benefit." It was just confused, and so many of my students didn't know. Were they supposed to go to a conference; were they not? I was very concerned about some students about their mental health, just making sure that they're OK. I always check in. If I don't see somebody for a couple of days, it's like, "Hey, you didn't show up at the meeting. How's it going? Where have you been?" That kind of thing. I'm definitely still concerned, but less COVID-related, by just the wellbeing of every student. That's one.

Some of the ways that set in was really funny. When we were still in the midst of COVID—and remember how I said everybody still came to lab; they just didn't come at the same time, and we had to keep away?—there was a certain pathway that the Greer group was supposed to enter, for example, from a different building and over the bridge. Then another group, the Painter group, goes the other way. I still come in in the same way. I enter in exactly the same way, enter the building through a different building, how it's always been. There's some patterns that are set. I think we're a little better at managing our time now. During COVID, I think that the biggest complaint that the students had is that there was no more structure in their day, so they didn't have to get up. Caltech students are already quite nocturnal, and so there would be no reason for them to go to bed because there was nowhere they had to be. They could just do a class on Zoom from your bed, and you just don't turn on the camera. They really started becoming very unhealthy, just not sleeping enough or sleeping at some random times, and not eating properly, and all that stuff. That was where I really felt like I needed to throw a lifeline to each one. We still did the group retreat on Zoom. We did all that on Zoom. We still had group meetings on Zoom. All the same structure was there; we just did it all on Zoom, but then everybody became zoomed out. It wasn't until this academic year that I feel like everyone's recovered, and all the COVID kids are finally fully socially integrated, and it's much better. Last year, I was still concerned. This year, I don't even know, other than that question of like [laugh] are the office hours going to be on Zoom? We no longer even have the testing. Nobody has to get tested anymore, so it's much better.

ZIERLER: Yay. That's really nice to hear.

GREER: It's so nice to hear.

ZIERLER: [laugh]

GREER: Being vaccinated is really nice. We all felt a little bit like we were doing something wrong. It was really uncomfortable, the feeling of being here during COVID. I had my letter that said, "Julia Greer is essential to the operations." I'm totally allowed to be on campus. But even when I was rollerblading in, and you had to get tested, I don't know, you just felt like you would be tainted if you were positive or something like that. I don't know. That whole atmosphere on campus was not happy. It's happy now. Now I feel a little bit like we're in the overdrive mode, honestly. I miss COVID a little bit because it was a lot more calm in some ways. The zoom sucked, but the not traveling, honestly, it was great. It taught me to be a lot more selective about my travel. I really learned that we can accomplish a lot of things on Zoom. A lot of these meetings that we used to have to go to, to the NSF panels, for example, all NSF panels are now virtual. You don't have to fly to D.C. The meetings, like team meetings for a DARPA team or something like that, are all done virtually, and it's so great because we all know how to use Zoom very well. We know how to use the whiteboard. We know how to share our screen. I've given so many talks virtually, and it's great. I've participated in so many panels virtually. All of those, think about the carbon footprint, it really reduces the carbon footprint.

ZIERLER: Just the dead time: getting to the airport, getting to the hotel.

GREER: Your own sanity and your family life, like, the quality of my family life is so much better because I'm there. The thing that backfired, I think, is that when you don't travel, everybody's used to you being there: the grad students, the postdocs, the kids, everybody.

ZIERLER: You're too accessible?

GREER: At that point, you become too accessible, and so then you're like, "You can learn how to do things on your own." It's a double-edged sword in the sense that being always available is like teaching them not to be independent or as independent. Everybody needs a lot of attention.

ZIERLER: Julia, now that we're happily and hopefully in the post-COVID reality—

GREER: Forever.

ZIERLER: —right into the present, just to bring the story right up to today—oh, are they doing the experiment now? [Ed. note, there are kids doing an experiment outside of Julia's office window.]

GREER: They're doing the experiment, look.

ZIERLER: We should narrate for the audio. What are we looking at here?

GREER: I think they're going to make this mixture, so they're going to slide that in. See, they're putting on the booties, their cleaner booties, I guess. [laugh] The bigger people in there are my grad students and undergrads. These two are grad students, and the other two are undergrads, and the smaller people are the elementary school students. I guess Seneca is explaining to them that they're going to slam. [laugh] They're going to put a lot of cornstarch in there, and dilute it. I forget what it is, but it's this cornstarch wet thing that if you hit it really hard, it feels like concrete, and it's called a non-Newtonian fluid. Then if you slide on it, it'll be very compliant and lovely and slippery.


GREER: That's what he's explaining right now. [laugh] Excellent.

ZIERLER: Real life. What a beautiful post-COVID experience.

GREER: They're all here.

ZIERLER: It's so nice.

GREER: Once they start sliding, I'll invite you to come and watch it [laugh]—

ZIERLER: [laugh]

GREER: —because I can see it too. Anyway, we're in the present.

ZIERLER: Now we're in the present, I think, first of all, what are you currently working on? What's on the agenda these days?

GREER: I already told you about the MPECs, so that's one.


GREER: But what are some of the—?

ZIERLER: No, today. I always like to ask, just as a time capsule. March 2023, what do your days look like? What are your responsibilities? What's the science? All of those things.

GREER: Why don't I tell you about my week, because that's a good glimpse into what our life is like? Every Thursday at noon, we have the big group meeting. Imagine, it's more than 20 people. This is where exactly one person gives a dedicated, more detailed, more professional kind of a talk about their one research project. Of course, we start by all the lab news, and who's doing what, whose conference abstract got accepted, safety, how are the tools doing, the general lab stuff. Then we'll listen to a 40–45-minute talk that's meant to be either a preparation for a conference or for a defense or for a candidacy or something like that, but it's one project, like a seminar almost. That happens on Thursdays. Every Wednesday afternoon, I have subgroups, so that's by project. The entire afternoon is dedicated to the different subgroups. [laugh] We now separate them by the rigid [laugh], so rigid materials versus compliant materials. All the people who work on metals and ceramics come for one subgroup, and then all people who work on hydrogels and collagen and biomedical-type things and DNA-type things all come at a different time, and then the batteries folks come at a different time. It's the entire afternoon that's dedicated fully to working meetings and projects. I probably have about six to eight maybe clearly distinct projects—maybe closer to 10, but something like that—projects that are going on. [laugh] The kids, the PhD students expect me to just know exactly what they're working on at all times—

ZIERLER: [laugh]

GREER: —and I have to put on a really good act there. I'm teaching them. I'm like, "Put everything in context. Even though you've presented this before, just say like, 'Remember how I'm working on this problem of understanding the cathode properties,'" etc. That's what happens on Wednesdays. Every Monday afternoon, I spend in office hours. That's when everybody gets my one-on-one attention. Whatever problem, whatever description they want, whatever advice they want, whatever, the types of questions range from: Who should I invite to be on my thesis committee? How do I start writing this paper? What do I do about this? I read this paper. I'm planning to get married. when's a good time to do it? I want to take vacation. I'm really struggling in grad school. What should I do? It's a huge range, and so it's an open calendar, and people sign up for a slot. That way, it creates this atmosphere in our group that they can always count on my undivided attention on a Monday. Say they didn't get to see me this week, but they really want to discuss something, they know for sure that on the following Monday, they will get that attention. That's where my Mondays go. Tuesdays and Thursdays, I teach. On Wednesday, I also meet with my executive director of the Kavli. That's my Kavli day. On Thursday morning, I also meet with my technical director of the Kavli. My days are nuts. Then in between all this, I'm in three different departments, so I have three different faculty meetings each month, and all the Kavli stuff, and all the research stuff, and then there are conferences, and preparing for lectures, and writing papers and patents, and submitting recommendation letters. It's crazy.

ZIERLER: I'm so honored that you've managed to see me again. [laugh]

GREER: No, I am enjoying this very much. If people think that professors go to their office and think, it's a myth. I wish. I would love to. I used to really protect my time, my mornings. I used to be very protective of my mornings, so I would come here at whatever time I got here, and until noon, I wouldn't meet with anybody. Somehow that's gone now too, and I think that happened during COVID.

ZIERLER: That's the accessibility thing probably.

GREER: The accessibility. I think that during COVID, our private lives and our professional lives were so integrated together that we just never unlearned how to set those boundaries. I'm working all the time. Of course I'm with my kids. I take my son to the baseball games, and my daughter to the soccer games and practices and all that stuff. But say I'm there at tae kwo ndo, but I'm still responding to Slack while he's doing this. I don't remember being this connected all the time. Some of it is just COVID, so when you're so accessible. Some of it is just having the phones all the time, the phones and the watches, that there's almost an expectation of immediate response. There's no stronger message than when you don't respond. Everything escalates if you just can't respond. It's amazing how much damage you can do by not doing anything. My daily life is a little bit nuts. It's very busy and context-switching.

ZIERLER: You'll have time to think. That's when you go emeritus. That's what that's about.

GREER: I have time to think at night.

ZIERLER: [laugh]

GREER: My second shift begins around 10 p.m. I used to be so productive from 10 p.m. until 2 a.m. That was my hardcore work time because that's when nobody's usually bugging me. Now I get tired a little bit [laugh], so now I can't last until 2 a.m. anymore. But that's when I do most of my writing. That's when I do most of my thinking. A lot of the thinking happens on rollerblades; a lot of ideas. All the random ad hoc meetings too, it's like, "Oh, I really need to talk to you this week. Oh, can you submit this? Can you meet? Can you meet?" I already don't have any time during the day. It's a lot. [laugh]

ZIERLER: Julia, I'm a little sad to say, I think we're at the end point. We have covered right up today.

GREER: To now, to the present.

ZIERLER: I want to ask, just to put it all together, a few retrospective questions about your career, and then we'll end looking to the future. A theme ever since you got to college is fearlessness. Obviously in the way you talk and the way you do research, you've never been encumbered by fear, because you are so visible, in ways that you embrace it, in ways that you might not embrace it. But it's just a fact of—

GREER: It just is, yeah. [laugh]

ZIERLER: How can you serve in the most positive way of conveying the value of fearlessness?

GREER: That's a very difficult thing because obviously I'm not fearless, but nobody is.

ZIERLER: No, fearless in your willingness to take risks, and not to be burdened by concerns of failure.

GREER: That's right. Everyone experiences that to a certain extent. Fear kills creativity. Fear kills everything. Fear makes you not believe in yourself. I've definitely had my fair share of people trying to shoot me down, and people attacking and throwing rocks and everything. Here's what I learned. I learned to take a step back, and to say, "What's the worst thing that can happen?" If I try this, what is going to happen? So-and-so is going to yell at me. That's unpleasant, but that's where it ends. Somebody's going to get mad. What's the worst that can happen if I try this idea and it doesn't work? We tried an idea and it didn't work. I taught myself how to transcend the present, and look at it from a perspective like what are the consequences of your doing this? Sometimes the consequences are great, and then it's more fearsome. Then sometimes the consequences are like, oh, I built this thing up. The consequences of not getting tenured are huge. But the consequences of going to a conference, and presenting something where you know the huge experts in the field are going to be there, and maybe you're not an expert, the worst thing that can happen is that you're going to say something stupid. We're all so worked up. We get so worked up about our insecurities, so if you say something that people perceive as stupid, or if you say something wrong. Being wrong is not a crime. It's OK. I am OK with saying something that I'm wrong about, and then just to say that that was a mistake, or something like that. I think it's very healthy to teach yourself to do that, to not get worked up as in like, "So-and-so is going to think I'm stupid," but to not worry so much about the perception and much more about the substance, because that allows you to try new things.

ZIERLER: I'll ask. It's definitely a philosophical question. I wonder if you've thought about it, your unique experience of making a really big field-defining experiment as a graduate student. You achieved recognition in a big way very early on. It's very unique across science. It's a philosophical question in the sense that there's obviously a large amount of serendipity to that. Who was your professor? What was the timing? You got the instrument. You worked during these times. You had this crazy idea. That's all the chance. But the stuff that's there regardless is your intellect, your hard work, your generosity, all of the other things that go into what makes for a great professor and a great scientist. Do you ever try to separate those things out in terms of what you would have achieved or who you would be if you did a perfectly good thesis defense that was 99% of thesis defenses, where they're good, you show promise, this is very impressive, but it's not blow you out of the water? I wonder if you've ever thought about how you might separate who you are innately from this very particular path that you might have been put on as a result of the serendipitous chain of events.

GREER: That is definitely a philosophical question. [laugh] I do think about that quite a lot, and it's hard not to feel very lucky. Having said that, one question, one counter question would be if it had been not me—a corollary to that would be if it had been not I but some other person in those circumstances, would they be here? That would be one corollary to that. How much of that was my nurture versus nature? How much of it was my perseverance, because I really did have to do a lot of experiments at 2 a.m. to 6 a.m. to get there, and not giving up when things weren't working, and really getting that experiment done? I think it's the grit. The grit was always there, and I was unassuming about these things, and grateful. I personally think that, for me, if I hadn't stumbled upon that discovery, there's no way I would've been in academia. It's not worth it. I guess I would say this. Everyone who becomes a professor at Caltech must have had a wow moment or a wow paper or a wow technique, or done something that was so unusual and unique that they landed here. Now think about who we all are. We're all type A's, we all did this, and because of that, we create this culture where we care about things with the same level of intensity. I was very lucky in grad school, definitely. All the grit and the perseverance and all this other stuff went in there, but it also is instrumental to my survival here. It's almost like if it had been not I, who also stumbled and, say, did all these things, and they would've ended up here, I don't know if that would've been the right place for them, or if I had done a perfectly good thesis but not monumental, I would've never gotten here. I think all of this together sets it up for the trajectory to get here. They are separate but also you can't decouple them from the same person, from the same human. There's another question to be asked. Was it worth it? There was a lot of trauma along the way. [laugh] There's a lot of work and a lot of trauma and a lot of things that happened, and that shaped me into who I am today, which is not necessarily to say anything other than this is who I am today. I think it worked out really well. I'm incredibly grateful for the career. But would I want my kids to go through that?

ZIERLER: [laugh]

GREER: I'm not sure. Probably not.

ZIERLER: Only if they want to do it.

GREER: Only if they want to do it, yeah. Looking back at it, I think we each can—especially women. Women in science, we really are different. It's not nearly as bad as it was in the '50s and the '60s. I just finished listening to this book, Lessons in Chemistry, which is incredible; absolutely incredible book. It's not so bad, and I'm so grateful to all these women pioneers who made it possible for us to be here, and to succeed, and to have a family, and this. But you have to be an incredibly intense person. I think intensity of the human being is what—the serendipity is coupled with the intensity. I think that the strongest survives really works well here.

ZIERLER: You read my mind, because my next question was about being a woman in science.

GREER: [laugh]

ZIERLER: Obviously, you don't have a perspective from the '50s or even the '70s or '80s.

GREER: It's a pretty awful time for women scientists then. [laugh]

ZIERLER: But for the amount of time that you have been in science, what really has changed for the better, and where are you really disappointed of how far things really need to go?

GREER: I am lucky to say that until I was in grad school, I didn't feel like a woman in science. I felt like just a regular person. It wasn't a thing.

ZIERLER: This is a credit to MIT?

GREER: A credit to MIT, a huge credit to MIT, for sure. Everybody was treated with the same degree of acceptance.

ZIERLER: We're all nerds?

GREER: We're all nerds. There was no gender or race or anything. We're just all nerds here together, and it was great. Then I went to Stanford, and it was very similar. There's the group. The boss's group had women and men and everything. I once went to a conference where some boy told me, "You're only here because you are a woman." He was clearly very jealous because we had just published that big nanopillars paper. I just looked at him like, "What?" I didn't even take it seriously.

ZIERLER: You didn't have the tools to process it?

GREER: I didn't even take it as an offense because I didn't realize that's what was happening. I was like, "Really? OK, whatever." [laugh] It was only when I started competing, or it was only when I started playing with the big boys, so to speak, where I saw there's the old boys' club, and there's the old white boys' club. I remember there were situations where I had to present a case in rooms full of men. I've given so many seminars in my life, and I would literally say, "What did you do with all your women?" I would be looking at an audience with hundreds of people in there, and not see any women—I might be exaggerating—but with very few women. I would absolutely say things like that. I'm a performer, so every time I give a talk or anything like that, it's a very natural thing for me to interact with my audience.

It's sad to see that they don't have a lot of women, especially overseas. Especially when I go to places like Israel, like even to Europe and to Asia, there are just not as many women in the audience. Then especially in China, there weren't that many women professors to begin with. In a personal experience, because of this extreme drive, and not being driven by fear, I had a few discrete incidents where it was very clear that there was some derogatory remark, or a mystery, or "you're a bad scientist, and women shouldn't be in academia anyway," and that kind of stuff. But, generally, I've been a pretty respected person. But I definitely see that. With my students, I had a guy student and a woman student who went to a conference together, and they're working on a similar project. A question came up, and when the woman student answered, it's like they didn't even hear her. Then the boy, the guy student, said literally the same thing to answer the question, and everybody was like, "Oh, OK." Then she just came to me. She's like, "Why is this happening?" I'm like, "I don't know." I walked her through this whole thing. But that I've encountered a lot, to others, that it's—if you are not allowed—

ZIERLER: That's today. That's not—

GREER: That's today. If you're not a loud, visible, bright person, that you already feel confident, at least you can show how you're so confident, you're going to get trampled as a woman at first. Now, Caltech is an incredible place, so everybody's respected, and that would never happen here. But at conferences and at meetings and at things like that, especially government meetings and things like that, you definitely see a little bit of this, still a little bit of the old boys' club culture.

ZIERLER: If you look at all of your students, and what they've gone on to achieve, as a composite reflection, what gives you the most joy in terms of your mentorship and looking at what they've done and where they are?

GREER: This is exactly what I said before, just watching them become professors. When Carlos became a professor at MIT, and Wendy became a professor at Stanford, and Ottman just became a professor at Penn and at Duke and at University of Washington, it's mind-blowing because now they're organizing all these symposia, conferences, and they invite a speaker, like Widi, the guy who just did the woven nano lattices. They invite me to come and give talks and things like that. Once a Greer group alum, once a Greer group member, you're always a Greer group member, and you're an alum. It's the most rewarding thing ever.

ZIERLER: Is it because the feedback mechanism is so strong in demonstrating that you're doing something right? Is that what it's about?

GREER: That I'm doing something meaningful.

ZIERLER: Meaningful?

GREER: I don't know if it's something right but something that was so meaningful to them that they built an entire career, and now they're the ones being visible in the field, and now they're the ones organizing these symposia, and they're the ones that are moving that field forward. I made that, I built them, and now they're taking that, and going somewhere even more interesting than what we were doing before. Watching them grow is the most rewarding thing ever. For me, the product are these young professors or scientists at Lawrence Livermore National Labs, but people who end up doing such meaningful work in grad school that they move on, that they build their own independent careers out of it. There's nothing more rewarding than that. It's amazing.

ZIERLER: What do we know about the natural world as a result of all the research that you've done? Not what you know but what humanity now knows about the nano world—

GREER: Architected materials? [laugh]

ZIERLER: —architected materials, and nanoplasticity? What do we understand now that we didn't when you were first slaving away as a graduate student?

GREER: The first thing is that you can uncouple properties. I don't think that was known at all. I think we were so used to being slaves to this, for example, coupling between anything mechanical, anything that indicates mechanical resilience and density. It was a dogma that if a material is strong, it must be heavy. You are not going to go build a bridge out of feathers. You're going to build a bridge out of bricks and out of concrete because they're coupled together. In converse, you're not going to send something into space or to be in an airborne application that's heavy, because it's going to drop. We demonstrated for the first time, my entire army, everybody, that any two properties can be fully decoupled, and you just have to figure out a way to architect them.

ZIERLER: There's always a pathway?

GREER: There's always a pathway. I think that's probably key. The parameter space in the nano world is infinite, because there's so many different materials, so many different nanostructures. The unifying theme is that all of them exhibit the so-called size effects. That's my whole PhD. The length scale at which it occurs is very different. It's different for polymers. It's different for glasses. It's different for crystals. It's different for material X. But it exists. That's something that wasn't known until I was in grad school, because all these properties were size independent. There's the nanoscale size effect, and everything, just about everything, can be architected. That's another thing that we didn't know before. Once you combine these building blocks with architecting, you create materials that are entirely artificial. They're called metamaterials. These materials embody every length scale from some nanometers to microns to eventually centimeters, etc. Every length scale offers something unique about it.

When you make these hierarchical materials, we don't even know what we can accomplish, because that parameter space is infinite times infinite times infinite. It's infinite. But what we know is that we no longer have to be slaves to all these thermal treatment processes. There's these quintessential materials science triangle structure processing properties, performance perhaps. We can break each one of these, or rather not break each one of these but take the triangle, and constrain it to a single unit. The world's your oyster by going out of that one single element into much, much bigger constructs. Then you can envision all of these robots that go in your body that people just talk about, or writing organs directly, or using artificial intelligence to really predict exactly what you need to make your pancreas work again if you're a diabetic, or something like that. All of these concepts are now within reach. It'll take some time, but I would like to believe that's what we showed. You can make things that we could never have made before, or you can write an organ [laugh] and have it function. We don't know yet how to make it function, and what serves what functionality, but it's no longer an impossible task.

ZIERLER: The proof of concept is there?

GREER: The proof of concept is there. There are many more challenges that we would face, but it's possible. I think it's just that shift of the overall paradigm of how we think of materials from being limited by these furnaces and this thermal treatment and these resources, to no longer needing that, and to only make what we need, and to being so much more aware of the sustainability of this process. That's what this whole additive manufacturing is about. That's what we're working on all the time. How do you create only what you need, and then you don't make as much waste, and you don't need to use as much material. You can build a bridge out of feathers as long as your feathers are very strong. Those are the kinds of things that I like to think about.

ZIERLER: That perfectly leads me to my last question, looking to the future. It's obvious what you have done, what your group has done, what all of your collaborations have done. You have built these universes of new fields to explore all of these things that will keep researchers busy for decades to come in all of these areas.

GREER: I'd like to think so. [laugh]

ZIERLER: That's obvious. But what does that mean for you as an individual, as the group leader? What is the frontier for you that you're not yet focused on but that the next time you get bored, that's where you're headed? What does that look like?

GREER: I think by definition it's I don't know yet. [laugh] I would like to understand a lot more how to build intelligence into materials at the material level. Not by doing what people are doing already, which is you provide some input, and then it responds to a stimulus so that we definitely have sensors and actuators and everything, but that's not done at the material level. What I would love to happen is when you need a shirt or something like that, you go to a computer, and then you say, "I live in Southern California and the temperature range is this. But I also often travel to Alaska or somewhere. Can you tell me what material I should use to make just that one shirt?" Then it spits out the architecture, the material. It gives you a name of a company where you would go and order that. Then you have this textile which keeps you warm in Alaska, keeps you cool in California, and you just have to wash it, and that's it. Just like we fully customize our coffee drinks, I would love to see the world that's fully customizable at the material level, so that women's shoes can be both pretty and comfortable [laugh]—

ZIERLER: [laugh]

GREER: —which is not—

ZIERLER: When will that ever happen? [laugh]

GREER: That will never happen, you're right, so that we're focused on what's important, and so that we can live in the world where we're comfortable, we're healthy, we're taken care of, and where you only make what you need. That can happen through building the intelligence into material as they're being made. That's something I'm toying with right now. When the part is being printed, how does it know that it's going to be good? What parameter do you track? But imagine the materials now have a way to control themselves, like they're being made and it's like "Oh, I'm not going to be a good part. I have a defect," or a different part says, "I was planning to be a flower, but now I'm going to be a coffee pot because the flower's [laugh] not working out," or something like that. Having that intelligence built in at the most fundamental level that you can imagine, I think so many diseases can be cured by doing this, because you can communicate with the cells, and you can change the cells, and you can provide these safe zones, which we can't right now. So many airborne applications, think about this. Imagine you have a tiny material, a two-dimensional material that's up in space, and you can propel it with a laser. You can go explore different galaxies. It's all in the material. It's all because you have this super lightweight material that has the optoelectronics built into it that can be propelled with a laser, and communicate the data back to us. All of that is possible. All of this exploration and all of these are enabled if you can build materials to make their own decisions.

ZIERLER: You're going to have fun every second of the way?

GREER: I will [laugh], absolutely, if I can get some funding.

ZIERLER: Julia, thank you so much for spending this time with me. This has been great fun. It's a treasure for Caltech history. I'm thrilled. Thank you so much.

GREER: Thank you so much. This was really fun for me.