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Credit: New York University
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Interview of David Pine by David Zierler on July 10, 2020,Niels Bohr Library & Archives, American Institute of Physics,College Park, MD USA,www.aip.org/history-programs/niels-bohr-library/oral-histories/45436
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In this interview, David Zierler, Oral Historian for AIP, interviews David J. Pine, Silver Professor, professor of physics, and Chair of the Chemical and Biomolecular Engineering Department at the NYU Tandon School of Engineering. Pine explains the background of NYU’s takeover of Brooklyn Poly and where these changes fit within the overall expansion of soft matter physics in the U.S. He recounts his childhood as the son of a pastor and moving many times as his father preached for different congregations. He discusses his interests and talents in the sciences during high school, and he explains his decision to attend Wheaton College. Pine describes how he developed his interest in physics in college and he describes his research at Argonne. He discusses his decision to go to Cornell for his graduate work, where he studied under Bob Cotts and did research on hydrogen diffusion in metals. Pine recounts his postdoctoral research at Pitt, where he worked with Walter Goldberg on spinodal decomposition, and he describes his first faculty position at Haverford, where he built a lab from scratch focusing on the diffusive dynamics of shear fluids. He explains his decision to accept a position with Exxon Labs, which he describes as an excellent place for basic science, and he describes the factors leading to his appointment on the chemical engineering faculty at UCSB, where he focused his research on polymer solutions and colloidal suspension. Pine describes some of the exciting advances in physics that were happening at the Kavli Institute. He describes his collaborations with Paul Chaikin and the prospect of joining the faculty at NYU, where he has continued his research. At the end of the interview, Pine reflects on how he has tried to maximize the benefits of working at the nexus of several disciplines, and he explains why entropy has been a concept of central importance to all of his research.
Okay. This is David Zierler, oral historian for the American Institute of Physics. It is July 10th, 2020. I am so happy to be here with Professor David J. Pine. Dave, thank you so much for joining me today.
All right, so to start, would you please tell me your title and institutional affiliation?
All right. So (laughs) I have a few. I'm affiliated with New York University. I'm a professor in the Physics Department. I’m also a Silver Professor, which is an honorary designation that the university gives some fraction of its professors. I've been there since 2005. And since 2014, I've had sort of a double life as Chair of the Chemical and Biomolecular Engineering Department at NYU Tandon School of Engineering. So those are my official titles.
And so you shuttle between Manhattan and Brooklyn? Is that your normal week?
Prior to the COVID-19 shutdown, yes.
Right. Of course.
It's a fairly easy subway ride. Although I've been doing it by bicycle recently. The engineering campus is in downtown Brooklyn. It's an easy commute. It's probably 20-30 minutes door to door. And I generally would spend a part of each day at each place. Some days I'll be all day at one place or the other.
Now, the Brooklyn campus represents what? Did NYU acquire something at some point?
Yes, NYU acquired Brooklyn Polytechnic University, generally known as Brooklyn Poly. It goes back to the mid-19th century. It's an interesting place. It educated a lot of immigrants who resided in Brooklyn in the late 19th and early 20th centuries. Particularly after World War II, it became a very prominent engineering school. Somewhat on the strength of taking in a lot of European refugees. A lot of Jews who had fled Europe because of Hitler. And it had some real stars. There's something called the Polymer Research Institute headed by Herman Mark, who I think was one of the first winners of the Wolf Prize in Chemistry. He is considered one of the fathers of polymer science and polymer chemistry. But there were lots of other people there too, so they had a pretty illustrious history, but both Brooklyn and Brooklyn Poly fell on hard times in the 90s, and it had a difficult time financially. Meanwhile, NYU was seeking to expand its science programs. I was recruited from UCSB as part of that effort, along with a number of other people.
That's the University of California Santa Barbara?
Right. While NYU was getting this going in the early 2000s, it looked like Brooklyn Poly might go under. So NYU thought they might be able to buy Poly and help salvage this really great engineering school. And they did. They purchased it, I don't know exactly when, around 2007, I'm guessing, 2008? And then in 2014, it actually became the official engineering school of NYU. And at that point, I joined it as chair of the Chemical and Biomolecular Engineering Department. I'd been at UCSB, I had been in the chem-e department there, and I had been chair of it for several years. So I knew the chemical engineering community and it seemed like a place where I could make a contribution.
And Dave, to what extent was your recruitment and NYU's rapid expansion in this field sort of representative of where soft matter physics was headed in the early 21st century?
Well, so first of all, Glennys Farrar, who's a theoretical particle physicist, who had moved into experimental astrophysics, was chair of the NYU Physics Department when the administration at NYU encouraged people to look for ways that they could expand and improve their various science departments. She cast about far and wide, talked to lots and lots of people, and eventually settled on soft matter physics. She had talked to people like Paul Chaikin, who was at Princeton, David Grier, who was at Chicago, and Arjun Yodh, who was at Penn. And then eventually, I was contacted. Paul and I knew each other from our Exxon days; we had published a number of papers together. And so Glennys put together this package deal, where David Grier, Paul Chaikin, and I would come to NYU all at the same time. What we were interested in doing was not merely just coming there ourselves, but to come and build an international center for soft matter physics. As part of that package, NYU promised us a number of faculty positions. NYU also agreed to support a visitor's program and provide a couple of NYU apartments for visitors. This allows us to host them inexpensively so they can stay for anywhere from a few days to six months or even a year. The idea was that people would come and visit us, and that NYU would become a center for soft matter physics. That was 2005. I think David Grier probably arrived in 2004, and then Paul and I in 2005, and then we started recruiting people. There are seven of us right now.
And Dave, you mentioned the name Silver?
Yes -- I'm a Silver Professor. It's just an endowed professorship. Silver is a family that has supported NYU for a long time. The chemistry building is the Silver Complex.
Oh I see. So the Silver family is not specifically endowing soft matter physics?
No, no. They have endowed professorships in the Faculty of Arts and Science so you have historians, for example, who are Silver professors, as well as scientists who are Silver professors. No, the program that funded us coming here was called the Partners Program, and this is something that John Sexton had set up. He raised quite a bit of money, I think on the order of $100 million, for this program. We didn't get $100 million, though, but we did get money from that fund to set up the soft matter center at NYU. So it was actually that Partners Program that got that going.
All right, Dave, let's rewind back all the way to the beginning. Let's start first with your parents. Tell me a little bit about your parents and where they're from and what their professions were.
Okay. My father was born in Kansas and grew up in Phoenix, Arizona.
How did his family get out to Arizona?
Well, I don't know the exact origins, but I suspect that it was his father, or maybe his father's father, that went out to Iowa and Kansas as part of the Homestead Act. And started farming. My dad was born in Kansas, but when he was small, his two older brothers came down with tuberculosis, and so they moved to Phoenix. The thinking was, you moved to a drier climate, so that's where my father grew up. In fact, every single one of his siblings, including my father, eventually got TB. Two of his brothers died from it. He got it right after the treatment using streptomycin was developed, or he would have died from it too, but that actually saved his life. And it's a good thing for me because I was born after he recovered. My father was a preacher, a minister. I was one of five kids. When I was young, my mom took care of us kids and stayed at home. When I was in high school, she went back to school and got a nursing degree, and then worked as a nurse probably from about age 50 to 65, something like that. So it's always surprised me a little bit that I ended up going into physics.
Did you grow up in the church?
Yes, absolutely. It's something I wandered away from eventually. I wouldn't consider myself religious at this point. But sure, that had a big part of my life when I was young.
Did you go to public schools growing up?
Yes, I went to public schools.
Is this in Phoenix, where you grew up?
No, no, so we moved all over the place. I was born in Los Angeles and lived on the West Coast until I was ten. There were three years in Oregon, where I went to first grade. But when I was ten, we moved to Royal Oak, which is a suburb of Detroit, and that's where I really grew up and went to school. There were a number of really important experiences educationally for me there. When I was in sixth grade, I was selected for a special program for talented kids going into junior high school, which started with the seventh grade. My family wanted me to do well in school, but it wasn't a big emphasis. I always liked school, but when I got into this class in junior high school, it was interesting. About half the kids in the class, I would guess, were Jewish. And they were from families that really valued education. This is something I've always had a great deal of admiration for, the high value Jewish culture puts on education. It was sort of interesting because the first thing I thought was, "Wow, these kids are like me." Because I sort of felt like I stuck out like a sore thumb--
In your family, you mean?
Yes, because I was interested in reading and studying and stuff. When I met these kids, it was clear they had a richer intellectual life at home. And I was in some sense sort of jealous of that. But nevertheless, they had a strong positive influence on me and opened my eyes to the world of thinking and of studying and learning.
Dave, I want to ask you about your father. Did he have, would you say, a literalist or a fundamentalist view of the Bible, or was, you know, integrating science into his faith an easy process?
So he was what people would call an Evangelical today. So Evangelicals are generally fairly conservative Protestant Christians. He wasn't on the fundamentalist end of that group. I don't know how much you know about this, but a large part of that movement is fundamentalist. I wouldn't say he was that way. He was more open-minded to learning and education.
So he would accept things like evolution and a 14-billion-year-old universe? That kind of thing?
Yes, I think so. I mean, we talked about this from time to time, and he didn't have any problem with things like evolution. I mean, it was interesting, because there were people in my church growing up who did. Because in any sort of organization like this, there's a spectrum of thinking. I remember one time in Royal Oak, he got in trouble with members of his congregation for participating in a panel discussion with a Catholic priest, a Jewish rabbi, and some guy from a liberal Protestant church, and this upset at least some members of his congregation. So I wouldn't say he was a liberal Protestant, but in the evangelical spectrum, he was on the more liberal and more open-minded end of things.
And Dave, where did you spend your formative years growing up, would you say?
So that was really in Royal Oak, Michigan, outside of Detroit. And, like I said, I got a good education there. The public schools were excellent, and I think I was well served by the public schools.
And were you a stand-out student in math and science in high school?
I was a good student in science and math. Actually, the thing that's funny to me, I often think about this because I was good at math, but I liked science more. I took biology as a freshman in high school and I thought this is pretty interesting. And then as a sophomore, I took chemistry, and I thought this is more interesting than biology. I honestly didn't know what physics was. Really, the impression I had of physics was that Einstein was a physicist, and that you had to be as smart as Einstein to do physics. And so in my junior year, I started taking physics, and it's really true, I fell in love with physics right away. I thought this is way better than chemistry. And right from the beginning I thought, this is the coolest thing ever. And I was surprised that I could do it. I thought, oh, you don't have to be Einstein to be able to do this. You know, mere mortals can actually do this. And so I was quite captivated.
I had no idea at the time that I would have a career in physics. None whatsoever. But I did like it enormously right from the beginning. I felt like I was really understanding how the world works. When I studied biology and chemistry, I felt like people were telling me how the world worked and giving me rules for it, but once I took physics, it somehow seemed like my own knowledge. Once you told me Newton's laws, I didn't need anybody else. I had everything I needed to understand the world on my own terms. And to me, this was magical. So I loved physics right from the first time I took it. But that doesn't mean I thought I was going to be a physicist.
I have a daughter and a son. They are 36 and 33. In comparing their experiences with mine, I realize that there were some luxuries we had back in the late 60s and early 70s when I was in high school, and in college then too. I didn't think very hard or worry at all. Or, I shouldn't say "at all." I didn't think very hard and I didn't worry very much about what I was going to do or how I was going to make a living. I figured, "Hmm, I'll go to college. After I go to college, I'll get a job. I'll do something. Things will be fine." And I think today, students feel that the world's more perilous.
Kind of with good reason, right?
Yes. But it's important to understand that I didn't feel, and I don't think most of us felt that way. There was the Vietnam War and we were upset about the Vietnam War, and so forth. But in terms of making our way in the world, I think we were pretty optimistic, and we figured, I certainly figured, things will work out. So I was perfectly happy just to do physics for the fun of doing physics without much thought as to where this might lead.
Dave, in thinking about colleges and looking at Wheaton as your choice, did you specifically limit your options to smaller schools? Did you not want to go to a bigger school?
So this is sort of interesting. Between my junior and senior year in high school, my family moved from Royal Oak, Michigan to Peoria, Illinois. When I was in Royal Oak, I had sort of made up my mind, I was going to go to the University of Michigan. I knew my parents would not be thrilled with that.
Yes, and they wanted me to go to some sort of church-based school. But I had sort of drunk the Kool-Aid--which wasn't bad Kool-Aid--everyone said that University of Michigan is one of the best state universities in the country. And indeed it is. It's an excellent university. And so I wanted to go there, I wanted to study physics there. And I had prepared all my arguments for going there and then my family moved to Illinois. So to go to the University of Michigan, I would have had to pay out of state tuition, and there was no way I could afford to do that. In my myopic view of the world at age 17, I thought that the University of Illinois, which everyone in Peoria I knew was going to go to, was a poor substitute for the University of Michigan. Now in fact, that's completely wrong.
Yeah, I was just going to say. Particularly in condensed matter physics, it's far better.
Yes. It's one of the best places, one of the best physics departments in the country, and certainly its physics department at that time and still today was a better physics department than University of Michigan, but I was 17 years old and had nobody to tell me any differently. It was just stupid. So Wheaton College is a religious-based school. My parents were happy with me going there.
You made the tuition work?
You made the tuition work, that was okay?
Yes, so first of all, it wasn't that expensive for a private school, and then secondly, with scholarships and loans, we could make it work. Actually my parents didn't pay, couldn't pay, any of my college costs. Back in those days, if you were a guy, it made a difference. I got jobs in the summer working in machine shops. So I was actually a pretty good machinist, running lathes, drill presses, milling machines, and so forth. And that paid a good hourly wage. And so I'd work over the summer from the end of school to the beginning, and I'd earn a fair bit of money. So between those various resources, I was able to pay my college expenses. I got out with a bit of a debt. It wasn't a debilitating debt. And it was one of those national student defense loans where they didn't even start charging you interest if you went to graduate school. So I didn't start paying it off until I was practically 30 years old, and inflation had killed off much of the cost. So, in terms of money, I was able to find a way to get through college on my own, and that worked out fine.
Dave, you were there as an undergraduate in the early 1970s. I assume it was a pretty culturally conservative place and, you know, things like the anti-war movement, civil rights, women's rights, that probably was not as big a deal there as it might have been other places?
Probably not. It wasn't non-existent. I mean, there was a sort of minority of people who did care about a lot about these issues, some of them on the faculty. But it was definitely more conservative. In some ways embarrassingly so. In 1972, George McGovern came to campus to give a campaign speech. And he gave it in the main auditorium. I still remember it. Just as he stepped up to the podium, some idiots in the balcony unrolled this big banner with a picture of Nixon on it, which I thought was in very poor taste. So he faced a bit of a rough audience. But yes, it was politically conservative. But there was an anti-war movement there, there were certainly people who were concerned particularly with feminism and women's rights. So it was conservative, but not completely isolated from the issues of the day.
Now, you were a dual major in physics and math.
Did you sort of keep career options and interests open in both fields, or you knew at some point that you were going to focus primarily on physics going forward?
Well, I actually focused on the physics right from the beginning. And the math major was sort of an afterthought. That is, I took so many math courses that by my senior year, I realized if I just took a few more, I could have a math major as well. And so that's what I did.
And that was probably just useful for physics anyway?
Yes, it was very useful for physics. That was terrific. I mean I was actually one course short. They didn't have enough courses to offer, so I arranged for a special topics course with one of the faculty members who was an expert in group theory. I thought group theory was pretty interesting, so I did an independent study with him in group theory and quantum mechanics. And that turned out to be quite a nice little course I did. And it enabled me to have a math major. So that worked out well.
Dave, when you were thinking about graduate schools, how well-defined was your identity in terms of the kinds of physics you wanted to study in graduate school? Did you know that you wanted to do sort of experimentation? Did you know that you wanted to look at soft matter? What were you thinking in terms of graduate school?
All right, so first of all, you have no idea how naive I was. You have no idea.
So it's 17 years old, all over again?
Well, by this time I was 20 years old, 21 maybe, but I had a professor my junior year who suggested that I apply for what we would now call an REU (Research Experience for Undergraduates) at Argonne National Laboratory. So I applied for that, and in the fall term of my senior year, I did a project at Argonne that involved doing superconductivity. There were all sorts of things that were amazing to me, that still sort of surprise me. The guy who was going to serve as my, advisor, mentor, wrote me a letter saying that we were going to work on superconducting thin films, and the way we made them would be to evaporate a metal. And I thought, "Metals evaporate?" I had never heard of that before. How do you evaporate a metal? And so I went there. I actually made a little evaporator. I made some superconducting films; I did a bunch of experiments. It was wonderful. It was horribly exciting. And the guy I was working for, a guy named Ken Gray, he said, "Are you planning on going to graduate school?" And I said, "No, I can't afford it." You know, I'd put myself through college, I couldn't see any way that I could go to graduate school. I said, "I can't afford it, my family doesn't have much money and I can't pay for it." And he goes, "You don't have to pay for it. They pay you to go to graduate school." And I go, "They do?"
I mean, this is how naive I was. I had no idea that they give you a stipend, you go there and they pay, not a lot, but they pay you enough to live. And so I said to him, "Oh, well, yeah, I'd like to go to graduate school." I said, "Where should I go? What schools are good?" He goes, "Well, I got my degrees at Cambridge and at Berkeley," but he said, "Truthfully, I think the best physics program anywhere is at Cornell." And indeed, this was the early 70s, and superfluid helium3 had just been discovered at Cornell. That work would eventually win a Nobel prize. Ken Wilson had just published his work on the renormalization group, and of course that would win him the Nobel prize. So it was a very exciting place to go. And I asked him, "Well, can I get in?" He goes, "Yeah, you can get in." And so I applied, and to my surprise, I got in. And I was off to Cornell. But really, I mean I was just a very naive kid. I just didn't know what was possible. And I was scared to death when I went there. I thought, "Holy smoke, am I going to get wiped out at this place?" I mean, there are all these smart kids coming from Harvard and Berkeley and MIT.
Yeah, David, I wanted to ask you exactly that question, because coming from a smaller school, you know, after you got over the initial shock of where your cohort were coming from and you were actually in the labs and in the classes, how well-prepared were you, not just by the diploma aspect, but substantively in terms of your education? How well-prepared were you vis-à-vis your fellow students?
I think I was prepared reasonably well. I wasn't prepared quite as well as most of them. There were some gaps. I didn't know electricity and magnetism as well as they did. I thought I didn't know quantum mechanics as well as they did, but that was wrong. I knew quantum-- I had had a very good course on quantum mechanics. My math was good, so that wasn't a problem. So I did fine. I did okay. I don't know whether this should be a part of the oral history, but I always think it's a funny story. I was scared, but I thought I understood classical mechanics, so I decided to sign up for a course in classical mechanics, even though that wasn't normally what people did. And so the professor was Vinay Ambegaokar, who's known for his work in superconductivity, mainly. A theoretical physicist. And he gave us Goldstein, which is the standard text for graduate classical mechanics. He gave us readings to do, gave us problems to do, and then he gave lectures that were on something totally different.
I didn't understand anything he was saying. It involved tensors and I really didn't know much about tensors. I talked to my fellow students after class, and I discovered that most of them were lost too, so, we just read the book, did the problems, and did just fine. But after about, I'd say, three weeks into the course of not understanding anything but taking comfort in everyone I talked to saying they didn't understand anything either, this one kid in the back raised his hand, and asked a question. And it was clear immediately that this kid knew exactly what was going on and Ambegaokar liked it. His eyes lit up, he was happy as could be. It was sort of the first interaction anybody'd had in the course, and then that scared me to death. But it turned out that that student was a very talented student. He ended up being the first person in my class to get his PhD. I think he went straight from graduate school to a professorship at Chicago. He's now at Stanford. He's a string theorist. I mean, he is a bright guy. (laughs) But that almost undid me. Because there were a lot of bright people at Cornell, particularly because of Ken Wilson and Michael Fisher and others' work. They attracted a lot of very, very talented young people. But I got a good education there. It was a great experience. I liked Cornell enormously. It was really terrific.
Who was your advisor?
So my advisor was a guy named Bob Cotts. He did NMR (nuclear magnetic resonance). He had done his PhD with Walter Knight at Berkeley and a postdoc with Felix Bloch at Stanford, and then he came to Cornell. I think I was his only student who didn't do a PhD on NMR. He had an idea for another project. I liked it because it involved building all the equipment from scratch. So I built all my equipment from scratch and did the experiments. This suited me just fine because I really enjoyed this kind of work, working in a lab, figuring out how to do measurements, designing and building equipment. This is something I liked a lot, so I had a good time doing that.
What was your dissertation topic, and how did you go about developing it?
Well, it was on hydrogen diffusion in metals. So hydrogen goes into a lot of different metals interstitially, and it can diffuse around quite fast. Anomalously fast. And there was some thinking at the time that the diffusion mechanism might involve quantum mechanical tunneling of protons between interstitial sites. And so the experiment wanted to see if that happened to be the case. In the end, it turned out that the diffusion was governed as much by defects and imperfections in the lattice as anything else, and I don't think there was any evidence for quantum mechanical tunneling. But it was a good platform to learn a lot of experimental physics.
One thing that was interesting was, during my thesis, I became interested in a part of hydrogen diffusion of metals that wasn't a part of my thesis. Namely, it's phase behavior. You can describe the behavior of hydrogen inside of a lot of metals using lattice gas models, and it can have a sort of liquid-gas phase transition, or liquid, gas, and solid phases, inside the material. In particular, there was some interest at the time in something that was really quite new, something called spinodal decomposition. And just on the side, I didn't do anything on this in my thesis, but on my own, I read a lot of the papers on spinodal decomposition, which has to do with how a fluid separates into a liquid and gas phase under certain circumstances. And the theory was developed by a guy named John Cahn, who died a few years ago. He was really an amazing scientist. So I read his papers dating back to the 50s. They were just beautiful papers with very exciting ideas that seemed counter-intuitive to me, but then described some experiments in metal alloys. And I just liked that.
So when I finished, I wanted to do a postdoc. I saw an ad in Physics Today for a postdoc at the University of Pittsburgh investigating the spinodal decomposition in binary liquid mixtures with a professor named Walter Goldberg. I didn't know who he was. But I thought this could be really exciting, so I looked at a few of his papers. I liked his papers, but I was a little bit worried. I'd never heard of this guy. So I asked my advisor about him. He goes, "Oh, Walter did a sabbatical here a few years back. And he was friends with Ben Widom." I don't know if you know who Ben Widom is?
He's a physical chemist, a very well-known physical chemist, who did really seminal work on phase transitions in the 60s and the 70s. And I'd had Michael Fisher for statistical mechanics, but Ben Widom had taught a few classes when Michael couldn't be there. So I knew who Ben was. And so I went to talk to Ben to ask him if he knew Walter Goldberg, if he had any thoughts about him. And he was extremely enthusiastic. He said, "Look, if you have a chance to work with Walter Goldberg, take it. You'll never regret it.” So I accepted the postdoc position. There was a little bit of irony there, in that about a week later, I got a call from somebody at Bell Labs who wanted me to come and interview for a postdoc there. And I told them I was very flattered but that I'd already accepted a postdoc at the University of Pittsburgh. And (laughs) he was incredulous. He goes, "This is Bell Labs." And I go, "I know." And he goes, "These are the best physics labs in the world." And I said, "Yeah, but I've already accepted this other job, and it's just what I want to do." So I remember he was pretty surprised that I didn't want to interview because I already had this job. So I went to Pittsburgh. I learned an awful lot from Walter Goldberg. I really feel like I learned as much about how to be a physicist from him as anybody I ever worked with.
And what research was Walter doing at the time you got there?
So he was still working on spinodal decomposition, and he was interested in the effect of mixing, physical mixing, on spinodal decomposition. And so I did some work on that. The experiments didn't amount to a lot, as experiments go, but working with him, I learned an awful lot about how to think about physics problems, about how to select them, about how to attack them. It was really a very close relationship. I mean, I talked to him almost every day. We spent a lot of time at the blackboard doing little calculations, trying to figure out what was interesting to think about, what was going on in experiments. When I was in graduate school, there was a professor named Bob Silsbee who was on my committee. Towards the end of my graduate career, I was in a bad mood one day. I was talking to Bob and I was feeling particularly ungenerous. And so I said to him, "You know, everything I've learned at Cornell, I've learned from my fellow students. I didn't learn anything from the faculty." That was false, but that's what I said, because I wanted to make Bob mad. And he looked at me and he goes, "That's exactly the way it's supposed to be." (both laugh) So I did learn an enormous amount of physics from my fellow students at Cornell. They were a terrific bunch. But working with Walter was really a great experience for me, and I felt like I learned a ton about doing physics. How to approach problems, what to do--
Were you working on the same kind of physics as Walter? Or were you there to expand and improve upon your dissertation?
No, I totally abandoned my dissertation. I mean, I learned about diffusion, and there was some diffusion that was involved in the work with Walter, but in a completely different context. But this area of physics, this sort of physics that had to do with statistical mechanics had appealed to me in graduate school, and I had actually wanted to work for Watt Webb at Cornell, but it turned out he didn't have any positions when I happened to be looking for positions. So this other project that I did with Bob Cotts was appealing to me precisely because I could build it from the ground up. But I think by the time I finished, I still wanted to get back to this kind of physics that involves statistical mechanics, and so I didn't feel bad about abandoning the field I had worked on as a graduate student. It was a fine training ground, but it wasn't particularly what I wanted to do over the long haul. So this opportunity with Walter was great. It allowed me to do just the sort of physics that I wanted to do, it introduced me to a whole bunch of new systems, and it wasn't until later, until I was an assistant professor at Haverford, that I sort of hit on something that I really wanted to do that was sort of my own, you know, my own project, something of my own making.
Dave, I want to ask you about the use of various related terms as they were relevant to your research, because they're overlapping, they change over time. So solid state physics, condensed matter, soft matter, rheology. What are the most important terms as they identify the kind of work you were doing at this point in your career?
Well, the work with Walter had to do with critical phenomena, with phase transitions and critical phenomena. In some sense, that field was winding down. I mean, it had been extremely active in the 60s, and then actually with Ken Wilson's work on the renormalization group, it cracked the field wide open, so the 70s was sort of its heyday when people were able to understand all sorts of things that previously had everybody flummoxed. But this field of critical phenomena is connected to statistical mechanics, as is the field of soft matter. So critical phenomena is sort of related to the field of soft matter. And particularly Walter told me about colloidal suspensions. I became interested in those. Probably Walter’s best-known graduate student was a guy named Peter Pusey, who is an English physicist, who became a member of the Royal Society eventually, who had a very distinguished career working at the Royal Radar Establishment, and finally at the University of Edinburgh. He was working on colloids. I met him when he came to Pittsburgh once and I got very interested in that kind of physics. And so that was what came to be known as soft condensed matter physics. Nobody really called it that at that time.
When did that term sort of come into wide use?
I would guess maybe in the early 90s? I'd say in the early 90s. At Exxon, we had called it complex fluids. De Gennes, who was sort of the biggest name in the field, didn't like that term. I'm not sure he was that fond of the term soft matter. But in fact, people in France called it soft matter, and I think, I may be mistaken, but I think we took the name from the French. And I'm not sure who coined it. I thought for a long time that de Gennes coined it, but he told me himself he didn't like the name. (laughs)
Maybe it sounds better in French?
Yeah, matière molle. But at any rate, yeah, so I'm not quite sure what the origins of it are, but eventually, that's the name that people settled on and so by the mid to late 90s, everybody was calling it soft matter. My first job was at Haverford College, which was a very good liberal arts college.
I learned all about Haverford. Joe Taylor at Princeton--
He went to Haverford as an undergraduate.
He did. Yes.
And he really emphasized what a truly wonderful department it was.
Yeah, his family is a sort of Haverford family. Matter of fact, one of his nieces, also named Taylor, took a couple of my classes when I taught there. I knew her before I knew him. But yes, Joe Taylor was an alum of Haverford.
Dave, were you looking specifically for faculty opportunities after? Because I mean, looking ahead to Exxon and the kind of work you were doing, which obviously had industry ramifications or possibilities, were you looking at both industrial opportunities and academic opportunities? Or were you looking specifically to be on a campus?
I looked, I thought about industry a little bit. In particular, Schlumberger had some very nice labs in Ridgefield, Connecticut that were very much in the same spirit as the Exxon labs that I eventually went to. And I had met Herbie Levine when I was at Pittsburgh, and through him I interviewed at Schlumberger, and I thought about it, but in the end, it seemed a little too small and a little bit too remote of a lab. I wasn't quite sure that my opportunities would be all that great there. I'm not sure that that was a correct assessment, because there were a lot of people there who launched very productive careers from that laboratory. But other than that, everything I interviewed for were academic jobs.
How was the market at that point?
It was okay but not great.
Yeah. Probably better than it was ten years prior, though?
Yeah, probably a little bit better. Yeah, as a matter of fact, I didn't tell you, but when I got accepted at Cornell, I told the guy who had recommended me back at Argonne that I had gotten accepted, and he said, "Congratulations, enjoy your six-year career in physics." Because in 1975, the job opportunities in physics were just abysmal.
And so by 1984, when I was on the market, they had indeed improved. And I had a number of interviews. I got some offers from okay universities, but not really the top-ranked universities that I wanted, and so in the end, I figured it was better to go to a top-ranked teaching school. I was a good teacher, I liked teaching. And rather than go to a second-tier research school, that's what I did. Also, Jerry Gollub was at Haverford. Do you know who Jerry Gollub was?
I know the name, I've heard it.
So he just passed away, maybe two years ago. He was amazing. He got his PhD at Harvard and then immediately became a faculty member at Haverford. At Harvard, he'd worked with Mike Tinkham and had done superconductivity. He had set up a superconductivity lab at Haverford. But he got involved in doing some experiments on turbulence because he had a student who wanted to become an engineer and was interested in fluid mechanics. So Jerry had him set up an experiment on Couette flow, which involves the flow of liquid, like water, between two concentric cylinders rotating at different speeds. Jerry took a little mini sabbatical and worked with Harry Swinney, who had just moved from NYU to CCNY. And they did a landmark experiment on turbulence.
Ok, this is a slight diversion, but when I went to Haverford I wanted to write a grant proposal, so I asked Jerry if he would be willing to give me one of his grant proposals so I could look at it and see how it was done. So he did that and he gave me his CV. His CV had the usual stuff on the first page, you know, schools he went to and stuff. And then on the second page, it had a little heading that said, "Research Accomplishments." All right? And the first research accomplishment was, "Showed that Landau's route to turbulence is incorrect." And I read that and my heart just sank, because I thought I'll never live up to this. (both laugh) I mean, it was very intimidating actually. And that's indeed what they were able to show, that there was this period doubling route to turbulence that was sort of the beginning of this whole field of chaos, and Jerry was one of the biggest players, one of the biggest names, in that field, and he'd done it all from this tiny little college at Haverford. That had a big influence on me and why I went there. I thought I would like to be at a place that was able to support that kind of work. It was also near the University of Pennsylvania which was strong in soft condensed matter physics. I developed strong connections to Penn that remained strong throughout my career. I still have very strong connections to the people at Penn.
Dave, I'm curious, at Haverford, it's a small school, it's a liberal arts school where the emphasis is definitely on teaching. Is there an expectation among faculty to conduct original research? Or that's sort of an above-and-beyond kind of thing that you wanted to pursue?
No, there was sort of an expectation. I mean, they didn't expect you to be able to produce research at the same rate as you would produce it at a research university, but they wanted you to do research. They wanted you to involve undergraduates in the research, and it's hard. It's not an easy thing to do.
But (laughs) everything's so funny, you know, in retrospect. They gave me $50 thousand as a startup fund, all right? Now, inflation, maybe in today's dollars that's $100 thousand or something. Maybe $120K, I don't know, but they gave me $50 thousand. Again, my reaction to that was not, that's not very much money they're giving me. My reaction was quite the opposite. I thought, do they know who I am? I'm like 30 years old and they're giving me $50 thousand? Really? I was (laughs) how do they know? I might just waste this money because I. Who am I? But no, I set up a lab and started doing some experiments and had some undergraduates working in my lab. Ultimately what happened was I was trying to do a certain kind of experiment where you see what happens when you shear fluids, how that changes their diffusive dynamics, and it was a technically challenging experiment. But I managed to set it up, I managed to see a signal, and get it working, but it was really tough.
Eventually, I realized that that there was an easier way to do this experiment but it involved equipment that I didn't have, and I didn't have the money to buy it. It would probably cost $100 thousand or more. But there was this guy who was a professor at Penn who I hadn't met, but he also worked up at Exxon part time, Paul Chaikin. And I had read some papers he did. He had done this work on something called Forced Rayleigh Scattering, and I realized that my ideas would be a lot simpler to implement if I could do them with Forced Rayleigh Scattering. So the whole episode is sort of hilarious. He had set up something called a Zimm viscometer, which is an amazing way of measuring the viscosity of very low-viscosity fluids. There's a wonderful story about how Zimm invented it, which he told to me himself while we were washing the dishes together at my house. I'll tell you about that later.
But at any rate, Paul had made this Zimm viscometer. You had to make them. And it was such a cool device. I didn't really have an experiment for it, but I wanted to think of an experiment I could do with it, because. And actually, that's not quite true. No, I thought I might be able to use it in the experiment I was doing, I forgot about that. At any rate, what I really wanted to do was interest Paul in the experiment I was doing so that I could do it in his lab with Forced Rayleigh Scattering. But I was chicken to ask him because I'd never even met him before. So what I told him was I wanted to learn about his Zimm viscometer, and would he be willing to show it to me. And he said sure. So I drove up to Exxon, and went there, went to his lab. He showed me the Zimm viscometer and how it worked. He was pretty proud of it because it was very cool, cool little device. And so then in the course of the conversation, I made my pitch for this other experiment, and to my surprise, he liked my idea. He had a new graduate student that he was trying to think of a project for, and he says, "Why don't we give this project to her?" And I said great.
So then I started going up to Exxon once a week to work with Paul and his graduate student. His graduate student was from Penn. And we worked on this experiment, we talked on the phone, and had a great deal of fun working on that. So at Haverford, you're reviewed in your third year to make sure things are going okay, and if things are, they then would give you one year off to do research, because they realized they hadn't given you much time and wanted you to actually do something serious that produced papers. So I took that sabbatical year at Exxon. And Dave Weitz was very kind. I'd met him in my going back and forth, I'd often talked to him about ideas and projects. And Dave arranged for me to get a small stipend, which together with the little bit of money I got from Haverford, enabled me to live up there. We moved up there for a year. And then during that year, I started the work that probably was sort of my first big hit, which was this stuff called diffusing wave spectroscopy.
So actually what happened to the project with Paul, which I was going to work on, the laser in his lab broke, and I couldn't do that experiment. And I had been reading all these papers on multiple light scattering and Paul and Dave were very interested in these papers. And so since the other experiment wasn't working, I asked Dave if I could go into his lab and set up and try and do some of these experiments on multiple light scattering. And so I started that, and that we had very quick success on. That worked spectacularly well. We wrote up a paper and published it in Physical Review Letters and it got a lot of attention. And what happened, actually, after that was the people at Exxon, spearheaded by Dave Weitz, liked the work so much that they offered me a job. And so I decided to leave Haverford and just go to Exxon, because I'd have much more time to pursue this line of research, which I was very excited about.
And Dave, I'm curious. You turned down the offer from Bell Labs and Bell Labs is Bell Labs. Going to Exxon, were you confident that it was a place that supported and even celebrated basic science to the extent that you didn't feel like you were leaving academia for industry? That this was just a place to continue doing the research that you wanted to do.
Absolutely. Exxon in those days was a fantastic place to do science. Dave and I and other scientists who worked there complained all the time about how we didn't get the freedom and support we wanted. A total lie. We got plenty of support. (laughs) We got to do pretty much just what we wanted to do, and we had a blast. We really did have a blast. Exxon wanted to compete with Bell Labs, and those of us who were doing what came to be known as soft matter science, we wanted to challenge them. Bell had a group of people working in this area, largely from the chemical engineering community, but from the physics community as well. And we wanted to compete with them. And so we had a very good group of scientists. A really stellar group of scientists. And we could compete with them, and we felt like we could. But there was a sort of feeling of being the underdog. Which was, in the end, kind of fun. And liberating because you don't have the heavy reputation of Bell Labs hanging over you.
So we were sort of the scrappy kids on the block, and we worked hard and we collaborated with each other. So that led to an awfully lot of really excellent science being done. And so I felt it was nothing but an opportunity to do great science. I felt that when I went there. They told me they liked the stuff that I had done on diffusing wave spectroscopy, and they said, "It's fine with us if you continue with that. and we would like you to think about company problems." And so I did work on some proprietary research that didn't get published. But truthfully, that wasn't a large or huge part of my time. So it was, I'd say, pretty similar to what people at Bell Labs had.
Right. So there was no concern that you would be involved in research about petroleum or anything affecting Exxon's bottom line? Nothing like that.
Well, no, I mean there was work on that. I did some work on some catalyst supports. It's not stuff that got published. It had to do with a new method for making polyolefins, and so I did some work on that. People like Dave Weitz did work on porous materials, and the whole idea there was to understand the physics of flow of fluids like oil in porous media, in rocks. And so the basic research areas were always connected to some aspect of Exxon's business. So soft matter, because it involves, you know, polymers, colloids -- all of these things are related to what the oil business does. And so that's why they were willing to support that kind of research. It was a long-term view. I mean, they pulled back from it somewhat starting around the time that I left. And that is in fact why I left. I had thought when I went there that I'd probably stay there eight to ten years and I ended up being there for a little over five. And that's because they decided to shift and they wanted more of the work to have more direct relevance to Exxon, which was a perfectly legitimate thing for them to want, but--
And was your sense, Dave, that that was a financial consideration? Was it a political consideration? What do you think accounted for that transition?
Well, we got a new VP in charge of the lab, and with him came a sort of a different mandate. Whether that mandate was of his own making or whether he had marching orders from people above him to move the lab in this direction, I'm not sure. I rather suspect it was the latter. But whatever it was, they did want to move the lab towards things that were a little more immediately relevant to Exxon's business. And like I said, I think that's an entirely legitimate thing for them to want. They're paying the bills, it's their company. The whole point is to have a business that makes a profit.
Yeah. And of course, the comparison with Bell Labs is, you tack a cent onto everybody's phone bill. You're essentially a nationalized utility.
Well yeah. And Bell Labs had this special deal with the U.S. government about being a monopoly and this sort of running Bell Labs as sort of being part of the price of having this monopoly. At Exxon, I think it was originally done because some people convinced Exxon that the long-term benefits would be to their advantage. So I mean they didn't entirely pull back from that. You know, the lab I worked in still exists today. And it is a very good lab and some very good science gets done there. It is more directly related to the company's business than it was in my day. But the science is still of a very high quality. They still publish in the open literature. Less than they used to, but they still do. And the people there are absolutely first-rate.
And Dave, in terms of your tenure there, saying it was a great place to do the science, how well-connected were you with your academic colleagues? Were you collaborating? Were you presenting at conferences? Were you doing all of the sort of scholarly work that you would have done at a research university?
I was. And as a matter of fact, so when I decided to leave, I think I made the decision maybe right at the beginning of 1995. I basically applied at two places for jobs. The physics department at the University of Pennsylvania and UCSB.
And who would you say you were close-- you maintained some close collaboration to?
So at Penn, I collaborated with Arjun Yodh. I remember that was funny because Arjun started as an assistant professor in the fall of 1989. And I had just come back from Exxon, and Tom Lubensky had invited me to give the colloquium at Penn. And Arjun told me later that Tom told him to pay attention to my talk. He thought it might be important. And so Arjun paid attention and when I went around to meet with him, he already had an idea for an experiment we could do together. And so I thought it was a terrific idea. It was really a cool idea. And so Arjun and I immediately started working together on this. And we started collaborating then, and we continued collaborating for the full time I was at Exxon. And so I knew Tom Lubensky. I knew Randy Kamien, I knew Paul Steinhardt. That was before he moved from Penn to Princeton. I mean I knew a lot of people at Penn that I really liked, and at the same time, at Exxon we had visitors in all the time. So Tom Lubensky had spent time at Exxon, and he spent a good part of his sabbatical at Exxon. But from UCSB (University of California Santa Barbara), Glen Fredrickson came to Exxon all the time, and it turns out that actually just before I left Haverford, I'd been up at Exxon, and I wanted to get involved. I wanted to think of something I could do in polymers because polymers seemed super exciting, and so I was trying to find an experiment to do in polymers.
And so there were these two articles in Physical Review Letters in '88 or '89, I don't remember which. One was by Gene Helfand and Glenn Fredrickson, who were at Bell Labs, and another one was by a Japanese theorist who I knew because he had worked with Walter Goldberg. And they were theory papers. They were kind of dense. I didn't understand either of the papers, except that I understood the thought phenomena they were trying to describe, and I understood that they made completely different predictions. And I thought of an experiment I could do and that the experiment could distinguish between these two theories.
So I went to work with a guy named Xiao-lun Wu who was a postdoc at Exxon. He had been a graduate student at Cornell. He was among the first group of Chinese physics students that came to the United States in '81 or '82, something like that. So I had met him at Cornell just as I was finishing up my PhD. When he finished his. PhD, he did a postdoc at Exxon. And we worked on this experiment together, and when we finally got it working and got good data, it showed that Glenn Fredrickson's theory was right, and the other fellow's was wrong. But through that interaction, I got to know Glenn quite well. And so Glenn said, "We have an opening at UCSB in the Chem-E department. You might be interested in applying for it." And so I did apply for it. And to my surprise, they offered me the position. And so I ended up taking the position mostly for personal reasons. My parents had recently retired and moved back to Southern California, which is where they grew up and is where my dad's sister was, and I have a couple brothers living in LA. So I decided to take the job at UCSB.
And what's the departmental breakdown? You're in the department of chemical engineering, is it?
So at UCSB I actually had a dual appointment. I was 2/3rds chemical engineering and 1/3rd materials. So the materials department at UCSB is a very good department. It was then and it still is.
And the materials colleagues are mostly physicists?
No, they. I mean material sciences typically come from all kinds of backgrounds. So some of them were physicists. There were a number of people, refugees from Bell Labs, who ended up at UCSB. But some were metallurgists. Some were chemists by background, particularly like polymer chemists and so forth. One guy, Tim Deming, he's a polymer chemist, and we collaborated. His lab was right next to mine, and so we got to know each other and we had a few papers together. But he was essentially an organic chemist working on polymers. He's at UCLA now. So it's a mix of people in the materials department there at Santa Barbara.
Also coming from Exxon, it's a pretty nice place to live also.
It was a wonderful place to live, and you know, our kids were small and they grew up in Santa Barbara. They had a blast. They had a really good time in Santa Barbara. I mean, I did think that I would stay in Santa Barbara for my entire career. I didn't have any intention of ever leaving. But this opportunity at NYU came up, and it seemed special enough, and the idea of living in New York seemed interesting enough, that I decided to take it. Even though I was very happy at Santa Barbara.
David, I'm curious. When you arrived at Santa Barbara, some of your colleagues that I've talked to-- I've talked to Jim Hartle and Doug Scalapino. They talk about how exciting Santa Barbara was 20 years earlier because that was when it was in real growth mode in terms of becoming a real center for science in late 60s and early 70s.
Where was the department of chemical engineering and materials when you arrived? How established was it at that point?
All right. Just to comment first on that background. I mean, I went there in 1995, and clearly there was no place that had improved in stature as much as Santa Barbara had over the previous 25 years. Starting with people like Hartle and Scalapino who came there around '69, '70, somewhere in there. And they transformed the place. They made a series of really great hires. They took advantage of a number of things. So they hired a number of people from Bell Labs, who wanted an academic career. They took advantage of the beautiful location of Santa Barbara. While I was still a graduate student at Cornell, I remember they made this bid for the ITP, which is now called the KITP (Kavli Institute of Theoretical Physics) , and I remember the people at Cornell were completely opposed to it, because Cornell was one of the powerhouses in condensed matter solid state physics, and they saw it as a threat. And indeed it was a threat, and I'd say that today, Santa Barbara has passed Cornell in terms of its reputation in condensed matter physics and in physics generally. But UCSB did an amazing job hiring people like Alan Heeger and Bob Schrieffer and creating an environment there that was really exciting. And I mean some of the same things that appealed to me about Exxon appealed to me about Santa Barbara because Exxon was this place where we were the new kids on the block. The scrappy kids trying to prove that we could play with the big boys. And Santa Barbara still had something of that feel to it.
And so the chemical engineering department had been transformed starting in the early to mid-80s. Then it was the department of chemical and nuclear engineering. Three Mile Island sort of killed off the nuclear part of it. They couldn't get any students who wanted to be nuclear engineers after Three Mile Island. And so by the time I had arrived, they had dropped the nuclear engineering and it was just chemical engineering. But in the 80s, they made several really remarkable hires. They hired Jacob Israelachvili from Australia. They hired Gary Leal and Henry Weinberg, two very prominent chemical engineers, National Academy of Engineering members, from Caltech. Gary became the chair of the department. They also hired Glenn Fredrickson from Bell Labs. And Glenn is, you know, one of the preeminent theorists in polymer physics and at the time, probably the youngest person of note in polymer theory. Actually, he and Ludwig Libler, who was a little bit older than Glenn, who was in Paris, had done a number of papers together that became landmark papers.
So UCSB had this core of really exciting people. They also had a guy named Dale Pearson, who had been at Bell Labs, and then at Exxon, and I knew Dale. Dale taught me about rheology. And then Dale went to Santa Barbara too as part of all this around the same time that Gary Leal went there. And then as department chair Gary made a bunch of really good hires of assistant professors. So everyone up to that point had been sort of mid-career or very well-established people. Sadly, it turned out that Dale had serious psychological problems and he ended up committing suicide. And in point of fact, that was why there was an opening when I applied there. They wanted somebody who's more mid-career, and so that's how I got hired. But it was clearly a very good department, and really an exciting place. They were very open-minded. They weren't worried by the fact that I was a physicist and not a chemical engineer. And I mean, Gary just said, "All we ask is that you participate in the chemical engineering community. You go to our conferences, you get to know our people. It's important for our stature in the community."
And so I already knew a lot of chemical engineers from my days at Exxon. I really tried to get plugged into the chemical engineering community. But I think it's ranked, you know, maybe eight or nine now. When I went there it was probably ranked maybe 17 or 18. By the time I left, I think it was ranked ninth in the country. So it's a damn good department. The material science department, it was really, has always been, one of the top four or five material science departments. The physics department was really exciting. The electrical and computer engineering department had a lot of really wonderful things going on. So there were a lot of really creative people at Santa Barbara. And of course, it all blossomed from the success of the physics department. Once people like Doug Scalapino showed what they could do in the physics department, it inspired these other departments like chemical engineering, materials, ECE, to go out and make some really great hires. There was really a marvelous intellectual atmosphere at Santa Barbara.
And Dave, what were some of your most significant research achievements at Santa Barbara?
Let's see, when I went there, I'd just done this work on polymer solutions and shear enhanced polymer solutions. So we continued that and we sort of finished that off. That's work I'm proud of. I liked that work a lot. At Exxon I'd been doing this work on multiple light scattering, and diffusing wave spectroscopy, and people started talking about these things called photonic band gaps, materials that might have photonic band gaps. And there was a physics professor at Iowa State who had been a postdoc at Exxon before I was there, named Costas Soukoulis, who published the first paper showing that it was theoretically possible to make a material that had a photonic band gap. This was in 1990. But he had been talking to me about this in 1993 and '94 when he would visit Exxon, and telling me I should work in this, and indeed I discussed some ideas with him. But I tried to convince my management at Exxon that I should work on this, and they said, "Absolutely not." (laughs) They said, "Show us how this has something to do with Exxon's business." And I stretched and tried, I came up with all cockamamy half-baked ideas. None of them worth much. And they saw through it. They weren't buying.
And so I knew that if I wanted to pursue that line of research, I couldn't do it at Exxon. It became crystal clear. But I was excited about trying out these ideas, and I could see the writing on the wall, that our days where we could sort of freely do what we wanted were coming to an end. So I set up to do that line of research at Santa Barbara. And I hired a postdoc form Holland, a guy named Arnout Imhof who was a marvelous postdoc. We went to work together on it. I worked with a guy in the materials department, Fred Lange. He was a ceramicist, and we were working with titanium dioxide and he knew all about the chemistries for making titanium dioxide and about their mechanical properties and so forth. And so I worked with Fred a lot. So that was maybe the biggest success I had there.
I got a big grant from the Department of Defense to support this work. It was this idea of making what are now called inverse opals as materials that might have a photonic band gap. And we published the first paper on that in Nature, it was probably 1998, something like that. And that launched a good part of my research group. I had several really good students, in particular one, Vinny Manoharan, did some spectacular work that sort of launched this area of colloid science involving patchy colloidal particles. I'd been working on that since 2001 or 2002, something like this, towards the end of Vinny's thesis, and the idea there was to make colloidal particles that had four patches on them arranged with tetrahedral symmetry as we wanted to make colloidal diamond. That is, we wanted colloids, colloidal spheres, to self-assemble into a diamond structure. And diamonds are four-fold tetrahedrally coordinated. And so we started pursuing this little idea we came up with back then, and like so many things, our ideas were a little bit naive. It took a long time to get them to work, and when they did work, they didn't work quite the way we hoped they would work. But we managed to do a lot of good science along the way.
For example, this led to a lot of work on creating some new materials—macroporous materials. Then, there was also a paper with Galen Stucky's group on making porous materials with a hierarchy of pore sizes. That was pretty interesting. The work we did at Exxon on shear enhanced polymer light scattering led to some work at Santa Barbara on worm-like micelles that got a fair bit of attention. That was rheology and structure.
So going back to the inverse opals, porous materials, and colloidal clusters—all of that was part of exploring ideas in the hope of being able to make materials that could have a photonic band gap. Now, I actually have some interesting news. I don't know if this is part of the history, because it's history that was made yesterday.
Oh wow, well, sure. Let's hear it.
So it turns out if you want to make a material with a photonic band gap, one of the best, maybe the best, structure is this diamond structure. And this goes back to this calculation that this guy Costas Soukoulis did back in 1990. There haven't been that many ideas about how to self-assemble colloidal diamond. And really the only experimental groups that have pursued it have been my group and Alfons van Blaaderen's group in Utrecht. On the simulation theory end of things, people like Francesco Sciortino at the University of Rome, Sharon Glotzer at the University of Michigan, and a few others, have pursued it. But it's generally, you know, I think people have never really had an idea that would really work. So a little over a year ago, one of my graduate students had an interesting idea. And we developed that and were able for the first time to make colloidal diamond. So something I've been at for about 18 years, and we finally--
And what is that? What is "colloidal"? What does that mean, Dave?
Oh, a colloidal suspension is a suspension of small particles in a liquid. Now, in order to stay suspended, they're suspended by collisions with solvent molecules, and that leads to Brownian motion. So the Brownian motion is what keeps them suspended. In order for the Brownian motion to be strong enough, they have to be smaller than about a micron or maybe a few microns in size. So generally, it's nanoparticles up to maybe a couple thousand nanometers in diameter for you to have a suspension. And the idea is to make these spheres -- or particles--so they'll spontaneously assemble into a diamond lattice. Now normally what they do, if they're just spheres, they will very easily organize themselves into being a face-centered cubic lattice, which is exactly the way oranges stack in a grocer's stand.
Ah, okay. Sure.
All right? And so that's a very natural way for spheres to pack. And colloidal spheres will do that, and as a matter of fact, opals, the gems opals, are dried-out colloidal suspensions. And the colors you see come from light scattering off the crystalline planes. That's what gives them their beautiful colors -- something called structural color that a lot of people are studying these days. And so making certain structures like face-centered cubic is easy, body-centered cubic is easy, some like cesium chloride structures. There's a whole cast of structures that are fairly easy to make, but nobody had any idea how to make a diamond structure. So my student had this idea, we developed it a little bit, and he made these particles, and they self-assemble into a diamond structure. Yesterday we just heard from Nature that they've accepted our manuscript on this, so hopefully we should have a publication, it will probably take a couple months, maybe end of August, beginning of September, I'm not sure.
Actually, for me it's a big deal because we've been trying to do this for close to 20 years.
Now David, when you say "diamond" are we putting De Beers out of business? Is that what's happening? Or this is a totally different kind of diamond?
No, no, no. The diamond refers to the crystal structure. So like I said, the way oranges pack, that crystal structure is called face centered cubic, all right?
And so in general--
So we're not going to be seeing these on engagement rings any time soon.
No, no, no. You won't see them on the engagement rings. Actually, if you made them the right size, they would look more like opals.
All right? They might look partially like mirrors, but what they are is they're the optical analog of semiconductors. In other words, these materials do for light what semiconductors like silicon do for electrons. And so the hope is that if you can make these kinds of materials, you can make some very interesting optical devices. And so the first step of making these diamond crystals is very exciting, and we're in the process of using them to try and make materials with a photonic band gap, and we hope to have some results on that in the next few months as well. So that's a nice recent development, and literally I just heard yesterday from Nature that they've accepted our paper on this. So we're very pleased with that. My time at NYU actually has been a really good time for me professionally. We've had a number of really good collaborations and have come up with some really terrific things.
Right as I was leaving Santa Barbara, I had this idea for an experiment that I wanted to do, and I had a graduate student who normally I would have given the experiment to, but I was literally packing up my lab to go to NYU and he was desperately trying to finish his PhD and didn't need any extra projects. So as it turns out, my old colleague, Jerry Gollub, from Haverford, was visiting the KITP, and he told me he was dissatisfied with the program at the KITP. It wasn't nearly as interesting as he hoped it would be. So I told him about this project. I said, "I don't have a graduate student to work on this, would you like to be my graduate student?" (both laugh) And he said yes. He liked the project. And so the two of us went into the lab, we used this set up that my graduate student had abandoned, and over a period of about six weeks, did these experiments that have to do with what's called a reversibility-irreversibility transition in periodically sheared particle suspensions. So we got a very nice publication out of that. That was again actually in Nature.
When I came to NYU, I told Paul Chaikin about this, and Paul Chaikin just really got irritated by this thing. He didn't understand why it did what it did. And he'd come into my office and we'd discuss and argue about it for hours. And eventually he came up with an idea for a model for how the particles behave under periodic shear. The model turned out to have a lot in common with the experiments but also made some new predictions about how the particles reorganize under periodic shear. So we did some more experiments to test the reorganization process that this model predicted, and the experiments agreed with the model. And we eventually called the process random organization. By the way, Jerry Gollub stayed involved in this. He had gone back to Haverford College, and so he'd visit NYU, and he and Paul and I and a postdoc of mine, Laurent Corté, the four of us worked on these experiments for a few years. And this actually launched sort of a new field. There's a bunch of people who work on these kinds of things now. So that's been a nice collaboration with Paul.
There was also another collaboration with Paul. I don't know if you looked around my website?
I did. Yeah.
Did you look at the Lock and Key colloids?
Did you play the movie where one comes and--
It's so cool.
I mean, that's really cool. So again, that started as a collaboration between Paul and me. Paul wanted to do some sort of lock and key interaction but he didn't know how to do it. I had an idea about how to do it and what the mechanism might be. As it turns out, I had just hired a postdoc named Stefano Sacanna. He came from Utrecht, which is a center for colloid science. And I still remember one of my first meetings with him. I told him my idea for how to do this lock and key thing, and he told me he thought it was a pretty good idea, but he wanted to think about it a bit. And so about a week later, he came back with an absolutely brilliant idea about how to make these dimpled particles. It really was a stroke of genius. And so he went to work on it, and it didn't take very long before we had our lock and key particles that you see in that movie. That was a terrific piece of fun. Stefano, after he finished his postdoc with me, got a faculty position at NYU in the chemistry department. He's a chemist by training. We still work together on different problems. And matter of fact, he's a co-author on this diamond paper because it uses some colloidal synthesis techniques that he and his students developed. My student, Mingxin He, came up with a very nice idea that turned out to be the key to making the colloidal diamond lattice. And so it's been just a super cool collaboration with all these different people, with different skills and different ideas coming together. It really has been a super productive time. And if you'll allow me to say one other thing that I'm proud of--
It's what we've been able to do in the chemical and biomolecular engineering department. So NYU's been very supportive, and in the six years that I've been chair, we've hired seven new faculty members. It is a fantastic group of faculty members. And we've created the beginnings of a very good chemical engineering department. I'll probably step down as chair next year. Let somebody take it to the next level. But we really have brought in a good combination of junior and senior faculty, with various backgrounds. It's a very ethnically diverse group of men and women. And our students, our undergraduate majors, we actually have a majority of women. We--
That might be unique in the whole country.
I don't know if there are other chem-e departments who have a majority of women. There might be, but there aren't a lot of them, if there are. They're really an incredibly diverse group of kids. So I have to say, I never made it my goal to be an administrator. (laughs) I still don't want to be an administrator. (both laugh) I like doing science too much. But I have to say, this has been a very satisfying experience, because assembling a team of people like this who really have an incredibly good spirit and who are incredibly creative and good scientists and engineers -- there's more satisfaction in helping to put something like that together than I might have imagined. And so I have enjoyed that a lot. I'll enjoy not having to do it too. (both laugh)
Well Dave, now that we've sort of worked up to your present-day research, I want to ask you sort of a few broadly retrospective questions about your career. And the first is, as you've gotten more involved, you know, at least departmentally, if not institutionally, in chem-e, do you feel like you have moved away from your more classical physics background, or does your career trajectory, is it suggestive of sort of a broader multidisciplinary approach to the kinds of things you study and the kinds of people who work in this field?
I think it's definitely more of the latter. I mean, you said you recently interviewed Dave Weitz, and Dave has always been in physics departments, you know. After Exxon, he was at Penn, and now at Harvard. But he has a whole slew of ex-students and postdocs who are teaching in chem-e departments.
And so in many ways, he's done the same things I have, but always with the official platform of a physics department. People in chemical engineering know him at least as well, maybe better than they know me. And my other colleague, Paul Chaikin, when he was at Princeton, probably his biggest collaboration was with Bill Russel, who was a very well-known chemical engineer at Princeton. So it's more, I think, characteristic of the field. Take another person I've worked with, Sharon Glotzer. Sharon is chair of the chemical engineering department at University of Michigan, but she's a computational physicist. Her PhD is in physics. She worked at NIST for a long time before going to Michigan. So I think it has more to do with the field. One way I like to think of it is. I mean, this is a caricature. It's not entirely accurate, but there's I think some truth in it. If you think about 20th century physics and all the achievements in physics and in chemistry and biology, which have just been amazing, people more or less stuck to the disciplines. You know, physicists did physics, chemists did chemistry, biologists did biology. Well, I think part of what that means is it left a whole bunch of problems that sit at the interface of these disciplines unexplored. And so it's a ripe place to find interesting problems. It's not the only place to find interesting problems, but there are perhaps more of them there just because previously people stuck more to their discipline. And so it requires a little bit of courage, maybe? I don't know what to call it. To get out of your comfort zone. I mean, in my group, we do a lot of chemistry. And I don't know that much chemistry. I certainly know a lot more now than I did 25 years ago.
But when I bring people into my group, I hire postdocs who are chemists. I sometimes have physics or chemistry graduate students, or usually chemical engineering graduate students. And that was the thing when I went to Santa Barbara and I started working with these chemical engineering graduate students. The problems I wanted to do were motivated by physics. That is, I wanted to do things having to do with photonics. How light interacts with matter, how light interacts with structured matter. And there are some very interesting things to do there. The problem is, you had to make that structured matter, and making that structured matter involved some fairly serious chemistry. And so part of the reason why I think I've had an opportunity here is because there haven't been that many-- a chemist wouldn't do this because a) the chemistry isn't quite interesting enough for them, and b) they don't know the physics. A physicist will want to do it, but the real barrier is there's too much chemistry, and no physicist is going to know enough chemistry to be able to do this. And I know that because we've gotten stuck a few times, and the only way we got unstuck is by getting a real chemist in who could deal with the chemistry problems we were facing and get us over that hump so that we could get to the physics that was motivating us.
But that tends to be the way I look at it. That at the interfaces of these disciplines, there are more opportunities. There are more things that people haven't looked at. And I think that there's been recognition of that in the science community over the last 20 years. And there has been more emphasis on multidisciplinary research. And I still think there needs to be more emphasis on a broader education. Broader and deeper. In particular, I think for physicists it's extremely valuable to learn a fair bit of chemistry. It really opens up opportunities to do science that you would otherwise back away from.
Dave, I want to ask you, what are some of the classical or foundational concepts or laws in physics that stay with you on a daily basis? As you sort of push the field far beyond where you were as a graduate student or even as a postdoc? As you pursue things in chem-e and soft matter, what are some of the sort of bedrock physics concepts that are just, you have an affinity to or are just really useful to you on a day-to-day basis as you pursue your research?
All right, so I'd probably need time to answer that definitively, but the first thing that comes to mind without a doubt is entropy.
Entropy is a profound, profound concept. A profound idea. And every single day of my life, I think about and use entropy to do stuff. I mean, you know, people describe it as disorder. That's not quite right. It's certainly not quite wrong either, but entropy can be a driving force. And as a matter of fact, is one of the chief driving forces for self-assembly. And learning how to use it and manipulate it is extremely powerful. And of course, it comes back and it surprises you from time to time about the way it works. But entropy is absolutely bedrock. I mean there's a lot of condensed matter physics these days that's exploring very, very interesting quantum phenomena. And it gets really intricate, really complex. Very, very interesting stuff. But I think in some ways, the discipline of statistical mechanics is more subtle than quantum mechanics. And it may not have some of the conundrums that people like to talk about in quantum mechanics, but there are real subtleties to the way multi-particle systems organize themselves, and the approach or approaches of statistical mechanics to these systems, to these ideas, is just foundational.
So you know, of course the heroes in the field are known to everybody. People like Boltzmann and Gibbs, these were scientists who were extremely deep, deep thinkers. Several years ago, right after I came to NYU, there was a woman who wanted to write a play about Einstein's first wife, and she wanted some technical advice from me, and so she gave me these books that had been recently released that were Einstein's letters between his first wife and him, both before and after they were married. One of the things that struck me about it, reading about it -- this is Einstein when he's like 19, 20, 21 years old. His biggest hero was Boltzmann. He loved Boltzmann. He thought that Boltzmann was amazing. And it was funny because statistical mechanics was just emerging at the time, and Boltzmann was criticized quite a bit, but Einstein at age 19 already had tastes and ideas of his own, and he thought Boltzmann was just amazing. So that's sort of an interesting thing. But yeah, so the first thing that comes to mind is entropy. Entropy just is, I'd say, a foundational concept in soft condensed matter physics. And one that you use all the time. You know, broadly speaking, many of the problems I work on are with self-assembly, and I do think self-assembly is just something we're only beginning to understand. So on a personal note, two weeks ago last Tuesday I became a grandfather.
So that's a very nice thing to have got to--
Which one of your kids?
My son. My younger child, he and his wife had a daughter a couple weeks ago.
This is quite an interesting time to have a baby. (laughs)
Yes. (laughs) Indeed. But there's a self-assembly problem. I mean, it's unbelievable, right? You have a sperm and egg, and they get together and they start this process that ends up with a human being. And it's just stunning in its complexity and in what it's able to do. So we humans are trying to do our own self-assembly, and so we get really happy when we can take a sphere and make it dock on another particle with a little dimple in it and we go, "Yay! (laughs) Self-assembly!" But you know, it's a pretty far cry from what nature's figured out how to do. And I think that those problems that deal with how things structure themselves, how they self-assemble, I think are really captivating problems. Or a captivating set of problems to work on. But in all of those problems, entropy plays a bigger role than you might think. It's interesting, harnessing the force of disorder to do something orderly. So I'd say that that's pretty foundational.
And probably it came to you so naturally. That's, even if you think about it for a long time, that's probably still and always going to be entropy.
Yeah, I think so. I think that's probably true. You know, one thing that's funny to me that I reflected on several times. When I took physics as a freshman in college, you know, I got good grades and so forth, but there were parts of it I didn't understand. And I almost felt embarrassed for getting good grades because I knew in my heart I didn't really understand what was going on. One of them was electromagnetism. I really felt like, you know, I could do all the problems and I could get the right answers, but it didn't really make sense in a deep way to me. And the other thing that I was completely dissatisfied with was entropy. I did not understand entropy at all. When teachers tried to explain it to me, it made no sense. Again, I could do the problems but I didn't know what it was. So it's interesting to me that in my career, I have focused on those two problems, you know, light, interaction with matter, and statistical mechanics my whole career. So you know, maybe most people, or most scientists, are that way. I mean, somehow the stuff I felt like I understood, that came naturally to me, I didn't want to study. It was the stuff that gave me problems, that I couldn't figure out, I couldn't understand, these were the things that kept me awake at night. And I think it's that kind of thing that makes for success in doing probably anything, but certainly in doing science. It’s just that you care about it a lot. It's not so much being smart or clever. It's caring about it. And if it bugs you enough, then you think about it and that's sort of the key to making some progress. But yeah, I've often thought about that, that it's definitely a retrospective look. I didn't see it coming.
I didn't plan it that way.
That's very cool to hear you sort of worked that out in real time about this natural gravitation towards things that you didn't fully understand from the beginning, and I think that's very representative of how a lot of good science happens, right?
Yeah. I think it probably is. I don't think I'm at all unique in that. I think that it's probably a very common feeling among scientists.
Well Dave, for my last question, I want to sort of blend a theme. I want to contextualize a theme of our discussion into a forward-looking question, and that is, I mean it's really obvious in your career that both you and the fields that you represent, that you've been involved in, there's constant evolution in the field. Things are always changing, things are always moving ahead, there's always new areas that are exciting and developing. And so I mean that just begs the question, what next? And I want to specify in answering it, I want you to consider both the issues that are intellectually compelling to you, and also the way that technology as it evolves in the future, is going to present new opportunities to do things that you might not have been able to do, or even conceive of doing 10, 15, 20 years ago. So in that vein, what's next personally for you, and what's next in the field at large?
Oh boy. I mean, it's really hard to predict in my opinion. Part of the reason is that a lot of good science that gets done. So it might take me a while to answer. So I'll tell you a story. So I told you that I collaborated with Arjun Yodh. So early on in our collaboration, we wrote a grant proposal together to the NSF and it got funded. All right? We did some nice research, published some papers, everything went well. So then, as the grant was running out, we wrote another grant to get our grant renewed. And so it did get renewed as I recall, but when the reviews came back, there was one reviewer who wrote, and it's always stuck in my mind, "The proposal that Yodh and Pine have put together is a perfectly fine proposal. There are some interesting ideas here, but frankly, they don't seem as interesting as what they did in their last round." All right? And I guess I wanted to meet that reviewer, because I had something I wanted to say to them. And it was this: the things that we did in the last round were way more interesting than the ideas we proposed.
The reason I say that is that one thing I think good scientists do, not all the time, but frequently, is you start out on a path and you see something in the lab that you didn't anticipate. This is one of the joys of being an experimental scientist, where you go into the lab and you observe things. I think that sometimes what distinguishes good scientists from less good scientists is recognizing that that's not to be ignored, that there might be an opportunity there. And it's because of experiences like that that I think it's really hard to predict what's next. This work on the reversibility that we did, and with Paul Chaikin getting involved and coming up with the Random Organization model, I really think that the work in total is quite profound, and will make a big difference. But I didn't plan it. I didn't see it coming. The initial idea was a good idea. I thought it was a six-month experiment and then we would be done. But it's now 15 years later, and it's still producing new stuff.
The key is recognizing new opportunities as you go along--the thing is, an awful lot of science is like that. This diamond thing that we just made. We're pursuing these tetrahedral patchy particles in spite of the fact that we knew on theoretical grounds that they weren't going to quite work, but we wanted to see what we could learn about it. And my graduate student in the course of synthesizing these, saw something and he realized it might be a way to solve a problem that we talked about a lot. We didn't think of this solution ahead of time. It wasn't like we were brilliant and had this great idea. He saw something in the lab. He didn't anticipate it, but he knew that there was this broader problem because we'd talked about it all the time, and he thought, "Oh, this might address that problem." And so after that it just took a little bit of talking and then the rest is history, so to speak.
But so much of science, at least in my experience, is like that. You know, I'd like to think that I was brilliant enough that I could sit there and fire the canon and see exactly where it was going to land, because it makes me look like I'm a lot smarter than I am. But it's not like that. It's more that you set off in a direction, and then you see something or talk to a colleague and you go, "Oh, I should be going over here." So it's a little bit of a cop-out, but it is so hard to predict the future in science because so much of it depends on that kind of activity. Now, on the other hand, and I just speak from personal experience -- not because I think my experience is so great, but it’s just the only experience I have. We've been able to make this diamond structure. This has sort of been a holy grail for people since it was proposed in 1990. You know, I think when it gets published, it will make a big splash. So the one thing I'd say that we've had is persistence. But as recently as a year and a half ago, I was thinking I may retire and we'll never solve this problem (I’m 67). Because I didn't have a solution in mind.
Well Dave, you do know that physicists never retire. You did get that memo, right?
(laughs) I don't--
I want to tell you, I talked to Bob Finkelstein at UCLA. He's 104 years old and he's working on revising the standard model. This is his current project. (laughs)
Yeah. Well, that is a really lovely thing, I think, about intellectual pursuits. I mean, if you're really pursuing it because you just like the things you're thinking about, then in some sense, you know, why would you retire?
But I really do find it hard to address those questions, because progress and new scientific directions emerge in many different ways. In the case of colloidal diamond, I identified a problem I was interested in, and stuck with it a long time, and it looks like we're going to make some pretty decent progress on it. But it wasn't guaranteed. I thought that I might have to, in the words of my old colleague from Exxon, Sunny Sinha, “declare a victory and move on.” (laughs) But there are also cases where unexpected opportunities arise, as in the case of Random Organization. At this point, the contributions are mostly Paul Chaikin's, and they're quite profound. But in 2005, I would have said, you know, "I'm pursuing this problem in hydrodynamic reversibility because I think there's something deep and profound at the end." I did it because there was a question I didn't understand. I thought there was an experiment I could do to address that question. It did answer the question to some extent, but then it raised some more questions, and then some really, really beautiful things have emerged from that. And there is no way on earth anybody could have predicted that at the outset. It's just impossible. Literally impossible.
So where is science going, or my area of science, soft materials? I don't know where it's going. Like I said, I continue to be captivated by this problem of self-assembly because I see what nature's able to do in terms of self-assembly. I mean, my wife bought this hydroponic planter. And she put six seed pods in it -- basil and mint and thyme and a few other things sticking in this water, all right? She adds a little capful of nutrients, chemicals, every two weeks, shines some light on it. And it produces all these different herbs and spices. They smell completely different. They're lovely. Think about that. How on earth does that happen? How do you take these elements and then assemble something like a plant out of it? And even though biologists understand or think they understand this halfway-well, they understand it on their own terms, and they don't understand it on terms that a physicist would find satisfying. That's not to say that they're not answering all the questions they want to answer. They ask a different set of questions that come at a different aspect of the problem. But I do think this issue of self-assembly and understanding it in a deep and profound way is important and it's a really interesting area to pursue. So this, again, is a problem that's at the interface this time of biology and physics. But there's probably more chemistry involved there than we care to admit. So this one's doubly hard because you really need a lot of different kinds of expertise to make progress. So I feel like I've danced around an answer to your questions.
Well, you don't have a magic ball, so that's as good as you can do. I wouldn't expect anything else.
Yeah. Yeah, I (laughs) it's like being the President's press secretary. You always feel that they're lying.
(laughs) It's really, it's a question, it's more about asking you to rely on your power of extrapolation. You know, that's really what it's about.
Yeah, and I don't know. I mean, there's all sorts of interesting things going on. Things going on in computer science and artificial intelligence. I think that has had and will continue to have a huge impact on all kinds of problems, including problems in my field. You know, honestly, I know I'm going to die someday. But I have this wish that I would be able to come back 100 years later, just for a day, and get to sit down and talk with a whole bunch of scientists and find out what they've discovered in the 100 years, what they figured out. Because I'm sure it's going to be cool and I'm sure they're going to answer a whole bunch of questions that I always wondered about, and it would just be exciting to know what it is they've managed to figure out.
But we only get one pass, so we enjoy it as best we can.
Well, Dave, on that note, it's been so fun spending this time with you. I really want to thank you for sharing all of your insights over the course of your career, and this is going to make a really important and engaging addition to our collection. So I really want to thank you for that.
Well, I do hope that people enjoy it and maybe get something out of it.
This is one scientist's experience, and there are lots of different experiences in science. But it's been a pretty good one.