Robert Liebermann (BS '64), Geoscientist

Mineral physics studies the connections between the physical and chemical properties of minerals and the behavior of minerals, particularly when they are exposed to high temperatures and pressures. Bob Liebermann is a leading figure in this field, and he has made important observations thanks to the cutting edge instruments acquired by Stony Brook University in partnership with Brookhaven Lab and the National Science Foundation.

Liebermann remembers Caltech's Seismo Lab from an earlier era - he arrived on campus in 1960, expecting, like so many in his generation, that he would pursue physics. A class with Bob Sharp was so inspiring that Liebermann switched to geology. He went on to complete his doctoral work at Columbia in 1969 and returned to Caltech for his postdoc, at a time when the old lab was operating "up in the hills."

Liebermann is a founding member of the Committee on Mineral and Rock Physics and he is a Fellow of the American Geophysical Union and the Mineralogical Society of America. He has been honored with the the degree of Docteur Honoris Causa from the Université Paul Sabatier in Toulouse, France. Liebermann has served as President of the Consortium for Materials Properties Research in Earth Sciences (COMPRES), at Stony Brook.

DAVID ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It's Monday, May 2nd, 2022. I'm delighted to be here with Professor Robert Liebermann. Bob, it's great to be with you. Thank you for joining me today.

ROBERT LIEBERMANN: Pleasure.

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

LIEBERMANN: I'm currently a Retired Professor or recategorized as a Research Professor of Stony Brook University.

ZIERLER: Now, as research professor, are you still active in the literature? Do you have any research projects currently underway?

LIEBERMANN: Yes. The difference between being emeritus professor and research professor is that as a research professor, I can have research grants.

ZIERLER: I see. Bob, questions about a few other affiliations. Tell me about being president of COMPRES, the Consortium for Materials Properties Research in Earth Sciences.

LIEBERMANN: Well, this was a network of what ended up being 58 US universities, and another 30 international universities, connected to obtain funds originally from the National Science Foundation and the Department of Energy to make connections for high-pressure, high-temperature research in the field we call mineral physics. I served as President of that entity from 2003 to 2010.

ZIERLER: What was the relationship between the Consortium and the Mineral Physics Institute?

LIEBERMANN: The Mineral Physics Institute served as the home base for the Consortium during the first year, and then subsequently when I was the President. When it moved to the University of Illinois in 2010, the headquarters moved there. Then in 2015, I think, it moved to the University of New Mexico.

ZIERLER: Bob, between your affiliations and your overall research agenda, is mineral physicist really the best way to describe you and what you do?

LIEBERMANN: Yes.

ZIERLER: Tell me about where that fits in within the disciplines of seismology or even geophysics.

LIEBERMANN: Well, it's very much connected to the disciplines of seismology and geophysics and material science, even geochemistry, which are main entities within the American Geophysical Union. Mineral physics, in a sense, provides the experimental and theoretical glue between seismological observations and interpretations of what the interior of the Earth is really like, and how it's been created, what its properties are, and what processes are occurring now within it.

ZIERLER: Bob, what do we know about mantle materials? What are some of the settled science, and what are some of the big questions still out there?

LIEBERMANN: Well, the basic chemistry is known, and the mineralogy is more or less known down to the core-mantle boundary at about 3,000 kilometers. The minerals that make up the upper mantle, the upper 400 kilometers, all transform to higher-pressure, higher-density phases between 400 and 800 kilometers. Those changes in density are associated with changes in velocity, which are revealed in the seismic observations. There's still some discussion of what's going on in the lowermost mantle of 2,000 to 3,000 kilometers, but I think it's settled knowledge. The core is the interior 3,000 kilometers, and it's predominantly iron and nickel. But it can't be just iron and nickel. That's too dense. It has to be alloyed with some lighter element. People are trying to debate and discuss this, whether it's silicon, sulfur, hydrogen, things that would lighten the iron-nickel mixture. But it's certainly convecting in outer core because, otherwise, we wouldn't have a magnetic field. The inner core of about 1,000 kilometers in radius is solid, or more or less solid.

ZIERLER: Bob, I'm curious if your area of expertise contributes at all to those debates about the extent to which the inner core moves or even rotates.

LIEBERMANN: No, it doesn't.

ZIERLER: What's the separation there? I wonder if you might explain how that's not relevant for what you do.

LIEBERMANN: Well, people in our field can study the properties of these materials at high pressure and temperature not directly, well, almost to the inner core if you have a very, very tiny specimen, and you're squeezing it between diamonds. But I don't think we obtain any information that's relevant to the rotation or lack of rotation of the inner core.

ZIERLER: Bob, how much of your research focuses on the lithosphere?

LIEBERMANN: Less, except that that's where earthquakes occur, and a lot of other things happen. [laugh]. My own research has been focused on the upper mantle and lower mantle, and the phases that are associated with that. But our laboratories also study the physical properties, rocks, and minerals that make up the lithosphere, and that has a lot of relevance to geological observations as well as dynamics of those reasons.

Under Pressure

ZIERLER: Bob, your work on phase transitions at high pressures and temperatures, what's creating the other? In other words, are the high pressures creating the phase transitions, or are the temperature fluctuations creating the phase transitions?

LIEBERMANN: It's primarily the pressure.

ZIERLER: Can you explain that? How's that work?

LIEBERMANN: Well, the pressure, if you take a simple mineral like quartz, SiO2, and you squeeze it, at about 20 kilobars, it transforms to coesite because there's no room to continue to squeeze the quartz. The atoms have to rearrange themselves into a more tightly packed arrangement. Then, subsequently, at 90 kilobars, it transforms to stishovite, which is a rutile-structure material. Even further, at maybe 300 kilobars, it transforms to an even higher-density phase. But it's primarily pressure. Now, the pressures at which these transformations occur depend on temperature mostly. First of all, you have to be at some high temperature, or the transformation is frozen, or it wouldn't occur. But even then, if you go to higher temperature, very often, the slope of the phase boundary is positive, which means you need more pressure to transform it than less.

ZIERLER: Bob, what do we know about atomic diffusion right now as it relates to mineral physics?

LIEBERMANN: Diffusion?

ZIERLER: Mm-hmm, atomic diffusion.

LIEBERMANN: [laugh] I don't know very much. You should ask Professor Karato at Yale.

ZIERLER: He's the authority?

LIEBERMANN: [laugh] Yeah. Well, diffusion's one way that heat is transferred, as are convection, of course. But I think in the mantle, convection probably is the dominant form of heat transfer.

ZIERLER: Tell me about your partnership with the NSF to create the Stony Brook High Pressure Laboratory.

LIEBERMANN: Well, we did that because I guess it was a question of chicken and egg. We applied for a grant back in the early 1980s for a special kind of high-pressure apparatus, and the NSF granted the funding for the apparatus and its installation. Then we went to the university and said, "Well, can you build us a laboratory where we could put this big monster?" So, they did. When the NSF found out that we had a place, and we were operating the press, in fact, several presses, they entered a proposal to allow us to have operating funds to make the facility available to other outside users, usually for cost. But, in any case, they could come and do their experiments themselves, or they could send us some money, and we could do the experiments. The preferred model was when they came and did their own experiments.

ZIERLER: What were some of the science objectives in creating the laboratory?

LIEBERMANN: It depends a little bit which one of us you talk to. For Professor Prewitt, who's a crystallographer, and was one of the Co-PIs, he wanted to understand the structure of materials at high pressure and temperature. My colleague Don Weidner developed an interest in the fracture properties and failure of materials somewhat related to earthquakes. My principal interest was measuring in the laboratory sound velocities so we could compare them directly with those revealed from seismic studies.

ZIERLER: What were some of the potential overlaps with regard to what was happening at Brookhaven at that time?

LIEBERMANN: Well, the big thing at Brookhaven was it had had a synchrotron and the powerful x-rays. With a smaller apparatus, we could take it to Brookhaven, put it in front of the x-ray beam, and we could see inside the specimen; not only take an x-ray of its crystal structure but also to allow us to measure the length of it directly in the x-ray beam. You shine an x-ray beam not because you want to know the structure but you want to see, have a visual picture of the specimen. As it shrinks, its length changes. What the velocity measurements measure is not the length and not the velocity. They measure a travel time, how fast the soundwave is moving up and down in the specimen. But you need to know the length to get the velocity, and so the synchrotron was incredibly valuable in obtaining the length directly and also the structure.

ZIERLER: While we're talking about national labs, I wonder what your interface was with the Advanced Photon Source at Argonne.

LIEBERMANN: We're users of the Advanced Photon Source at Argonne through one of the beamlines that's operated by the University of Chicago. The head of that is a former graduate student of mine.

ZIERLER: Bob, tell me about the transmission electron microscopy tool or TEM. How do you use that in your research?

LIEBERMANN: Mostly, it reveals the defects and other characteristics of the materials. But it has to be done once the material is in your hands, and not still in the press. It can only reveal aspects of the material that are so-called quenchable. In other words, you squeeze it to high pressure and temperature, and you get it back out of the press, and then you take it to the TEM, and study its microstructure.

ZIERLER: I'm curious if your research has ever gone into industrial uses, given simply the value of minerals.

LIEBERMANN: No, not directly. But, certainly, it has for other institutions like Carnegie and some places in Japan, where they're making artificial diamonds in large quantities and large sizes, much larger than original.

ZIERLER: As computers have grown in power over the decade, have you become increasingly reliant on simulation and modeling in your work?

LIEBERMANN: I haven't but some of my colleagues have, and that's why I mentioned theoretical or computational things, aspects of mineral physics. It's very powerful, and it's also very insightful.

ZIERLER: Beyond the United States, who are some of your key collaborators worldwide?

LIEBERMANN: For me, personally?

ZIERLER: Yeah.

LIEBERMANN: Japan, Australia, France, less so Russia and Germany but also. My collaboration with China has been primarily through some very outstanding Chinese students who have come to study for the graduate work at Stony Brook.

ZIERLER: Bob, just as a snapshot in time, what are you currently working on?

LIEBERMANN: In my semi-retirement, I'm working on history of science.

ZIERLER: Really?

LIEBERMANN: Yeah, well, I'm doing a couple things. I'm an unofficial co-advisor to some graduate students of my colleague Baosheng Li at Stony Brook. For about 10 years with my colleague Lars Ehm at Stony Brook, we carried out a diversity program, trying to bring in initially African-American students to our graduate program and, subsequently, Hispanic-Americans and students from disadvantaged backgrounds. In the course of 10 years, students in that program obtained master's degrees that made them marketable either at national laboratories or in industry. Now, more recently—and I guess "recently" means the last 10 years—I've started to write some papers about the history of high-pressure science, mineral physics, and I have a series going now of connections or collaborations between myself and our laboratory and foreign countries. I first did France, then the Czech Republic, then China, then Russia, then England. What am I on now? I guess there's one in review from Germany, and I have one on my computer for the Japanese. It's really more a personal thing. It's given me a chance to interact with a wide range of people from other countries who share similar research interests.

New Directions in Mineral Physics

ZIERLER: Bob, in your interactions with younger scholars and even students who are focused on their future, what are some of the exciting new directions in mineral physics that they might focus on?

LIEBERMANN: I think the most important thing is that they get trained in the techniques and theory associated with the field. Whether they go into industry and try to figure out how to make new materials, or try to solve some of the still unresolved questions of the deep mantle and the core, most of them probably won't go into academia but some of them have. Of the eight PhDs that I've supervised over the last 40 years, four of them have academic positions in the United States or in Australia.

ZIERLER: Well, Bob, let's go all the way back now to your time at Caltech as an undergraduate, just to set the stage. When you were thinking about applying for colleges, was it specifically geology and geophysics and seismology that you were interested in, even in high school?

LIEBERMANN: Well, in high school, I think I thought I wanted to be a mathematician. I went to Caltech in 1960, and my freshman roommate from San Diego was a real mathematician, and I realized [laugh] very quickly that I wasn't a mathematician. [laugh]

ZIERLER: [laugh]

LIEBERMANN: I started to think about physics but it was very competitive at Caltech. I tried electrical engineering but, fortunately, I attended the first-term class of Bob Sharp, the chair of the geology department, and he just was captivating. He was a glaciologist. I never studied glaciers but he was just fascinating, and it drew me into geology. When I finished at Caltech, I wanted to go to graduate school in geophysics, and so I applied to a number of places. The thing that attracted me to Columbia was the seismology program, and the first few years, I worked in seismology. Then a new professor came from Bell Laboratories to set up a high-pressure laboratory, and study mineral physics. He didn't have any graduate students, and the seismology professors had a lot of graduate students, so I sort of figured I might get more attention from him. The rest is where I finished my PhD.

ZIERLER: Bob, from that first class with Bob Sharp, how long before you were spending time at the Seismo Lab?

LIEBERMANN: As an undergraduate, I only spent time as a visitor. We'd go out and see some of the materials. This was back then people like Gutenberg and Richter and [laugh] Benioff—well, maybe not Gutenberg—but Richter and Benioff [laugh] still were alive. It was sort of like field trip for the undergraduate [laugh] students. At that time, Frank Press was the director. Then later on, as I was transitioning from Columbia to Australia for my research faculty position in Australia, I spent 10 months at Caltech as a postdoc, funded by Don Anderson, who thought I was going to work on high-pressure mineral physics. But, at that time, a few underground nuclear explosions occurred in Nevada and the Aleutians, and I got sucked into analyzing those. I don't think Don ever forgave me because [laugh] he didn't really count beans so much [laugh] but he probably was paying me out of his mineral physics grant. [laugh] But one of the advantages of being there is that Hartmut Spetzler had been setting up the high-pressure laboratory for Don, and I got a chance to interact a lot with him and with Rick O'Connell. He'd finished his PhD, and he was doing some experiments with Spetzler.

The Importance of the Coffee Hour

ZIERLER: Bob, even as a visitor, when you went to the Seismo Lab as an undergraduate, what sticks out in your memory? What was special about it?

LIEBERMANN: Well, all the seismographs, I think, were the first impression. Although I didn't participate then, of course, when I was back as a postdoc, the biggest impression was the coffee hour in the morning and the afternoon. It was in the basement. Even for non-coffee drinkers, that was such an incredible, stimulating experience because you could ask any one of the professors or staff any question you wanted to, and they'd answer it, and you didn't have to get an appointment to go in their office. Especially for young people like me, and some of the other postdocs, it was just fantastic. When we weren't in the coffee room in the basement, we were out on the tennis court playing. There was a beautiful tennis court at the lab. I don't know whether it still exists. My wife and I would go out on the weekends, and we had a young 5-month-old baby, and we'd put her in a carry cot. While we played tennis, she slept. That's not really a scientific observation.

ZIERLER: [laugh]

LIEBERMANN: But the old lab had a character. When I went back to in the 2000s to visit Caltech on a number of occasions, of course, it was stimulating to see old friends and colleagues. I understand why the Seismo Lab moved to the campus, because then there was a much stronger interaction between the people at the lab and the rest of the geology department or geological sciences, I guess, department. But you lost the character, and you lost the coffee hour.

ZIERLER: [laugh]

LIEBERMANN: They still had coffee but it didn't have the same atmosphere of informality and stimulation.

ZIERLER: As an undergraduate, did you ever have interaction with people like Press or Benioff?

LIEBERMANN: Not with Benioff. With Press, certainly, except that he was so busy negotiating test ban treaties in Geneva that he couldn't teach his class, so they had to bring in Leon Knopoff [laugh] from UCLA to do it. Somewhat later when I was a graduate student, Press was important for me because I was studying nuclear explosions in Algeria, funded by the US Air Force. After we finished the research and wanted to publish the paper, the Air Force embargoed our paper, which is not very helpful to a graduate student who needs a degree. Frank Press intervened because he wanted the results of the paper to help him in his negotiations in Geneva, so that was my connection with Press, which wasn't so direct. But Don Anderson was an incredible influence, not only in the undergraduate course he taught but stimulating me to go on in mineral physics, and just a fantastic role model for me, and a good friend. He passed away a few years ago. But he was the director when I went back after as a postdoc.

ZIERLER: Now, as an undergraduate, do you remember what Anderson was working on at that point?

LIEBERMANN: It was probably still seismology. Yeah, it was still seismology. It wasn't till later on that he decided he wanted to get in the mineral physics game, and so he got a Guggenheim Fellowship, and just wrote a check to Hartmut Spetzler and said, "Build me a lab." [laugh] It's a good thing it was Hartmut Spetzler because he's a very clever engineer, and he literally bought some things and built the laboratory for Don. Don always had an interest in the composition of the Earth and mineral physics—I mean, the composition of the Earth. He figured out an important way to learn more about it was to get into mineral physics. We have a competition between Don L. Anderson at Caltech and Orson L. Anderson at Columbia. They published papers almost simultaneously in the mid-60s. We sometimes had put their first name in because D.L. and O.L. was hard to distinguish in small print. Anderson was certainly a fantastic influence on me—Don Anderson from Caltech.

ZIERLER: Bob, what was your major at the end of the day at Caltech? What degree did you graduate with?

LIEBERMANN: Geophysics.

ZIERLER: Geophysics, so how come you were not spending the majority of your time at the Seismo Lab? Was that not common for undergraduates at that point?

LIEBERMANN: No. Well, it was for some but not for me.

ZIERLER: What was different for you?

LIEBERMANN: Well, I wasn't doing much research. It was almost completely an academic degree with courses.

ZIERLER: What kind of advice did Anderson or others give you about what graduate schools to apply for?

LIEBERMANN: We looked for places that had strong geophysics programs. That's been a long time. University of California at San Diego was just forming at that time. I applied there. Columbia. I don't know whether I applied to MIT or not. There were a couple of others, including Princeton. I'm sorry, I'll have to dig it out. [laugh] Maybe UCLA too.

ZIERLER: Why, ultimately, did Columbia win out?

LIEBERMANN: Well, a couple of reasons. They gave me a very handsome fellowship, and my girlfriend, about to be my wife, was a French major, and we thought it'd be nice if we got a chance to go to graduate school together. She was admitted in languages at Columbia. I was admitted in geophysics. I could've gone to Princeton but she didn't want to go there. She could've gone to Yale but I didn't want to go there. [laugh] It was a good decision.

ZIERLER: What kind of geophysics did you want to specialize in once you got to Columbia?

LIEBERMANN: The first three or four years, it was clearly seismology. I suppose, in some ways, it's an accident. A large earthquake occurs in 1964 in the Aleutians. Then, a little later, the Americans set off an underground nuclear explosion in the Aleutians. Professor Oliver said to some of us graduate students, "OK, you study this part, you study that part," and I got the part looking at the underground explosions.

ZIERLER: What were some of the big debates at that point in the field?

LIEBERMANN: The biggest debate, of course, was whether plate tectonics was a reality, and I spent six years at Columbia doing nothing relevant to [laugh] plate tectonics. But it was such an exciting time to be there. Studies in the Tonga region by Oliver and Isacks and Sykes revealed the way plates were subducted beneath the trenches in the Tonga Trench. Things were developing in England. The name "plate tectonics" was given to it by a British scientist. But Oliver and Isacks and Sykes called theirs "new global tectonics," which was an accurate description of the phenomenon but it wasn't sexy enough to be plate tectonics. I guess McKenzie and Parker and others won out on that one. But even if you weren't working on that, there was just no escaping how exciting that was.

ZIERLER: Bob, what was the process for putting your thesis research together?

LIEBERMANN: I put together a number of papers that I had written. One of the things that was helpful is Anderson encouraged us to write papers in advance of submitting a thesis. I think I had four or five papers. He said, "Well, why don't you paste them together as chapters, and write a summary, and we'll see what happens." I had three or four papers in seismology, and I asked Jack Oliver, "Should I put those in because it's more bulk and heft?" He said, "Please don't. Then I'd have to read them again." [laugh]

ZIERLER: [laugh]

LIEBERMANN: To me, what they guided my graduate research in a significant way was to realize that you don't wait to the end to publish anything because it's much easier to write a 10-page paper than a 100-page thesis, and it's also much easier for the supervisor to help you learn how to write science. I have the same problem with my own graduate students. I'd rather they learn to write science papers, short ones. It doesn't have to be earth-shattering. But then when they are ready to write their thesis, you don't have to micromanage every line and paragraph.

ZIERLER: What were some of the central conclusions of your thesis?

LIEBERMANN: My thesis was focused on the effect of iron, and its role in other materials that were mostly magnesium and silicon and oxygen. That helped us understand some of the features that occur as you bury minerals deeper inside the Earth. I don't know whether it was during the—no, it was during the PhD. I also discovered somewhat esoterically that if you take the material hematite, Fe2O3, and you cool it at about -10 degrees Celsius, it undergoes a magnetic transition, which may have nothing at all to do with the Earth because it's at below room temperature. But it was fascinating because of the way the soundwaves interacted with the magnetic structure, and those were some of the chapters of the thesis.

ZIERLER: Bob, did you have to do much field work for your thesis research?

LIEBERMANN: I didn't. I was a little foolish. I guess I was homebound, and enjoyed New York and our new wedding. But my colleagues were running off to Tonga and Fiji and the Aleutians at a moment's notice. My big field trip was to Upstate New York where a small earthquake occurred in Attica [laugh]—I don't know—magnitude 3 or 4. Oliver sent a couple of us up there to put seismographs out to see if there were any aftershocks. But that was the extent of my field work, so not very exciting.

ZIERLER: Bob, what was the means for data coming back into Columbia when you were a graduate student? Would it come on disks, paper? What did it look like?

LIEBERMANN: Some of it came on paper or photographic copies. The Air Force had helped set up the World-Wide Seismic Network some years ago, and you could get paper copies. But Lynn Sykes, a former graduate student and now a professor at Columbia, decided he would buy the entire catalog of all the seismic stations operated by the World-Wide Seismic Network. You had these little magnetic chips, and you put them in a reader, and you could study them. That was the level of technology, but there were no disks at that time.

ZIERLER: Who was on your thesis committee?

LIEBERMANN: Orson Anderson, Lynn Sykes, Jack Oliver, a physicist. There must've been somebody else—maybe Chuck Drake.

ZIERLER: Did you know even before you defended that you would want to come back to Caltech for your postdoc?

LIEBERMANN: I'm not sure because, primarily, I had applied for a research faculty position at the Australian National University, and I had that in my pocket. But I wanted to spend some time between Columbia and Canberra. I was lucky enough that Don offered me a chance to spend 10 months at Caltech. As I said, it had the distinct advantage of being able to think about how to set up my laboratory in Australia because I could work with Spetzler and O'Connell.

ZIERLER: Now, when you got back to Caltech, did you see it more as an opportunity for new research, or did you want to refine and improve your dissertation?

LIEBERMANN: I guess my primary things I hoped to get out of the 10 months was a little more exploration of the question of distinguishing between underground nuclear explosions and earthquakes, and learning a little bit more about the technology of setting up a laboratory in mineral physics.

ZIERLER: Now, by the time you returned, had the Seismo Lab already moved to campus?

LIEBERMANN: No.

ZIERLER: You were in the Mansion for your postdoc?

LIEBERMANN: I was in the Mansion, yeah. It was great.

ZIERLER: Tell me what had changed even from your time as an undergraduate.

LIEBERMANN: Well, it was a high-pressure laboratory, a few more offices. I think at one point in that period if time, Clarence Allen was the acting director. Anderson must've been off doing something else. Since I had had only sort of occasional visits to the lab, I'm not sure I could distinguish it. The big difference was when they moved the Seismo Lab to the campus.

ZIERLER: Tell me about your project. What were you focusing on when you were back at Caltech?

LIEBERMANN: Well, I think I got distracted, as I mentioned before. [laugh] I thought I was going to do experiments, but I mostly watched Spetzler and O'Connell do their experiments, and think about how to set up a lab. Mostly, I studied a few extra nuclear explosions in the Aleutians.

Seismic Waves from Earthquakes and Explosions

ZIERLER: What were some of the challenges in that project?

LIEBERMANN: One was to figure out how the seismic waves from explosions might differ from natural earthquakes that occurred in the same region. We noticed that earthquakes of the same body-wave magnitude had much smaller surface—earthquakes had much larger surface waves than underground nuclear explosions. We could almost distinguish an explosion from an earthquake just based on the size of the surface waves for materials and for events of the same body-wave magnitude. Gutenberg and Richter had drawn a line years ago of surface-wave magnitude versus body-weight magnitude, and they put a lot of earthquakes on it. But if you went region by region, whether it was Nevada, the Aleutians, Algeria, or the Russian explosions, and you plotted the earthquakes and the underground nuclear explosions on this surface-wave magnitude versus body-weight magnitude diagram, there was a clear separation in every region. We wrote that up in a couple of papers ending up in '71, by which time I was in Australia.

ZIERLER: What brought you to Australia at that point?

LIEBERMANN: Well, they were among the major high-pressure laboratories in the world. It was one that Ted Ringwood had set up years ago. He was primarily a geochemist and a petrologist, but he wanted to hire somebody to set up a laboratory to measure sound velocities. There were a few of us graduating at about that time who were obviously qualified to do that—some more than me. Spetzler went to Colorado. O'Connell's family didn't want to move that far away from France, where his wife was from. My wife was willing to move to Australia, sight unseen. [laugh]

ZIERLER: A bit of an adventure for you?

LIEBERMANN: Yeah, I got the job, and we spent six years, had two more children, and my wife worked at the French Embassy in Canberra. She never would've been able to do that in New York. But, of course, there weren't that many near-native French speakers [laugh] sitting in Canberra, so she did that.

ZIERLER: Tell me about seismology.

LIEBERMANN: It was really the Ringwood laboratory. Jaeger and Ringwood had set up the Department of Geophysics, which later on became the School of Earth Sciences. I would argue and have argued that it was one of the 10 best departments in the world.

ZIERLER: How far back does geophysics and seismology go at ANU? Is it a long-standing program?

LIEBERMANN: It probably goes back to the mid-50s.

ZIERLER: Are there some Australian-specific components to seismology in geophysics there? Are they focused specifically on the Australian continent?

LIEBERMANN: No, they've done work in the continent, but some of them are studying all over the world, seismology.

ZIERLER: Tell me about the lab. What were the objectives that got it up and running?

LIEBERMANN: I had worked at Columbia on materials that we could buy or find in nature. Ringwood's specialty was in phase transformations at high pressure that he studied from a petrological or geochemical point of view. He said, "Do you think we could make artificial specimens of these high-pressure phases, get them back at room temperature and pressure, and measure the sound velocities?" I said, "Well, if you and the people in your laboratory can make the specimens, I'm sure we can measure them." My job was to measure the specimens. Initially, we'd do five or ten experiments before we got something. What we wanted to do was create an artificial rock of some high-pressure phase, and it had to be fine-grained, homogenous, no cracks, no pores, high-density, and able to transmit high-frequency acoustic waves without attenuation. That became the challenge. Once we had such a specimen, I wouldn't say it was trivial but it was much easier to then measure its sound velocities. We did that to relatively modest pressures in Australia. Later on, we've learned to do it at pressures equivalent to the lower mantle of the Earth.

ZIERLER: What were you finding in some of this research? What were some of the big answers that you were looking for?

LIEBERMANN: We were looking to see whether we could use these data to interpret the changes of velocity and density that occurred within mostly the upper mantle, and the transitions going from 300 to 600 kilometers—700 kilometers, I'm sorry. We wanted to see how the effects of pressure, temperature, and change of crystal structure affected the velocities. We found out that it depended a little bit on how the atoms were rearranging themselves. Were they just being squeezed together more tightly, or were they actually breaking bonds, and rearranging themselves in a new configuration? Those differences of how the structure was changing was critical in being to predict and utilize their velocities?

ZIERLER: Did you join the faculty in Australia?

LIEBERMANN: I did. I went there as a short-term postdoc; a three-year appointment that could've been renewed for another three years. After three or four years, a new director came, and I said, "Look, I need to know something about my future here in Canberra." He said, "Well, I'll appoint you as senior research fellow," which could've been a career appointment. It turned out I left after six years, but that was the structure of it.

ZIERLER: What were the circumstances of you returning back to the United States?

LIEBERMANN: I think both my wife and I felt that we'd like to live back in the States while our parents were still living and could enjoy the grandchildren. Don Anderson had an important influence because he came for a research visit to Canberra. He said, "You're running the risk of getting too old to be hired as a junior faculty member in the States. You better think about this." I decided to apply, and see what happened, and I had offers at a number of places—not Caltech but a number of other good places. Then, oh, I also had asked Ringwood and his colleagues, "Is there any future for me at Canberra?" They said, "No." Then I went out and found a couple jobs, and walked into the director's office. I said, "Well, I'm leaving." He said, "Well, we're just about to appoint you a professor here." [laugh]

ZIERLER: [laugh]

LIEBERMANN: I said, "I'm sorry, it's too late." [laugh]

ZIERLER: They changed their mind midstream, and didn't tell you?

LIEBERMANN: It was a professional decision but also a personal one. It was a good decision because our kids got to know their grandparents. Coincidentally, we moved to Long Island, and their grandparents lived there. I never told my wife's mother that we didn't go there because of her.

ZIERLER: Of course. [laugh]

LIEBERMANN: [laugh] But it won me a few points. [laugh]

ZIERLER: [laugh] Tell me about the program at Stony Brook when you joined in 1976. How big was it?

LIEBERMANN: The geophysics program was one person, Don Weidner. They decided they were going to advertise a job in geophysics, and he was the chair of the search committee. Quite surprisingly, or nicely, he decided he'd recommend that they hire another mineral physicist, even though we didn't have any seismologists [laugh] or geodynamicists or anything else. It was great because, in addition to Weidner, there were a number of petrologists and mineralogists and crystallographers. The department was really oriented—unlike many American universities—to be experimental and analytical. I didn't have to go find a transmission electron microscope. I didn't have to go find an electron microprobe or an x-ray laboratory. All these things were there, run by other faculty, and it made it a perfect place for us to develop high-pressure mineral physics.

ZIERLER: How did you and Don go about growing the program over the years?

LIEBERMANN: Initially by students and postdocs, and then, gradually, we added a rock mechanics guy, even one of the theoretical mineral physicists, and this crystallography program [was started] and Prewitt left for Carnegie. Parise came and then later Lars Ehm, who were crystal chemists, crystallographers, but much more interested in mineral physics. If I say, "What is the geophysics program?" it doesn't include them but there's this very strong intellectual connection on a day-to-day basis.

ZIERLER: Was the NSF always the primary funding agency for your work at Stony Brook?

LIEBERMANN: Yes. Later on, I got involved in some work with—not the DOE, no—part of the Department of Energy, monitoring the seismic threat to nuclear facilities like the ones on Long Island, or one that was never built on Long Island but was planned power plants.

ZIERLER: What were some of the big research projects you wanted to take on once you joined the faculty at Stony Brook?

LIEBERMANN: Well, I think it was primarily to begin to explore at higher pressures and temperatures the things that we had developed at modest temperatures and pressures in Australia, and try to use those to interpret Earth models that seismologists handed to us.

ZIERLER: To go back to the earlier question when you were a student, how much field work were you doing at this point, or was it all laboratory experiments?

LIEBERMANN: It was all laboratory experiments.

ZIERLER: Where did the samples come from? How do you obtain samples to work with?

LIEBERMANN: We mostly made them in a laboratory.

ZIERLER: Everything is synthetic, essentially?

LIEBERMANN: Well, there were some natural materials, pyroxenes and others, quartz, that were natural. But a lot of them were synthetic.

ZIERLER: What were some of the safety considerations you had to think of in developing these experiments?

LIEBERMANN: Well, you're putting things under extremely high pressures, and that involves some high-pressure hydraulic lines, and we had to be very careful to have those shielded. The operators had to operate it at some distance. If you've ever had a hydraulic line blow up on you, you realize you could lose eyes [laugh], arms. These were solid media apparatus. It wasn't like you're compressing a gas. When you're compressing a gas, you really have serious safety issues, and so you build a whole room around the apparatus, and nobody goes in when it's under pressure. We didn't have to do that.

ZIERLER: When you created the High Pressure Laboratory, how much instrument building did you need to do? What was off the shelf? What did you need to create from scratch?

LIEBERMANN: Most of it was off the shelf from small companies in the United States, one on the West Coast, and one in Massachusetts. But most of the apparatus that we built, we imported, came from Japan. They had pioneered a lot of this, and it was senseless to try to reinvent the wheel. It was much more sensible and realistic to find the money to go buy the apparatus. The NSF was very generous in supplying us money to do that.

ZIERLER: Given how unique the laboratory was, did it become a magnet for outside researchers who wanted to come and use the facility?

LIEBERMANN: Yes. In addition to our students and faculty, there were people from the other departments on campus, and all over the country would come. Now, that's not necessary because there are a dozen or more equivalent laboratories in the United States built by people that had some association with us initially, or developed their own apparatus independently. But it certainly created a magnet for people to come, and that was great because then we got intellectual interactions as well. That was part of the continued connection with Australia; a developing connection with France. The Japanese had their own high-pressure apparatus, but they would still come, and we'd swap secrets.

ZIERLER: Did the High Pressure Laboratory offer possibility for scientists even beyond mineral physics?

LIEBERMANN: Yeah.

ZIERLER: Like what? What kind of disciplines could use it?

LIEBERMANN: Well, some people wanted to study magnetic materials at high pressure. I had a colleague in the physics department who funded a postdoc to do experiments in our lab. DuPont sent some people initially to do experiments to improve the materials they were producing. They later decided that wasn't cost-effective, so they paid one of my graduate students to do the experiments. [laugh]

ZIERLER: The hydraulic presses you were using, can you explain the difference between the SAM or the SAM85 and the SAM95?

LIEBERMANN: It's primarily a question of scale.

ZIERLER: Scale relative to what? What does that mean?

LIEBERMANN: Scale relative to the size of specimen you can produce or study. That's true. You probably know that diamond anvil cells are used throughout the world to compress materials to extremely high pressure, much higher pressure than we can reach. But the specimens that are produced or studied are tiny. For us, the reason to get a more powerful hydraulic press was to make a bigger specimen; not necessarily to reach higher pressure, but you could do that too.

ZIERLER: When researchers from DuPont or other industry came to the lab, were there any applications that were created as a result, or materials that weren't known before?

LIEBERMANN: Not that I remember.

ZIERLER: It was all basic science, essentially?

LIEBERMANN: Yes.

NSF Support for High Pressure Research

ZIERLER: Tell me about the creation of the NSF Science and Technology Center for High Pressure Research. Was the High Pressure Laboratory the impetus for that larger endeavor?

LIEBERMANN: Yes. It was back in the Reagan era when President Reagan decided we had to catch up with the Japanese. [laugh] He encouraged the NSF to create these Science and Technology Centers. There were originally, I think, 12 set up. Then in the next round, another 11 or 12. We were in the second round, having learned how to write a better proposal. But ours was to link three different institutions: Stony Brook University, Princeton University, where our colleague Alexandra Navrotsky was, who was a geochemist. By that time, Charlie Prewitt had moved to the geophysical laboratory in Washington at Carnegie. We created this triumvirate where each of the three nodes would specialize in some aspect of mineral physics using some of the equipment at the other places or sending specimens or sending students. The primary impetus was to create this triumvirate of complementary research programs, but also to have sustained funding. We got funding that extended for 11 years, and then there was a natural—what do you call it?—not death. [laugh]

ZIERLER: Requisitioning?

LIEBERMANN: [laugh] No, none of the Science and Technology Centers had more than an 11-year lifetime because the NSF didn't like to have things that went on for perpetuity.

ZIERLER: Right. What happened after 2002 to the Center?

LIEBERMANN: The Center dissolved, in a sense, and COMPRES grew out of it. What we decided to do, to a certain extent, the Center for High Pressure Research, CHPR, was an elitist collaboration. We worked with and talked to other people but, basically, we were trying to dominate the field. The idea with COMPRES—and Weidner had this concept—was to sort of expand the domain of these new techniques that had been developed through the entire geophysics and geochemistry community. It was a little bit more of a service organization.

ZIERLER: Now, with the creation of COMPRES, I'm curious, at what point do you start to focus really deeply on the polymorphic phase transformations in minerals?

LIEBERMANN: We had done that—

ZIERLER: Throughout?

LIEBERMANN: —some 20 years, throughout, yeah.

ZIERLER: With COMPRES, did that change at all what you were working on?

LIEBERMANN: It didn't change what I was working on, no, except that we—as you asked before—we made increasing use of the synchrotrons at Brookhaven and at Argonne.

ZIERLER: Where did you make ultrasonic measurements?

LIEBERMANN: Anyplace we could. [laugh] I knew how to measure things with ultrasonic apparatus from my graduate days at Columbia, and I learned even more when I worked with Ian Jackson at the Australian National University. We've developed techniques. My former student Baosheng Li, and now faculty colleague, collaborated with Jackson in the '90s to figure out a way to do these high-frequency ultrasonic experiments inside the high-pressure apparatus. We weren't taking a material, and squeezing it, and making a specimen, then taking it out and studying it on the bench. We were actually measuring the velocities in situ.

ZIERLER: When did you first meet Olivier Jaoul?

LIEBERMANN: I met Olivier Jaoul in 1976 in what was then Czechoslovakia. He was a young student of a French professor, and he brought the student along, and we talked. Later on, I decided I wanted to have a sabbatical from Stony Brook, and so I applied to the Université. It's called Paris 11 in Orsay. I walked in the first day, and the professor said, "Well, you have to do something while you're here. I'm giving you part of a salary but there's this guy Jaoul. He's doing measurements of diffusion at high temperature. Why don't you go see him and work with him?" I spent most of that year, and those experiments were done at atmospheric pressure. Later on, Jaoul and his proteges came to our laboratory, and we learned how to do those experiments at high pressure, so 1976 to when he died a few years ago.

ZIERLER: Then your later visit in 2002 and 2003 when you were in Toulouse, was that a continuation of your previous research?

LIEBERMANN: Yes. Jaoul and his colleagues, had moved their laboratory from Orsay to Toulouse, and so I said, "Well, maybe it'd be fun to be in the South of France." You must've read my CV.

ZIERLER: Absolutely, I prepare. [laugh]

LIEBERMANN: [laugh]

ZIERLER: Bob, in between, you spent some time at the University of Tokyo. What were you doing there?

LIEBERMANN: What was I doing? In the first time, the sabbatical, it was primarily in France but there were a couple months in Japan. I was consulting with Akimoto's laboratory in Tokyo. But, at that time, we had just received some funding to buy a high-pressure apparatus or install it at Stony Brook. With Weidner and Prewitt, I did a little shopping trip in Japan. I didn't do any experiments in Tokyo but I got a chance to talk to Akimoto and his colleagues about what kind of apparatus made sense for us to import to the United States.

ZIERLER: Bob, when you stepped down leading COMPRES in 2010, what happened to COMPRES? First, is it still in existence today?

LIEBERMANN: It is. It's about to transform to a newer configuration. But when I stepped down in 2010, the COMPRES executive committee appointed Jay Bass from the University of Illinois to be the president, and he served for five years. COMPRES headquarters moved to Urbana-Champaign, and we continued to be an integral part of it but I had no specific role in it. Then, as I said, it's now in New Mexico.

ZIERLER: Bob, tell me about winning the Edward A. Flinn Award from the AGU. What were you being recognized with that honor?

LIEBERMANN: It's a service award for service to the community. It's not for research, not for education, it's for spending a lot of seat time in committees—

ZIERLER: [laugh]

LIEBERMANN: —and serving on advisory committees for the National Science Foundation. It was a great experience, doing those things. But I got a nice reward and a little trophy for the seat time. One of the most meaningful things is—it's the Flinn Award, right?

ZIERLER: Yes.

LIEBERMANN: When I was a graduate student, Ted Flnn was just leaving Caltech, and so I got to know him. He was later a program director in the Air Force and Department of Defense, and we managed to arrange some funding. But it was nice to be able to have his name on that award.

ZIERLER: Another fun honor, there is a meteorite named the Liebermannite after you. I wonder if you could tell me about that and how that came about.

LIEBERMANN: Well, that was a surprise. Colleagues at University of Nevada and at Las Vegas—and where's the other one? UCLA maybe.

ZIERLER: No, I think it's Caltech.

LIEBERMANN: It's Caltech? No, that's Caltech. It's the electron microscopists at Caltech. They discovered in the meteorite this high-pressure form of potassium, aluminum, silicate, and it has a so-called hollandite structure. They offered to or invited me to—they'd proposed my name to name it after me. I had to agree. The International Mineralogical Association oversees this. I had to agree to that, and I had to agree to never allow that to happen again, so I can't have another mineral. I never worked on that material but I worked on the equivalent one that has germanium in the place of silicon when I was in Australia. I don't know whether that had anything to do at all with their choice, but it was a nice thing.

ZIERLER: Bob, more broadly, that leads me to wonder if any planetary research beyond Earth has ever been relevant for your research, like, for example, Mars Sample Return in 2028. Are there things that are potentially exciting in terms of what you do?

LIEBERMANN: I'm sure there could be. I'm not directly involved but two or three of our faculty at Stony Brook are heavily involved in the Mars, planning for that mission. I'm sure if they bring back specimens, there'll be somebody who wants to measure them.

ZIERLER: Bob, moving closer to the present, when you decided to become research professor, what opportunities did you have with that extra bandwidth, not doing so much service work? What kind of research did you want to focus on really from 2014 right up to the present? What's been most interesting to you?

LIEBERMANN: Well, I would say two things, both of which I mentioned before. One was to continue to have a connection to some of the research graduate students of other faculty. The other was to be eligible to obtain research funds. Some of those research funds came from the NSF for diversity. You probably know that, except for physics, the geological sciences have the worst reputation or worst record for diversity in all of science, all the STEM fields. I thought, well, I'd had a former student from Delaware State University, who was originally from Cameroon but now is an American citizen. He had come and done a PhD with me in the '90s. We thought, well, maybe we can do something small about this in the NSF division. No, it's the Directorate of Geosciences created a program called Enhancing Opportunities for Diversity in Earth Sciences. We applied for a small grant for that, and got some money, and were able to recruit some students, partially from Delaware and other institutions. Gabriel said, "Please don't make it a high-level research PhD program only because these students, they might've been the first in their family ever to go to college. They might've accumulated a lot of debts. Maybe they're supporting their younger siblings. If you try to recruit them into a five- to six-year program at a graduate student's salary, they're not going to be able to do it." We created a program that was designed to be a two-year master's, coursework plus immediate involvement in research that could be publishable, and that's how we recruited the two students from Delaware, one from South Carolina, and one from Trinidad, and then a young woman who was a single mother. It's a little bit embarrassing because this is a small drop in the bucket of the issues associated with enhancing the opportunities for a diverse population in STEM. But that was an important part of what I did in the last eight or ten years, plus the history of science.

ZIERLER: Bob, for the last part of our talk, I'd like to ask a few retrospective questions, and then we'll end looking to the future. Between your time as an undergraduate, and then circling back as a postdoc, what did you learn at Caltech in the Seismo Lab that stayed with you, no matter what you've done in your approach to science, in problem-solving, in collaborating with your peers?

LIEBERMANN: Well, I think most of the experience as an undergraduate was associated with courses. You'll probably get a debate on the campus about this but not only were the geology faculty among the most collegial people, unfortunately, at that time, only men, but an outstanding mineral physicist is now on their faculty, Jennifer Jackson. But they were outstanding teachers. Many of the physics courses I took and the ones in applied mathematics were just so cold and analytical that you never thought you wanted to be like that. I think it was the atmosphere of the people in the entire geological sciences faculty that influenced me most as an undergraduate.

ZIERLER: Finally, Bob, last question looking to the future. For however long you want to remain active, you want to remain a research professor, what's the research out there that you haven't done yet but you want to?

LIEBERMANN: I'm not doing experiments in the laboratory anymore but I'm trying to encourage the young graduate students to develop their interest and expand their horizons. In some cases, I actually get involved in the research but only rarely. One of the students wanted to study the high-pressure form of quartz called coesite a few years ago. I said, "Well, I think I have a specimen that I made in 1975 in Canberra." We found it, and they published a paper. In that case, I became the co-author. The other role I'm playing is English editor. [laugh]

ZIERLER: [laugh]

LIEBERMANN: These students write incredibly well in English. I'm not sure the average American [laugh] student coming out of high school or undergraduate writes any better. [laugh] Writing science is different. I'm not trying to alter their science. I said to their advisor, "Baosheng, look, if you're sending me a paper to look at, I'm not going to change the science, and I'm certainly not going to change the style because everybody has their own voice in the way they write. But to help the reviewers and editors of these papers when they're submitted, I'll make pretty sure it's in perfect English." That's part of what I'm doing.

ZIERLER: Finally, Bob, last question looking to the future, what are some of the remaining question marks in mineral physics for which you have optimism you'll be around to see them, or the students that you've trained and you've been a part of, they'll be there to make those breakthroughs?

LIEBERMANN: I think it wouldn't be so much as expanding the pressure and temperature ranges that are going to be achieved in the laboratory. It would be moving on to other experiments that are more difficult, different kind of physical properties, properties of diffusion and other things, unlike just the sound velocities.

ZIERLER: Bob, it's been a great pleasure spending this time with you. I'm so glad we were able to do this and to capture your memories. Thank you so much.

LIEBERMANN: Well, you're very welcome.

[END]