Robert J. Cava

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ORAL HISTORIES
Robert J. Cava

Courtesy: Robert J. Cava

Interviewed by
David Zierler
Interview date
Location
Video conference
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In footnotes or endnotes please cite AIP interviews like this:

Interview of Robert J. Cava by David Zierler on April 9, 2021,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
www.aip.org/history-programs/niels-bohr-library/oral-histories/47044

For multiple citations, "AIP" is the preferred abbreviation for the location.

In this interview, David Zierler, Oral Historian for AIP, interviews Robert Cava, Russell Wellman Moore Professor of Chemistry at Princeton. He describes his dual appointment in the Princeton Materials Institute and he reflects on the distinctions between being a solid state and not a condensed matter chemist. Cava recounts his childhood in Brooklyn and the opportunities that led to his undergraduate admission to MIT. He discusses his studies in materials science, and his decision to stay on for a PhD to study crystallography and the properties of sulfide materials under the direction of Bernie Wuensch. Cava describes some of the advances in ceramics that was important to him, and he discusses his work on sodium electrolytes at MIT’s Lincoln Laboratory. He explains his decision to join the Sold State Chemistry Research Department Bell Labs, and he describes some of the exciting developments in ceramic superconductors and why superconductivity is a window onto the complexity of solids. Cava discusses the significance of the YCBO collaboration, he describes the impact of the breakup of Bell Labs and his subsequent decision to transfer to Princeton. He explains some of the cultural shifts that allowed Princeton to become more involved in applied science, and he discusses what he learned about academic politics during his time as chair of the Department of Chemistry. Cava discusses his career-long search for new compounds and studying transition metal oxides, and he describes the many advances in thermoelectronics. At the end of the interview, Cava reflects on his scientific contributions, and he emphasizes the value in science of being a good listener.

Transcript

Zierler:

Okay. This is David Zierler, oral historian for the American Institute of Physics. It is April 9, 2021. I am delighted to be here with Professor Robert J. Cava. Bob, it’s great to see you. Thank you for joining me today.

Cava:

Thanks for talking to me. It’s really nice of you to do this.

Zierler:

Bob, to start, would you please tell me your title and institutional affiliation?

Cava:

Right. I work at Princeton University. I’m in the Department of Chemistry- in chemistry and materials science. Princeton is a weird place. We don’t have a materials science department for some reason, but they did make several positions available that are shared between different departments and a materials research institute. So, we have a research institute for materials science plus academic departments. I’m in the chemistry department half-time and the materials institute half-time, and my title is the Russell Wellman Moore Professor of Chemistry.

Zierler:

Russell Wellman Moore is a very Princeton-sounding name.

Cava:

Yeah, no doubt (laughter).

Zierler:

Who was or is Russell Wellman Moore?

Cava:

Well, Russell Wellman Moore is presumably an alumnus who made it in the world and decided to give back to Princeton. I don’t know how he made his fortune, but you have to deposit a substantial amount of money with Princeton University out of which they pay the salary of the chaired professor. I don’t know how he did it, but that’s a great question. Okay, when I was chair of the chemistry department, I was involved in at least one negotiation about how named chairs happen, and it’s not a small matter. It’s pretty impressive.

Zierler:

Now in terms of your affiliations, is it 50/50? Are you as likely to have graduate students in one or the other? Are your teaching responsibilities roughly equal?

Cava:

Yeah. The teaching responsibilities are equal. The Institute, I don’t know that they admit their own graduate students. Maybe not, but basically, I definitely teach an introductory materials science class. I’ve taught freshman chemistry for a long time, and I teach a graduate course in chemistry. I used to teach a graduate course in materials science, too. When I first came to Princeton, my labs were all in the materials science building. Now they’ve kind of morphed over into the chemistry building. It’s kind of dynamic. But the basic story is many of my graduate students, or maybe all of them, get a joint PhD in materials science and chemistry. There’s a set of requirements that they have to satisfy and basically, they all do it, so I’m not sure whether the materials institute admits their own graduate students or not, but they may- Knowing the way Princeton works, they probably said, “We’re not going to admit students into a specific materials science program. We’ll admit them into standard academic departments, and we’ll give the departments slots in which to admit extra students,” but I don’t know whether that actually happens. They must do that with physics and chemistry and electrical engineering, mechanical engineering and chemical engineering, anything that has a materials science component to it. It’s just the way they came up with a solution.

Zierler:

Bob, a question we’ve all been dealing with. How has your science been affected for better or worse over the past year in the pandemic?

Cava:

Yeah, that’s definitely a good question. Well, I think about that. The thing that’s really missing is personal contact. I know we’re all supposed to be nerds and that we’re supposed to only love science, but you know- Okay, we love science, but there’s a lot of personal stuff too. If I look back over a lifetime, there are memorable events that happened that put me off in different directions in science that just had to do with running into somebody in a hallway at the APS meeting or going out for a beer with somebody after some meeting or something like that, just opportunities that come up and can generate a whole career. I find that missing. I just gave a talk at the ACS meeting (American Chemical Society). You know, that’s a way that I can connect that culture to the physics culture, but do I attend all the conference talks by Zoom? No. I’ve got too much to do. So, I give my talk and then I disappear. And how can you socialize with people this way? You can’t do it. So anyway, I miss that. The socializing in terms of the way that impacts your work is gone. I guess we all probably believe that if you do a good job in life, it’s because you personally cared about it and you were present for life, and it’s harder to be present for life by virtual reality- I mean, for my generation, anyway. Maybe younger people can deal with this, but I need to be present. And it’s a physical presence, okay? So that kind of thing has had a big impact, a big negative impact for me, but here we are almost on the other side, so we stay optimistic.

Zierler:

Bob, let’s get some nomenclature on the table from the beginning. As a solid-state chemist, let me just be provocative. What makes you not a condensed matter physicist?

Cava:

Well, right. I think about that often. Solid state chemists know or believe that every atom in the periodic table is different and we kind of personify them. It’s like an atom has a particular character, it does certain things. When I think about the difference between how I think and the way a physicist thinks, I think that they care about Fermi surfaces and interactions and mathematical ways to describe the world, and I just think, “Okay, but what about the atoms?” So, I think there is a fundamental difference between the way physicists think and the way chemists think that is- you know, I guess that’s an important thing to try to merge those two ways of thinking, or at least bring them together somehow. Solid state chemists should have the job of discovering new substances or doping old substances to direct their properties. Solid state chemistry is a small but happy community of people that don’t seem to step on each other’s toes very much, and you know, we’re all experts in different kinds of chemistry. You could say that I’m an expert in oxide chemistry, but I’ve always also been interested in the properties of those materials. Most chemist’s kind of throw up their hands and say, “I don’t want to think about properties,” and most physicists throw up their hands and say, “I don’t care what material you saw this in. I just want to know: what’s the Fermi surface?” or something like that. So, I’m kind of in between. I listen to what the problems are in physics and then I try to embody them in some real chemical thing, and that’s a different way of doing it and it’s been a good way. Yeah. I always say they think in k-space; I think in R space. I think in real space; they think in inverse space, but it’s okay. It’s a nice marriage.

Zierler:

Are you delightfully anachronistic in the use of solid state, because mostly in physics, people have abandoned the term solid state as old-fashioned and they say now condensed matter, particularly because soft matter physics is a mature field at this point.

Cava:

Right. Soft matter physics is a mature field, and I guess condensed matter physics will include liquids and things like that, which are obviously condensed phases, but I guess that when I grew up it was called solid state physics. Things have to change names every once in a while to help fields, I think things have to change names to get a new identity, or at least to embrace changes in the way people think. Okay. Maybe I just think of it as solid-state physics because I’m an old guy, but who knows? Yeah, you probably interview a lot of old guys who call it solid state physics.

Zierler:

Bob, sort of an institutional and a cultural question. I’m sure you know Princeton, and of course I know much more about the physics department than the chemistry department, but for a long time, there was a hierarchy in the physics department of theory over experiment-

Cava:

Right.

Zierler:

-and particle physics over condensed matter. Has that institutional heritage, for better or worse, transferred to the chemistry department, and are there any vestiges of that? Here we are in 2021.

Cava:

Yeah, I think there are. In physics we recently had the passing of a wonderful character, who I don’t know if you got a chance to interview Phil Anderson. He was a very, very smart man. He was presumably one of the smartest people who ever lived, and I know that he started to get condensed matter physics accepted in the physics department as a form of physics. Now in chemistry there’s another kind of hierarchy, I think, and you know, each field has its own politics. Honestly, I never felt stupid in the presence of Phil Anderson. He was obviously a genius. He never really gave me any trouble about not understanding everything that he was thinking or anything like that; I just live in a different world. So, you could say that math is better, is higher than theoretical physics and theoretical physics is higher than experimental physics or something like that, but I guess Phil’s argument is that complexity makes the world go round. The way condensed matter physics has evolved now is that it’s a very complex field, and they’re observing things in condensed matter that are not so easy to observe in pure physics. They have a couple of books, or at least one book, about how complexity is present in solids that’s absent in simpler systems. So, you may want things to be simple so you can understand them, but there’s a certain joy in having things be so complicated that you can’t figure out what they’re doing. I think kind of what chemistry is all about is that it’s so complicated that we can’t understand what’s going to happen, and I’m old-fashioned enough that I don’t even want to try to understand it, okay? I want to have an intuitive feeling for how it works. I don’t want to have to try to calculate how it’s going to work or how to model it, but some people make models. So, your generation and younger, they make models and they try and predict stuff. I don’t want to predict it. I just want to do it! (laughter) Yeah, there’s definitely a hierarchy, and that even extends to chemistry departments. Chemistry departments also have a hierarchy that involves people who understand what they’re doing and people who don’t understand what they’re doing. It’s all what kind of a scientist you want to be. Like what kind of scientist do you want to be? Do you want to be one who understands what’s happening in the world, or do you want to be one where you work in a world where you don’t understand what’s going to happen? I think there are multiple ways to succeed in science. This sort of addresses your question. You can understand what’s going to happen and work on that, or you cannot understand what’s going to happen and work on that. You can be successful either way. You can have this hierarchy in departments, an intellectual hierarchy, but nonetheless, the people who really do something I think are working on things that they don’t understand, and that can happen anywhere.

Zierler:

Bob, let’s take it all the way back to the beginning. Tell me about your parents and where they’re from.

Cava:

Right. Okay, thank you for asking. Well, like a lot of people in the world, I must be a strange combination of different outlooks in life. Both sides of the family are from Italy and they came about one hundred years ago. My mother was the youngest of five children, and my father was one of the oldest of five or seven or some big number. They’re all gone now. My mother’s family is very artistic. I don’t know if you can see it- there’s a painting in the back there that was made by my uncle a long, long time ago in nineteen-something.

Zierler:

Oh, wow.

Cava:

Yeah. You know, my mother was very artistic and a very, very artistic person, and her whole family was artistic. They made a lifetime of being artists. My father was kind of exactly the opposite. He was a very focused, details-oriented individual who just had his nose to the grindstone the whole time and never was a flighty character. He was very stable. So, I always think of myself as this bizarre combination- well, a lovely combination. I have a very intuitive approach to science, which I’m convinced that I got from my mother, yet I am a scientist, which would be about as far as my mother’s family as you can imagine being. So, it’s a lovely combination. I was a lucky kid for sure. As with a lot of cultures in our country, you maintain a lot of your culture in life. I mean, my kids all even speak Italian, and our holiday traditions are all Italian. That all comes from the culture that we came from a long time ago.

Zierler:

Bob, what were your parents’ professions?

Cava:

So, my father was an accountant for a shipping company in New York City. My brother and I think of our father as the most serious person who ever lived. This guy never smiled. He was so serious. But we went to visit the place where he worked in New York City, which is way downtown on Wall Street- I mean, a building near Wall Street. It’s actually right across from the Wall Street Bull, and that part of New York City has all sorts of bars and restaurants and things in it. It’s really fun. So, we were trying to imagine, “What did Dad do? What did he do at lunch hour? Did he go out and have fun? Was there any fun in Dad’s life?” I don’t even know, but anyway. Sorry. What was the question?

Zierler:

What your parents’ professions were.

Cava:

Yeah. Thank you. Dad was an accountant, and he definitely was a nose-to-the-grindstone kind of guy. He was committed to supporting his family, I think first and foremost, and he was very serious. On the other side, my mother, before she got married, she was actually an artist who drew fashion things for newspapers. So, way back- It can’t be before photography, but when there were fashion advertisements in New York newspapers, she drew the fashions- the people wearing the clothing. That was like what she did, and her family supported themselves when they came from Italy by having one of these apartment-style sweatshops that you can see in the New York City Museum like where they made clothing in their apartment in New York City. So she was an artist and she continued to be an artist, although she didn’t get paid for it. She made a lot of paintings during my lifetime. I have a lot of them still. So she was kind of a classical struggling artist and wasn’t employed- probably not employed much after the kids were born, but she continued to do artwork. So, she was an artist, and Dad was an accountant. How far different can they possibly be? I don’t know. ZIERLER: (Laughter) Bob, what neighborhood did you grow up in?

Cava:

Oh, right. I grew up in New York City, which was very lucky. I was born in Brooklyn in a neighborhood now that’s heavily Polish, Polish immigrants. It was Italian immigrants at the time, and then-

Zierler:

Was this Greenpoint?

Cava:

Yeah, Greenpoint. Exactly. Is that where you are? Where are you?

Zierler:

Oh, I’m in New Jersey, but my whole family is from Brooklyn. I know Brooklyn well.

Cava:

Yeah, so this was exactly Greenpoint. Exactly. So, I first lived in Greenpoint, and then my family moved to a place in Queens, in Long Island City, where I lived until they moved another time. They just kept having more kids and they needed more space, so they ended up staying in New York City, but they just moved further out in Queens. When I was in high school I had to- I did lots of stuff. New York was a great place to grow up.

Zierler:

Public schools throughout?

Cava:

Public school, yeah. Public school throughout from top to bottom, and I got a really good education. New York- I hope it’s the same, but the New York City schools were great at the time, and the teachers really cared. I definitely had some teachers who helped shape me as a person, you know. Elementary school teachers are like unsung heroes or something. How do they do it? How do you get swamped by all these kids all the time and see who was to be encouraged? I had some great teachers, I have to say. So somewhere around fifth or sixth grade I discovered I really loved science. That is when I had really good science teachers - good teachers in New York City public schools who noticed that I was a smart kid and helped me out. So, it was great. I guess you hear this from people. I don’t know anymore. Can people do this anymore? When I was a kid, I took the subway into New York City to go to a band or stuff like that, and I was on my own. Like parents said, “It’s Saturday. Go to band practice,” whatever, so I just took the bus or the train to New York City and went and played in a band and then wandered around New York City and then came home. Really, that was me when I was sixteen years old. Really? Wow! How great is that! New York is a great place to grow up. It certainly was a great place to grow up, and I love visiting there now. I definitely keep that going.

Zierler:

Bob, what high school did you go to?

Cava:

I went to Martin Van Buren High School. It’s a high school in Queens Village and it’s called Martin Van Buren. Obviously, it’s named after that president. I’ll say it was a very diverse neighborhood and there were lots of kids from all sorts of walks of life. But they had special programs for kids who were really interested in science, so maybe there were thirty kids or something in my science classes that already just went into some kind of interest in that field. So, they had a really good science program. They had a really good music program. They just had really good teachers who were really good and really cared about the kids. Yeah, I hope that kids can get that nowadays before they get to college. You have to have confidence. You can’t let the world beat you. You have to keep fighting. You can’t give up, and I think it starts at an early age. Kids have to be encouraged to follow their talent. I still think that. So, the good thing about New York City schools was it was a big world for us, and we were encouraged to do what we had to do or do what we liked to do. I mean, there was a good music program. There was a good drama program. There was a good science program, and these teachers did extra stuff to keep the kids going.

Zierler:

Bob, did you ever consider one of the technical high schools: Brooklyn Tech, Bronx School of Science, Stuyvesant?

Cava:

Not really. There are a couple of these high schools in New York City like Bronx High School of Science. No. This Queens high school was the natural one. It was near where I lived and I could walk to high school from home. I just walked to school and that was just the natural place. I could have gotten this really special science education at one of the New York City science schools, but I just didn’t do it. But when it came to colleges, that was interesting because, what is it, Brooklyn Polytechnic is a nice college in Brooklyn and I loved New York City, so Brooklyn, that was a big choice. Columbia, I love Columbia University. If you’ve ever seen it going uptown to Manhattan, it’s like a little oasis, a little intellectual oasis uptown. There were a variety of other choices, too, but if you get into MIT, which I did, you just do it. Yeah. I was lucky. I never felt deprived even a little bit by not going to a science-directed high school like one of the fancy ones in New York, one of the nice ones. Yeah, I probably suffered quite a bit when I got to college in the beginning, but then things straightened out for me later.

Zierler:

Bob, how well formed were your ideas in terms of what kind of science you wanted to pursue in college? CAVA: (Laughter) I certainly evolved a lot. I like to tell the story that when I first got to college, I wanted to be a physics major. Somebody who had a big impact on my decision just recently passed away. It was Millie Dresselhaus. Did you ever talk to her?

Zierler:

No. Millie is a legend.

Cava:

Yeah, she’s a legend. So, I ended up being a freshman at MIT and Millie was my freshman advisor and she somehow saw that I was interested in applied physics and things like that. So, I originally started as a physics major, until I took a physics class at MIT and I got a twenty-three on the first physics exam and a bunch of other kids got one hundred or ninety-six or whatever they got. I thought, “I’m not smart enough to be a physicist.” I became an electrical engineering major and then- I was in electrical engineering, and then electrical engineering didn’t appeal to me either because it wasn’t very intuitive at the time. It was very, let’s say, analytical. I am just not an analytical thinking person, so I eventually evolved to become interested in materials science, which was a real major there, and that stuck because it was more intuitive for me. I guess you could say the way complexity makes materials have the properties that they have was difficult to model in the day. Even though nowadays you can model things, that doesn’t mean that’s exactly what’s going to happen. That just appealed to me as a person. Obviously as a person you can have a more analytical side or a more intuitive side; I’m just a very intuitive person, so I presume I got that from my mother, but you know, I’m very intuitive. So presumably if you ask people to this day, even in my senior years, I have a very intuitive view of the world. It’s not an analytical view of the world. If you ask me to analyze something mathematically, I just can’t do it, and am I ashamed of that? No. It’s just the way I am. Some people are analytical and they do what they do. In a way I always say this is why God made physicists, because they can think that way. I can’t, okay? So, this is why I love working with physicists because they can be very analytical and really get to the nuts and bolts of things, and I’m just up there in the sky somewhere.

Zierler:

Bob, in the materials science world as an undergraduate, the binary between theory and experimentation that we all know in physics, is that basically the same in materials science?

Cava:

I would say not really. There are not too many- well, there were not too many theorists. There probably are more now. Now that you can actually claim to have described the properties of matter by being a theorist, you can claim to be a materials theorist. There is a hierarchy in physics too, right, because some theoretical physicists are pencil and paper physicists and some are computational physicists. I presume that the pencil and paper physicists have a different view of the world than the computational physicists do. They’re all theorists to me. I think that back in the day there were only pencil and paper materials theorists, and there weren’t too many of them. Nowadays there are more, obviously. There are more computational materials theorists than there were before, many more. So, a lot of people are computing the properties of matter now, and for an old character like me, I think, well, if you can compute it, then it’s not interesting, but that’s just what they do.

Zierler:

Bob, was the draft something you needed to contend with?

Cava:

Yeah! (laughter) Yeah, the draft was interesting. Yeah, it’s exactly my time. I lucked out. Back in those days, universities did something to help people not get drafted. I went to college for an extra year, so my degree was delayed by a year. I should be class of ’73, but I ended up being class of ’74 because they delayed my bachelor’s degree for a year so I could get a bachelor’s and master’s degree at the same time. This prevented me from going into the lottery back when they were drafting people. So, I got my draft number. It was sixty-three, which is a low number, so I would have been drafted, but the very year that I graduated, they called off the draft. So, I never went to Vietnam. My best friend’s older brother went to Vietnam and got wounded, but I didn’t have to go. So yeah, the draft was all part of that and the Vietnam War was a big part of my generation. That did have an impact in my career, I would say.

Zierler:

Were you active in campus politics, anti-protest movements, all that stuff?

Cava:

Not so- this is something to say, but you know, the materials science department at the time I was there was very conservative. Nowadays we’d say that they are Republican or whatever, but back in the day, the people who were very against the Vietnam War had long hair and they went to protest marches and they did all sorts of stuff. They went to Woodstock and all that. You know, I’m the Woodstock generation, okay, so look, you can see in movies what that was like. That was pretty wild. Anyway. But we did protest stuff. The department, I just didn’t feel very welcome there, and then one professor saw something in me, even though I was obviously an outside kind of character politically. He saw that I had a brain and he turned out to be one of my best life mentors. I became his graduate student, and that really taught me what is some wonderful science. He was quite a man. I guess the story a lot of people should tell you is that, you know, there I was being me and somebody saw something special. Some older person saw something special in me and encouraged me. I had a couple of those in life. That was a special thing, and it took a very interesting person to see that in me through the politics, to see that I had a brain. I always think, “How did that person see my brain through all that?” but he did. Anyway, so that’s- and then, yeah, because of my PhD training, that impacted the rest of my life. Somehow somebody seeing that was the big difference. ZIERLER: Was the master’s at MIT sort of a placeholder, or did you really see it as part of your overall educational trajectory?

Cava:

I think it wasn’t really a placeholder. I think it could have been a terminal degree. So back in the day- and I don’t know where they are now, but the materials science department was in the engineering school. In engineering you can graduate with a terminal master’s degree and then go work at some company somewhere. So, the master’s degree was really an extension of the undergraduate degree to take more classes, and that’s what I did. Then I got master’s and bachelor’s degree after five years, which was, I guess it’s typically six or five and a half or something like that. Nowadays, in chemistry at least, terminal master’s degrees are rare. Either go for a bachelor’s degree and then go out in the world, or you go for a PhD and go out in the world, but in engineering they still do that. They still have master’s degrees and the people go out in industry to work and they are perfectly fine. So yeah, I guess it was an integral part of the education, but there is a transition. I always think about that in my own students. There’s a transition. The first year of graduate school, or the first two years of graduate school, it’s almost like being a super undergraduate. You’re not doing stuff. I mean, the difference between that and a PhD is you worked on some project where nobody knows what the answer is and it’s up to you to make some new information. So, there’s like a phase transformation in human beings somewhere in graduate school where they figure that out: “you know what, I can generate information myself. I don’t need to learn from somebody else; I can generate something.” I think this is a profound change in people. Obviously, I’m spoiled. I have a lot of smart people that come through my life, and it’s a joy to see them wake up and suddenly realize that they can generate information themselves; they don’t have to learn from somebody else. So, for me, that’s the difference between a master’s degree and a PhD.

Zierler:

Did you ever think about leaving MIT and going for a PhD elsewhere? CAVA: (Laughter) Well, that’s a great question. Well, basically the story is this. I definitely thought about leaving MIT. I got my master’s degree and I was interested in art and materials science because I had an artist family, and I applied for a job at an art museum in Boston and they didn’t give it to me. So, after my master’s degree, I thought I might go to work in an art museum, but I didn’t get the job. Then when I didn’t get the job, the next choice was graduate school, and then the graduate school thing happened like this. The person who ended up being my PhD advisor, in a class I was taking from him at the time, said, “Bob, did you apply to graduate school?” I said, “No.” He said, “Okay. How about if you apply to graduate school and you become my graduate student?” I said, “Okay” (laughter). That was it. This is a little strange nowadays because this was back in the seventies. You know, the guy could say to me in a class, “Did you apply to graduate school?”

Zierler:

Yeah.

Cava:

And I could say okay. He said, “Okay, you can be my grad student.”

Zierler:

Who was it, Bob? Who ended up being your advisor?

Cava:

His name was Bernie Wuensch. You rarely heard of this person. He was a mineralogist. I loved mineralogy because it was my first introduction to real complexity. So, I took a couple of classes in the geology department when I was at school at MIT. The person who was my PhD advisor was a sulfide mineralogist, and he studied the structures of minerals, things that grow in the ground that have sulfur in them. It turns out that some of them have some interesting physical properties that I helped to figure out for my PhD. So, he kind of made a leap from mineralogy to materials science. I don’t know how he ended up in the materials science department, but I always say that this mineralogy background, because minerals can be so complicated and have so many elements in them, was the thing that got me going to appreciate complex materials. So, he was great. Anyway. My PhD was on the properties of some sulfide minerals- actually, the crystallography. He taught me crystallography. I can tell you a story about that. I teach crystallography as one of my graduate classes, and this fellow, Bernie Wuensch, has an online class in that- you know, MIT has online crystallography classes, and I thought that he was the best teacher I ever had for anything. So, one day a student asked me a question in class that I couldn’t answer, so I went to the website and looked up what was Bernie’s answer to this question? Somebody must have asked him. Then I got to that exact spot in one of his lectures and he said, “Well, this is too complicated. I’m not going to explain it.” I thought, “Wow! Bernie, you didn’t explain it! How am I supposed to explain it?” (laughter)

Zierler:

Now the department was ceramics or that was your focus within materials science?

Cava:

That was my focus within materials science. The department started out as a metallurgy department. Then it switched to metallurgy and materials science, then materials science and engineering, then maybe just materials science; I don’t know. But basically ceramics was a specialty in there. So, for my PhD in ceramics, I had to take introductory classes in ceramics engineering and ceramics science, and basically that has been really valuable in my career. There were a lot of interesting characters who did that. I guess that’s the important part about everybody’s personal growth. You meet people who are interesting characters who help you, and maybe they don’t even know they’re helping you. They’re just who they are and you’re a young person and you’re observing them go around doing their stuff every day. So, you’re just motivated, or at least influenced, by what they did. The ceramics thing definitely had some interesting characters there who didn’t particularly like me, I guess, but there I was. I learned from them and I learned something about just being who you are. Just be who you are. Yeah. So, I think- sorry for all that, but ceramics turned out just to be a specialty, and I did that because the rocks in the Earth are oxides and what’s a ceramic? It’s an oxide. Minerals have oxygen in them. One of the most abundant elements in the Earth is oxygen and so minerals are often combinations of metals plus oxygen, and ceramics are also metals, plus oxygen. So, it was a perfect match of how the properties of matter match up with crystal structures, which is what I got interested in.

Zierler:

What was the process of developing your thesis research?

Cava:

Basically- yeah, that’s- I think about that all the time too because Bernie was more of a hands-off kind of guy than I am, so basically he- I think he did it exactly right. He came up with a basic problem. Let’s say he saw a world that was much bigger than I could see as a graduate student. He came up with this problem that certain minerals that he knew about had high diffusion coefficients for silver and copper. This is a problem that goes around and comes around in the world a lot, so you know, there are some solids where atoms move unusually fast, let’s say, unusually well. These are called solid electrolytes. Back in the seventies, we were still developing some fundamental understanding of what was going on there, and he realized that some sulfide minerals are really good at this. So, he said, “Bob, why don’t you look into this. Learn about crystallography and then make this thing that is the prototype material, make a single crystal out of it and determine where the silver atoms are.” He kind of let me alone. I mean, basically he introduced me to his friends who were mineralogists, and then he did something really, really critical for me, which was he got me to get my diffraction information at Brookhaven National Lab out on Long Island. So, I have now a lifetime association with Brookhaven because I made a lot of friends there when I was going there to do my thesis, and he arranged all that for me. Basically, I just had to do the experiments or whatever, but he did all the hard work, which was to arrange everything so that I could be successful. Basically, Bernie was hands-off in a way that I can remember. I might be a type A personality though, and my students have to work their butts off, okay? And I don’t know what I did in graduate school. I can’t even remember. All I know is there were a bunch of successful experiments, but I don’t know how I did them (laughter). I have no idea. Anyway, there it was. So, I’m more picky, but anyway-

Zierler:

Bob, what were some of the larger issues in ceramics at that point, and where did you see your contributions to them?

Cava:

Right. Well, I think it’s still an issue. You weren’t around in the seventies, right, so you don’t know that in 1974 you can remember there were big, long gas lines. When OPEC finally realized that they could manipulate the price of gasoline to make themselves richer, they really did it. They did this by decreasing the supply so the demand would outpace the supply, obviously. So, there were two-hour-long gas lines. There were an original- at least in my lifetime now, two crunches that have to do with “can we replace gasoline?”, so in the seventies is when the initial attempts to replace gasoline became important. We were wondering about making batteries out of the materials that didn’t use gasoline, and a lot of my early work is on these batteries. Nobody knew exactly what was going on. Like how could the atoms be moving in these things? The big issues in ceramics at the time were- and you are not even aware of this because you use it but you don’t know it’s in there, but your car has a sensor in it that detects the difference in oxygen content of the atmosphere and the gas fumes in your vehicle. It continuously adjusts the air-to-gas mixture in your car so that the oxygen partial pressure in the exhaust fume is a certain level, and that is a solid. That is a ceramic object. It’s a tube made of stabilized zirconia, and it passes oxygen, yet it’s mechanically stable. So, it has a high diffusion coefficient for oxygen and yet it acts like a toilet bowl. It’s as hard as your toilet is. How does that work? How is that possible? I think this is the question people were asking then. People were asking, you know, can we develop batteries that don’t use gasoline, just like now. I don’t know what Tesla’s super battery is or whatever, but it’s a big question. Can you just replace fossil fuels with something else? It’s still a gigantic question for us, and ceramics I think are still a potential part of the answer for that. There are a lot of basic questions, like how do you get a material that passes ions so well and yet has the chemical properties that make it suitable to build something out of it? That’s still a big question. How does it work? How can you do it? Yeah. So, for me, that was a big deal. Now because I was interested in the crystal structures of matter and how they relate to the properties of matter, this was a perfect project for me because how the materials work depends on the crystal structure, where the atoms are. There were lots of proposals for what was going on, and then actually figuring out what was going on was a joyful thing to do. Even though the things I worked on directly were never practical, something practical appeared from that generation’s work, from our generation’s work. I wonder what Tesla’s battery actually is. Maybe it’s one of these- I know people were looking at these solid electrolyte batteries a lot lately. Yeah. It’s a lot of fun to ask why.

Zierler:

Bob, tell me about your work at Lincoln Laboratory. What vestiges of the Vietnam War did you see, given the fact that there was so much controversy surrounding that issue?

Cava:

Right, right. Lincoln Labs. You know about that. So, Lincoln Labs, that was one of the things that was owned by MIT back in the sixties or something like this. Then it was divested. We have this word called divestiture; presumably they still use it, but yeah. So, I think Lincoln Labs was a defense lab and it got divested from MIT, but basically what happened there was that my advisor, this person who saw so much in me as a young person and sent me off on a project, ran out of money for my PhD work. Whatever grants he had must have disappeared. I don’t even know. He never told me why. Somewhere around the fourth year of my graduate school there was no more money. I had to go out and get a job, so I got a job at Lincoln Labs because he probably had a friend at Lincoln Labs who was interested in fast ion conduction, this motion of atoms. I remember that. So, I had a friend from college. Okay, sorry for the story, but I had a friend from college who was interested in speech recognition. You know, nowadays it’s very annoying. You use your telephone and a mechanical person talks to you over the telephone and it recognizes your speech, right, sort of, and back in the seventies there was no such thing as that. People had to invent that. So, I had a friend who is still my friend who worked on that at Lincoln Labs. I guess it was a Defense Department thing to make something work to do that. He rode to work every day on a motorcycle, so I sat on the back of his motorcycle and he drove me to Lincoln Lab every day when I was a fourth or fifth-year graduate student. At Lincoln Lab I worked on a sodium electrolyte. I guess nowadays- well, that’s part of the problem here is to make a battery that can put out enough power and yet doesn’t have such reactive components in it that if you get in a collision it starts a fire that you can’t put out. So back in the seventies, we were trying to invent batteries that used sodium as one of the electrodes, and the sodium went through something called beta alumina at the time. I worked on something alternative called NASICON (sodium superionic conductor). An alternative to beta alumina that was actually invented by one of my heroes who just got the Nobel Prize, John Goodenough. Thank God he lived long enough to get it. This is a fantastic guy. By the way, did you talk to him yet?

Zierler:

I have not.

Cava:

He must still be alive. So, John Goodenough. He’s like ninety-seven or something like that.

Zierler:

Wow.

Cava:

Yeah. He’s a sharp. I hope he’s all right to talk. He’s one of these people you meet in life and you just never forget. He was at Lincoln Labs. He invented this solid electrolyte. Then he left and went to Oxford and became a professor of inorganic chemistry at Oxford. I almost went to Oxford to work with him, but I didn’t. I went to Lincoln Labs, so we kind of missed each other. But he’s been kind of one of my heroes the whole time in my life. He went to Texas at some point. He’s a really exceptional character. Obviously, I know he got the Nobel Prize in Chemistry, but he’s always been one of the people who tries to cross the line between the two things. You know, chemistry culture and physics culture are very different, and how do you cross? How do you get one side to listen to what the other side is doing is one of these questions that’s a hard one to solve? You know, John has lots of ideas for things to do that he couldn’t get physicists to listen to or had trouble, so he just went off and invented lithium cobalt oxide eventually. You know, I don’t know if you know, but he invented the lithium cobalt oxide battery and then when it turned out that cobalt is too expensive, he invented the next one, lithium iron phosphate. So, some of these batteries use lithium iron phosphate, and that is also John’s invention. So, this guy is stupendous. Okay. I shouldn’t say too much. So, there are two batteries invented by him. He probably considers himself a materials scientist. He’s fantastic, so he’s a good person to talk to. Another one is Roald Hoffmann. He’s a chemist. He’s at Cornell. He’s probably still working; he’s in his eighties. He’s a terrific person who has also tried to cross this line between physics and chemistry. He’s a great person. Roald is a Holocaust survivor or something. I don’t know whether he was born after or before or was actually in a concentration camp as a child or not. I just don’t know his story, but Hoffmann is his name and he’s at Cornell. He’s a theoretical chemist and- he also has insights into how the properties of matter are related to their crystal structures, so he’s one of my heroes, too. So, John and Roald. Also, Phil Anderson, who is now gone, and Millie who is like a legend (laughter).

Zierler:

Bob, who was on your thesis committee? CAVA: (Laughter) That’s entertaining. So of course, your advisor and then there were a few other people. One was the chair of the department, and his name was David Kingery. He was a super ceramics guy. Then there was a guy named Harry Tuller, who at the time was a young professor, and then John Vander Sande, who at the time was also a young professor in materials science. They were on my thesis committee. I have never been a shrinking violet, okay, when it comes to being a scientist, and I remember that I got into an argument with Harry at my thesis defense. So, Harry Tuller, he objected to something that I said and so I ended up being in some kind of a verbal battle with him during my thesis defense. I can’t remember what, but I also remember that in my youth I definitely got challenged by people a lot and I just didn’t back down. In a way, that was good. But in a way, it’s also not good because you don’t want to be the toughest guy in the block kind of thing. You want to defend yourself scientifically, but you don’t want to have a reputation of being impossible, okay? So, I definitely calmed down later in life, but in the beginning I was a tough character. In my PhD defense, I did fine, but there was not universal joy about the way I was thinking.

Zierler:

Bob, did you ever think about entering industry, or you wanted to stay on an academic track?

Cava:

No, I think I never actually considered academics as a track. I think basically when it came time to graduate- yeah, there are multiple stories there. Bernie, my PhD advisor, because he was a geologist, he had a lot of friends who were geologists, and my second-best mentor in life was a guy named Robert Roth, who was at the National Institute of Standards and Technology. This person was a geologist who was the senior editor for a compilation called Phase Diagrams for Ceramists, and he was responsible for making all these phase diagrams make sense. He was another wonderful character who really cared about mentoring a younger person, and I remember there were many discussions with him about “why do you care about what the properties of something are? You should just be interested in the crystal structure”, but you know, he really mentored me in terms of that, of seeing that connection between them. So, what this had to do with this question is this. When it came time to leave graduate school, I had a choice of what to do, and the choices were- actually, I don’t think there was too much of a choice. I became a postdoc with this guy at the National Institute of Standards, and it must be because he was friends with my advisor. So, I went to work for this guy Robert Roth at NIST. (It used to be called NBS at the time.) I expected to work there for my whole life, and when you work in a national lab like that, I think it’s still the expectation that if you’re a postdoc there, they get to look you over and see whether you’re any good or not and then decide whether they’re going to give you a job. So, I remember- Of course- does your generation know the song The Boxer? I think of The Boxer. There’s a line in The Boxer that says, “He carries a reminder of every glove that knocked him down.” Anyway, you remember the insults in life. You remember people who have been good to you, but you also remember the people who have been bad to you.

Zierler:

Sure.

Cava:

I mean, when it came time to look for a job, I never even thought of academics. I thought I’d just work at NIST for my whole life. I went to the boss of this place and I said, “Okay, I’m ready for my job now,” and he said, “Oh, who are you?” I thought, “What do you mean, who am I! What do you mean? Why don’t you give me a job?” He said, “No, no job.” So I got no job offer from them, and then I started working for another job. I had a couple of job offers and I just went to Bell Labs, which was a really good thing to do. So, I had a seventeen-year career in an industrial laboratory where I learned that you’d better be serious, okay? That was a serious place. There were very smart people who were very, I would say serious scientists. They taught me that you can’t just invent something. You have to make a realistic contribution to see if it’s going to make it in the world or not.

Zierler:

And Bob, you joined Bell Labs very much in its heyday.

Cava:

Yeah, I did (laughter). I lucked out again! I lucked out. Yeah, so Bell Labs was like heaven on earth for scientists, basically. I remember. So, I got hired and my department chair took me to an empty lab. The lab was completely empty and on the desk in there he put a yellow notepad, this legal-size yellow pad with a pen. It was sitting on the desk; everything else was empty. He said to me, “Okay. Now do something,” and he walked out. That was the whole thing, and I said, “Okay. I guess I’d better do something” (laughter). Okay. You probably end up talking to a lot of people who cut their teeth at Bell Labs, and it was a special place because it was just like everybody was there to do something. I always like to think you got more than you bargained for. I mean, you could collaborate with people, but they always gave you more in return than you expected to get. You know, anybody, just anybody. There was just room after room of experts in something and you just had to go find them. There are all sorts of stories about that.

Zierler:

What group did you join initially when you joined Bell?

Cava:

It was called the Solid-State Chemistry Research Department. I think that’s what it was called, and the fellow who was the head of that department was named Jack Wernick, who was a metallurgist who actually worked on the Manhattan Project. So, this guy, his job- it’s fun to think about this. The guy who put the yellow pad of paper and the pen on my desk, his job as a scientist at los Alamos was to cast the casings for Little Boy and Fat Man- whatever they call the two bombs they dropped on Japan. That was his job at Los Alamos, to do the metallurgical casting for those things. He used to tell the story that he- I don’t know if you know how they do that, but basically you have to pour molten metal into a mold, and if you have molten metal in contact with air, it’s hot and air has oxygen in it, and oxygen plus hot metal can make a fire, right? All you need is just something to set up a fire. So, he told me that one day, the giant crucible that he was using to melt this metal in got stuck somewhere and then the surface- basically, I think the surface of a metal, if a molten metal is in contact with air, it will burn, so they used to put something on the surface of the metal to protect it from air, but that will also burn if you get it hot enough. So he somehow made a mistake that caused a fire at Los Alamos that burned down the building where they were making the bombs. He told me that his job was to make this casing and that people in Hiroshima got to live two weeks longer because they had to repair this building because he burned it down. Anyway, that was his story. He might have also been a Holocaust survivor or something. Yeah, he was great, too.

Zierler:

Bob, what was the research culture like for you? Could you jump in on an existing project? Were you told to come up with stuff on your own? How did all that play out?

Cava:

You had to come up with stuff on your own. I’m sure that you get hired because the people who were there- at least at Bell Labs there was this thing where your expertise could complement something that they needed to know about. You could provide something that they needed to know about. So, when I first got there, the first projects were all on batteries, and obviously, in a place like that you want to invent a battery that’s going to be useful twenty years from now. Our research horizon in basic research was: “twenty years from now what technology is going to exist? Invent it.” So, there was a very active battery group. They did a lot of good stuff, but they didn’t know where the atoms went in these batteries. Like if you make a battery that has lithium metal on one side and some kind of electrode on the other side, where does the lithium go, or how do you see it? Well, I knew how to see it, so my initial projects were all about that, and that was kind of like a starting point. But I distinctly remember this, being thirty-something years old and thinking, “Okay, I know a lot. I’ve been successful, whatever. Now I need something big. I hope that somebody’s going to give me something big.”

Zierler:

And Bob, “big” means you’re operating in a purely basic science environment? Is there any desire to help Bell’s bottom line?

Cava:

Yeah, there is (laughter). There is definitely that. There was a balance. I know that books have been written about Bell Labs. It was a really wonderful place to work. Basically, there was a basic research wing and there was an applied research wing and you met in a central cafeteria where you got to meet people. So, you knew that your basic research had to support the company. You had to be the answer person if the applied research people had a question that they couldn’t answer because they were specializing in something else. You had to be able to answer it, so we definitely did that. There was definitely pressure felt to invent technologies that would work at a longer-length time. Now you couldn’t be a dreamer to the point where you just didn’t care like whether your research was going to be relevant to electronics or not. You had to do something relevant to electronics, but it was kind of broadly defined. When you think about it, obviously there are all kinds of people. There are people who like to do stuff that’s going to be applied next year, and there are people who like to do something that’s going to be applied in five years. There are people who don’t care about applications at all, and there are people who like to do stuff that’s going to be applied in twenty years. So, you just find out where you fit and then you- well, at least so far, you’ve been able to find out where you fit and then join that particular culture and then go. So, for me, because I was interested I properties and structure, the twenty-year horizon was exactly right. You know, how do these batteries work? I can tell you another story about that. So, I was a young person. Like how do you pick what you’re going to do? Well, I decided when I first went there and I got this pad and the guy said, “Now do something,” I said, “Well, okay. I want to do something different. I don’t want to do what everybody else does.” So, what I did was, when I first got there, the first couple of weeks I went around the building and I asked people, “I would like to do this. Is that a good idea or not?” and the answer I got from everybody was, “No, don’t do that.” So of course, being a rebellious person, I said, “Okay, if all these people say, ‘No, don’t do it,’ then I’m definitely going to do it.” So, I got involved in a variety of projects that were still not really mine that were things that people told me not to do. The one that was finally mine came up by some bizarre coincidence- well, not bizarre. So, we started this conversation with: “What did the pandemic do to hurt or help your research?” For me, it hurt it because of personal interactions. I’ve had many times in my life where personal interactions with other scientists have set me off in some direction that has been critical. In particular, a big one is one day I was walking in the hall at Bell Labs and I ran into a theorist, a theoretical physicist, Peter Littlewood, who I knew from work on charge density waves. I can’t remember why we first met, maybe because of some cafeteria meeting or something like that. The guy said, “Oh, somebody’s going to give a talk about the new high-temperature superconductors in the seminar room at 4:30. Are you going?” I said, “No, I don’t know anything about it.” He said, “Well, why don’t you go?” So, I remember going to the seminar, which was full of physicists, full of theoretical physicists, and I was sitting in the back row, literally in the back row in the auditorium. The person was talking, Koichi Kitazawa was his name, and he was visiting Bell Labs from Japan. He had a graduate student back in Japan named Hide Takagi, who is currently a Max Planck director. (This is now thirty-five years ago.) Hide was a graduate student at the time in Tokyo, and this guy gave a talk. He had some connection to IBM. So, the new ceramic superconductors at the time, which this was ’86 I think, were discovered in a lab in IBM in Switzerland, and this Japanese guy knew the scientists in Switzerland for some reason. After he went to Switzerland and he saw this result, he came to Bell Labs and gave a talk because he knew some other scientist at Bell Labs, a theoretical physicist. They were talking and they decided to spontaneously generate a seminar because they knew that this was an important discovery. So, the guy gave a talk at 4:30 or 5:00, and during his talk he made a landline telephone call to Tokyo. It was 5:00 in the morning in Tokyo and Hide Takagi was in the lab making ceramic superconductors. So, I suppose that Takagi was the one who actually figured out the formula of the superconductor that the people had discovered in Switzerland. I don’t know who actually did it. But I was sitting in the back row, and I said, “Wait. This is a ceramic superconductor. I know about ceramics.” So, I went back to the lab and a few days later I had a material with a superconducting transition temperature that was even higher than the one that these guys had because they didn’t understand something about the chemistry that I understood. So basically the chance meeting of a person who I knew because I don’t know how I met him generated this trip to this back row of a seminar that I shouldn’t have been in because I was a chemist in a room full of physicists. That person called Tokyo by telephone, and that inspired me to do this. How crazy is that?! So that started me out on superconductivity. It was very personal. Yeah, obviously- so, there are other people around who are my age, around my age who lived through this time. It was really pretty special. It’s different. Well, we share a common history. I don’t know, but there are some interesting characters who you’ve probably talked to. One is this character Paul Grant, who was at IBM at the time. Yeah, maybe you talked to him, and then there’s a guy at the University of Houston, I don’t know if he’s retired now, Paul Chu. Did you ever hear of this guy?

Zierler:

Sure!

Cava:

So, Paul Chu. He might be in his eighties now, I’m not sure. But basically, he and I were sort of competitors at the time, but we lived through an important time together and we all became friends. Paul Chu and M. K. Wu were the two people in the United States who found the ninety Kelvin superconductor, so they did something to the Swiss formula that made it into ninety Kelvin instead of, well, I had thirty-seven at the time, the Swiss had twenty-eight. But you know, I saw what Wu and Chu did in Houston and I thought, “Well, chemically that doesn’t make sense.” I did something to it and a few days later I had discovered what the real superconductor was in their samples. We all became good friends. M. K. Wu and I exchange Christmas cards every year. I know what his grandchildren are doing, and Paul and I run into each other at meetings all the time. So, you know, it’s all good. Life is good and you have to appreciate the people you run into. That’s definitely it.

Zierler:

Bob, there were so many theoretical and observational and experimental challenges with superconductivity at this point. From your vantage point, what were those key challenges?

Cava:

Right. The theorists had a big challenge, which was how could it possibly be that some superconducting state could be stable at such a high temperature? Even if you stretch the conventional models for superconductivity like coupling of electrons to lattice vibrations, I’m pretty sure that very early in the game a person who was a friend of mine at Bell Labs came up with a theory that said, well, you can’t go above thirty Kelvin. So above thirty Kelvin, atomic vibrations have to disrupt the pairs of electrons, break up the pairs of electrons that are responsible for superconductivity. So how is it possible that something could superconduct at ninety Kelvin? How is it even possible? So, I think the theorists faced the biggest challenge. Even now, how many years later- that was 1986, right, so it’s thirty-five years later. Nobody knows why they superconduct yet. The smartest people on earth have been thinking about this problem for a really long time. They still don’t have a consensus. Nobody says, “Oh well, we understand that one,” and everybody’s happy. They’re still fighting. Not really fighting but disagreeing. I think for me, my perspective is it was a window into the complexity of solids that you didn’t typically have the motivation to study. The superconductors are so complicated. There are so many different phenomena that are observed it’s hard to know which one is important to yield this ridiculous superconductivity and which one is not important. I think, depending on how you view the world, some things you’re going to think are important and some things you’re going to think are not important, but basically it’s like looking at the whole person and saying, “Which part of this person is the critical part that makes them function?” Well, maybe it’s one part of that person, but maybe it’s all parts put together that make that person function. Honestly, obviously some theorists will tell you that it’s already done; they already understand it, “so I’m done with it; it’s boring.” But some theorists might tell you, “Well, I understand it my way. They understand it their way.” Yeah, so I think the theorists faced the biggest issues. Experimentalists, once as chemists we got the idea of what could lead to superconductivity, we were able to find them, many. That brings up something else about the difference between physicists and chemists. There was a recent discovery of a nickel-based superconductor supposedly by a young man who I respect very much in a group in Stanford, Harold Hwang. I’ve known Harold ever since he was a graduate student, and I know he’s a very smart kid. So, this must be right, but I am shocked that it works because it says to me- I don’t know whether it says this to anybody else, but to me it says if this nickel oxide is superconducting, then all that matters is the Fermi surface where the electrons are in the band structure. It doesn’t matter what the atoms are. So basically, he says that nickel, under certain conditions, can yield a superconductor, and I guess the point is it’s an explanation for the cuprates that says that the superconductivity has nothing to do with which atoms are there; it only has to do with what electrons are doing at the Fermi surface. I honestly don’t believe that. I still don’t believe it. I still think it’s the atoms that matter, so that this nickel thing can’t possibly be right, but you know, a lot of smart people think that it’s right, so it must be right. As a chemist, I think that the atoms have to matter. I don’t know if I explained that well, but you know, if you can find the same phenomenology or what looks like the same phenomenology in a nickel compound that you see in a copper compound, that must mean- well, that either means that it’s right and my concept is wrong and the atoms don’t matter, or it means that only the Fermi Surface matters. Human beings have a way of picking out stuff that they’re looking for. That’s something for a scientist to be very aware of.

Zierler:

Sure.

Cava:

Do we only see what we want to see?

Zierler:

Bob, if I can just editorialize, it’s probably the key reason why things remain unknown. Like if we don’t know what the dark matter is, maybe it’s because we don’t want to look in places we’re not comfortable looking.

Cava:

Yeah (laughter). It could be. Yeah. Yeah, right. Yeah, there’s dark matter and there’s dark energy. Who knows what the hell those things are, right?

Zierler:

Right.

Cava:

What’s dark energy? What the hell is that, okay (laughter). I have to tell you a story. What happened? I’m trying to think of what the context was, but once a science reporter was interviewing me about something and I told him that I didn’t believe it. I said, “This is what happens, not this.” He said, “You mean you scientists want me to believe that the universe came from some kind of quantum fluctuation out of nothing? You do want me to believe that, but you don’t want me to believe that electron-phonon coupling gives rise to superconductivity in the cuprates? Are you kidding me? You want me to believe- What’s the big question? Where did the universe come from? My god, is it really a quantum fluctuation of nothing? Really? We’re supposed to believe that?” I guess so. Okay, whatever. Anyway. So, we’re people, after all. We see patterns, and they’re not necessarily really there. And some places you just don’t look. What is that story? Oh, somebody drops a coin in the street and it’s dark in the street and they’re looking under the lamppost for the coin, but that’s not where they dropped it. But they look under the lamppost because they can see over there. But they can’t see in the dark, so they’re not looking in the dark. They’re looking under the lamppost where they can see something, but that’s not where they should be looking; they should be looking somewhere else. Anyway, that’s a story that’s out there for scientists.

Zierler:

Bob, how insular was your world in superconductivity at Bell Labs? In other words, there’s a whole community of superconductivity beyond Bell Labs at this point. Did you feel integrated with that, or this was an entirely in-house world for you?

Cava:

No, it was definitely integrated, but it was integrated differently. Nowadays, if a group discovers something, everybody around the world can hear it at the same time. Because we have these wonderful things like on-line archives or whatever where you can just post something right away, the whole world can see it, and at the time, it was definitely a privilege of working at a lab where there were personal connections that could get you information before anybody else got it. I think that could still extend to universities, to some elite universities where people get to go out in the world and do stuff like the one I work in. It was not insulated, but the rate of information transfer was much lower. We interacted with the human race enough to know what was going on all around the world, but the rate at which we learned stuff was much slower. I would say months instead of hours. Like in superconductivity, since we were one of the good players in the game, you got to go to conferences where other people gave talks, and you got to hear talks about what they were doing. So, because you worked in a place of privilege where there were lots of good data coming out, you could attend these conferences and learn about what people were doing and use that information to do something better. So, we were not insulated, but we were privileged. Nowadays the playing field is a lot more level in the sense that anybody can post anything on the internet at any time and have it discovered by anybody on earth.

Zierler:

Who were some of the key people who came to visit Bell during these years?

Cava:

Well, I would say the big one was Koichi Kitazawa because he got everything going on superconductivity, and I’m trying to think. Who else visited for that? Well, lots of young people came and went. Hmm. Lots of people could tell me, oh, there were post-docs at Bell Labs back- until the end, so there were people who came for two years and then left. They’re all out in the world nowadays. They did well. The big influences for me were people like Phil Anderson, who was already at Princeton at the time. He had already left Bell Labs and then came back and forth, or maybe he was like a visitor’s program or something. I don’t know, but he was around. And this guy named Ernst Buecher, who came from Germany, was around quite a bit. He became notorious or famous, at some point because he was the advisor of this character who was a postdoc at Bell for a while, Jan Hendrik Schön. You’ve probably heard of him.

Zierler:

Sure.

Cava:

So, for me, definitely there was the privilege of the visitors, but then there was also the fact that there were people who I knew who went around the world and did stuff who would report back to Bell Labs. I remember one time walking in the hallway at Bell Labs and running into Horst Störmer, who is now at Columbia. He eventually won the Nobel Prize for the fractional quantum Hall effect. But I remember he went to the National Magnet Lab to do an experiment. He saw people from Paul Chu’s group measuring the superconductivity of yttrium barium copper oxide. He didn’t know the formula of what they were measuring, but the material went to zero resistance at ninety Kelvin. Well, I remember just standing there in the hallway and having him come back and say, “I just saw a superconductor at ninety Kelvin. Oh my god! How insane is that?!” I guess- yeah, that was one of the things that the people who worked there actually went out in the world and could report back on what was happening out there, so we had a lot of that going on, just people who went out. So, I remember Horst Störmer, and there was this theorist, a person who Kitazawa visited. Len Mattheiss was his name. He was an early electronic structure calculation guy, and so he- he was a big source of information. He was a good guy, too. I wonder if these people are around anymore. Probably not, but anyway.

Zierler:

Bob, when did you really start to get involve with YBCO?

Cava:

Oh. So basically, YBCO, I think there was- and notice it comes down to days, right? I think that the story was that- so, there was lanthanum barium copper oxide and I heard about that in Kitazawa’s talk. That might have been after the MRS meeting in December of 1986. Then somewhere around January of 1987, there became rumors that there was a superconductor at ninety Kelvin, not twenty-eight Kelvin or whatever the Swiss people had. We had thirty-eight or thirty-seven, I don’t remember what the number was, in some other variant of the original Bednorz and Müller formula. Then there became rumors that there was a higher temperature one, and then part of the rumor became that it was Paul Chu’s group that had found it. At some point- actually, now I’m not sure whether it was a Friday morning or a Thursday morning. It must have been a Thursday morning. Paul Chu gave a talk somewhere in California where he said it was yttrium barium copper oxide and he gave the formula, which was a variation of the formula that they made in Switzerland, which couldn’t have possibly worked, I knew, for yttrium and barium and copper oxide. I think I heard this rumor on Thursday or something like that, and I went to the lab and made what I thought should work. I think I made three samples of yttrium barium copper oxide. One of them was pure. So, I had made that, and by Saturday I think we knew- I had already made the material and then it had to get tested. We had to test it for superconductivity. The collaborators on this project were me, my technician at the time whose name was Ed Reitman, and a guy in physics named Bertram Batlogg, who became a little bit notorious for the Jan Hendrik Schön disaster, and then a guy in materials science named Bruce van Dover who went to Cornell eventually in the materials science department. Anyway, Bruce and I and Bert figured out what this was. Bruce tells a story about after he measured the resistance of this stuff I had made and it went to zero resistance, he got very excited. He came and told me, and I was still dazed out from being awake for so many days that I didn’t realize what he was saying to me, but finally he made me understand what it was. Then Bertram figured out that the whole thing was actually superconducting, so we had gotten it. I don’t know if I told these stories before, but basically, after we figured it out, the first thing we did was we filed a patent. The patent attorneys were having coffee with us. The patent attorneys came to work on the weekend at Bell Labs, so this started on like Thursday. By Saturday I had already made the pure substance, but another person in the lab had made the formula that Paul Chu said by Friday. She was a physicist and there was a meeting about it. There was a lab-wide meeting. The whole Bell Labs got together for a meeting in the auditorium on that Friday afternoon where I remember- I think it must have been Bertram had wires attached to a superconductor and he dumped it in a bucket of liquid nitrogen and the resistance went to zero. The whole audience exploded in applause. It was a historical moment. The lawyers came for coffee on Saturday and Sunday, and I think it was Sunday night or Sunday late afternoon that we figured out what the superconductor really was. Then we filed a patent on a Monday because the lawyers had been sitting with us the whole time. Then we submitted a paper to Phys Rev Letters with the formula of the superconductor and its crystal structure in it. I became friends with the physicists at Phys Rev Letters at the time. You know, Phys Rev Letters has an office across the street from Brookhaven Lab, right? At the time there was a physicist who was acting editor of Phys Rev Letters, Myron Strongin. He was a wonderful character. We submitted a paper to Phys Rev Letters, and in those days, it was paper submission, so you had to submit a typed manuscript to Phys Rev Letters. We sent it by FedEx or something like that, and the FedEx driver realized that the labs were closed. I forget what day we submitted it. It was after hours or something when it got to Phys Rev Letters. So, he found Myron Strongin’s house and delivered the paper in the envelope to Myron Strongin’s house with our yttrium barium copper oxide paper in it, and then Myron did whatever he did with it and it eventually got accepted. I do remember that. Okay, so this was important. I guess Paul Grant can tell you the story that a week later they figured it out at IBM, which was our corporate competitor. They figured it out one week later, and Paul actually literally got on an airplane and flew to Long Island to deliver the manuscript to Phys Rev Letters by hand. When he got to Phys Rev Letters headquarters, they said, “Well, you’re second. We’ve already had a manuscript from Bell Labs for a week, so you guys are not going to be the first.” I wonder what- I’ve heard Paul tell that story, but I don’t remember what he did at that point. What did they do with their paper? It must have gotten published in Phys Rev Letters somehow.

Zierler:

Bob, at this time, what was immediately apparent to you in terms of just the basic discovery and potential applications?

Cava:

Well, the applications, I don’t remember whether Paul Chu has it in the original paper, but it’s like the Holy Grail of physics. To make a regular superconductor work, you have to cool it with liquid helium, right, so you need a big thermal insulator, and helium at low temperature doesn’t have a very high heat capacity. So, if you can have a superconductor that works at liquid nitrogen temperature, you can immerse something in liquid nitrogen and you can encase it in an insulator that’s much less serious than the insulation you use to insulate helium, which is like four degrees Kelvin. Seventy-seven Kelvin is much easier to deal with, and you have a higher heat capacity all around. So, if you have a fault in a wire or something like that, or the resistance suddenly is not zero anymore, a lot of heat is dissipated and the stuff surrounding it can absorb the heat without causing a catastrophic failure. So, this is like a dream. The fact that something could superconduct at ninety Kelvin is just so shocking. It’s so potentially important. Of course, there was- you can only say: “does nature ever give you everything that you want as a human being all at once” and nature doesn’t give you everything you want. That’s my excuse. It took another twenty years for somebody to figure out how to make a good wire out of a ceramic, but they eventually did. So, you could do it; it’s just too expensive to do it right now. Basically, the high-temperature superconductors themselves like the cuprates, BSCCO (bismuth strontium calcium cuprate) and yttrium barium copper oxide all superconduct at a temperature that’s high enough for them to be useful, but it costs too much money to do it right now. So, I think someday when lots of other world problems are solved and there’s money around to do it, they’re going to be… What happens? Maybe my grandchildren, if I’m lucky enough, maybe it will be in my grandchildren’s day. Yeah. Do you remember when New York got flooded, when Hurricane Sandy hit? I know this is kind of a diffuse thing, but remember when Hurricane Sandy hit, Lower Manhattan went under water. You remember that?

Zierler:

I do.

Cava:

Lots of electronic stuff got destroyed by that, although they eventually dried enough of it out to use it. But you know, if you put electrical cables underwater, they’re not very happy. So, there was a brief time period when there was a discussion about replacing the electrical wires in New York City with superconducting wire because it’s obviously much smaller and since they have to start over again anyway, they might as well do it, but then they just decided it was too expensive to do. It’s still- the technical problems are solved. It’s just do we have the money to do it? Maybe another way of saying it is the technological problems may be solved, but they’re not solved in an economic way, so we have to keep trying or be more patient.

Zierler:

Bob, was that apparent to you then? Did you recognize even then that, even with this technological breakthrough, the infrastructure problem would be one that was long-term?

Cava:

No. I think the thing that I thought at the time was, “Oh, this is a ceramic. This is a rock.” The reason this is such a dramatic thing, really from a materials science perspective, is that all superconductors that were good before this one- first of all, they all work at twenty Kelvin and lower, which you can do nowadays, but they’re metal and metal is fundamentally different from a ceramic. Ceramics are brittle. You can’t bend them, so how am I supposed to make a superconducting wire out of a ceramic? That is something I recognized as a problem right away. So, the technological problem of making something that you can bend or at least support while you are bending it or at least get the current to go from one thing to another, one crystallite to another for a kilometer was something I realized right at the start. But some very clever people who have focused on that for twenty years figured out how to do it! Yikes! It was obvious that there was going to be a big technical problem, but smart people figured it out. It just took a long time to figure out. Yeah. I didn’t think about the money part, and that was all about how much it would cost to make this work. I only thought about could you make it work? Yeah.

Zierler:

Did you stay on this or did you move on to the next big project?

Cava:

Well, that was kind of the beginning and then stuff started to happen at Bell Labs. You’re probably familiar, I don’t know. As a person interested in history of physics, you know, the world- Bell Labs was like heaven on earth, okay? There were places like that. I mean, IBM was like that, too. DuPont was like that in chemistry. They’re also gone now. So, you had the money to look ahead twenty years in the future and do something useful, and for me it was perfect. But then at some point it became that scientists were no longer running the show. I mean, this is the way we saw it from the bottom. It was like then everybody had to do something to make the company make a profit in a couple of years because that was the new time horizon was years, not twenty years, but three years, okay? And then it came time to change to a different kind of project, and I did that for a while. Other people did other things for a while. I don’t know. Did it get into one of these books about- what’s the book called? Plastic Fantastic. I don’t know if it got there about how the pressure to save basic science at Bell Laboratories had an impact on scientists who were looking for high-temperature superconductors that were plastic. This has a lot to do with what happened with Bert and Schön, in my opinion. They were just making plastic or polymeric stuff, organic materials to do stuff that we had always hoped that they would do, and a lot of the motivation was presumably to save basic science at Bell Laboratories, but it was not enough to do it anyway. I definitely changed projects, and there was kind of a fishing around period where I was trying to find some way to do something that would be more directly relevant. I made a couple of discoveries of materials that I thought were perfectly good but that I got told that they weren’t good enough. Then I like to say that at around age thirty-nine I hit a classic midlife crisis, like what am I going to do for the rest of my life kind of crisis.

Zierler:

Yeah.

Cava:

You know, here I am. I’ll be forty. I remember sitting around on the night before my fortieth birthday thinking, “Oh my god! Is this it? Is this my life?” So, I hit this midlife crisis at exactly the time that Bell Labs was going to hell, and it just motivated me to look around for something else to do.

Zierler:

Did you feel, Bob, sufficiently integrated with the academic world? Did you have colleagues? Could you put out feelers?

Cava:

No. I don’t think I was well integrated with the academic world at all. Part of the struggle with that was that the academic world didn’t trust me. I think that largely, like anything you do in life, it’s like a club in a way. You have to get in, and if you’re not already in the club, they’re just not going to let you in. You have to do something to prove that you belong. I remember, obviously at the time I lived in New Jersey. I had three kids already. I had a wife. I had a stable job at Bell Labs, but I was forty years old. A lot of my friends were being fired at the time. Not me yet, but I knew they would get to me eventually. Bell Labs was on its way to collapse and knew I’d better get out while I had a choice of something to do.

Zierler:

Bob, did you consider, as the lab was breaking up, one of its subsidiaries like Bellcore, for example, or Lucent?

Cava:

Well, Bellcore- no. So Bellcore broke off in the eighties, and then Lucent- some of my good friends went to Bellcore, but I don’t remember why I didn’t. Basically, some other person who is now in France who is the director of a laboratory in Paris, who is an exceptional solid-state chemist, his name is Jean-Marie Tarascon, went to Bellcore in the 1980s, the mid-eighties, and I didn’t go for some reason. I don’t remember why, but that’s okay. Bell Labs was still going strong. We still did fine until the nineties, and then somewhere in the ninety's things started to fall apart. It all kind of started when- so it was AT&T Bell Laboratories. Then it became Lucent Bell Laboratories because AT&T must have figured out, they could make more money by separating the people who made equipment from the people who sold telephone service, so they separated off the equipment wing, which was Lucent. I went with them because my job was to invent equipment or technology of the future. Then the management, at least from my perspective, but history people know more than me, the management at Lucent started turning the screws on the basic research people, saying, “You have to do something that’s going to be useful in three years,” or something like that. Then eventually they decided we were all useless and they were just going to fire everybody. So, they just started firing people and either you read the tea leaves or you didn’t. It kind of depended on how crazy you were. Obviously, all my friends, my entire department disappeared at some point because everybody had been fired or left. Whether you stuck it out, how long you stuck it out at Bell Labs depended on how conservative you were, how much you were worried about what your family was going to do if you couldn’t find another thing to do with your life. Yeah, so Bell Labs was definitely heaven on earth, and it began to unravel when Bellcore first came out in the eighties, but it didn’t unravel very far until Lucent, which was another unraveling. Now it’s Alcatel Bell Labs, Alcatel is like a French telephone company. I went back there to visit. They actually tore down the wing, the building that I used to work in. It’s gone! They took it out. They got so mad or whatever that they just tore down the whole building. Really? Anyway, whatever. I don’t know why they did that.

Zierler:

Bob, just as a matter of geographic proximity, were you aware of what was happening at Princeton? Did you have friends there?

Cava:

I did have friends there. It was Phuan Ong over in the physics department. He and I became friends in the seventies because we both worked on charge density waves. Phuan is a very serious, very understated kind of condensed matter physicist who is the person who- I don’t know if they’ll ever give him enough credit for it, but he discovered the fact that charge density waves can be unglued from the lattice because charge fluctuations in a solid can actually carry current. Anyway, so I kind of knew him and I kind of knew Phil Anderson, but I didn’t really know them, and they weren’t my close friends. Basically, Princeton was like an hour and a half drive from Bell Labs, so it seemed like a good place to leak into if you were going to have to leave Bell Labs. Maybe you could live in the same place, live in the same house you live in with your family, just get a new job and drive to work somewhere else. I think that was the plan. My case was a little bit different because I- my wife has passed away, but when she was alive, she had a different plan. We lived in Bridgewater, which was perfectly fine for me. I was perfectly happy. But then she said, “I want to move to Princeton,” and so we moved to Princeton two years before Bell Labs collapsed. ZIERLER: (Laughter) Wow!

Cava:

Yeah, which was insanity. I told her, “We’re going to be looking for a job. I can read the tea leaves already,” two years before it happened that I was going to need a new job somewhere. But she insisted, so we moved here and then Princeton University became the obvious place to look. Then I didn’t get a job offer from them. I got job offers from other places that I think are less conservative than Princeton is. Basically, I used an industrial connection in a weird way. At the time, I knew there was no materials science department, but there was this materials institute, the Princeton Materials Institute, and the head of the Materials Institute at the time was named Peter Eisenberger. Peter Eisenberger had been a scientist at Exxon, which was an industrial research lab out in Clinton. Well, they moved. They were originally close to New York City; then they moved out to Clinton. But I knew Peter because he was an industrial scientist. So, I remember one day I called Peter on the phone and I said, “I’m looking for a job, Peter. Can I get a job at Princeton?” and he said, “Bob, if you want a job at Princeton, get a job somewhere else first.” That was great advice, so I went out and I went to places that were less conservative. I got some job offers and then I came back to Princeton and I said, “Okay, I have some job offers. Now you’d better take me seriously.” Then years later, I guess they were busy looking for somebody else, they finally deigned to hire me, and they hired me and I’ve done fine. But it was definitely a struggle. I was not their first choice, that’s for sure, but I’m okay now.

Zierler:

Bob, how much experience did you have teaching? Did you adjunct at all during your Bell years?

Cava:

No teaching experience. I had no teaching experience, but here’s something you discover. Students like life experience, so if you- obviously, I have a lot of stories, right, so you can tell students stories and they don’t mind. There’s stuff they can learn from a book and they’ll just learn it from a book. If they care, they’ll learn from a book. But stories about life, like what did you see in your lifetime, that is something that student’s value. I think having gone through this career where I spent time at a national lab and I spent time at the best industrial lab and you know, I just had a lot of life experience. I think that makes me a pretty good teacher because I don’t have to teach from a book all the time. Basically I hate teaching from a book. This is why I hate Zoom, because I have to actually behave, you know. But telling stories, the kids like that.

Zierler:

Bob, tell me about your work with the Princeton Materials Institute.

Cava:

Right. The way Princeton did this is they- and I think it’s a strategy they have in other areas, too. They don’t have a materials science department. They have a research institute that somebody, I imagine Peter Eisenberger, convinced them to make. At that Institute, they have equipment in central facilities that are useful for people who are interested in the properties of matter whose departments are not really about the properties of matter. So, let’s say you’re a mechanical engineer and you’re interested in how well concrete buildings do in a fire, for example. Well, I have friends who work on that. (I had friends who worked on that.) You know, the fundamental properties of concrete are interesting for a materials scientist. How do you measure the properties of this thing? Well, you need a certain kind of equipment to do it, so they put that over at the Materials Institute. In my case, I might need an electron microscope to understand where the atoms are, and where do you keep that thing? Well, you put it in a materials institute so that other people can use it too. It’s very expensive. One person can’t buy it, so you put it in some central building. They built a nice little building that’s the Materials Institute, but it’s only a research building. There’s an interesting history to this at Princeton. So, the Materials Institute is there, and Princeton’s strategy for hiring people who are experts in a certain subfield or field without actually creating a department is to make what they call faculty-equivalent positions that can be had in halves by other departments. So, let’s say the Materials Institute has six positions, six total. They can give out twelve halves, so this is exactly what happens. The Materials Institute got six positions when they built the building, so they could give out- they could not hire a whole person, they could only use these in increments of a half. So, they had twelve half-people that they could hire. Because departments typically have more responsibilities than they have people to cover. If you want to create a good education for people, you have to have enough people to teach. Yet the institution itself can’t get too big. Anyway, the way they use these six positions is they use them as twelve halves and so there are like twelve people scattered around the campus. Obviously, there are people in physics, and I think that Phuan might be a half-materials and half-physics person, or maybe he’s all physics. I don’t know. But I’m half-chemistry and half-materials science. So definitely I’ve had a lot to do with the materials science at Princeton. Back in my day they hired mechanical engineers, chemical engineers, electrical engineers, all sorts of engineering people, and some scientists. In the chemistry department, there’s a good chemical theorist named Roberto Car who has a partial appointment there too, as does Sal Torquato, who is a statistical mechanics expert.

Zierler:

Bob, was the Institute set up to encourage visiting scholars, senior people to come through?

Cava:

No, I think it was set up to provide central facilities for doing research in materials science and also for getting materials scientists on campus when there was no materials science department. Let’s say Princeton had decided to create a materials science department. They would have had to hire five or six faculty members, do that if they make a small department, or twenty if they make a big department. So, they must have decided that the way to do it was to just have these people have one foot in a classic discipline like chemistry and one foot in a newer discipline (well, newer on the scale of Princeton) like materials science. Yeah, that was their solution, and I think it was to encourage research in materials science and to get people on campus who viewed themselves as materials scientists. I definitely view myself as a materials scientist, so it got me there and it got other people there too, in engineering departments in particular whose specialty is the properties of materials. So that was actually a good thing to do.

Zierler:

What was the intellectual property environment like, contrasting Bell and Princeton, in terms of patents and ideas?

Cava:

Right. That was an interesting thing that happened during my time. I think Princeton used to be- used to be- this is now twenty-five years ago, sort of was proud of the fact that it had no practical impact on technology. It was like “we just have deep thinkers. We don’t actually have to apply anything.” Okay, this is just my interpretation. Then somebody in the engineering school said, “What? Are you kidding? You don’t want to make patents? You don’t want to apply your technology?” I think that this guy’s name was Steve Forrest. He eventually became a dean over at the University of Michigan or something like that. But I think that Steve was the one who made Princeton come out of the eighteenth century and told them they’d better get a good patent office going because a lot of engineers are really interested in making patents of stuff. He was really interested in that, and I’m sure he founded a company. If you talk to somebody at MIT about something like this, it’s obvious. They think practical applications are what they do for a living and are part of a big story. I think that that’s relatively new to Princeton; I’m not sure. They’ll probably tell you we had something perfectly fine a hundred years ago, but I don’t think it was perfectly fine. Now they have a really good patent division, and in fact, I know the people there well. I don’t even know when they got this person John Ritter, but it might have been around that time because now somebody is proactively in charge of the patent things at Princeton and they will now encourage you to get patents, whereas before they didn’t. At Bell Labs it was an important part of the action. It was so important that the patent attorneys came to the research labs to watch us work. They wanted to witness what we were doing, and I can remember countless, countless hours in the office of the patent attorneys at Bell Labs. I think I have thirty patents filed at Bell Labs, you know, and some of them are obviously useful and they obviously sell them to different companies. They do whatever they do with the patents, but they’re their patents. But patent attorneys were a big part of it. You can ask someone in the engineering school here just how much they are interested in patents nowadays, but they probably are. But anyway, I would say that was one of my big shocks coming to Princeton, like, “Really? You don’t just make patents all the time? What are you doing?!”

Zierler:

Bob, when did you start to take on graduate students? Was it right away?

Cava:

Yeah. I guess. In the beginning, like every faculty member, you start out with almost no money. I had some money, they give you what’s called a startup package, so you’ve got some money to start with. That’s supposed to get you some preliminary results. I came to Princeton and I had enough money to get a post-doc and a graduate student and an undergraduate. Undergraduates are Princeton’s secret weapon. They’re very, very smart people and they have a limited time horizon. They can only do research for like a year or a year and a half, whereas graduate students get five years to do something and post-docs get like six months to do something. They’re under a lot of pressure as post-docs. But by the time you’re a postdoc, you’d better know what you’re doing. Okay, that’s my opinion. So, I got to have a postdoc, a graduate student, and an undergraduate student that helped me set up the lab, and that was a great joy. Scientists love that. Young scientists love that. I came into a lab with nothing and I made it into something, so I remember these three people. I remember their names. Aki Hayashi was the first; Aki was Japanese. He went back to Japan. I don’t know what he eventually did. He’s the only one I don’t know where he ended up. The graduate student was Peter Khalifah, who is presently a professor at Stony Brook. He was my first graduate student, and Job Riesenbeck was the undergraduate. Job went to Northwestern for graduate school and then went to work for GE. GE used to have a research lab. They probably do still have a research lab associated with their products. That’s in Schenectady, New York. So, I did take on this graduate student right away, Peter, and then the postdoc Aki and then the undergraduate Job. They had to set up the lab from nothing. So, they started doing that. My memory of Peter is that he only came into the lab when he was sure that I would not be there, but he says that’s not true. Obviously as a starting professor I started older. Most people start this business in their late twenties, and at some point, funding agencies realized that they needed to have funding venues to get people started on their careers and that it was not fair, I guess in their minds, to have young people compete with older, established scientists for the same money, so they started these things. I don’t know what they’re called, but it’s like early career awards. There are things called early career awards that young people get when they first start, and they compete with people their own age. I was already past forty, so I was too old for that. I didn’t know where I was going to get grant money from. You have to be part of the club. I wasn’t part of the club, so I had trouble getting a grant. My group had to stay really small until I could get some kind of research funding, and by research funding, that means people don’t pay for graduate school. They pay for undergraduate school, but they don’t pay to be PhDs. They have to get paid by their advisor. The U.S. government or some funding agency pays for graduate education in science and engineering, so in order to have graduate students and post-docs, you have to raise the money to get them. A lot of the job is about raising money, and the whole thing about raising money is getting into the club. I remember my big break. I remember I was three years into the job. I hadn’t gotten a grant, but somebody in the industrial relations department over at the central administration got me an interview with a lady who was in charge of the Seaver Foundation in California, which normally funds medical research, but I convinced her that she should give me funding, so we got money. Finally. So, the first grant came three years after I started. That was rough because I needed to get one to stay in my job at Princeton and I knew I could never go back to what Bell Labs had turned into. We got the grant from a foundation, and the person in charge used to come around once a year to inspect the lab to make sure it was okay. At some point, I told the kids they’d better clean up the lab (I had a lot of undergraduates; I still do.) You know, “So-and-so is coming to inspect the laboratory. You’d better clean it up so it looks nice when she gets here,” and the kids thought it was hilarious that I only asked them to clean up the lab when she visited. Okay, then somebody else convinced somebody at the DOE (Department of Energy) to give me money to do work, and then once the Department of Energy gave me money, then I was fine. I’ve never been able to do well with the National Science Foundation, so unlike a lot of people, I don’t get any money from them individually. I’m in some group grants, but I don’t have an individual grant with the National Science Foundation. But luckily, a lot of people other than them have seen the value of what I do. You know, the beginning is a struggle for everybody. One thing about me is I got to go through this period of not being sure about myself at a place that was brutal like Bell Labs, and then by the time I got to be forty, I knew what I was doing and I didn’t have self-doubt. A lot of young people have self-doubt, like, “What am I? How am I going to contribute?” Well, I did that already, okay, so I didn’t have to do that at the same time that I went to a university and had to raise a lot of money. So, I think I lucked out.

Zierler:

Bob, to talk about insider/outsider status, when you were named chair of the department, was that more because you had learned to become an insider, or it was valued that you were an outsider?

Cava:

Yeah, I- yeah. Do you talk to people about department politics? Every academic department has a power group and then everybody else.

Zierler:

Absolutely.

Cava:

Yeah. So, I gather that the chemistry department at Princeton at some point had a power group that was organic chemists, and then it became physical chemists. Physical chemists can be difficult. They are who they are. Everybody is who they are, but they were the power structure. I don’t know why I became the department chair, but I did and then- oh, I know. I started out as associate director of the Materials Institute when somebody left, and something happened, I don’t remember what. Then I became the director of the Materials Institute, so I demonstrated that I was a functional human being. Then when it came time to find a chair for the chemistry department, I became the chair, but I was an outsider. So, because I had never really been a part of the chemistry community very much, I mean it’s getting more, but in the beginning, I wasn’t- I felt like I was immune to whatever local politics were going on. I disrupted the power structure in the chemistry department, and so lots of very powerful physical chemists got angry at me for what I thought was an even-handed treatment and they left. So, what happened was I guess it was because I was an outsider, I was able to do stuff an insider would have been more sensitive to and who couldn’t have done what I did. But I did it. I changed it all. Now I guess the power lies with the organic chemists, whatever, but at least it changed because of me. I had a lot to do with it.

Zierler:

Both politically and academically, what do you see as your accomplishments as chair?

Cava:

Well, my big accomplishment as chair I think is the chemistry building. We have a beautiful new chemistry building. For a long time, the chemistry department was in one of the very old buildings up campus, and at some point, it got really old. It was built in the 1920s and it was a lovely building from the outside, but on the inside it was not that functional. So, it became one of the oldest chemistry buildings in the country and the department just kept asking for a new one, but they never got one. Then the president of the university must have decided that I was a responsible human being, at the same time that one of the professors in the department who has since passed away, I’m afraid, invented a cancer drug and the university’s share of the patent deal was on the order of several hundreds of millions of dollars. So, they used the money to build a new chemistry building, and they built it. They could have done whatever they wanted with the money, but they built a new chemistry building. They had the money to build the building and they had me, and they knew that I was going to change the department (or I had already done it). I think that my big accomplishments as chair were the new chemistry building, which is a spectacular building, and changing the political structure in the department. Maybe some people think for the better. I know some of the physical chemists think it’s for the worse, but whatever. They’re not around anymore, so yeah. I think the building is my big accomplishment as chair. Then as chair you think the young people who you hire is a big thing, so I know I hired some smart young people. That was a good thing to do. Intellectually. And that was before- well, so being a chair of a department, I think is a largely thankless job. Nobody likes you. Your colleagues don’t like you because you have to decide something. If you decide something, they don’t like you, if you don’t decide something, they don’t like you. The administration doesn’t like you because they don’t like your department. Everybody doesn’t like you, so it’s not a job to take if you’re a delicate person, okay? So, I survived that. I survived it for however many years I did it, I can’t even remember now, but two terms. It was five or six years or something like that. Then there was an intellectual life after that. I wasn’t done yet. I still had a brain left, thank God, and then came topological insulators and I had a brain left and I just did it.

Zierler:

Bob, were diversity issues on your radar? Was that a thing that people talked about when you were chair, or was this sort of too early in the game?

Cava:

Well, there were. Yes, there were definitely diversity issues going on. Yeah, so the way Princeton typically deals with stuff is they provide a motivation to do it. It’s just like by providing these faculty positions that were to be shared with other departments to get materials scientists on campus, they motivated departments by saying, “Okay, we have these positions that we’re going to hold in the central administration. You can have a half position from us if you come up with a half position of your own for a person we approve of.” So, they have this way of encouraging diversity without actually telling you that you can only hire a certain kind of person. They effectively tell you, “We’ll make it easier for you to hire someone if you pick from a group that we like.” So that was going on when I was chair, and there were definitely a lot of conversations about that with the central administration when it came to hiring people.

Zierler:

Bob, did you get involved with topological insulators right from the beginning?

Cava:

Yes, the dead beginning. The dead, dead, dead beginning.

Zierler:

So how did it originate? What wasn’t there and then what was there?

Cava:

Well, two things. I think the thing that happened was that this guy Charlie Kane, who is at University of Pennsylvania, a theorist named Charles Kane who was a graphene theorist, he’s an interesting guy. So, Charlie Kane and Liang Fu, who is a young person at MIT now, and Gene Mele, who also is at University of Pennsylvania, they came out with a paper where they actually predicted that certain specific small band gap semiconductors should have surface states that were different from anything else. I forget why I saw this paper, but basically I saw the paper. Zahid Hasan took the paper to me one day and said, “Bob, can you make any of these?” But I already had a project going on in thermoelectrics. Thermoelectrics are heavy metal small band gap semiconductors, and the things in the Kane, Fu, Mele paper were heavy metal small band gap semiconductors. So, I knew exactly what they were- literally I reached into a drawer and I pulled out a sample of one of the materials that was in the paper. I gave it to Zahid and said, “Here it is.” The thermoelectrics project was an interesting one. That’s the one that I got the money for from this foundation lady back when I first started at Princeton, to work out thermoelectrics. I was always kind of an outlier on that too, but we did fine. That project gave me a way to reconnect with Millie Dresselhaus who knew me when I was a kid, Millie was involved with thermoelectrics. So, we had a nice project later on about thermoelectrics together. That was fun. I keep getting distracted, but that project was funded by the Air Force. So where did we have our meetings? We had them at Sandia Laboratory, which is on an Air Force base out in New Mexico. What did you hear about that happened in New Mexico that had something to do with the Air Force? Well, Area fifty-one, right?

Zierler:

Yeah!

Cava:

I remember this place where we had the meeting had a special display case about “What really happened at Area fifty-one”. Really? I thought, “Well. If you have to try to explain to me what really happened, then that means you’re probably covering up what really happened.” So that was my impression, but I remember Millie and I and a couple other people went out to this Air Force base to have these meetings about thermoelectrics. That was pretty wonderful, actually. That was a lot of fun. This Air Force base in Albuquerque has the longest runway in the world. It’s seven miles long, so that’s where they land these giant airplanes. I remember one day on a coffee break I went outside the building. I was standing there and I watched some F-16s take off. Have you ever seen them? Oh my god! They’re so fast and they go like almost vertically. They’re just incredible machines. I don’t know how people invent those things, and I don’t know what kind of person you have to be to fly one. My god. Okay, anyway. Sorry. What were we talking about? Oh yeah, topological insulators. So, because I had a project on thermoelectrics and because the materials were the same, I already had something in the drawer that was in the Kane, Mele, Fu paper. So, I handed it to Zahid and he did the ARPES on it to show that the surface states were weird. Then he came to me one day and he said, “Bob, can you think of something that is not in the theory paper?” I said, “Sure! No problem,” so I came up with another thermoelectric that I gave him- that was bismuth selenide, which is now what is called the hydrogen atom of topological insulators. It’s the simplest, best one. That one just popped into my head. So basically- yeah, you never know. It’s something to tell students. You never know what’s going to turn out to be important in life, so pay attention to everything. So how did I know about small band gap semiconductors? Let me tell you that story. Back at Bell Labs, there was this thing going on. People had mercury cadmium telluride, which is a small band gap semiconductor that is used to detect human beings on the ground from a satellite. You’ve probably seen those pictures from these aircraft where they’re following trucks or something driving around on the ground, and basically mercury cadmium telluride is used to detect hot objects on a cold ground because you can use infrared radiation to excite a carrier from the valence band to the conduction band. So back at Bell Labs I wrote an internal paper that never saw the light of day that said, “Mercury cadmium telluride is a stupid material. Why are you working on it? You should be working on some other small band gap semiconductors.” I proposed bismuth telluride and bismuth selenide as the things they should work on, but they didn’t do it. In fact, the little memo was so unpopular that it never got out of the building, so I never even submitted it to a journal. But that was in my mind that small band gap semiconductors could be made with bismuth telluride and bismuth selenide. So, when it came time to study thermoelectrics, I knew they’d be good thermoelectrics, so I began working on them for thermoelectrics. Then when it came to be topological insulators, I thought, “Well, it must be the same,” so we gave them bismuth selenide and it turned out to be great. You know, it’s just a matter of being in the right place, putting two and two together, but I’m lucky because physicists have not felt shy about telling me what’s on their minds and we find stuff. It happens all the time. So, physicists say, “I have this concept that’s really interesting. I need something to do it with.” They can’t- theorists can think in thin air, but experimentalists have to actually have some object on which to work. ZIERLER: (Laughter) Bob, when did your group start to really look for new compounds? When was that most active in your career?

Cava:

Probably right from the start, basically, but not when I was a graduate student and not when I was a post-doc. When I was a post-doc and a graduate student, I worked on things that already existed, but already when I got to Bell Labs, in the battery business we started looking for new compounds. I got a couple of new battery compounds which some young person who must be a post-doc says they’re going to use, and some startup company is making batteries out of them. So, I used what I knew about solid state chemistry or mineralogy from my mineralogy mentors to apply it to this technology and it worked. Then there was something about charge density waves, so this was when I started to know Phuan Ong because we were competing on this aspect of carrying current by a new mechanism that he had found. One of my best friends at Bell Labs was working on that, and so we got involved in discovering new materials in that and we made some. Because I was good at crystallography, I could determine the crystal structures of things, and it turns out that’s an important aspect of why something has the properties that it has. What’s its crystal structure? Where are the atoms? So that sort of went hand-in-hand. I guess some people could just specialize in crystallography and never worry about making new substances, but typically solid-state chemists invent new things. Obviously you have elements in the periodic table that occur in the Earth, but they don’t always occur next to each other in the Earth, so you combine them in ways that nature didn’t do it and something new can appear that way. Basically that’s what the community of solid-state chemists does for a living. Just like an organic chemist might say, “Well, I want to help biologists cure some fetid disease, but I know that if we put this chemical into a human body, it’s going to kill the human being that we’re giving it to. I want to have it maintain one function but then lose some other function. I’m going to add different parts to this organic molecule until it behaves itself.” That’s kind of what they do, and they do it. So solid state chemists can say, “Well, I would like to focus on some property of matter, and I’d like this property to happen, but not that property.” That’s the way I do it. Some solid-state chemists are more like purists. They don’t have that in mind when they say, “Well, I want to be an expert in the chemistry of one particular element. Let’s take all the compounds that that one element makes and learn about how they work and then make as many as we can and then determine the crystal structures and then learn how that element combines with other elements in the periodic table to make compounds. Then maybe we can extend that to…” Actually, they make a lot of new ones. So, they first look at what came before and then try to see how you understand it and then extrapolate to something that doesn’t exist. So, the community thinks of me as an oxide chemist because I know a lot about transition metal oxides because the Earth is made of oxides. That was really my first love. Like what is the Earth made of? It’s made of metals plus oxygen - rocks. If you go to my office, you can see a lot of rocks in there. So, I got good at that kind of chemistry, and it turns out that oxides are good at having certain physical properties that the world cares about. And I know about properties. You just collect a lot of information. You know, listen to everybody. Okay. That just reminded me that my uncle who did that painting had a saying, which is “Believe all religions. One of them may be right,” So the same thing goes for science. Believe everything! You can act on it or not but listen to everybody. Somebody might have an idea that’s right and then you just act on it. So that’s what I’ve been doing.

Zierler:

Bob, I love the anthropomorphic terminology “frustrated magnets.” Who came up with this wonderful term?

Cava:

I don’t know. That’s a good question. Frustrated magnets, yeah. For that one you have to go back further in time than me.

Zierler:

What is frustrating about these magnets? Why are they not just happy, normal magnets?

Cava:

Well, they’re not happy, normal magnets because you make it impossible for the atoms to satisfy what they want to do. Basically, every atom that has electrons in it that are not paired so that their spins are canceled, every atom has a magnetic moment. Every atom in the periodic table has electrons that are not coupled with other electrons, not every atom, but the ones that have high numbers of electrons. I don’t know if this is a good analogy, but let’s say that one adult partner of a trio wants to eat pizza and the other adult partner wants to eat ramen noodles and the third member of the trio, their child, has to wait to eat until the adults decide what to do. But the adults really resist compromising, so they can’t decide. Dinner time passes and nobody gets to eat. Three days later they have still not compromised so there is still no eating. That’s frustrating for all three of them, right? So, you do that for spins, too. You have a spin with two neighbors and it has to pick one to line up with and it can’t do it. If each choice is equally attractive, then what does it do? It gets frustrated; it doesn’t know what to do. Yeah, so it’s like an anthropomorphic term, but you notice we do that all the time. Chemists will do this all the time. I know I give elements personalities. Each element in the periodic table has a personality to me, yet they’re not living things. So frustrated magnets are not living things, yet we use the term “frustrated” to describe them. Basically, we give them choices of equal value and then they have trouble picking and they typically don’t pick fully. Sometimes they do pick but it’s the systems that don’t that turn out to be interesting. It’s the ones that can’t pick that are the most interesting. This has been a really lovely field, and it’s been lovely because theorists have had a lot to do with telling us which lattice types would be best at this. For experimentalists, once you know what the lattice type is, you can put different kinds of spins on this lattice type and ask what they do, and if you’re really good, you can grow crystals of those things for an expert experimentalist to do something on.

Zierler:

Bob, what have been some of the advances in thermoelectrics?

Cava:

Well, a lot of them. Let’s say there are niche applications for thermoelectrics now. There are beverage coolers that you can buy where you plug it into a socket and they cool drinks with no coolants - they just use electricity. They don’t use cooling agents. There are no widespread uses of thermoelectrics right now, but they can theoretically be good for certain things and also, they are practically good for certain things, some things you probably never thought of. Let’s say you send an interplanetary probe to Pluto or Neptune or Saturn. Where does the electricity come from to make that thing work? Well, people in general don’t know it, but they have a thermoelectric generator on the end of a long stick. It sticks out of the side of the spacecraft. They have a little fission thing that is not using fission energy to make power; it’s using fission to make heat. So, they have a little chunk of uranium or something out there. It’s undergoing fission, so it’s hot. They put a thermoelectric in contact with the hot thing and then on the back side there are cooling fins exposed to the temperature of space. So, they get a temperature gradient and they have a thermoelectric out there on the stick and it’s turning this temperature gradient into electricity. So, in my mind that’s a big function of thermoelectrics. As spacecraft get bigger, you need more and more power to power them. On Mars you can have a solar array that powers the spacecraft, but if you go past Mars, the sunlight is not strong enough anymore to do it, so they use thermoelectrics. Yeah. The thing they sent to Saturn is the size of a school bus or something like that, so they needed a lot of power to do that. But thermoelectrics have not made a big impact yet. They could, obviously, if there were convenient sources of heat to use. Maybe- I think I heard at some point, although I don’t know it, that Toyota or somebody is putting a thermoelectric generator in their automobiles because the catalytic convertor gets really hot, so that’s wasted energy. That heat is wasted. Maybe you can use that heat for something. So, I remember hearing- but I don’t know whether they did it, that some car companies were going to use thermoelectric generators on their catalytic converters to try and convert some of the heat into electricity. Then they can use that electricity to power some part of the car. Anyway. I don’t think there’s widespread use of them right now. There’s also, of course, the widespread use of superconductors in the- what’s it called? The Large Hadron Collider where you need very strong magnets to direct particle beams, things like that. So, particle accelerators use superconductors. There are some levitating transit systems that use superconductors. There are also some that use conventional magnets. I don’t know if you’ve ever been to Shanghai, but they have a levitating train there. I think that one uses conventional magnets, but superconducting levitation is out there somewhere. There are a few applications. The thing in my mind that happened in thermoelectrics is that people explained stuff. They didn’t actually discover anything remarkable. The original thermoelectrics are things like bismuth telluride or bismuth antimony telluride. They were invented in the 1950s I think in Russia or the Soviet Union or something like that, and they’re really good. I don’t think anybody ever made anything that’s enough better to actually replace it. There’s this thing about technology, right? In order to replace an existing one with a better technology, you have to have a certain threshold of better-ness. If you’re twenty percent better, that’s never going to matter. If you’re fifty percent better, it’s never going to matter. You have to be many times better to replace something. So, if there’s an imbedded technology. I definitely ran into this in lots of things in my career. For example one thing that I’ve done is to invent transparent conductors, and I remember the head of some department at Bell Labs telling me, “Well, this is only fifty percent better than the ones we have now, so we don’t care.” I thought, “Wow! Fifty percent is way better,” but no. It had to be ten times better or else it didn’t count. ZIERLER: (Laughter) Bob, just to bring our conversation up to the present, what are some of the things you’ve been working on recently?

Cava:

Well, I think the good thing about me is I can see stuff early. It’s good to take risks in the world. Sometimes the risks don’t pay off, but sometimes they do. But right now I think my favorite project is on quantum information systems. This computer that I’m talking to you on is a regular digital computer. It stores information as ones and zeros, right? But someday, maybe for my grandchildren or your children or you, there will be computers that work by storing information a different way. Those computers might be better at doing some problems than the ones we have now, but they have to make them out of something. What will they make them out of? There are these deep conceptual issues about “how do we do it,” and even if you think of how you do it, you still have to make it out of something. So right now, I’m excited about the fact that there are a handful of candidates for making quantum computers, but none of them is the perfect one yet. It’s just like anything else. Somebody has a favorite one; they promote it. But does that mean that this is the last and best one? No. Does this mean in my mind that the materials complexity has reached a point where now things are going to get so complicated that they don’t work anymore? No. I think there’s a big opportunity in new materials for quantum computing, so that’s what I’m working on and like as usual, there are some very, very, very smart people around who understand how a quantum computer is supposed to work and can tell me, you know, what does the material have to do for this happen? My job is to translate what a property of matter should be into a real material, but how do I know what those properties should be? Somebody has to tell me. So right now, I’m involved with some people who really know a lot about quantum computing and actually single-atom detectors. There are multiple parts of this quantum information thing. There are a few parts to this that I know of: quantum sensing, quantum computing, and quantum- I forget what you call it, but it’s something where you transmit information from one thing to another. So let’s say you have a computer and you want to transmit quantum information like entanglement over a long distance. You must be familiar with this. Einstein called quantum entanglement “spooky action at a distance,” right?

Zierler:

Yeah.

Cava:

It is spooky! How does it work? Well, you know, if we’re going to design quantum systems that work, they have to actually do that and so somebody needs to do it and you need the hardware to do it. Where is the hardware going to come from? Well, hopefully me plus a million experts who know a million other things will all figure out how to put that together.

Zierler:

And you see this mostly as the domain of chemists, or chemists and physicists?

Cava:

I would say physics and electrical engineering, and chemists are not in there much at all. There is one other chemist who I know of who has noticed that this is an interesting problem. This is a young lady that- I don’t know where she is now. I don’t think her materials can work in a practical system, but that’s only my opinion because I’m more of a classical materials scientist. But anyway, there are multiple problems here and they all depend on finding some material to do it, as far as I can tell. That’s the big problem I have. That’s the big interesting thing right now. Obviously, topological insulators have been going on for ten years now. I’m bored with that. I’m tired of that. I’m hardly working on that anymore. This quantum information systems idea is a big one and we’re working on that. Then I’m just fishing around for something- not fishing. I shouldn’t say fishing. I’m seeing what else is out there that would benefit from my knowledge that I’m trying to be the first to find it. So that’s good.

Zierler:

Bob, for the last part of our talk, I’d like to ask a few broadly retrospective questions about your career, and then we’ll end looking to the future.

Cava:

Okay.

Zierler:

So first, you have been bestowed with a ridiculous number of awards and honors over the course of your career, too many for us to talk about here in detail. Is there anyone that stands out that’s most personally meaningful to you?

Cava:

Yes. That’s an easy question to answer. Well, it’s because- it’s the Super Lifetime Achievement Award. So, my whole life I’ve been an admirer of history and how a single human being can make a difference in the world, how a single individual can make a difference. Something happened to me that matters a lot, and it’s when I became a member of this thing called the Royal Society of London, which was founded in the 1600s by King James II or something like that. It’s included Isaac Newton and Charles Darwin and all sorts of people who really did something with their lives. For me, that was the big one and when that happened to me, I was shocked and really happy. That one happened really late in my life, like 2016 or something like that. For me that’s the special one. Oh, and by the way I got five free trips to London for that (laughter). Wow! What could be better than that? ZIERLER: (Laughter) Can you use one of them after the pandemic is over or have you used them all up yet?

Cava:

It was five because five were before the pandemic and number six was going to be in March of 2020, so I didn’t get to go. I love traveling and London is a really cool place to go. I discovered some interesting Malaysian restaurant in London somewhere. I love London pubs and I love that whole thing. And I went to the British Museum, so yeah, I love going to London. I got to stay in a really cool building that Royal Society people own in London. I love that. Anytime they want to call me and ask me to do something else, I’ll do it.

Zierler:

Bob, you’ve also been, over your career, a publication machine. It’s almost too many to count. What stands out in your memory as something that you were inspired to publish but you didn’t think it would be so much of a game-changer, but it really resonated far beyond your expectations? What stands out in your memory in that regard?

Cava:

Well, that’s a good question. There are some publications that really stand out in my brain. One that really stands out is one we didn’t talk about and that’s about barium potassium bismuth oxide. This material is a thirty Kelvin superconductor or thirty Kelvin, somewhere around there. I remember when we discovered that, or when we found out what that was, that was a shocking event and for a long time that thing held the non-cuprate record. Well, that material is based on the chemical principle that bismuth is a bizarre element in the periodic table because it’s a “valence skipper.” That was one of those things that happened at Bell Labs because some smart people did some things. A very smart theorist, this guy who was visited by Koichi Kitazawa, Len Mattheiss, made a comment about bismuth. He had noticed that bismuth was odd. Then I realized that bismuth is odd and we began working on that and we wrote a paper. I remember spending the night in Bertram Batlogg’s basement on a pullout bed because we were writing the paper till late in the night and his wife making us some strong European coffee somewhere during the night there and we finished the paper. You know, in those days you had to write it by hand and submit a paper copy that somebody typed. There were people at Bell Labs who were experts at typing papers. That was a significant one. That was really good, and that- I think this impacts people to this day because, in a way, it was a bizarre extension of oxide superconductivity, so it was a good one. Yeah. A lot of things that people did with the materials that I made are really remarkable. I guess you talked to Phuan Ong. He must have talked about the chiral anomaly, which is one of his big discoveries lately. This was a concept in physics that- for me it’s an obscure concept, but if you can embody it in a real material and make something that does it and then prove that it’s true, you proved some fundamental idea in physics about charges that get pumped in a chiral system or something. I don’t even understand it, but basically, he said, “Bob, can you give us something to test to see if it has the chiral anomaly in it?” (Laughter) So he found it in something that we made. I’m sure that that’s going to go a long way. ZIERLER: (Laughter) Bob, you’re not a physicist, but you’ve been as physics-adjacent as one can get over the course of a career. What are some of the foundational concepts or laws in physics that inform everything that you do, the way you approach your science?

Cava:

Well, I think you could say quantum mechanics. For me it’s like what are the electrons doing all the time? Obviously, different kinds of chemists have different views about that. You know, organic chemists think of an electron as a little dot or an arrow that they just move around, but I never think of them as being that. I think of them as being like quantum mechanical things that are just obeying the laws of quantum mechanics in a way that is mysterious. Quantum mechanics is not an intuitive thing for me, but I guess if you had to say what is it about physics that most clearly connects to what I do, it’s what are electrons doing? What they’re doing is something quantum mechanical and that’s basically physics. So, I guess I always think I should have paid more attention in quantum mechanics classes, but now I have people like Phuan to explain to me quantum mechanics or Nathalie de Leon in our EE department or Jeff Thompson. They know a lot about quantum mechanics. They think about it and they really get it. You know, if I can get them to explain stuff to me, there’s actually less of a gulf, I would say, to me than to most chemists because I like it. So, I guess the thing that informs what I do most is quantum mechanics. I love all sorts of expressions about quantum mechanics. Like “spooky action at a distance” is definitely one of my favorites and- oh. And who said it? There was a quote by somebody like Niels Bohr that says, “Those of you who are not disturbed by quantum mechanics have not understood it.” That’s good. Okay, so-

Zierler:

Bob, looking to the future, last question. As you say, you keep an open mind about what you might do next. So, using the powers of extrapolation, looking back over a long career where you’ve picked winners, you’ve picked interesting and impactful things to work on over many decades—how might you use that experience in the future to continue picking research projects that are foundational, that have real societal application, and are ones that will remain academically interesting to you?

Cava:

Right. So basically, I guess the best thing in life is to be a good listener, and to have people around you who care to explain to you what they’re thinking about. I guess my strategy- the successful things have been to listen to people, to hear what’s on their minds, and then be able to embody that in something, in a real thing. That’s how I’ve succeeded. Basically, I need to keep cultivating the human interactions that allow me to see things before other people see them. I guess this quantum information systems thing is a good example of that. I remember going to Nathalie’s talks like five years ago. She’s an assistant professor, so she’s fifty years younger than me and tuned into much different things. I listened to her talks, saying to myself, “Well, there has to be something in here for me to do.” People have the patience to explain to me what the interesting problems are so that I know what they are, and she and her husband Jeff Thompson have spent a lot of time explaining what they do to me. But a strategy going forward that extrapolates from backwards is to keep talking to people and keep learning what they think is interesting and then seeing how my background in materials can help me to make something to do it. So far, and it’s a long time, I’ve been very lucky that people will explain to me what’s on their minds and then I can find stuff. That’s worked and that’s the plan for the future, okay? I’m not done yet. I have at least one more big thing left. I don’t know what it is, but it’s going to be.

Zierler:

I love it.

Cava:

So, I’m not done.

Zierler:

Bob, it’s been a great pleasure spending this time with you. It’s been so fun listening to the way you’ve narrated your career, the way you’ve worked with all of your collaborators, and really your sense of humility, which stands in stark contrast with your record of achievement. So, it’s really been wonderful listening to your story. I’m so glad we were able to do this. Thank you so much.

Cava:

Thank you for talking to me! Wow, how cool! Thank you.