Douglas Scalapino

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ORAL HISTORIES

Credit: University of California, Santa Barbara

Interviewed by
David Zierler
Interview date
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Remote Interview
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Interview of Douglas Scalapino by David Zierler on May 7, 2020,Niels Bohr Library & Archives, American Institute of Physics,College Park, MD USA,www.aip.org/history-programs/niels-bohr-library/oral-histories/45434

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

In this interview, David Zierler, Oral Historian for AIP, interviews Douglas Scalapino, Research Professor at UC Santa Barbara. Scalapino recounts his childhood in San Francisco and then Scarsdale, New York, he discusses the circumstances leading to his admission to Yale, and he describes how he settled on physics as an undergraduate after getting to know Professor Larry Biedenharn. Scalapino discusses his graduate research at Stanford, where he worked under the direction of Mitch Weissbluth conducting radiation chemistry using a small linear accelerator to see free radicals created by the electron beam. He describes his burgeoning interests in electronic spin resonance and magnetic resonance. Scalapino explains the circumstances leading to his decision to finish his thesis work with Ed Jaynes at Washington University while working for Kane Engineering. He discusses his postdoctoral research at the University of Pennsylvania with Bob Schrieffer and Henry Primakoff. He discusses his work at Bell Labs, where he worked with Phil Anderson, and he describes his first faculty position at Penn. Scalapino describes how UCSB recruited him, and he explains how his hire was part of a broader effort to raise the stature of the physics department. He recounts the virtues of working in a small department, where opportunities were available to collaborate with Bob Sugar and Ray Sawyer on high-energy physics, and Jim Hartle on astrophysics and general relativity. Scalapino describes the origins of the Institute of Theoretical Physics and how the National Science Foundation came to support UCSB’s proposal. He reflects on how the ITP has benefited the department of physics over the years, and he provides an overview of his research agenda at UCSB, which includes his contributions to the quantum Monte Carlo project and high-Tc and unconventional superconductors. At the end of the interview, Scalapino discusses his current interests in the numerical simulation of quantum many body systems.

Transcript

Zierler:

Okay, this is David Zierler, Oral Historian for the American Institute of Physics. It is May 7th, 2020. It's my great pleasure to be here with Dr. Douglas Scalapino. Doug, thank you so much for being with me today. 

Scalapino:

Thank you, David. It's very nice to talk with you at what is, I know, a difficult time.

Zierler:

So, to start, please tell me your title and institutional affiliation. 

Scalapino:

I'm a Research Professor at the University of California - Santa Barbara and work partly at Oak Ridge National Lab in Tennessee. 

Zierler:

In what capacity? As a consultant?

Scalapino:

I have a joint DOE contract with Oak Ridge National Lab where part of the funding comes to UCSB. 

Zierler:

Great. Let's take this right back to the beginning. Tell me about your birthplace, your family background, and your childhood. 

Scalapino:

I was born in 1933, December 10th, in San Francisco. My parents had both grown up in Kansas. My mother’s parents had immigrated from Norway and my father’s parents from Italy. They lived in a town called Everest, Kansas, not far apart. They were married in 1929 and came out to San Francisco where my father worked. Earlier, two of my father’s brothers had come out to Santa Barbara. I grew up in the San Francisco bay area but remember many visits to see my aunts, uncles and cousins in Santa Barbara.

Zierler:

What brought your father to San Francisco?

Scalapino:

He wanted to be a lawyer, and he was in law school at Berkeley when the Depression hit. He was lucky enough to find a summer job and stayed on working for a company called Graybar Electric. He gave up being a lawyer and became a businessman. So, we lived in the bay area, San Mateo, until 1947, when we moved to Scarsdale, New York, when my dad was transferred to the main office of Graybar. That was somewhat of a shock to me. I had been in a school that had 12 of us in my class. We'd had the same teacher for three years, and we stayed in the same classroom. I arrived for 9th grade in Scarsdale, at Scarsdale High School, which is a very fine high school, but very different from what I was used to. You had to go from room to room, of course, and it was a very elegant place, and a very good education. I was lucky and went on from there in 1951 to college. A friend of mine had decided to go to Yale, and I thought, well, that probably sounds fine. So, I decided to go to Yale. Of course, it was very different than nowadays where it's very hard to get into schools. But in those days, somehow, it was different. 

Zierler:

I'm sure you're being modest. In high school, were you a standout student in math and science?

Scalapino:

I was what I suppose now days would be called dyslexic and struggled with languages but I could certainly do math and science. I think the one thing that perhaps was relevant to getting into Yale was the Chemistry part of the SAT test. It was the beginning of taking specialized Subject SAT tests, and you had to sign up for some Subject test, so I signed up for chemistry. I had had a little bit of chemistry, but when I saw the exam, I remember thinking I don't understand a lot of these questions. However I had determined I would do one thing: I would answer every single question. I believe, David, this was at a time where they had yet to deduct for wrong answers. And although I knew relatively little chemistry, I scored quite high solely due to the fact that it was a very long exam, and I finished it, by simply checking answers. I just would read a question and guess. So that may have actually helped me get into collage. However there was another consequence. I arrived at Yale, not knowing what I would do. I thought maybe I could be an engineer so I signed up for various math and engineering courses. I also signed up for an introductory chemistry course, Chemistry 12. But based on my SAT test I was put in an advanced class, Chemistry 14. This class was the kind of course you gave the Bronx School of Science valedictorian. These were students who really knew chemistry already. I mean, they were pros.

I arrived in class and realized I not only didn't understand what the professor was saying, I didn't understand the questions that were being asked by the other students. So, I went up and saw the professor afterwards -- his name was Professor Keach. I said, "Professor Keach, there's been a mistake. I should be in Chemistry 12. I'm going to be in engineering. I should be in Chemistry 12. Can we arrange that?" He said, "Oh, no, Mr. Scalapino. When I was here in 1912, I was a very nervous student. I was very nervous, I thought I couldn't do this." I said, "Professor Keach, it's not that I think I can't do this. I want to be in Chemistry 12. That's the regular chemistry." "Oh, no, Mr. Scalapino. You're going to be just fine here." So, I couldn't get out of it. Well, as one might imagine, things didn't go well. They didn't go well for three or four weeks. Then, I decided that I had to do something about it. So, each night, I would study for three hours, seven nights a week. As you might imagine, by the end of that first semester, I was getting better. I even thought I was getting better enough that when the end of that year came, I decided to be a chemical engineer. But then sophomore year came and I had to take physics. I had a marvelous physics teacher, a man named Larry Biedenharn. Biedenharn was a nuclear physicist who did theoretical calculations and was very good at group theory.

At any rate, after a year in Biedenharn's class, which was the end of sophomore year, I said, "I like physics. I'm going to transfer." I went in to see Biedenharn, who I liked, and I remember him saying to me, "Scalapino, you may be a very good chemical engineer, and you should think about it." So, anyway, with that “encouragement”, I did switch, although there was great suffering involved. Once you left the school of engineering at Yale, and got into the college, you had to have a language. Well, I was never any good at languages. I was okay at Latin, but the other ones, I seemed to be awful at. So, I thought to myself I'd had a little French in high school, and I knew at that time you were going to have to take two languages in graduate school. At that time, that was the way it was. You were supposed to show in physics you could read German and French literature, or better yet, Russian. So, I thought, alright, I'll get ready for it by taking German. So, for two years at Yale, I took German, and I suffered. I just suffered. Anyway, senior year came and having not thought much about what would happen next I had applied to only one graduate school. I thought I'd like to go to Princeton, so I applied to Princeton. Of course, I didn't get into Princeton. I remember thinking what will I do now, since I was about to be married, and my graduate school prospects didn't look too good. So, I went and saw Biedenharn again, and he said, "Why did you apply to just one graduate school?" I said, "Well, it hadn't occurred to me.”

Zierler:

Why just Princeton?

Scalapino:

I thought that would be a good place to go. I hadn't talked with anybody about it. I was fairly naive. Anyway, fortunately, Biedenharn said, "Well, you could consider Rice or Stanford. You could apply late." So, anyway, he helped me, and I applied and got accepted and decided to go to Stanford. So, my wife and I were married upon my graduation from Yale in 1955, and we drive out to Stanford. And so how did I get into physics? Well, I thought physics was interesting, so I would try it. 

Zierler:

Coming back to Stanford, did you feel like you were coming home, since you were 14?

Scalapino:

Yes, having grown up in San Mateo and Burlingame it felt very natural, and we both liked Palo Alto. My wife was fortunate to find a job as secretary in the microwave lab, she was secretary to Ed Ginzton, and Marvin Chodorow. Ginzton and Chodorow were well known at Stanford in terms of microwaves, and Ginzton, in terms of Varian. Ginzton went on to be chairman of Varian. You know, the klystron -- the whole microwave scene at Stanford was very impressive. So, anyway, that's where I started graduate school, again, not really knowing what I wanted to do. I became an experimentalist. For five years I was an experimental student working for a man named Mitch Weissbluth. Mitch was doing radiation chemistry, and at that time, they were using a “small” linear accelerator, called the Mark IV, in the basement of the microwave lab. It was used during the day for cancer patients, and at night, I would use it to study the lifetime of free radicals created by the Mark IV electron beam. My goal was to understand more about the processes that occurred when patients were exposed to high-energy electrons and free radicals were produced in the body. What type of radicals were produced and how long did they live? Of course, I was using much simpler liquid systems, placing the liquid in the electron beam to see free radicals created by the beam and measure their lifetimes. At any rate, I struggled with this project for four or five years during my graduate school career. That time was very important to me, although I didn't appreciate why at the time. I was learning about microwaves because I had to build an EPR spectrometer that had a resolution response time of milliseconds, so I could watch the free radicals decayed. We didn't have a commercial spectrometer. Varian hadn't put out theirs at that time, so I had to rig this system up, so that it could resolve free radicals on short time scales.

Zierler:

Now, Doug, were you operating on your own with this, both in terms of formulating the research questions and putting the instrumentation together?

Scalapino:

Let me go back a bit. What had happened was Hofstadter, whose group was doing electron scattering off neutrons and protons, had offered me an opportunity to join his group. You took graduate exams at that time, and somehow afterwards, magically, you would maybe get an offer to join some group. So, I went home and told my wife. I was quite excited. Hofstadter just asked me to join this group that does high energy electron scattering off nuclei. My wife asked me what I'd be doing, and I said I'll be sweeping up after Ed Dalley who's working for a graduate student Mason Yearian who's ahead of him and who's actually the student doing the experiment. My wife says, "Do you really want to do that?" And I said, "No, but that's just the way it works in that operation." She said to me, "You don't have to do that." David, it sounds strange, but that was the first time it occurred to me that no, I didn't have to do that. So, I went around campus the next day, or the next few days, talking with people and looking for a project. A man named Mitch Weissbluth, who was over in the Hanson microwave lab, but was associated with the physics department, said, oh yes, he wanted to do electron spin resonance to detect free radicals. The reason was that they were using the Mark IV to irradiate cancer patients and wanted to know more about the free radicals that the electron beam was creating in their patients.

Well, this seemed too complicated, but perhaps one could detect free radicals in blood or better yet simpler liquids. I was interested in magnetic resonance because I had been going to some of Professor George Pake's graduate student meetings. I wanted to work with Professor Pake. He was doing electron spin resonance, but there wasn't an opportunity. So, I thought, okay fine, electron spin resonance can be used to detect free radicals so this project with Mitch will work out. Indeed, Mitch Weissbluth was very good to me, but his expertise was more in radiation chemistry and actually dealing with these patients. So, I was somewhat left on my own, and it wasn't going so well. Then I found another graduate student, an electrical engineer named Larry Anderson to help me. Larry was a crackerjack electrical engineer in his second year of graduate school, so he and I put this electron spin resonance spectrometer together all on our own. I ordered parts and salvaged parts from pieces of the microwave lab. Some people later came after me because I had their magic T's in my spectrometer, and they wanted them back. We would have arguments. But anyway, we designed this rapid response spectrometer to detect the decaying free radicals.

On the side, Larry and I were also doing something else. Larry was Canadian, and he knew French. As I mentioned, I had had two years suffering with German at Yale. We both had to pass language exams. So, we would work during the morning, the afternoon, and sometimes the evening, on designing this spectrometer and building it. But at lunch time, I would get out Pauli’s “Handbook on Quantum Mechanics”, a classic article in German on quantum mechanics, which I would read to Larry, and Larry would read to me a copy of Abragam's book “The Principles of Nuclear Magnetism” in French. So, Larry would read me that, and I would listen and watch how he did it, and I would read him Pauli’s article, not very well, and he'd listened and watched how I did it. This way we both planned to pass our language exams, because at that time you could bring a book in that you wanted to read for the person examining you. Mind you, he and I had both read these books to each other. So, when we took them in, we thought that we could pass. The only mistake I made was I read Abragam too rapidly. The instructor testing me said, "No, no, no," and he got another book and I struggled. Anyway, we both passed that way, and what we also did was built this spectrometer, and it worked. It worked well. However, there turned out to be a major problem with the project, and that was why I ended up doing a theoretical thesis working for Ed Jaynes.

Zierler:

Yeah, you're not really on a theory track at this point. 

Scalapino:

I'm not on a theory track, no. I'm trying to figure out how to make measurements of the free radicals created in various liquids by the Mark IV electron beam. As I mentioned, if you put a test sample with frozen free radicals in the spectrometer, it worked beautifully. The next step was to put in a liquid sample and set the spectrometer up at the end of the Mark IV beam line. I would go in at the end of the day after they were through with the patients. It would be 5:00 in the evening. I would wheel down this large Varian magnet. I would bring it into the room in the basement where the electron beam came out, where the patients had been. I would set up the spectrometer in such a way that the beam would shoot straight through, between the cores of the magnet. This was 10 kilogauss, which would bend the beam a bit. Then I would position the sample holder so the beam would go right through it. Now, after you got it all lined up, and you turned on the Mark IV you would see a rising signal right about where we expected it. A free radical would typically have a g-value of 2. Unfortunately, I would see a signal rising, and rising, and rising, a permanent signal at about a g- of 2. It turned out that the electron beam was making F-centers in the glass container that held the sample.

Zierler:

Which was telling you what?

Scalapino:

Which was telling me that the electron beam was creating electron spin resonance sites that were pinned in the glass sample holder. The signal from those sites was swapping the signal coming from the liquid that I was trying to study. So, I tried all sorts of different materials for the sample holder. However, the electron beam kept making these F-centers in the sample holder.

Zierler:

And you figured this out on your own, or you were talking to people and they suggested this was the problem?

Scalapino:

Well, unfortunately, by that time I wasn't talking to too many people. I was figuring it out as I went, because you have to understand, this is pretty much a disaster. I finally came to realize that I wasn’t going to be able to do the experiment the way I had planned. So, I went to my advisor and told him what was happening. He said, "Stanford Hospital was moving down from San Francisco to the Stanford campus. They have X-ray machines, and you can irradiate a frozen sample. Freeze it, create free radicals in it, and study that." I said, "But that won't be studying the lifetime of radicals relevant to the patients." And you know what? By that time, David, five years had passed, and it occurred to me that when I finished this project, I was going to go out, and the jobs available were going to be some radiation chemist job, or some job working testing patients, and I didn’t want to do that. 

Zierler:

Also, where is the dissertation?

Scalapino:

The dissertation isn't going to happen. So, that's five years, two children, and we're broke. However, over the previous three or four months, during which I was trying to get the experiment to work, I spent a lot of time replating the radiation damaged microwave cavities. During the turn around time associated with the plating, I would go down the hall, and there was a man named Professor Ed Jaynes there, who I had taken a course from. I liked very much the way he talked, and how he explained things. Ed would have his students sit outside with one inside working at his blackboard with the door open. By sitting outside, you could watch what was happening inside, and you could benefit from each of the problems that the students had. So, while I was plating, I used to sit there and listen to the theoretical problems that these students were working on with Jaynes. And then I began to work on some of them and found it interesting, more interesting than plating. At the time, when it was clear to me my experiment wasn't working so well -- by the way, I did finish the free radical project.

We published a report, which is at Stanford, on this project. We finally made it work by using UV light rather than electron radiation to create the free radicals. The UV light didn’t create f-centers in the quartz sample holder. It wasn't the original project, but anyway, we got that done. About then, Ed had posed a problem, and in my spare time plating, I’d solved it. I went in to show Ed, and began talking with him. I said, "Look, what if I were to switch out? I've been here five years. I'd like to do theory." Now, Jaynes was very good to me, because I think if I'd seen a student who for five years had been doing experimental work and then decided to switch to theory, I would worry about him being able to finish. At any rate, Ed took me on, and I started to work for him. This story has gotten too long, but I will finish shortly. About six months after this, Jaynes tells me he's leaving Stanford to go to Washington University in St. Louis because of a chair he's been offered there. So, I told him, "Well, Ed, this has been fun, but Diane and I have two children, we're broke, so I'm going to go off and work at Varian." Ed says, "Oh, no. Come along. I'll get you a consulting job. You come along, finish your thesis, and you can work for this company called Kane Engineering, one day a week." At that time, to give you an idea, one day a week was $50. Now, I was earning $3700 a year. Diane was no longer working because we had two children. So, you can imagine, $50 a week extra, we could make it. So, we packed up and went to Washington University in St. Louis, and I finished my thesis with Ed on a maximum entropy problem in statistical mechanics. The time at the Washington University St. Louis physics Department was special. When I arrived there I was given a desk in a castle-like room on the upper floor of Wayman Crow Hall with some of Eugene Feenberg's students. Clayton Williams, Woody Jackson, Walter Masey, Fred Wu. Walter went on to be Director on the NSF and President of Morehouse College. Fred Wu became well-known for his work with Elliot Lieb on exact solutions of the one-dimensional Hubbard model. I was new coming in from Stanford but the students at Washington University -- that group of graduate students was extremely friendly. We played basketball, volleyball, and it was a special time during which I finished my thesis and attended a wonderful many-body course given by Eugene Feenberg.

Zierler:

What research was Feenberg involved in at that time?

Scalapino:

Feenberg was doing work with his students on helium-3 and helium-4 based on variational approximations for wave-functions.

Zierler:

Was this concurrent with the work that Feynman was doing? Do you know, were they collaborating?

Scalapino:

This was later. They were not collaborating, but Feenberg and his group were well aware of the beautiful work of Feynman and Cohen on the back flow of the excitations in liquid helium. Feinberg and his graduate students were studying many-body wave-functions using Monte Carlo based numerical calculations. During this time I finished my thesis. I went to take my thesis final exam at Stanford two days after our third child, our son, was born. Ed arranged for me to stay on at Washington University for a year as a post-doc. Then Ed, who had been at Princeton with David Pines, said, "Look, you're interested in the many-body problem. Why don't you go to work with David Pines at Illinois?" And I said, “That sounds wonderful." So, Ed and David were very nice, and they lined this up. David even gave me a problem I could work on while I was still in St. Louis. But then what happened was David and Susie decided to go to Paris. David says, "Oh, just come along." I said, "David," -- I probably called him Professor Pines at that time. I said, "You know, we've got three children. We're at tap city. We can't do that." He said, "Oh, it'll work out." Well, I didn't think it would, so I told Jaynes. I said, "No, no. I can't do that." "We’ll go back to Palo Alto and I’ll work at Kane Engineering." 

Zierler:

You had a full-time offer there?

Scalapino:

No, but I had been consulting for Kane and had worked there for a summer. 

Zierler:

Oh, it hadn't developed beyond that. 

Scalapino:

Oh, yes. It had developed. In St. Louis I had been working on this project for Kane related to the BMEWS radar system in Canada. They wanted to upgrade a part of their system so that it could go from X band (10 gigahertz) to K band (30 gigahertz). They wanted to triple the frequency they were operating at. Jaynes had this idea that one could put a material with local electron spin centers in an intense beam of X band microwaves and up convert from X band to K band. My job was, to do calculations to determine under what conditions this would happen. I had tried various analytic techniques, and they were only partially successful. So, I had taken to going down in the basement of Crow Hall at Washington University where there was an old analog computer that nobody was using. I could program the analog computer so as to simulate this problem. It had worked, but suggested that one would need a very special material. I had gone out to work at Kane the summer after getting my PhD degree and Fred Kane had encouraged me to join the company after my postdoc year with Jaynes at Washington University ended.

As it happened, I went on to the University of Pennsylvania to work as a postdoc with Bob Schrieffer. But to finish the Kane Engineering story, Kane Engineering had a contract with Ling- Temco-Vought, a large conglomerate who among other things build fighter planes and was tied in with the BMEWS radar instillation. In the Fall of my first year at Penn, I got a call from Jayne saying, "Can you fly down to Dallas? We're meeting with McMurphy whose one of Ling-Temco-Vought ‘s Vice Presidents. They were excited about our progress. Will you give a talk?" I said, "Sure, I'll give a talk," because I had done this analog calculation. When I arrived, we went in this conference room, where there were four or five people. I started giving a talk, showing some slides of how this worked. I got about halfway through when McMurphy interrupted, "Scalapino, that's just theory. I want to see something that's real."

Zierler:

You were not expecting that question. 

Scalapino:

I said that what I’d done was only a simulation and experimental work was beginning. Unfortunately, on a prior visit to Kane Engineering, members of his team had gotten the impression that the experimental work was well underway. In fact there was an internal report that it was actually working. So, he was not interested in a simulation. He said, "Scalapino, let's go outside." I said, "Okay," and my talk stopped. He took Ed Jaynes, Fred Kane, and myself outside where we were on a tarmac, and they had a fighter plane on a crane about 15 feet off the tarmac. We're standing there, and I'm looking up at this thing. He raises his hand, and they drop it. That thing drops, what always seemed to me, five or ten feet away from me, and lands on the tarmac, you can imagine, quite loudly. He said, "Scalapino, that's the way we test whether our equipment can stand shocks. That's real." I’ve gone on to do other simulations, but since then I’ve tried to keep in mind what’s real.

Anyway, as it turned out, in 1962 we went to the University of Pennsylvania. Again, to explain how this happened I need to give you an idea of the times and how people were, because it was different than today. Schrieffer was arriving from Illinois to be the Mary Amanda Wood Professor at Penn. I didn't know him, but I was able to go to Penn because of Henry Primakoff. Primakoff had previously held the position Jaynes now held at Washington University, and had gone to Penn as a chaired professor. After telling Ed that we’d decided that we couldn’t go to Paris with Pines and I was thinking about going back to Palo Alto to work at Kane, Ed phoned Primakoff about my situation and said, "Can you help Doug?" Primakoff didn't know me. "Doug would like to come and work at Penn because his parents live in Bryn Mawr and Doug and his wife have three children. I'm hoping he could meet Bob Schrieffer and maybe work with Schrieffer." Well, Primakoff was doing high-energy physics, he has a contract in theoretical high-energy physics, but he hires me. I arrive at Penn, and Primakoff has me in and talks to me about what he's doing. He says, "Now, Doug, you can work on this, but Bob Schrieffer is just arriving, and you might enjoy working with him." That's how it was. I don't know whether you can imagine that now, but Primakoff said, "Doug, you should work wherever you want to." So, I did interact and work with Henry a little bit, but I basically then began to work with Bob Schrieffer. How was it at Penn? Well, when I arrived, they had taken one of their labs and partitioned it into eight offices. Eight small cubicles. Two or three had windows. I was put in a middle cubicle where if I reached out my arms I could touch the walls, and it was just long enough to have a desk. I felt pretty senior by this time, having worked at Kane Engineering, having worked at Washington University, and having done experimental work. I was going to go in and see Professor Wilbur Ufford, who was chairman, and tell him this just wasn't suitable. Fortunately, I didn't do it the first day I was in the office, and the next day, a guy comes into the office next to mine. It has a window, but it's still about the same size as mine. The partitions between these offices are very thin. I can hear him. He's picked up the phone, and I can hear the following, "Oh, Wilbur. It's just fine. I'm just so glad to be here. This office is perfect. Please don't worry about it. I'll be just fine." That was Bob Schrieffer. He was in the cubicle next to me. So, here's a post-doc, which is me, who fortunately the day before has not gone into the chairman to complain. That's how I met Bob, and that's the kind of guy he was.

Bob had come to Penn with a student named John Wilkins, and Bob proposed that the three of us should see if we could understand some recent electron tunneling experiments. Giaever at GE had reported electron tunneling results on lead which showed wiggles in the I-V characteristic that occurred at bias voltages which corresponded to characteristic lead phonon energies. At that time John Rowell at Bell was also doing very beautiful tunneling experiments on lead which he shared with us. Bob raised the question to John and myself of can we understand the tunneling data in lead based on the theory of superconductivity? This sounded interesting but I didn't know much about the theory of superconductivity. Fortunately, Bob was teaching a course at Penn on superconductivity, and as you can imagine, with Bob having been the S of BCS, it was a marvelous course. So, I learned what I could about superconductivity, and Bob and I and John Wilkins worked on this problem. With Bob's leadership and insight as well as a remarkable computer that Glenn Culler had put together on the West Coast, we did a calculation that provided a reasonable fit to the lead I-V data. These results provided evidence that the pairing interaction in lead was mediated by a retarded electron phonon interaction. During this time, Bob had taking me with him to visit Bell Labs, where I met Phil Anderson. Phil suggested that some structure seen in Rowell’s I-V tunneling spectrum might have to do with Van Hove structure in the phonon spectrum. I did a little calculation on that and presented it at the first Gordon Conference I ever went to. It was the first paper I ever published. So, it was for me really the beginning.

Zierler:

How was this paper received?

Scalapino:

The tunneling paper with Bob and John was well received. I’m not sure I appreciated it at the time, but since then having been involved over 30 years with high-Tc research, I do know when papers are not well received. This paper was certainly well received. It was well received, of course, because of Bob, and being with Bob opened many doors in many places. 

Zierler:

Did you have a longer collaboration with Phil Anderson?

Scalapino:

No, but as I mentioned when I visited Bell, Phil had proposed that some of the fine structure in Rowell’s Pb tunneling data might be associated with Van Hove singularities in the phonon spectrum. I had gone back to Penn and done a small calculation that showed that indeed this was the case. There was to be a conference at Colgate. And Phil said, "Doug, put in a paper on your Van Hove results." And I thought it would be from both of us. However Phil said “No, you did the calculation. You put it in.” Later, Phil and I published a longer paper on this. So, it was very generous of Phil, we had a good relationship—it was later on, that we had our disagreements over high-Tc.

Zierler:

So, you're not on the tenure line at this point yet?

Scalapino:

I'm not only not on the tenure line, David -- Penn had put out a call for assistant professors, and they have just hired two in condensed matter theory. At that point in time, I went home with a stomachache that lasted for about six months. Diane would tell me, " It's going to be alright." I would tell her, "No, it's not going to be alright."

Zierler:

Did you have any senior faculty members at Penn who supported you and championed you?

Scalapino:

Certainly, but at that time, you have to picture my situation. I had been a post-doc at Penn for a year and a half. I work with Bob Schrieffer; I see John Wilkins. How to put it? It doesn't look promising on account of they have just hired two very good people as assistant professors in theoretical condensed matter. It's not anybody's fault. It's just the timing of things. I think anybody with any sense would look at it and say, "This doesn't look too good." So, that's the way I was feeling. But then the following thing happened: a graduate student named Bob Eck came in to see me with a long roll of strip chart recording paper. He and Barry Taylor, who was an assistant professor, were doing tunneling experiments with lead tunnel junctions, and Eck was seeing a strange signal in the current-voltage I-V characteristic. The structure changed when he brought a small magnetic field near the junction. By small magnetic field, I mean like the field from a magnet you use on the refrigerator to post notes. Eck kept telling me it was real. He would sit down, and he and I would look at this strange data. We must have looked at it for two or three days in a row, and it looked crazy to me. But then something happened. I took him seriously, because he kept saying, "No, this is real. This is what happened." At about that time, Brian Josephson had come out with a paper describing how superconducting pairs could tunnel, which I only vaguely understood. However I did understand something about microwave strip lines from my experimental work at Stanford. It occurred to me that the lead–oxygen-lead tunnel junction Eck was studying could act like a microwave cavity, and that something was exciting the microwave modes in it. We thought how could that be when you're tunneling DC current through it? The answer was that we were seeing the ac Josephson effect. The junction DC voltage V was creating an oscillating Josephson pair current at a microwave frequency 2eV/h and the small magnetic field was, as Josephson had predicted, changing the spatial structure of this oscillating current density which controlled its coupling to the cavity modes. We were seeing the effect of Josephson radiation in the strip line. So, we wrote a paper that explained this, and then Don Langenberg joined us, and we began to work to try and see how we could observe the emitted microwave radiation. What I knew about this stemmed from the time I had spent at Stanford working on the microwave ESR spectrometer. So, this was in a way a kind of payback for those years and I believe that it was what lead Penn to hire me as an assistant professor.

Zierler:

Did your stomachache go away?

Scalapino:

The stomachache went away. At any rate, things happened that had to do with my time as an experimental graduate student at Stanford and the nights down in the basement with the Mark IV accelerator looking for free radicals. The work with Kane Engineering and the interaction with Ling-Temco-Vought was also part of my education that I didn’t fully appreciate at the time, but I believe helped me later in the competition for the NFS Institute.

Zierler:

With four kids. 

Scalapino:

Yes, and two years later we had our fifth child. You can imagine that this was a large family for me, having been an only child. At any rate, I liked Penn very much. I made some of my longtime friends there: Don Langenberg, Allen Heeger, Dan Hone and of course Bob Schrieffer. 

Zierler:

Who got to Santa Barbara first?

Scalapino:

My friend from Penn, Dan Hone, did, but let me go back for a moment. I think it's impossible to convey how much Schrieffer meant, what I learned from him, and how things evolved. Bob's come in and out of my life all during it 

Zierler:

Right, and he clearly believed in you. 

Scalapino:

Well, whatever it was, he was a very special friend. Without Bob, things would have gone in an entirely different direction.

Zierler:

What was your sense of Penn in those days in terms of the physics department? Were they building? Were they trying to gain in stature?

Scalapino:

They were building, they were gaining in stature. It was a wonderful department. My parents lived in Bryn Mawr. Diane and I lived nearby in Devon. We liked all of it, and we loved the people. The problem was I had grown up in California, and in '66 we'd gone to La Jolla for six months where we lived in a home which was on the beach in Del Mar. It started me thinking about coming back to the west coast. But some time passed and it was a special time at Penn with Schrieffer, Langenberg, Taylor, and a new experimental Asst. Professor Tony Jensen who became a close friend. So some time passed and it was December of ‘67 when for about the third week in a row I went down into our basement in Devon, Pennsylvania, and there's six inches of water. I remember after cleaning up again, telling Dianne, we're not going to live this way.

Zierler:

You were looking for the straw. What was the straw that was going to break the camel's back? That was it. 

Scalapino:

That was it. So, I went upstairs and phoned Dick Blankenbecler at UCSB and talked with him about it. We had been close friends in graduate school at Stanford. Vince Jaccarino, who I knew from Bell Labs, had also by then gone to UCSB and he and Dick arranged for us to visit the next school year.

Zierler:

Were they recruiting you? Was there an open slot, or they were going to make something new for you?

Scalapino:

The UCSB department was building, and had offered me a position. So in the fall of ’68, Diane and I with our five children came out to Santa Barbara. At that time the Physics Department was in Sycamore Hall, a World War II Marine Airforce barracks. The site of the campus in the '40s had been a Marine Air Force base and there were still barracks that had been left from that time. Broida Hall, a six-story building with labs and offices, was under construction, and we would move into it in the Spring of ’69. It was a big change from Penn, but we had hopes. How to put it? The department had people who wanted change. 

Zierler:

It was clearly the beginning of something exciting. 

Scalapino:

Yes, and the department did offer something special. It was small and because there were relatively few theorists, we often found ourselves working together on projects that overlap our own subdisciplines. Nominally Bob Sugar and Ray Sawyer were working on high-energy physics, Jim Hartle was working on astrophysics and general relativity and I was working on condensed matter problems. But because we were small, we began working together and had found various common projects. Probably sometime in '75, we began to think about writing a proposal to support such interdisciplinary efforts. Ray Sawyer had visited with Boris Kayser at the NSF about this and was encouraged. So, Hartle, Sawyer, Sugar, and I put together a modest proposal requesting support to establish a program at UCSB that would bring together faculty on leave along with post-doctoral fellows interested in working on interdisciplinary problems. We submitted it to the NSF, but then later I remember being discouraged. NSF put out a request for proposals for a major Institute for Theoretical Physics, which they proposed to fund at $1,000,000 a year. This was going to be a competition for a large theoretical physics institute, and quite frankly, I thought our chance weren’t good. But then, after a little time passed, I thought more about a recent Departmental Review. Three faculty from UC Berkley had been asked to review the UCSB Physics Department and they had come down to visit with individual faculty. I had told them how Sawyer, Hartle, Sugar, and I had been working together on various problems. While I don’t remember the full report, one sentence stuck with me “The Santa Barbara Physics Department may in time develop a strong experimental program, but they will never be known as a theoretical center.”

Zierler:

Ouch. 

Scalapino:

Yes "Ouch!" So, while I was dismayed when I learned that the NSF was requesting proposals for a major interdisciplinary Theoretical Physics Institute and thought about all of the competition we were going to have, I was annoyed by this comment in the Departmental Review and this motivated me.

Zierler:

Doug, let me ask, on what basis was Berkeley in a position to judge you? Aren't they peers?

Scalapino:

Berkeley was up at the very top. If I came down from Berkeley, to review the UCSB Physics Department, and visited with a young condensed matter theorist who told me about work he and his colleagues were doing on pion condensation in neutron stars, and a statistical theory of particle production, I think I'd say to myself, "Yeah, maybe." So, you know, I think they were not so unfair. They were just wrong. 

Zierler:

So, what was the department's response to this report? Did it have a galvanizing effect? Demoralizing? What did it do?

Scalapino:

I know it galvanized me. Beyond that, I don't think it did much one way or another. The then chancellor didn’t give us any fewer positions, or anything, but it galvanized me. I figured if we're going to do this, we're going to need some help. We’re going to need an Advisory Board. So, I started phoning some friends. Dick Blankenbecler, Leo Kadanoff, Bob Schrieffer agreed to help. Ray, Jim and Bob asked others and soon we had a Board of well know physicists , Paul Martin … if the names were in front of me now, they'd all come back, but they were well-known physicists and it was great of them to be willing to help us on this. Some of them didn't really favor the idea of the institute but thought that if there was going to be one, they would help make it the best it could be. It wasn't an immediately popular notion because it was going to possibly take money away from single principle investigators. I wasn't for that either, so it wasn't uniformly liked. So, we began working on this proposal, and time evolved and there were a number of proposals submitted.

One day, we got a call that we were to go back to the NSF for a meeting with four other groups (CalTech, UC Santa Cruz, University of Illinois at Urbana, and a consortium involving Yale, Columbia and Cornell) to present our proposal. I was in the LA Airport on my way to Washington for this meeting when it occurred to me that the proposal had four of us on it, but we were professors, and we were teaching, and the question would be who would really be at the institute? We had a director and a deputy director, but who else would be there to help? Wouldn't it be important to have some permanent positions at the institute? So, from the LA airport, I phone the acting chancellor, a man named Alex Alexander. We had talked about the fact that we were trying to get this institute at Santa Barbara. I said, "Alex, we need positions for it. What would happen if we had three dedicated positions paid for by the university at the institute?" Alex, who was a careful man, said, "That sounds pretty agreeable." So, I got back there, and the next day gave the presentation at the NSF. So, I'm up there describing our proposal, and then I add, "There will be three positions given by the university who will be at the institute while it lasts." You remember the institute was a five-year proposition. However as soon as I said that, several people on the NSF review board said, "Well, that wasn't in your proposal," which was true. They said, "Can you vouch for this? What did the chancellor say?" I said, "Well, we don't have a chancellor right now. We have an acting chancellor, and he said it was agreeable." I just couldn't bring myself to say, "pretty agreeable". But this didn’t go over well with the review committee. They said, "Look, it's not in writing. We have no reason to think that -- you can really do that. We have nothing on this." It brought back the feeling I’d had at the Ling-Temco-Vought meeting.

So, Hartle, Sawyer, Sugar, and I left the meeting a little downcast. I should have been more careful with what I said. We decided that we have to phone the chancellor." How are we going to do it? It's 1:00 or 2:00 in the afternoon.” Someone says, "Well, there's Blacky's Bar across the street." Sure enough, Blacky's Bar is there, and there's a payphone. We knew that the new chancellor was at Caltech, and his name was Huttenback. So we got Huttenback's phone number, and I phoned. Frida, Huttenback’s wife, whom I didn't know at the time answered. I said, "Mrs. Huttenback, this is Doug Scalapino. I'm a member of the physics department at the University of California Santa Barbara." You see, Huttenback had been appointed as UCSB Chancellor, he just hadn't left Caltech yet. He was about to come. I said, "I'd like to speak to your husband." Well, he was out in the garden, so he comes and I tell him, "I'm Doug Scalapino. I'm a member of your physics department. I'm back here with three of my colleagues. We're proposing a Physics Institute at Santa Barbara, and we're telling them we're planning to have three faculty positions at the institute. They don't buy that. We have not much to go on." I still remember exactly what Huttenback said to me. He said, "Doug, so they want to play hardball. You tell them that we will do what you have proposed, we will have these positions and we will do all we can to make this work." Huttenback was a great supporter of the institute and indeed did all he could.

Zierler:

Were you surprised by his response?

Scalapino:

I didn't know him at the time. It turned out that he had done some work on history with my cousin Robert at Berkeley, which I didn't know about. Huttenback, otherwise, didn't know me, and I certainly didn't know him, but that's the way he responded. There was one more thing which I learned later. Murray Gell-Mann who lead the proposal from CalTech had seen Huttenback earlier that week. Murray knew Huttenback was going to become chancellor at Santa Barbara and said, "Well, I'm going back to the NSF to present our proposal for the NSF Theoretical Institute, and your bozos from Santa Barbara are going to come and compete, but they don't have a chance." I heard that later and whether he said those exact words, he had downplayed us and what Santa Barbara could do, and Huttenback had heard that prior to our phone conversation.

Zierler:

So, it was almost personal for him. 

Scalapino:

Yes, Huttenback was a strong supporter of the Institute and of the Physics Department. Later when Bob Schrieffer was thinking about joining our department and we had invited him to visit UCSB, Huttenback rented a white Cadillac convertible. He drove down to LA and picked up Bob at the airport and drove him up to Santa Barbara taking the coast route through Malibu. 

Zierler:

Amazing, wow. Wow. 

Scalapino:

Huttenback did a great deal for the Physics Department, the Institute and for UCSB.

Zierler:

To say the least. That is service, right there. 

Scalapino:

Well, he made a real difference. 

Zierler:

Did Schrieffer appreciate the gesture?

Scalapino:

I think that was great fun, and certainly impressed Bob with the support that the department had from our Chancellor. Getting back to the Institute, our great fortune was to have Walter Kohn as the first director. Walter did a magnificent job.

Zierler:

Where had Walter come from? Where was he coming from?

Scalapino:

Walter had been a widely respected professor at UC San Diego La Jolla. When they established the Physics Department at UCSD, they started from the top down. They initially housed the Physics Department which was a graduate school at Scripps. Walter was from those early times when they established a physics department with luminaries. Walter was certainly that, and when he came to the institute, his leadership, and his judgment as to how things were to be done played an important role.

Zierler:

Now, in these early days, were there any models to look for in terms of other institutes, other stand-alone programs to emulate, or was this really an inward-looking process?

Scalapino:

For me, at least, in thinking about the proposal, I spent some time talking with Allen Luther, who was then at the Bohr Institute and Sugar, Sawyer, and Hartle all had talked with different people. I knew of the Landau Institute. I had been fortunate in 1966 to attend a joint Soviet - U.S. meeting there that David Pines had organized. There was the Center for Theoretical Physics at Oxford that Rudolf Peierls had established. There was also the Aspen Institute for Physics which ran in the summer. Our idea for the NSF institute was that the programs could be longer and that would allow something that couldn't happen at short meetings, or summer schools that lasted two or three weeks. These could last six months or longer. As it turned out, our programs now run a shorter amount of time because people find it harder to get away that long, but the original idea was that these would be longer programs and that was different than the summer institutes. 

Zierler:

So, how long did it take until the vision was realized?

Scalapino:

I think that when the institute was renewed after the first five years we felt that it had worked. We are always very glad when it is renewed, and we remain that way. Several months ago, we were to have a celebration of what we called the 40th anniversary. I think it actually would have been the 41st, but it got cancelled because of the COVID-19 situation.

Zierler:

Do you look at most of your work in research projects within the context of the institute? Is that really your home in terms of the research?

Scalapino:

No. My home has been the physics department. However, I was active at the institute during its first year. There were a number of remnants that remained from what had been promised in developing our proposal. Now when the KITP asks for suggestions for programs, groups compete to run them. However, as you might imagine, in the beginning before UCSB had been selected by the NSF, it was difficult to get senior individuals to commit to running a program at an institute that didn’t exist. I would end up promising things that were not necessarily in the cards. I remember Roman Jackiw, I promised him that if he would come to the ITP and be a program organizer, we would take a charter boat out to the Channel Islands off Santa Barbara. Indeed, when he arrived, after he was here for a week or two, he said, "Doug, when are we taking the charter?" It escaped me that I had promised this. At first, I thought, I'll ask Huttenback about it, and then I thought that just wouldn't be fair. So, I went down to the Santa Barbara Pier, and I met a Captain Don. As I remember, Captain Don wanted some $400, maybe $500, to take us out to the islands and back for the day. When I came home and told my wife, she said, "You're out of your mind." But I had promised Jackiw we would do this. So, I put a notice out, and it said, “The institute is sponsoring a trip to the islands. It will be $50 a person.” Fortunately, we had enough takers that we could do it. But in those early days, it was not easy to get people to come and run programs. It was not easy to get people on the Advisory Board. Now, it's quite different. 

Zierler:

In what ways has the institute benefitted the department in general?

Scalapino:

I think in many ways. It brought to the department physicist who would become Nobel Prize winners: Walter Kohn, Frank Wilczek, and David Gross as well as Bob Schrieffer who had already been awarded the Prize before arriving at UCSB. It brought us other exceptional members: Joe Polchinski, Matthew Fisher, Leon Balents, Boris Shraiman and others.

It also brought visibility in terms of attracting graduate students. Potential graduate students realize that when they come here, just like other faculty and visitors, if they want to attend programs going on at the institute, they are certainly welcome. They can attend lectures; they can interact with the visitor at the institute. It's changed other things. People who have left here know about the Physics Department and UCSB. I think it helped the entire campus. The campus at the time that the institute came was not thinking in that way. It was not thinking nationally, that we should have institutes, that we could be a leading UC campus. I think, somehow, when you have something like the institute happen, you look at it and say, "Yes, we can do this.” UCSB now has a number of national institutes in materials, engineering, biology and earth sciences.

Back now to your question of whether I look at my own research in the context of the institute. Most of my work has been in the department, with the department's graduate students and my own postdocs. However, the institute postdocs and visitors have also played an important role in this research. I feel like a man who's had two lives. A life before the institute came, and a second life afterwards. It's nice when you're given a second chance.

Zierler:

Well, Doug, I want to ask you a broadly retrospective question, and that is, looking back over your decades of research at UC Santa Barbara, what do you see as your primary contributions to the field?

Scalapino:

I think that the quantum Monte Carlo work with Sugar, and Blankenbecler, and Hirsch and with a number of UCSB graduate students and postdocs, and later work with Steve White (UCI) , Thomas Maier ( ORNL) and Steve Kivelson ( Stanford) has shown that numerical simulations are useful in understanding the properties of many-electron systems. I also like to think that our work on the high-Tc superconductors and the unconventional superconductors has provided insight into the pairing mechanism in these materials.

This question actually brings me back to your question regarding my research in the context of the institute. Two pieces of work associated with the institute have played an important role in my later work. In ’81 with Bob Sugar, who at the time was the first Deputy Director of the institute, and Dick Blankenbeckler who had visited the institute, we developed a Monte Carlo algorithm for the numerical simulation of many-electron systems. Later with Jorge Hirsch who was a postdoc at the institute we extended this work making it more efficient and into a method, DQMC, which is presently used. Then in ’86, John Wilken and I were leading a program at the institute on valence fluctuating materials. Jorge had returned to the institute from UC San Diego to participate in this program. We became interested in the pairing mechanism responsible for superconductivity in the heavy-fermion superconductors and the organic Bechgaard salts. During this program Jorge along with a UCSB graduate student Eugene Loh, and I wrote a paper describing superconducting d-wave pairing driven by anti-ferromagnetic spin fluctuations. I now believe that spin-fluctuations underlie the pairing mechanism for the class of the “unconventional" superconductors.

Zierler:

In reflecting on all of your research in all of the different areas that you've worked in, do you see an overarching research questions or a curiosity that links all of your projects?

Scalapino:

As I mentioned, I feel like I’ve had two lives. One before the Institute and one that came some time after. Before '80, I was broadly interested in the physics of many-particle systems. I had worked on a variety of condensed matter problem as well as dense nuclear matter and theories of high energy particle production. As we discussed, some of this work with Sawyer, Hartle and Sugar underlay our original ideas for an institute. However, as things evolved with the work on numerical simulation and then the experimental discovery of the high-Tc cuprates, and later the iron-based superconductors, I've focused much of my work on the question of what underlies the superconductivity in these unconventional superconducting materials. Are they related?

Zierler:

When you ask the question about high-Tc cuprates, and what underlies superconductivity, and can it be known, it's a fascinating question. So, the question, can it be known? What's standing between now and knowing it? Is it a technological problem? Is it a problem of -- there's a "eureka" moment that needs to come along? What needs to happen?

Scalapino:

Let me go back to the traditional superconductors. What happened there? Well, certainly in the BCS theory it was the virtual exchange of phonons that mediated the superconductivity and prior to that there were isotope experiments that motivated Bardeen and others to believe that it was the electron phonon interaction which was responsible for superconductivity. So when Schrieffer, Wilkins, and I started our calculations, and wanted to calculate the tunneling and relate it back to what caused the pairing, we expected it to be phonons. But it was the detailed fingerprints of the phonons and their vanHove singularities that came out of the electron tunneling measurements and the fact that the transition temperature Tc determined from the tunneling data, along with a reasonable estimate of the Coulomb pseudopotential, agreed with the measured transition temperature that was exciting. Eventually Bill McMillan and John Rowell did their beautiful work relating in detail the tunneling to the electron-phonon pairing interaction. So, how will we know what interaction mediates the pairing in the high Tc cuprates? We know in the cuprates that the momentum dependence of the gap is d-wave, and in the Fe-based superconductor s+-. Both of these gap symmetries arises naturally in the spin-fluctuation framework. In fact prior to the discovery on the Fe-based superconductors, numerical calculations had found s+- wave pairing in a system with a Fermi surface similar to that of the Fe materials, but it was not recognized and the Fe-based superconductors were discovered experimentally in a search for new transparent optical coatings. So I believe that rather than a “eureka” moment, it may be the wide range of unconventional superconducting materials that will tell. There is now work on nikelate materials as well as highly overdoped Ba and Sr based cuprates for which spin-fluctuations have been proposed as giving rise to pairing. I believe that it will be the reach of the spin-fluctuation based theories in predicting and explaining the occurrence of superconductivity in this wide range of materials that will providing evidence for this mechanism rather than a "eureka" moment.

Zierler:

I'll ask an even deeper question: how do you see understanding superconductivity and magnetism as helping us understand the deeper questions that physics asks about the way the universe works, and how the universe came into being?

Scalapino:

The theory of superconductivity contained ideas that crossed sub-disciplines—-the Anderson-Higgs phenomena and Nambu-Goldstone bosons— it played an important role in our understanding of quantum field theory that underlies today’s standard model of strong, electromagnetic and weak interactions. With respect to the way the universe works, you need to ask someone like my colleague Gary Horowitz who's been studying the black hole equivalents of the cuprates. He and his colleagues have applied holographic duality to black holes and found relations to d-wave superconductivity. Alternatively, my last graduate student, Roger Melko might give you an answer. Roger is now at the University of Waterloo Canada, and is a leader in artificial intelligence, and in neural networks. At UCSB he did his graduate work on strongly-correlated many-body systems and algorithms for the study of strongly-interacting systems. Recently he’s developed machine learning neural network programs to analyze phase transitions. The complexity and the response of the neural networks raises interesting questions possibly related to how the brain works. We wanted to use numerical simulation to study quantum systems, but now the applications of these techniques has really broadened out.

Zierler:

That's a fair point. Well, Doug, for my last question, I want to ask you something forward looking. Physicists never retire. You're still active, you're still engaged, you're still excited, so I want to ask you, looking forward in your field or in relation to your colleagues and what's going on at the institute, what are you excited about for the future, either in your own career, or in terms of things that are on the cusp of discovery, on the kinds of technologies that might allow physicists to see things they don't see today, what are the things you're most excited about looking ahead?

Scalapino:

I’m of course still interested in obtaining a more detailed understanding of the unconventional superconductors. I also believe that the numerical simulation of quantum many-body systems will continue to develop. Just as numerical simulation plays an essential role in the design of cars, planes, buildings, I believe that it will become increasingly important in the design of new materials. Beyond this, I'm excited about the work with the neural networks, the work that Roger Melko, is involved in. It's a different direction, but it's a direction addressing complexity, and addressing, perhaps, the most complex object we have, which is the brain. I do think that understanding the brain is an incredible opening for physicists who have worked on the many-body problem. I think that it will be one of the areas that physicists can contribute to. They’ll be well-trained for that type of complexity, having seen for a much simpler system like the cuperates how complex things can get. 

Zierler:

Yeah. So, in reflecting back to the beginning of your career, there are connections now linking these disciplines that weren't really available or fruitful to consider 40 or 50 years ago, but now we're getting there. 

Scalapino:

Yes, thinking back to some of the problems that brought Hartle, Sawyer, Sugar and myself together I can see how much the field and the questions have evolved. Where does the standard model break down and what lies beyond the standard model? Where are we in understanding black holes as we start to actually look at their event horizons? What underlies the near degeneracy of the many phases of the unconventional superconductivity? There are new questions of topological order, quantum computing, and machine learning. I do think that what hasn’t changed is the opportunities for interdisciplinary work.

Zierler:

Well, Doug, it's been an absolute delight speaking with you today, and I want to thank you for your time. 

Scalapino:

David, thank you for listening.