Wick Haxton

Notice: We are in the process of migrating Oral History Interview metadata to this new version of our website.

During this migration, the following fields associated with interviews may be incomplete: Institutions, Additional Persons, and Subjects. Our Browse Subjects feature is also affected by this migration.

We encourage researchers to utilize the full-text search on this page to navigate our oral histories or to use our catalog to locate oral history interviews by keyword.

Please contact [email protected] with any feedback.

ORAL HISTORIES

Credit: Sarah Wittmer

Interviewed by

David Zierler

Interview date

March 16, 2021

Location

Video conference

See catalog record for this interview.

Usage Information and Disclaimer

Disclaimer text

This transcript may not be quoted, reproduced or redistributed in whole or in part by any means except with the written permission of the American Institute of Physics.

This transcript is based on a tape-recorded interview deposited at the Center for History of Physics of the American Institute of Physics. The AIP's interviews have generally been transcribed from tape, edited by the interviewer for clarity, and then further edited by the interviewee. If this interview is important to you, you should consult earlier versions of the transcript or listen to the original tape. For many interviews, the AIP retains substantial files with further information about the interviewee and the interview itself. Please contact us for information about accessing these materials.

Please bear in mind that: 1) This material is a transcript of the spoken word rather than a literary product; 2) An interview must be read with the awareness that different people's memories about an event will often differ, and that memories can change with time for many reasons including subsequent experiences, interactions with others, and one's feelings about an event. Disclaimer: This transcript was scanned from a typescript, introducing occasional spelling errors. The original typescript is available.

Preferred citation

In footnotes or endnotes please cite AIP interviews like this:

Interview of Wick Haxton by David Zierler on March 16, 2021,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
www.aip.org/history-programs/niels-bohr-library/oral-histories/47187

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

Abstract

Interview with Wick Haxton, professor of physics at UC Berkeley. Haxton recounts his childhood in Santa Cruz and his early interests in math and science. He describes his undergraduate education at the newly created UC Santa Cruz where his initial interest was in mathematics before he was given the advice that he did “mathematics like a physicist.” Haxton discusses his graduate work at Stanford where his original intent was to study general relativity before he connected with Dirk Walecka and Bill Donnelly to focus on nuclear theory and dense nuclear matter. He discusses his postdoctoral research at the University of Mainz where he concentrated on photo-pion physics during the early days of chiral perturbation theory, and he explains the opportunities that led to his next appointment at the LAMPF facility at Los Alamos. Haxton emphasizes the excellence of both his colleagues and the computational capacity at the Lab, and he describes his faculty appointment at Purdue and the solar neutrino experiment he contributed to in Colorado. He explains the opportunities that led to him joining the faculty at the University of Washington where the DOE was about to fund the Institute for Nuclear Theory. Haxton explains the “breakup” between nuclear theory and particle theory and how the INT addressed that. Haxton discusses the opportunities afforded at the INT to engage in nuclear astrophysics and he explains the rise and fall of the Homestake DUSEL project. He explains his decision to go emeritus at UW and to join the faculty at UC Berkeley and to be dual hatted at the Berkeley Lab, and he describes his tenure as department chair. At the end of the interview, Haxton describes his current work organizing the new Physics Frontier Center and the challenges presented by the pandemic, and he credits his formative time as Los Alamos for the diverse research agenda he has pursued throughout his career.

Oh, it’s somewhat complicated. I almost moved to Berkeley around 1990. In fact, I accepted the offer [chuckles], but things got a little confused then because that was just at the time the Institute for Nuclear Theory was approved for the University of Washington. So, I became really worried that if I left, since I was very much a sparkplug of that effort, that it could jeopardize the INT. So that, plus the fact that my family situation then was complicated with kids in school and so forth, eventually led to me backing out. I still remember that Berkeley was incredibly graceful about letting me do that.

So, my parents both had more challenges than my generation experienced…They experienced the War and the Depression. They had a much more difficult and disruptive life, I think, than we do today. Those of us from the baby-boom years, we had pretty uneventful lives, at least up to COVID-19. The previous generation went through a lot more. Of course, in common with a lot of other folks of that era, they became rather conservative about finances and things of this sort, very determined that their children would do better than they had done. It was a matter of really great importance to them that all of their children went to college and got a degree, so we had lots and lots of positive reinforcement as we were growing up.

Oh, very, very early on. In fact, I can remember some great stories. My dad in particular took pleasure in teaching us practical mathematics, so I probably was six or seven years old when I knew about how one could square the corner of a building using the Pythagorean theorem. The importance of a 3-4-5 triangle my father would bring out.

I can remember him…This is something I did with my own kids because I enjoyed it so much when it happened to me. My father taught us how to measure the height of a tree from its shadow, and I remember repeating that experiment with my kids and being delighted with how clever they were in figuring out how to do the algebra associated with that. So, I liked that a lot.

My father was this very practical person who still understood basic mathematics and really thought it was terribly important, so we somehow got the idea while growing up that it’s good to be able to write well and all that sort of thing, but the math and the science are really quite special. So, I got that message very early on.

I also was very lucky. We had a neighbor who had a big influence on both my brother and me. Living immediately next to us was a retired fellow who had come from England. What was his name? I’ve lost it right now. It was so many years ago. He was the nephew of Bertrand Russell and had had a storied career as an engineer. When still quite young he was one of the principal engineers on the Trans-Siberian Railway and did all kinds of other interesting projects during his life.

He was interested in science and while there were a lot of kids in the neighborhood, few of them were interested in such thing. But he found out that my brother and I were the exceptions. He subscribed to a number of magazines: he’d bring Scientific American and Scientific Digest over to us every month so we could read them. We got really interested in Martin Gardner and things of this sort. Our neighbor would do experiments in his garage. I remember a Cartesian diver he constructed once. We were just fascinated by that, so he enjoyed the fact that there were two kids in the neighborhood that were interested in science, my brother and me, and took care of us.

I remember my mother was horrified once by one of my neighbor’s ideas. My parents left on vacation for 10 days during the summer, and the lawn usually required mowing every four or five days. My grandmother was taking care of us. Mikey (my brother) and I were talking “Gee, you know, the lawn looks pretty bad. We should try to cut it,” but my father, being a tough guy, had a push lawnmower and we could not push it through the lawn. So, we told our neighbor that we had a problem, and he said, “Well, I can fix that up for you.” [Laughing] So, he constructed a harness for us so that one of us could pull the mower while the other one pushed, and it worked marvelously well. We mowed the lawn that way. We were really proud of this.

So, when my parents arrived home, we excitedly told my mother, “We’re going to mow the lawn for you now,” to show her this harness. She looked out the window and saw what we were doing and she was horrified! [Laughs] What would the neighbors think of her treating her children this way?! So, she immediately ran out and told us, “Take off the harness and come inside quickly!” J.W. Bournier. That was our neighbor’s name. Mr. Bournier was really a fabulous guy. [Overlapping voices]

Zierler:

You went to public schools throughout?

Haxton:

[Yes.] Actually, you know, of mixed quality, but what I remember are a half a dozen fabulous teachers that had a huge influence on me while growing up. I never really thought about this deeply, but I think I benefited from exposure to an older generation of teachers. There were some very talented teachers who were just about to retire, where I had the opportunity to attend one of the last classes they ever taught. They were especially rigorous.

I remember that sophomore math in high school was geometry, and my teacher was in her very last year of teaching. She was obviously a very, very bright woman who probably went into teaching because it was a career that was open to women, when many others were not. She was very rigorous and liked challenging us. I remember we had to prove the Pythagorean theorem by a particular method that she chose, and she knew exactly that if you didn’t cut any corners, there had to be 102 steps. So that proof was one of our challenges. If you gave an answer that had 98 steps and not 102, she went through it until she found what little conceptual mistake you had made. So, she made a lasting impression on me…

Then I remember my senior year there was this fabulous fellow who…I think he was a wonderfully gifted pianist. He had been very close to his PhD in mathematics and something happened that prevented him from finishing. Mr. Greene gave us some magnificent problems. He would save special problems for the most talented students, which he would give out year to year, hoping that a few might actually solve them. So, we had lots of great challenges in the public school.

There was also a fabulous physics teacher, a very young guy. Somehow folks had noticed that I really liked science, and so I was put into physics as a junior, though physics was a senior class. Things were very regimented in those days. You carried a label that determined which section you would go into, and the strongest students were directed into a college preparatory system of courses. So, I took the physics course that year and did really well.

I remember him giving me some of his college textbooks to read on the outside because he thought I could do that. He was always frustrated that we didn’t know enough calculus yet, that our math training lagged. He taught us a kind of “backyard calculus” during the physics course. It took maybe a week to get through that, but it was enough for me to understand the basics of calculus and then to use it in physics, so we were really lucky. His name was Wayne Zeck, and I believe he continued as a teacher for many, many years, working in a private school somewhere in the Northwest for most of his career. He was a marvelous teacher.

He was also an experimentalist. He was married and working on his PhD part-time in geophysics when he taught us, but he would do experiments in the classroom that probably would not be allowed in any classroom today. [Laughter] I remember the one that was most scary. He put a kid inside of a big oil barrel and put the lid on top and then charged it on the outside to some high voltage, then de-charged it and opened it up and the kid was still alive. That was how we learned about Gauss’s law. [Laughter] Zeck was a marvelous teacher.

Exactly! I guess when I was a junior, I wound up in research with Mike Nauenberg. I didn’t have any idea what I was doing, but Mike was…We were kind of scared of him. He seemed in the classroom to be particularly rigorous, but I greatly enjoyed working with him. I remember he gave me a problem that he thought I should be able to solve, an electrodynamics problem. I worked on it for a while, and it turned out I had solved it. I just didn’t realize that. The solution was one I wasn’t familiar with. It was a parametric solution, and so finally he insisted I show him what I had done. I gave him my work and he said, “That’s what I wanted. That’s the correct solution!” [Laughs] Then he told me, “I gave this to the mathematicians, and they couldn’t solve it.” [Laughs] So, I felt very, very good about that.

Mike was also another person who had a great deal of influence on me. Later on, when I went to graduate school, he would often come over to Stanford because of the connections with SLAC. I noticed that there were a couple of young people in the department, students, that he knew, and I always appreciated the fact that whenever he showed up -- he would be interacting with the senior people at Stanford—but if he saw one of us, he would come over and say hello and ask how we were doing and so forth. Also, he was very important in me pursuing a career in physics because I had--As an undergraduate at Santa Cruz, I took majors in both math and physics. In fact, I probably did more math because there was a better variety of advanced courses available, and some graduate courses were opening up then. So, I took a lot of those.

Zierler:

What about the astronomy program, Wick? Were you involved at all with astronomy?

Haxton:

Yeah. Astronomy became a major UCSC focus somewhat later. I didn’t really think too much about astronomy in those days, although it did turn out that when I went to graduate school, my initial choice of subfield was general relativity. As an undergraduate, I had worked with J.W.T. Youngs, a mathematician at Santa Cruz. He had solved, with Ringel, an important problem in mathematics, the generalization of the four-color map problem called the Heawood conjecture. He had reduced it to something called graph theory, and the require proof basically became kind of like a game, requiring one to impose certain patterns on distinct classes of graphs. It was a problem that was accessible to an undergraduate who worked really hard, and so I got involved with it. I was always good at patterns and so forth, so I was able to help them improve a couple of sections of their proof, finding alternative solutions to the ones that they had published.

In part because of him, I applied to graduate school in mathematics, and I was convinced that that’s what I should do. Youngs had a connection with Stanford, and he was particularly interested in me applying to Stanford and perhaps continuing to work with him and getting a very quick PhD. It turned out he passed away that spring from a sudden heart attack, very unexpectedly.

I can’t remember if it was Michael Nauenberg or others, but I remember a couple of the physics professors came by and talked to me about changing my graduate school plans from mathematics to physics. I recall them telling me “You do mathematics like a physicist.” [Laughs] “There are certain kinds of problems you can do well because of your physics,” and I realized, thinking about it, that they were absolutely right. They persuaded me that I should go to graduate school in physics.

I remember telling them that I was leaning toward going to Stanford in mathematics. I had not applied in physics nor supplied a GRE score in physics. One of them said to me, “Give us two weeks. We can fix that,” and sure enough, two weeks later I got an offer to attend graduate school in Physics at Stanford and it was a great choice. I was very grateful that my Santa Cruz professors looked after me and had a sense of what I was good at.

Relating it back to classroom work, I remember I got involved in a very strange course at UCSC that was taught by Robert Hermann, who was a well-known group theorist in mathematics, and very interested in mathematical physics. This course was a graduate course, a rather advanced one, a pro seminar, but there was a typo in the catalog that made it appear to be a sophomore course. So, I showed up at this course along with a lot of my sophomore friends, prepared to take it. It sounded very interesting, mathematical physics, linear algebra, things of this sort.

On the first day of class, he pointed out the catalog error. He started going down the rows and asking, “What have you had? What background?” “Professor Hermann, I’ve had linear algebra and calculus,” and he would say, “Well, you’re not qualified. You’re going to have to leave.”

So, one after another, all of my friends left. I was the very last guy in the very last chair. He was about to do the same thing to me. There were four graduate students left in the course at that point, and one of the graduates spoke up and said, “Professor Hermann, you need five students to make a course.” [Laughs] He asked me what I had, and I told him I had algebra and calculus and he says, “If you stay, I’ll guarantee you a B.” [Laughter]

So, I stayed in this course, and I loved it because it was all kinds of crazy things about deformation and rotations and so forth, and I could see physically what he was doing. He was very much a mathematician, so I remember he was just amazed that I knew that a top that was slightly deformed would wobble when it rotated. You know, that would be obvious to any physicist, and yet a mathematician might not have the same intuition. [Laughs]

So, it was a good work…not particularly profound, but useful and rewarding. I learned a lot by doing it. Basically, experimentalists wanted to know the implications of what they were measuring, and I was able to help. The calculations were kind of a messy combination of the nuclear physics of response functions and the pion production mechanism.

Also, I benefited very much at that time from the fact that my friend from graduate school, John Dubach, had also gone to Europe. He joined the Dutch facility Nikhef on a NATO fellowship, and it didn’t quite click for him. I had only been in Mainz for a short time when John called, saying “I’m actually thinking about leaving Amsterdam. I can take my fellowship anywhere in Europe.” We had worked together as graduate students, doing one paper. He said, “Why don’t I come down and work with you in Mainz?”

So, that’s what he did. He arrived with his fellowship, and we did work on electron scattering, exchange currents, and related issues. I enjoyed tremendously working with John. John taught me everything I know about computing, and I always felt my computational skills ceased developing when John left me [laughs] because my method of learning was, “Hey John, how do you do this?” He would then tell me. [Laughing]

Zierler:

Wick, what was your funding while you were in Germany? Were you on NSF funding?

Haxton:

No. It was done through the German government, the DFG. That was another interesting story. The first time Laura and I had come there we had Eurail passes because we wanted to take a nice European vacation at some point. We decided I should get a six-month start on my physics, and then at the very end we’ll take the vacation. The pass had to be used within six months.

It turned out that week corresponded to a meeting of the German Physical Society, and Dieter wanted me to give a talk on the work the DFG had so kindly funded. This looked like a problem with no solution. But Dieter was the Dean, it was still a time in Germany when university professors commanded great respect, and deans even more. The local train officials had told me “There’s nothing we can do. We can’t extend this due date,” But Dieter offered to make a call to the headquarters in Frankfurt. I was invited to headquarters—it turned out to their executive office—where someone with apparently great authority put his stemple on my Eurail pass extending it two more weeks. [Laughing] So, that’s how we got our vacation in Europe. We had a great time in France and Spain.

It was a really wonderful institute environment, not only Dieter but Arenhoevel was there. They had both worked in Europe and in the US. They had created in Mainz a very open American-style group, so it was a terrific environment for me. I always enjoyed it. I didn’t stay too terribly long because I was always a bit concerned about returning to the US, before too much time passed.

I started to apply for positions back in the US, and I was very fortunate to be doing this at the same time as John. I had known about Los Alamos and their new facility, LAMPF, which produced the neutrino beam discussed in my thesis. When I thought about where I’d like to go, Los Alamos was very, very high up on my list, and so I applied. The Lab advertised in Physics Today for postdocs, and I responded.

Then, somewhat to my disappointment, John got an offer from Los Alamos [laughs] and was invited to interview. About the same time, he also got an offer from MIT which he decided to take, before he arrived in Los Alamos. So, he told Los Alamos this while he was there—the theory group members in T-5. On returning to Mainz he told me that someone there had responded in roughly the following way: “That’s terrible because we needed somebody who does weak interactions because of LAMPF and you’re the only one we could find with the right skillset.” He responded, “Well, what about Wick?” and they responded, “Who?” It turned out my application had gone into some—it’s a huge laboratory—elsewhere, never getting to the theory division and T-5. With that hint, they found my CV and they agreed it was a really great match and I received a very nice offer.

Los Alamos, for me, really that was a career builder. I thrived in that environment. I had fabulous mentors there. Two young theoreticians, Peter Herczeg and Joe Ginocchio, were my official postdoc mentors, and in the years I was there, there was an extraordinary flow of nuclear and particle visitors to Los Alamos. We had what would be regarded today as a huge visitor budget for summer visitors, and it seemed like everyone in physics passed through at least once. Problems discussed with the senior researchers tended to filter down to us postdocs, so we would be presented with so many ideas for new projects. We postdocs would hear “Why don’t you work on this? Why don’t you work on that?” So, I got some great ideas.

That’s where I learned about double beta decay, for example. It had a big influence on my career as I was able to modernize both nuclear and particle physics aspects of the underlying theory. But the need for this work came from a T-Division advisor who was critical of existing work. The suggestion came to me that somebody ought to work on the formal development of the theory of double beta decay, and I decided that was a good idea.

I got ideas about parity violation and time reversal violation studies from Peter, Joe, and others. They were always fabulous in looking out for me, very smart, very modest theoreticians who were always putting me first in the work we did together. I never could write a paper with Peter because if I did my part, then Peter felt he didn’t do enough. [Laughs] And Joe and I actually did collaborate a little bit there, and then we had some great collaborations after I left Los Alamos.

And then it turned out that John and I again intersected there later on, and we spent a lot of time using up all of the computing resources we could find. VAXes were a new thing and by that time John and I had worked together and kind of mutually decided that we needed to understand many-body theory and computation, so we kind of taught each other that. We rewrote a shell model code together…a reworking of the famous Glasgow code, which was in part in machine language. I always thought John and I complemented each other beautifully. He was much more the computer scientist, and I thought a lot about algorithms, and together we could do some really, really good work.

I just loved working with George. He was such an interesting guy, and through him connecting with Tony and others…It spun me off into double beta decay experiments, and then interactions with Ken Lande…We work on experiments that could be done in the LAMPF neutrino beam, and so I got involved in this experimental-theoretical interface that I acquired a pretty deep way of thinking about the experiments. I remember Ken made me really happy one day when he said, “You’re about the only theoretician I know that actually understands experiment.” [Laughs] That was an exaggeration, but I did get a pretty good handle on the experimental details.

Then years later, a few years later I wound up…Frank Avignone and Frank Calaprice did an experiment on axions—again, with a connection to Ray Davis because they used a neutrino source that came from Davis. He wanted to use the source in the Homestake mine, but it turned out to be too heavy to get down the lift, and so the Franks borrowed it for this axion experiment instead. They completed the experiment, but they had a disagreement on how to do the data analysis, for which I had previously done the background theory. They wanted to know how do axions interact in matter, so I had worked out the theory they needed.

I waited and waited and there was no draft paper because they couldn’t come to agreement. I finally said, “Well, look. Give me the data and let me try—you know, a third opinion.” [Chuckles] They did that, so I made up…You know, I had never done data analysis before, so I just made up an analysis, folding it in with all the theory I had done. They both liked it and we published a paper.

Wick, was your sense that UW was in growth mode at that point, that it had a great group of physicists, but it was really looking to enter into the next tier of departments?

Haxton:

I think so. Clearly, Ernest Henley had a huge influence on my career. I always liked working with him as a theoretician, but he was a marvelous man in terms of how he knew how to interact with people and also because of his style of leadership. He was incredibly important to the UW. He was dean during some of the really, really difficult times they had, and he steered them on a very, very good path. I would just see him, how he reacted to difficult situations. I was never blessed with innate tact [chuckles], so I would just marvel at him. I would see him in situations that were socially awkward with four or five people, and there would be one person that instantly reacted in the right way, and it would always be Ernie. He had this ability just to know what to do to help other people, so having somebody like him as a mentor was incredibly important to me. It helped me…

A friend of mine competed for that, and the final choice came down to Santa Barbara or Santa Cruz. This guy looked at me and said, “If you don’t have a beach, you’re not in the competition.” [Laughter] It struck me that Seattle is a really great place to visit all times of the year, and folks like the city with its amenities and so we had some advantages.

Then when we designed our version of the INT, we focused on creating a national institute that would serve the entire country. I think that the major contenders made the mistake of saying, “Well, we’re the strongest place in the country. We have all this talent. We’re going to advertise this talent, and it will be a privilege to come here.”

Zierler:

Yeah.

Haxton:

And we took this very other different viewpoint of focusing all of the resources on the community and trying to be good stewards. Instead of flaunting our Nobel Prize winners, of which we didn’t have any at that time [laughter], in our presentations we would feature the students and the education they were getting and things of this sort. Of course, that was very, very wise because, as the big universities and labs were competitors, the selection committee came from places that…Most of the faculty that were on that committee came from smaller places. So, what we said really resonated with them.

It was a shock to the DOE when the committee wound up…I guess there was one holdout to the very end, but in the end they all decided that they would be unanimous in picking Seattle as the site, and the DOE was not at all happy about that report. [Laughing] I won’t go into political details, but it went up to a very, very high level nationally whether or not this report sees the light of day. But in the end, the DOE decided that we were okay, that they would site it at Seattle. David Hendrie initially wasn’t happy with the decision, but to his great credit, two years later, I remember having a conversation with him during which he said, “You know, I wasn’t a supporter of you guys, but this is a great institute. I’m really happy with it.”

Zierler:

Wick, this idea that one of the things that your proposal stood out as that you would be stewards for the community and you would be outwardly looking in terms of the service that you would provide for the whole country—what does that mean in the world of nuclear theory? How can you be of service beyond the academic questions that are happening onsite?

Haxton:

Yeah. So, I think for us what that meant was two things. First of all, the DOE concept behind the INT was to prepare theory to help support the big facilities that we were then creating, RHIC and Jefferson Laboratory. That problem comes back to the fact that our community in nuclear physics, especially at that time, was very dispersed. Remember that experiment was always done, up until that time, in small tandems, so there were small experimental groups in lots of different universities, and they tended to have one or two theoreticians associated with them. So, you had this problem of a lot of good people in a lot of random places around the country. How do you get them organized to support a big facility?

So, that’s why we emphasized programs and workshops that would bring the community together, focus on a certain theme, get folks interacting, and then send them back out to their home institutions with the notion that those partnerships and collaborations would continue. What we proposed had that concept behind it. What we actually said in the proposal—I was amused a few years later to go back and read the original proposal and compare it to what we had done. We actually did much, much better. [Laughs] The idea was there, but the actual implementation required trial and error: we learned as we went along of what worked and what didn’t work.

What we wound up with was an institute that would bring in somewhere between 600 to 800 people a year for various workshops and other events. Especially at the beginning, we focused on these long, intensive three-month programs where folks really got deeply into collaborations while they were in Seattle. We took the viewpoint that we wanted to push back the boundaries of nuclear physics, that we saw a lot of the opportunities in areas like astrophysics, nonlinear physics, atomic physics, particle physics, and so we wanted to feature these intersection areas in the field. So, we put a great deal of effort into recruiting program organizers from these boundary areas.

I remember one of the things that really helped us in the very early years is that Norman Ramsey came for one of our workshops on electric dipole moments and time reversal. He had a great time, and he went back to the DOE at a very high level and said, “This is a fantastic institute.” I remember my old friend Mike Nauenberg came and he was very skeptical about nuclear physics, but he spent a week there and he said, “I would have told you before coming that this was a dead field, but this was terrific.”

There was a feeling among many that if you weren’t doing high energy physics, you were no longer modern. We and condensed matter were in the same boat at the time. This was not some…Condensed matter had to deal with the “squalid state” view of that field, so…And to our credit, I don’t think we ever gave up. I do think that in my generation, there were a number of good people who took a little bit of the criticism to heart and tried to move out into different areas and push these intersection areas that brought vitality into the field. That was very, very important to us.

So, the formula at the INT was right for the entire field, recognizing there’s a lot of talent and a lot of interesting problems, but also a lot of opportunities in these boundary areas. So, if somebody measures an electric dipole moment in an atom, you’d better understand the atomic physics, the nuclear physics, and the particle physics, and the hardest parts of that are the many-body physics and we are necessary for that.

It’s a theme in much of my research throughout my career. I often take on problems…a recent one was dark matter scattering off nuclei…and really drill down to understand how to create the interface between the particle physics and the nuclear physics. How can you distill the nuclear physics in the simplest possible way, but in a theoretically rigorous way, to make the connection with the high energy guys who are worrying about the UV theories and integrating down to the nuclear level? How do you teach a particle theorist what you can and cannot learn from direct detection at very low energies? That’s a problem they have a hard time with, but we can help. So, I’ve always appreciated the importance of establishing this interface.

I’ve gotten a lot of support from my particle physics colleagues over the years that…You know, they still cheat in some ways. Some particle friends have argued that, you know, “We like what you do because you’re not a nuclear theorist,” and I’d say, “No, you don’t understand. I’m definitely a nuclear theorist. You like what I do because it’s relevant to what you do.” There’s a really important distinction there that I think was lost on the field for quite a number of years.

Zierler:

Wick, just to clarify the politics beyond this and also the science, so what you’re saying is there was no specific breakthrough in nuclear theory that fostered interest in the creation of the INT. The science had always been there; it was more of a gradual PR understanding that there needed to be more heft behind the field. It wasn’t that it was a backwater and then something happened that made it exciting. That was not really the issue, you’re saying.

Haxton:

Yeah. But I would say it’s not quite so clear. I think that it was a backwater in the sense that we were not sufficiently reaching out to these other fields and [overlapping voices]—

Zierler:

But again, that’s a PR issue; that’s not a science issue.

Yeah. We were kind of lucky. We argued for something that the University had not done before and they agreed to it, which was to make us fully-tenured faculty members, but treat us as if we were on permanent leave from the department. We had few people in the UW administration who were willing to create new policy for us. Especially the Vice-Provost for Research, Alvin Kwiram, who did so much for the INT.

Zierler:

Meaning no teaching responsibilities? Did not have to take on graduate students, that kind of thing?

Haxton:

Zierler:

To go back to this theme about your appreciation and comfort in both the world of experimentation and theory, as director how did that inform your mandate or the way you wanted to see the INT unfold?

Haxton:

We made an effort in every program to have the experimentalists come as well. They were generally willing, and not only willing but they often found it kind of a delightful experience. The few who joined were the belles of the ball. Two or three experimentalists in a group of 20 theorists get a lot of attention, and the experimentalists enjoyed that. Our experimental colleagues have always been incredibly supportive of the INT.

In fact, that’s one of the great strengths of nuclear physics in general. I’ve been in many DOE and NSF meetings, and the experimentalists in this field really do support the theorists. They understand why theory is important, why it’s relevant. We’re often easy to forget because we’re a small part of the budget, but if they’re pressed with “Should we find some way of helping out theory,” experimentalists in our field are inclined to say yes. They really do appreciate what we do. That helps us, adds to the stability of nuclear theory. In contrast to particle physics, where parts of that field have gotten so abstract that making connections with the experimentalists is difficult, we have always enjoyed a partnership.

I can remember once being invited to give a seminar for a prestigious experimental group in high energy physics as part of their normal series. [Chuckling] “We invited you because we thought we might be able to understand you.” [Laughs] It helps a field to be grounded in phenomenology, and that aspect of nuclear theory has worked out really well for us. In an area like the solar neutrino problem, we were right in a sweet spot. We knew enough to critically look at solar models and the error analysis that goes into that, drawing the right conclusion—there’s something really interesting going on here that we should invest time in.

Zierler:

Wick, what opportunities did you see at INT to engage nuclear astrophysics, nuclear astrophysicists into the overall framework of INT?

Haxton:

Well, you know, neutrinos were really a focus, a key component of nuclear astrophysics in those days. One project that we launched—and I wish I had done this better—was DUSEL, the NSF program to create a national Deep Underground Science and Engineering Laboratory. Hamish and I had come to the conclusion that we needed something like Gran Sasso or Kamioka in the US to keep up, and so we called a meeting to engage the community in this discussion. We had some ideas going into that meeting about where we would wind up.

Zierler:

Wick, what opportunities did you see as director of INT to serve in a mentor capacity either to undergraduates, graduates, post-docs, or even junior scholars?

I went back to research. During that period, I began to realize that I was in danger of continuing to do the same things [laughs] that I had done earlier. No, being INT director is a great administrative job because I could continue to do research at a reasonable level throughout. It wasn’t like being department chair, which is all-consuming, and thus I didn’t have any trouble getting back into research.

Primarily, the decision to leave UW after that period was just that I felt there was a danger of being stuck in a rut, that if I were ever going to make a change and take advantage of the last 10 to 15 years of my career, it was the time to make the move…A move would force me to form new collaborations, new interactions, and to think about new problems. I just sort of intuitively knew it would be good for me to make a change. Indeed, I always had some regret about turning down Berkeley in 1990, because of the variety that would have come from that move (and because Berkeley is close to where I grew up).

In fact, when I actually made the move, my mother and my sister were both ill and living in Santa Cruz, and I thought, “Gee, being closer to them during this period could be really helpful.” So, that started my thoughts. It wasn’t…In the end, neither one of them survived long enough for me to make the move to join them, but it got things started for me.

Then when I visited Berkeley, again, the aspect of the department that just overwhelmed me was the friendly welcome I received from its various groups. I felt like each one of them wanted to welcome me to the department. Then I started meeting the folks that run Berkeley, and they were all scientists. The administrators were not administrators; they were scientists volunteering as administrators following Berkeley’s philosophy of faculty governance. Any university that has Bob Birgeneau as chancellor and Frances Hellman as a dean will value research. It was just amazing, the feeling I got that this is…I never thought I’d find a place as good as the UW, but I was convinced from my Berkeley visit that a move would be great for me, and it’s worked out that way.

Berkeley has been so supportive, both at the laboratory and on campus, you know, doing everything they could possibly do to help me succeed. The lab helped me start up the astrophysics effort that led to the hiring of Dan Kasen, who is quickly becoming a superstar in that field. It helped me start up a lattice QCD effort…The idea we ran with is still very fascinating—making lattice QCD talk to effective theory in a way that’s compatible with how we actually model nuclei. So, we created a program called CalLat. André Walker-Loud came to us as a postdoc, then returned to the LBL staff. Connections with the Japanese lattice community led to a partnership with RIKEN, Japan’s national laboratory, that now extends to areas like explosive astrophysics and quantum information.

In the department, I have links to both particle theory and astrophysics. I returned recently to dabbling in condensed matter, and my condensed matter colleagues took an interest. They saw a paper I wrote, invited me to give the 290 Seminar, and later persuaded one of their students to give me a hand. [Laughs] He told me “They say that you need to know more about the literature.” This student became a coauthor on the next paper. Berkeley faculty look out for one another and cheer each other on. I know other universities where groups are jealous of each other. Berkeley has a very different sociology. And it’s so fun—

Zierler:

Now the appointment from the beginning, was it dual appointment that you would be co-located at the lab and the physics department?

Haxton:

Yeah, and this furthered a long-term goal of the laboratory. The Nuclear Science Division had tried for many years to bring somebody in that would reestablish the connections with campus. LBL has a Physics Division, the home of particle physics and a Nuclear Science Division, the home of nuclear physics. The Physics Division has always been connected with the physics department on campus. The Nuclear Science Division, because of Seaborg and other great nuclear chemists, was initially partnered with the campus’s chemistry department. But over the years, nuclear chemistry declined in importance in chemistry, and so the connection between the Nuclear Science Division and campus atrophied.

Yeah. I think it’s always been pretty positive, but certainly the lab helped me tremendously with our recent recruitment and retention efforts. They’ve been a strong partner, and very frequently we share a vision of coming physics opportunities. During my term as chair, we worked together to strengthen campus and LBL in areas liked collider experiments, condensed matter experiment, and quantum information. All of our peer departments are in private universities with deep pockets. Berkeley is the only public university among the top ten physics departments, and our partnership with LBL is one of the reasons we compete so well. As we have fabulous people, we also have many retention battles to fight, and the laboratory has consistently helped us. They also often partner on new hires. Their LDRD program is a source of funding for young faculty with LBL connections. But benefits flow in both directions. Our department helped LBL conclude several recruitments successfully this past year, and several of our faculty are in leadership positions at LBL.

So, it could not be better, and we’re really blessed to have a national laboratory on our doorstep with such a record of Nobel prizes and big-science leadership. LBL is often called the crown jewel of the national laboratory system. Being right next door to UC Berkeley and its fabulous students is not a bad deal for LBL, either. It’s a marriage made in heaven, and we’ve been lucky that folks like Mike Witherell and Horst Simon who run the laboratory recognize this, and work to keep our partnership really strong.

Zierler:

Wick, just to bring the narrative up to the present, when you recovered from being chair, COVID was still happening. What have you been doing in recent months? What’s been on your agenda?

Haxton:

Yes, I’ve gone back to doing some work, getting my students on track…reconnecting with my students to make sure that they finish with strong theses. And then I’ve been spending a lot of time organizing the new Physics Frontier Center. We just did our first batch of hiring for that. Of course, everybody is working virtually now, but we hope actual people will be arriving this coming fall. We had a previous program, also supported by the NSF, that resembled a mini-Physics Frontier Center. This project morphed into the Frontier Center. Thus I’m closing out one project while starting up a second, trying to engineer a smooth transition between the two. So, I’m excited about that challenge. I’ve got some great collaborators around the country: George Fuller at UC San Diego, Sanjay Reddy at the INT, Gail McLaughlin at NCSU, and Baha Balentekin at Wisconsin. Really, really terrific people who are part of the PFC executive board.

So, we have the task now of putting together this project with generous NSF support. It’s basically about multi-messenger astrophysics, which with gravitational wave astrophysics at a threshold, is going to be a huge deal. If one looks at the resources that are going into the astrophysics instrumentation to extend the fidelity and depth of our probes of the universe, it’s staggering. It’s many billions of dollars of new investment, and a lot of the physics underneath involves nuclear, neutrino, or atomic physics, the stuff we do. The theory wasn’t responding adequately to the growth of experiment and observation. Perhaps the PFC can do for these fields (nuclear astrophysics, neutrino astrophysics, dense matter physics) what the INT did for nuclear theory in support of RHIC and JLab. The NSF and its referees really resonated with our arguments and were willing to support us through the Physics Frontier Center program. A lot of credit goes to some terrific program officers at NSF, who were not hard to persuade because they were aware of the needs. NSF has long had a vision for this field, as one can see from its early and consistent support of gravitational wave astrophysics.

Competing for a Physics Frontier Center is not something one does lightly. It’s a year-long effort of coordinating a team and developing a science case. So, I’m excited. The PFC effort has been a good use of my experience in the field and my talent for organization. I still get more enjoyment sitting at my desk and working on my personal research. But while the PFC is a big effort, it still leaves some time for my research and for interacting with my students and postdocs, so I’m in a nice situation at the moment.

Zierler:

Wick, I’m not familiar with the term multi-messenger. What does that mean?

Haxton:

It means that now…A great example was the discovery of the neutron star merger a few years ago by LIGO. They detected the gravitational wave signature of the merger, which if you distilled down to basic physics, probes the structure and deformation of the stars as they merge, ultimately reflecting properties of the exotic dense matter at their cores. After they merge they produce an accretion disk and later a radioactively powered explosion known as a kilonova. The physics is multi-messenger because we have many different probes of a single event—gravitational waves, a variety of optical and other electromagnetic observations, a short duration gammas ray burst, and forensic evidence of nucleosynthesis. Dan Kasen, my colleague, with Elliott and Metzger worked out the theory of the kilonova to explain the radiation signatures that we would see: the optical observations, the gamma ray burst, the gravitational waves, the nucleosynthesis. These are the messengers. Multiple observations now constrain the underlying theory, testing whether we really understand what happens when two neutron stars merge.

There is so much physics going on in a merger—the multiple signals from one event—that the interpretation of the data is beyond the capacity of any one person. Our Center represents a collaboration of some of the best people expert in the various areas, who are committed to work together in order to make progress. Frequent interactions lead to progress. Our group is involved in the modeling of these events—the use of high-performance computing to simulate the events, thereby connecting observables with the theories that describe the underlying microphysics. Connecting the dots in this way should lead to progress, so that’s the idea behind N3AS. I think it’s a great idea. The problems are hard, but I think we got the right collaboration and right organization.

Central to our plans is the training of young people, including giving them unusual opportunity to build scientific breadth, as that is so necessary for success in this kind of field. We do not want to train postdocs as specialists because they’ll never recognize what the important problems are or who they should collaborate with, as the field is broad and interconnected. Thus, we started by forming a national collaboration that includes many of the field’s leaders, and we created a post-doctoral program that allows young researchers the freedom to interact with anyone in our network. Our postdocs do not belong to the individual sites, and they have the resources they need to travel throughout the network to collaborate in person (though COVID now restricts interactions to Zoom). They are free to seek mentors and advisors anywhere within this collaboration. I think we’ve so far succeeded marvelously with this training model.

Prior to COVID-19, I noticed that when a half a dozen of our young people showed up at a meeting, they would link up. [Chuckles] They recognize themselves as a group as opposed to individual members from Northwestern, Kentucky, UCSD, etc. They interact every week, and that builds community. It’s great to see. So, the PFC is built on an emerging science theme of multi-messenger astrophysics and a plan to train postdocs to be broad scientists, and we’ll see in five years how successful we are in making an impact on the science.

Zierler:

Wick, in what ways is this collaboration offering research that might make a big impact on some of the most intractable problems in cosmology?

Haxton:

Yeah. It can. We’re interested in dark matter, for example, because the explosive astrophysics we study provides environments that are far beyond the capacity of any laboratory to reproduce. One can explore the possible signatures of dark matter in such settings, then check to see if there is any observational evidence of such signatures. Many of our interests are cosmological, for example, the neutrinos in the early universe and the possible consequences new “sterile” flavors or new interactions. We may learn within the next five or ten years what the absolute mass of a neutrino is from its influence on large-scale structure formation. We may learn more about sterile neutrinos, or at least place limits on their existence, from their impact on nucleosynthesis in the Big Bang. We might detect dark matter through its interactions within a supernova or a neutron star, for example altering how a neutron star cools. They might be produced directly through interactions with or within these objects. One has to work through the various possibilities to determine whether interesting opportunities exist.

Yeah. I think it all goes back to Los Alamos, where so many different problems were offered to me. I began to learn that by stretching a bit, one can learn more and then later one can do more. It’s a good strategy for developing. It may seem like at the beginning that tackling new problems is costing too much time. One will not generate the same number of publications as somebody else who decides to redo his thesis in six different ways, producing quick publications. Nevertheless, one begins to see connections and opportunities for new work.

For example, at Los Alamos I wandered into a collaboration with Kevin Schmidt, a many-body theorist who used Monte Carlo methods, who was interested in the fractional quantum Hall effect, and saw advantages in solving this problem not in a plane, but on the surface of a sphere. It turned out that Haldane had already introduced this idea. But once this mapping is made, interesting connections with group theory techniques used in nuclear physics emerge. The many-body states of interest have total angular momentum zero. So, that makes one curious whether one can contribute something that others have missed, because one views the problem in a different light.

I’ve always been lucky, fortunate, and grateful that my primary sponsor, the Department of Energy, has been willing to let me explore. Our field is not at all narrow. I mean, it has core interests but there are no strict boundaries today. As I mentioned earlier, this has not always been the case…If one is at the core a nuclear physicist, but pursue an unconventional topic that arises, it’s okay with them—if the quality of the work is high. [Chuckles] If one has a long track record with the DOE, there is a level of trust that the work will prove to have some relevance.

I remember a time at the INT—a bad year as too many tasks were coming across my desk. I was unhappy with my own research progress. My DOE program officer called about the INT budget. Then we turned to my own contract. I said, “You know, I’m really embarrassed about how little I did this last year,” and he says, “Oh, don’t worry, Wick. We know you’ve been busy!” [Laughs]

The DOE has always taken this long view. Researchers have ups and downs, obligations to the community, and so on. It takes away from the physics. DOE seems to have faith that we researchers are making good decisions, and they tend to grade us on our long-term record.

Great. I enjoyed it tremendously. Thanks so much.