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Credit: Barbara Grannis
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Interview of Paul Grannis by David Zierler on July 6, 2020,Niels Bohr Library & Archives, American Institute of Physics,College Park, MD USA,www.aip.org/history-programs/niels-bohr-library/oral-histories/45471
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In this interview, David Zierler, Oral Historian, interviews Paul Grannis, emeritus professor of physics at Stony Brook University. He recounts his childhood in Ohio and describes his early interests and talents in math and science. He explains his decision to attend Cornell University and his reasons to focus on engineering physics while also developing an interest in theory. Grannis describes his graduate work at Berkeley, where he joined the Chamberlain group, which had focused on aligning the proton spin with the magnetic field by transferring the electron polarization to the proton polarization. He reflects on the differing approaches in particle physics as represented by East and West coast institutions. Grannis discusses his research work on the Cyclotron and Bevatron, and he describes his dissertation research on Regge poles and measuring the polarization of lanthanum nitrate crystals. He discusses his postdoctoral research at the Berkeley Radiation Lab, and he explains his decision to join the faculty at Stony Brook, which struck him as an exciting and up-and-coming place to pursue a career. Grannis describes the additional attraction of being in close proximity to Brookhaven Lab, and how he contributed to the overall broadening and improvement of the physics department. He explains his involvement in the ISABELLE project, and he describes the origins of the D0 endeavor and the feeling of excitement at Fermilab during that time. Grannis provides perspective on some of the inherent challenges in the SSC planning project and the existential challenges Fermilab faced as a result of focusing so exclusively on the Tevatron project. He describes the current state of high-energy physics and Europe’s leadership in this field, and some of the hypothetical advancements that could be made with the ILC endeavor. At the end of the interview, Grannis discusses his current work as co-spokesman of D0, his ongoing planning work on the ILC, he muses about what science projects he would fund if he had discretion on where to deploy 10 billion dollars, and he shares what he sees as some of the most exciting short and long term prospects in the field.
This is David Zierler, oral historian for the American Institute of Physics. It is July 6, 2020. It is my great pleasure to be here with Professor Paul Grannis. Paul, thank you so much for being with me today.
It’s a pleasure.
All right. So, to start, would you please tell me your title and institutional affiliation.
Strictly, I’m an emeritus professor at Stony Brook University. I’m also a research professor, which gives me the opportunity to still have grants and carry on with my research.
And absent the pandemic, were you still going into the department with any frequency?
Yes. Ordinarily, I would be there every day.
Every day? Oh, wow. And what year did you go emeritus?
2006.
Okay. So, let’s take it right back to the beginning. Let’s start with your family background. Tell me a little bit about your parents and where they’re from.
Both of my parents were from northern Kentucky. My father was trained as an architect, became a civil construction engineer after surviving the Depression. My mother started out as a teacher but then was a housewife. So, they moved early in their marriage to Ohio from Kentucky and lived there ever since, and I grew up there until I went to college.
What formal training in engineering did your father have?
In engineering, none, I think. His degree was in architecture.
And did he involve you at all in math and engineering issues growing up?
No. I wouldn’t say that he did, particularly. I mean, it was always an interest. They expected me to learn math and to be good at it, but I don’t think my father was particularly mathematical. As I say, he was trained as an architect. Although, [laughs] he had problems keeping buildings standing upright. It’s more of an art, perhaps, than a science sometimes.
And what town did you grow up in, Paul?
In Dayton, Ohio.
And did you go to public schools throughout?
Public schools throughout, yes. The schools were quite good for the time.
And were you interested in science as a young boy, even before you were introduced to physics and biology and chemistry?
Yes. First thing that I can remember that turned me on to science was a visit to the Hayden Planetarium in New York, on a visit when I was probably 12 or so. And I thought it was absolutely grand, and I got a bunch of little paperback books describing the solar system and what was then known about the galactic astronomy. And that certainly turned me on and stayed with me as an interest all through my life, although I’ve never been directly an astronomer, [laughs] although I tried at one point.
[laughs] And at what point did you start to exhibit strength in math and science, academically? Was that early on, like in junior high?
Yes. Yeah, it was always the case that I was among the top two in the class in science and in other things as well.
Now, when you were thinking about colleges, were you thinking specifically about physics, or you settled on physics but already during your time as an undergraduate?
My choice of college was based on the fact that I rather fell in love with Cornell University. My sister went there, and my father had gone there. His degree was from there. And we had visited, and I thought it was a grand place. So, in fact, I did not apply anywhere else.
Oh, wow.
I was going to apply also to one other place, but I got into Cornell, so I didn’t need to. So, the choice of university was not based on the kinds of strengths that they might have academically. On the other hand, I applied to the engineering school, in part because that’s what young people in those days did.
Right. Were you influenced by your father to think about engineering?
Probably yes, and also by my sister, who is considerably older than I am, and was in — had gone to university and was herself a scientist. She was trained as a chemist. So, I chose engineering physics because somewhere along the line, I heard it was the hardest major that they offered, and so I thought: that sounds great. And from engineering physics to physics was a relatively short step.
So, before you got there, you had no idea the quality of the physics program at Cornell and the world-class professors that were there.
I don’t remember that I did, but I’m sure I was aware of it, and there were, after all, some fairly luminous people: Hans Bethe, Phil Morrison, Tommy Gold, and Ken Greisen. And I’m sure I knew about those folks.
And so what was the tipping point for you to decide to switch over to physics when you got there?
I never did as an undergraduate. I finished as an engineering physicist. We took as much physics as the physics majors. We had — it was a five-year course, and so we had also some engineering things. But we had every physics course that the majors had. So, I stayed with it, but by the time I was finished, it was clear to me that my interest was in physics of a fairly fundamental sort. And so, I applied to graduate school in physics departments.
So, even with an engineering focus, your exposure to theoretical physics was more or less equal to those of physics majors?
Oh, yes. They were the same courses. We were in the physics majors’ courses.
Right. And with the five-year program, did that come with a certification?
It came with a bachelor’s in engineering. All of the engineering at Cornell in those days was five years. I think the notion was that they should be training people who were not only technically well-educated, but also, to some extent, culturally. There was a fairly strong emphasis on the arts, or history, or whatever.
I’m curious, as you transferred over into a traditional physics program at Berkeley, if the engineering focus served you well in any way.
Not really, I think. My degree in engineering physics, by the time I was done, was essentially all physics thrust. I mean, yes, I took a course in machine tools, and I took a course in mechanical drawing when I started out, but [laughs] by the time I finished the engineering side of things, it was sort of in the distant past.
Did you go to Berkeley with the intent of working with a particular professor, or is that the best program for you that you got into?
No. I got into several places, and I was looking for a place where I could do astrophysics, where there was a strong astrophysics component. And there was a reasonably strong astronomy program at Berkeley. I considered going to Michigan which, at the time, had pretty strong astrophysics. And I considered going to Princeton, which also did. So, I started out thinking that astrophysics was what I was going to do, and I took courses with the astronomers. And in the end, it seemed to be a little bit like library science. [laughs] They were working out the details of stellar evolution, which is a great story, but the ideas and all the underlying principles had pretty well been established, and it didn’t seem all that exciting at that moment.
Right. As opposed to particle physics, where the early 1960s was some of the most interesting and exciting time in the history of physics.
Right. Yeah, so the particle physics won out. In the long run, of course, nowadays cosmology is one of the most interesting [laughs] subjects going. So it would have been interesting to stay with it. Fashions change, and the excitement levels of different subjects change. Yeah, so in those days, I had that idea for a year and a half and then sort of sloped off and did a summer research position with the Chamberlain group at Berkeley and stayed on and did my Ph.D. there.
How did you first connect with Professor Chamberlain?
He was, in fact, my advisor, so he was the first faculty member I met. In my second year, I took a course with him in electrodynamics, so I knew him at some level prior to starting with his group.
And was that how it worked at Berkeley? Were you connected with an advisor first thing, or you had to make that connection yourself?
No, I think it — we were told to speak with our advisor. I remember educating him on the quality of this engineering physics program at Cornell, which he didn’t know anything about. So he, like you, was saying: so, your training is in engineering. You must be deficient in physics. And I said, [laughs] “No, that’s not the case. All the brightest people, in fact, were in the engineering physics program, and not in the physics major. But anyway, yes, we crafted our initial sequence of courses with the advisors.
And what was Chamberlain’s research? What was he doing with his group when you arrived?
He had developed, essentially, the first polarized proton target. So, it’s an optical pumping thing. You use microwaves to... and — oh, I should ask, David. What is your kind of physics?
I’m a historian, so history of physics.
You’re history of physics.
Yeah. So, I can —
Your Ph.D. is in history.
Correct. So, I can track with you, but I’m not a physicist myself.
Okay. So, he developed this method of aligning the proton spin with the magnetic field by transferring the electron polarization, which is large, to the proton polarization, which is ordinarily small. And so, we measured all the particle reactions that had been looked at before, but now with the protons spin up or spin down and measured this difference in the scattering for one orientation relative to the other. In a way, it was more interesting for the technical side of building this polarized target than it was for the physics results that came from it.
And if you can give a sense, just for some historical context — I mean, Berkeley is such an exciting place to be at this time. Particle physics is such an exciting place to be. Working with Professor Chamberlain is exciting. What are some of the biggest questions that were going on in particle physics generally during this time, and where did you see your interests fitting in?
Well, the east coast and the west coast particle physics communities were focused in quite different ways.
Right.
And in many ways, the east coast side of things was somehow for me the more vibrant or the more interesting or uncovering more puzzles that were of fundamental importance. The Berkeley school was focused upon the notion that there is no hierarchy among particles. Any particular particle was made from the combination of others and they built themselves. And so, we made a lot of measurements of these scattering cross sections that were of use in trying to build this picture.
Who were some of —
Meanwhile, on the east coast, there were — go ahead.
I was going to say, when you were talking about this east coast/west coast divide, who were some of the leaders on each side that were driving these different research agendas?
On the east coast, it was T.D. Lee and Frank Yang; theoretically, Murph Goldberger. On the experimental side, they had just built the Cosmotron at Brookhaven, and it was during that time that I was a graduate student, the first observation of CP violation in the weak interaction was made, which had everybody very puzzled indeed. So, there was a focus on symmetries and underlying forces and field theory — a theory where you can calculate how things go based upon there being some kind of fundamental entity that made matter constituents. And the west coast, as they say, it was this democratic bootstrap thing. Regge poles were big, and it seemed, I think, to me then, and in retrospect, that the much more promising way forward and the more pregnant set of studies were the things that were going on on the east coast rather than in Berkeley, anyway.
Did you work with Professor Chew at all?
No. I took a course from him. This is Geoff Chew.
Yes. Correct. And how did you go about developing your dissertation topic?
We were doing a series of experiments. We’d do one experiment at the Berkeley Cyclotron at lower energy, and then we’d go to the Bevatron for higher energy. And the next experiment up when I joined was going to be this proton-proton scattering at the top energy of the Bevatron, which was up to 6 GeV. And they didn’t have a student to take it as a thesis, and I was new in off the block, but they said: well, why don’t you do this as a thesis? We’ll make a deal with you. You do this as your thesis, but you will then work on a series of other experiments and [laughs] pay your dues on all of those. So, I did that. I didn’t choose it. It was there to be done. It was the next thing in the sequence of experiments that the group did.
Up to the time when you settled on this topic, did you think of yourself more as a theorist or as an experimentalist?
I think most physicist undergraduates, early graduate school, think of themselves as theorists or want to be a theorist. Steve Weinberg was on the faculty at Berkeley and taught me field theory and I asked him if I could be his student. He said no! I did start with another theorist on a problem that I thought was not so exciting. That summer I worked for Chamberlain on his experiments and this opened my eyes to the pleasures of experimental work. I began to be excited about doing experiments, and the fact that in the course of an experiment, you go through a cycle of different things that you have to work on. For a while, you’re a plumber. For a while, you’re a carpenter. For a while, you’re doing computer science. And then, you can come back and do physics. And then it goes through the cycle again. It’s a broad-based thing, which I found that I enjoyed.
What was Professor Chamberlain’s style as a mentor? Did you work closely with him? Was he hands-on, or you pretty much only went to him when you had a problem that you needed help with?
He was as hands-on as he could be. By that time he was famous, because he had won the Nobel Prize not too long before. But this was also during the Vietnam War. He was a very strong anti-war advocate, and Berkeley in the ’60s, as you probably know, was a hotbed of anti-war and student protest and the like. And he was involved in that.
Even as early as 1965, which is relatively early for the protest movement?
Mario Savio was in Berkeley — this was probably ’64, and the takeover of the administration building.
Right.
It was earlier than it was in Columbia, for example, which was several years later, when they took over the library. No, it was a big deal. But anyway, Owen was always a part of the group taking the data. He took his shifts. He tended not to be the one who was leading the charge in the experiments, but he would sort of watch over things. I remember in the first experiment — what turned out to be my thesis experiment — I was trying to build a light-tight box around a phototube, because — and I was doing it with black tape. And he came along and showed me. “No, Paul. This is not the way you put tape on something to make it stick and make it light-tight. This is the way you put tape on something.” [laughs] It was nitty-gritty kinds of instruction, often.
Paul, what do you feel were your contributions with your dissertation, either to Chamberlain’s research group or to the field of particle physics generally?
I think the results from my thesis were interesting and have been used for testing models, but they certainly are not ground-breaking, or not very incisive. Within the group — what did I do? Well, this was the days of Regge poles, and I think I was one of the first to apply the Regge pole phenomenological theory to our data. So, that was an opening that was then followed by many others. One of the things I was fairly proud of was the measurement of the polarization of this polarized target, which was a lanthanum nitrate crystal of some sort, and it was immersed in liquid helium. And there were pickup coils that measured the frequency of radiation from flipping protons from one side to the other side, that would tell you what the polarization of the target was. And all of these things were nonuniform. And I developed a way of calculating — what was the nonuniformity of the measurement coils, and then writing the programs to take what were measured and convert it into what the real average polarization was. And that was the largest single-systematic uncertainty in the experiment, and that was a nice problem that I got to work on and solve.
In what ways did Regge poles really move the field forward?
Well, you know, like zombies, they’re still alive. [laughs] And in fact, one of the papers that I’m working on now in collaboration with an experiment at CERN is back to the old Regge pole stuff. We’re demonstrating the existence of the Odderon. But as an influence for the development of the field, as far as I’m concerned, it was a dead end. It did, however, form the framework for understanding the apparently simple process of scattering a particle on another particle and having them emerge in the final state intact. So, elastic scattering. And it still is — the theory is used to describe that. But that’s not really the main thrust of particle physics, as far as I’m concerned. It’s an interesting, theoretically difficult, dominated by Russians, subfield [laughs] that just has a life of its own.
Right. Now, your position as research associate at — did you call it the Rad Lab? Was that the phrase in vogue at the time?
Yes, it was.
Was your position there a postdoc, or was that a regular staff position?
It was postdoc. It was one year after my Ph.D., and I stayed on, and I was doing an analysis of the scattering of pions on nucleons. We were trying to decompose it into the various partial waves and resonances that might be there. So, it was a joint analysis of all the cross-section data and all the polarization data.
Intellectually, did you see it as a very smooth transition from your dissertation, or was it more of a new branch for you?
No, no, that was very much a continuation.
Was the option available if you wanted to stay on full-time at Rad Lab? Was that something that you had considered, or were you looking to go to an academic faculty?
I’m sure I could have stayed on for a while. In what capacity, I don’t know. In fact, at that point, I felt a desire to come back east. And so, I went on a tour of a good many universities in the spring of 1966, I guess. Some of them had postdoc jobs. Some of them had faculty jobs. Those that had faculty jobs were the new, just-formed universities that were struggling to come up out of the soup somehow. So, I had postdoc offers from Princeton and from Harvard — Cornell, maybe — and faculty offers from University of Illinois in Chicago, which was barely a campus at all at that point, and from Stony Brook, which was [laughs] not so much further advanced, either. But it seemed to me that Stony Brook had a real future, because at that point, we knew that Frank Yang was coming. We knew that Ben Lee was coming. I knew that Myron Good, who was a well-known experimentalist, had agreed to come and would be there in another six months or so. So, I could see that Stony Brook was going to be a place that was going to make a mark on the field.
Paul, I’m curious. Before you left California, were you curious at all about what was going on at SLAC, what Pief Panofsky was putting together at Stanford? Was that something that was just sort of generally of interest?
That was happening toward the end of the time I was there. I’m not sure that SLAC had turned on the accelerator by the time I left. There was enough of a divide between that kind of electron-positron — sorry, electron-proton scattering — that it was going on at Stanford University for some time. It was not the sort of thing that I was doing, and I didn’t pay a whole lot of attention.
Now, it’s interesting, when you talk about the opportunities that Stony Brook had in its future in terms of all of these impressive faculty hires, how much was Brookhaven a part of the equation? In other words, was Stony Brook becoming an attraction because Brookhaven was essentially in its backyard?
Yes. Absolutely. Moreover, at that time, there were the beginnings of designing and building the new large accelerator, which became Fermilab in the end, and there were several different possible sites, one of which was Berkeley, and one of which was Brookhaven. And I think most of us expected that it would be built at Brookhaven. That was a little bit later maybe, but that certainly — that whole kind of thing colored, I think, many of the people who came to Stony Brook in physics. This was going to be a center where you want to be associated.
And since you were there, essentially present at the creation, was the goal for the department to build its strength in essentially all the subfields in physics, or was it looking to be strong in a particular area with Brookhaven in mind?
I think there was always the intent to have a fairly broad-based department. There had been a little bit of atomic physics in the very early days, and they hired a few people who were quite good. Atomic physics, in those days, was pretty dull. It was going through this period of “let’s measure another molecular transition or atomic transition”. So, it hadn’t yet become the truly exciting field that it became 20 years later. Nuclear and particle physics were certainly a major part of the building of the department, and that was influenced by the presence of Brookhaven. But there was also a little accelerator, a Van de Graaf accelerator, on campus. And the nuclear guys mainly worked there, in fact. It was very strong on the theory side because of the institute that Yang was asked to form. And there was a long struggle over many years in trying to build up a credible presence in condensed matter physics, and it didn’t quite jell, and it didn’t click, and the people came, and then they left. And that went on for 30 years. I mean, nowadays, there is a fairly strong condensed matter community, and it’s become a good deal more stable, but it was a hard lift. But I think the intent was always to build that relatively broad base among all the fields within physics.
And when you arrived and you were establishing your own research agenda, what fields were you looking — or what projects were you looking to get started at that time?
Well, I was clearly intending to work at Brookhaven and help start a new group. The first two experiments that we did were done in collaboration with the University of Wisconsin, measuring a variety of cross sections for scattering of — production of strange particles, or antinucleon, cross sections. And we did that in conjunction with the University of Wisconsin, which is where Bud Good had come from. And so, it was with a couple of his ex-colleagues at Wisconsin. So, we did these experiments at the Brookhaven AGS. It was a big struggle, because we had no infrastructure whatsoever. For the first experiment, we used spark chambers, which none of us had any expertise on. And since we were building everything else — online computing and the mechanical aspects and all the rest of it — we actually bought these spark chambers from an outfit in Connecticut who jobbed out instrumentation to people. But it was a big struggle to build a group and, as I say, to build the infrastructure that was required to really mount a major experiment. By the time we got a little further on, we improved that, and we were better equipped to innovate and build instrumentation for ourselves.
Now, when you say you lacked infrastructure, is that to say that Brookhaven wasn’t in a position to offer you these things — that essentially, these academic collaborations were responsible for putting their own groups and instrumentation together themselves?
Yeah. There was a fairly well-defined demarcation between what Brookhaven typically did and what they universities did. And since most of the universities that worked at Brookhaven were the Ivy League schools, plus Rochester and places of that sort — they had the machine shops, and they had the electronics shops and had their non-faculty professional research physicists who were full-time and tended to be primarily working on instrumentation or technical things. So, Brookhaven didn’t really set itself up to provide that kind of service. It was often left to the universities to do it.
And who were some of your key collaborators with the Brookhaven experiments?
As I say, the first two were Stony Brook and Wisconsin. So, the people from Stony Brook, there was Bud Good, who was the leader of the group; Janos Kirz, who is now retired, at Berkeley. He became an X-ray and optics person. Y.Y. Lee, who has now retired from the Brookhaven accelerator department; a fellow by the name of Guido Finocchiaro, who stayed at Stony Brook until he retired. At Wisconsin, it was Don Reeder, who had been a good colleague there, a fellow roughly my age.
And Paul, what do you see as some of your principal accomplishments and contributions with these initial Brookhaven experiments?
I would say that the experiments themselves did not make a lasting mark. They were measurements that needed to be done, that were important for testing theories and the like. Nobody’s going to look back and say: wow, that was a really pivotal result. My own contributions were in managing the experiments, which I sort of did; in doing all of the online data acquisition; and in leading the analysis efforts.
Let’s talk a little bit about the beginning of the Tevatron collider project at Fermilab. Who initially approached you to become involved in this?
It’s a good deal more complicated story than that. If you go back, at Brookhaven, there was a plan — and this must have been the mid-’70s to late ’70s — to build a new machine which was originally going to be called ISABELLE, the Intersecting Storage Accelerator. So, it was a collider, proton-proton, two separate rings, superconducting magnets, at energies of up to 400 GeV. And so, together with the collection of other people at Brookhaven and Stony Brook and some other places, we began to develop a proposal for an experiment to be sited at this collider, whose name turned from ISABELLE into CBA for the Colliding Beam Accelerator. One of the chief collaborators was Sam Aronson, who you talked to recently. Then there were people at Brown, people at Columbia, who were major players in that. But the Brookhaven machine in particular the superconducting magnets, just weren’t working. It just was a project at which was the money was being thrown. It probably wasn’t managed as well as it should have been and wasn’t converging.
And what was the problem with the magnets? Was it a theoretical problem? Was it a problem of instrumentation?
Instrumentation. I think in — I’m not a magnet expert, but I think probably the problem was that they were not sufficiently constraining the coils, which would move around, and when they move around , heat from the friction would cause them to quench. That was typically the problems in early magnets. So meanwhile at Fermilab, which had had only recently started up, in 1972, I think, decided that they would like to think about sticking antiprotons into their 400 GeV, and later 1 TeV, ring. And this was an adventure, because first of all, you’ve got to make antiprotons, [laughs] and you don’t make very many, no matter what you do. On the other hand, it was cheaper, because it was only one ring of magnets that you have to make. And also, Fermilab was somewhat ahead in building these superconducting magnets. So there was, in the spring of 1983, a DOE panel, of the sort that happens often to decide on the major new strategic plans for the field, that met in Woods Hole, and considered the question as to whether or not to shut down the Brookhaven project. But in the meantime, there had been a call for proposals for experiments at a new location in the Fermilab project, and that was well before the Brookhaven decision was announced. So, my colleague, Mike Marx at Stony Brook, and I put in pretty much the same design that we had built up for Brookhaven into the basket for Fermilab. We spent a couple of years developing the proposal. In the summer of ’83, the panel’s decision came out to shut down the project at Brookhaven. So, now we had the proposal live at Fermilab, and in the two years past we had done a fair number of test-beam and development studies to try to refine the design and the detectors. And so in 1983, the Fermilab advisory committee that decides on the experiments that are going to be approved to run, met as they always did in Aspen, Colorado. And by that time, there had been nearly two dozen proposals for this extra site, the DZero experimental location in the Fermilab accelerator. Some of them were small, some of them were larger, and they were all being considered at this meeting in Aspen. And on a certain day in late June, I got a call from Leon Lederman, the director at Fermilab, saying that the committee had decided to not approve any of the experiments. None of them were ambitious or good enough to — as they would have liked. But instead, they would like to ask me to head up a collaboration, to build a collaboration, to do an experiment. And it was approved sight-unseen. Whatever it was we proposed, would be approved. So, at that moment, it was an experiment of one person. I went around the corner and talked to my Stony Brook colleagues Marx and Finocchiaro, and we decided in the end to go and do that. I had a lot of trepidation in trying to build a new collaboration to do a major experiment in a lab that I had never worked at before.
Paul, I want to ask: did you have a sense of why the advisory committee sort of took a sledgehammer to all of these other proposals and went all-in on this new idea that was sort of sight-unseen? Did you have a sense of some of the big considerations that led to these decisions?
I think the committee felt — well, first of all, Lederman had advertised for an experiment which was small, cheap, and would last for up to two years. So, was supposed to be quick, dirty, and clever. And so, the experiments that were proposed tried, in some way, to do that. And the committee, I think, told Leon in the end: no, you should do something that is more ambitious, more — with a broader reach, more capable. And none of these proposals are doing that. I think our experiment was one of the more ambitious of the proposals that were put in. And I guess what they decided was that I was a less negative prospect to build up a collaboration than some of the prima donnas who were leading the other proposals.
I wonder if also you had gained a reputation as being an effective manager with your collaborative projects at Brookhaven.
Maybe, but those were smaller and — I mean, at the time, the models for large collaborations were mainly from CERN, because they had this proton/antiproton collider, and Carlo Rubbia and Pierre Darriulat ran large collaborations with very different styles. And that was what was being imagined should be done at Fermilab. So anyway, we started after this phone call, and called around to — well, first of all, we gathered in the various collaborators on our proposal, which had been called LAPDOG, an acronym for something or another. So, all of those people joined with us, and then selectively, we asked people from the other proposals to join us, and selectively did not ask others, who we didn’t think would play in the sandbox well with others. So, that was in the beginning of July, and by the end of July, we were meeting regularly. I’d gone to Fermilab by that time. We were having pretty much weekly meetings. We had a design that was sort of grown out of the original proposal that my group had put forward and was just getting more and more cumbersome, [laughs] and more and more problems with it. And every time we looked at it, it was sort of squishing out. You would push on it here, and it would squish out over there. And we came to what was then a set of weekly meetings in Fermilab, and everybody had pretty much come to the conclusion that this is not going to work. And we, at that meeting, talked about and eventually decided to do something that was completely new and different, and to base it on a calorimeter, which is the central energy-measuring portion — piece of the detector, and to base it on a liquid argon calorimeter, one of which had been built and used in the world previously, and half of which didn’t work. So, this was a real flip of the dice in the dark to imagine that we could pull it off. None of us had ever done anything like this.
And in thinking about new directions, would this have required going back to the committee for approval, or you were already operating within a general framework where you felt you had the latitude to change this up as you saw fit?
We explicitly had the latitude to figure out how we were going to do it. We were told to come back to the committee at the end of November or early December and tell them what direction we were going. So, we made this decision in early September, and between September and December developed enough of the outline and technique of the experiment to be able to write it down in a conceptual design report and to present it to the PAC. So, we did. I did. And it was the one time I’ve ever heard applause from the PAC [laughs] when the proposal was presented. I think — well actually, I should say something about the composition of this particular committee.
Yeah.
It was chaired by Vera Luth, who was an eminent experimental physicist at SLAC. But on the committee, there were several very prominent theorists who liked to think of themselves as really capable at designing experiments and talking about how experiments should be done. One of them was Tini Veltmann from Holland, and the other was Stan Brodsky from Stanford. And I know from talking to both of them over the years that they very much drove this whole process of: “let’s be adventurous. Let’s go out on a limb. Let’s try to throw long with this new experiment.” And they were very, very proud of themselves that in the end, it worked out. And they take credit – “I’m the person who made this work!”.
And why Fermilab? Did this have to be at Fermilab, or were other national laboratories considered?
The Fermilab machine was much higher energy than any other place, including CERN, at that point.
Right.
They had an almost 1 TeV accelerator. They had already planned, and were building, the antiproton circulating in the same ring, so now when they collide, that’s 1 TeV on 1 TeV, so it’s 2 TeV. And they had an experiment that was four years ahead of us called CDF that was in the process of putting their experiment together. But Fermilab could have a good deal more energetic collisions than any other place.
And just to orient ourselves chronologically, as this project is coming together, you received this applause. What year are we talking about now?
We talk about the proposals — the call for proposals for this new region, the so-called D0 location in the ring, was in 1981. The decision to approve the new unseen experiment was made on the 1st of July in 1983. The decision to go to the liquid argon was in September of that year, and the first presentation to the PAC occurred in November/December of ’83. And then, we got to work and tried to make a more technical and complete design proposal that could be reviewed by the Department of Energy, who had gotten itself into very careful reviewing of any major project. And they were inordinately proud that projects in the DOE came in on budget and on time, and so on, we were scheduled to have a review by the DOE committee in November of ’84. So, we rapidly transitioned to doing a much more detailed, quasi-engineering kind of technical design report for that review.
Paul, I’m curious. 1983, 1984, if I remember correctly, that’s the earliest murmurings of what eventually would become SSC. I’m curious if you were aware of these very initial planning discussions…
Yeah.
…and in thinking about a new facility that would redefine high-energy physics in terms of its energy, its power, if the prospect of this project affected the way that you conceptualized D0, or even thought about where it most appropriately might live long-term.
[laughs] Yes. Indeed, 1984 was about the time that the SSC was becoming — started. We were at the end of an era where all hell had been breaking loose in physics: new discoveries all over the place, the J/psi in ’74, upsilon and all the rest of the things like — neutral currents, and finally the W and Z bosons. So, there was a feeling of optimism and euphoria, and that extended to building a new machine, so yeah, that’s going to be expensive, but hey, we can do it. We’re cowboys, and we know how to do things. So, it was foreseen that the SSC would come on sometime, I don’t know, early ’90s. So, the notion was that the life of the Tevatron would be relatively short. We imagined that our experiment would be up and running by 1986 and would go until — well, we were told that we had two years of running it. I don’t think we believed that literally. But it was limited. So, yes, the SSC was a specter on the horizon. As time went on, our experiment got delayed. The SSC got delayed. Our experiment delayed even longer. It finally came on in 1992. And in 1993, the SSC was dead. So, now we had an unlimited time prospect.
[laughs] Right.
Somewhere along the line, we wrote a paper, a note on how we could put the D0 detector on a barge and float it down the Illinois and Mississippi rivers and around the Gulf and up into Dallas and be one of the initial experiments at the SSC. So yeah, [laughs] it was in our frame.
Paul, who coined “D0,” and what does D0 mean? Why is it a good name to discuss this overall research endeavor?
First of all, it’s a terrible name. The Fermilab machine has six sectors of a repeating sequence of magnets, and they are labeled, imaginatively, as the A, B, C, D, E, and F sectors. Within the sector, there are locations that range from 0 to — I forgot. 12. The 0 point is the beginning of the sector, and that’s where there’s a gap between the magnets. And so, if you want to do an experiment, that’s where you put it. So, the CDF experiment was at the B0 intersection point, and the one that was open for us was the D0. And one of the first things we did when we formed the collaboration was to try to decide on a name. And there were all these people from different areas, different previous proposals and what have you, and we could not decide. And so, in the end, we chose the least common denominator, and we called it after our address.
[laughs] And what were the initial major research questions of D0, and how did those questions change over time?
We imagined that we were going to be focusing on the study of the electroweak interaction, which we understood to be a combination of the electromagnetic and weak interactions, and the force carriers, the W and the Z bosons, which had been discovered a few years before at CERN. And there were a lot of outstanding puzzles, and the CERN machine was limited in intensity and statistics in the number of W’s and Z’s. And so, I think our primary focus was: what can we do with a much larger sample? And so, the questions of the W boson mass, its couplings, the production with photons — are there anomalies that betray the presence of something fundamental at a higher energy scale? We talked about maybe we would be able to uncover the quark-gluon plasma, which in the end, [laughs] we didn’t do a thing about, but the ISABelle successor machine — well, that’s a whole other story, an interesting story in its own right. We knew about the need for the top quark at the time we wrote our proposal, but we were so blinkered by the notion that the CERN machine had, or was about to, discover it. And indeed, they made a false start. They made an announcement: “we have discovered the top quark”. It turned out it was background. But we did not focus on that, although we certainly knew that if there were something like that — and we did talk about that — at a higher mass, we would be in a great position to discover it. So, it was new things that were enabled by the energy of the machine and by this study of the weak interaction. And I did a scorecard sometime later in the 2000s. The things we wrote down, most of them we did and succeeded in important measurements. Some of them just weren’t there, and we never came, obviously, close to it. But by and large, I think the list of topics that we wrote in our original conception and design report were a good guide for what we did.
And were these goals — would you say — were they most stable over the years? Did they change as the experiment got underway and matured?
Surely, they changed. They became more refined in some ways. They veered a little bit as theoretical advances were made. But the broad outlines were pretty much intact. The search for the top quark became critical once we understood that CERN hadn’t done it, and wasn’t going to do it, and that in our first running at the Tevatron, we failed to find it and set limits on its mass, and so now it’s way up there where nobody else but us, if anyone, could find it. So, that evolved and became much more acute and much more pointed. The other thing, which I think was surprising, which we didn’t identify in our original studies or our original proposal at all, was that we were in a position to make real advances on the study of the middling-heavy quarks, in particular the bottom and charm quarks and the way in which they form new states and their properties. The popular wisdom had been — or was, at the time — that that was the preserve of the electron-positron machines. So, Stanford, SLAC, DESY in Germany, and then in Japan. And so, they were doing this stuff, and nobody thought that the hadron colliders, proton/proton or proton/antiproton, could have a shot at this, because our environment was just so much messier. But the fact was, we had enough energy to produce these things, copiously, and that turned out to be a major thread, and in the fact at2#$d this moment, in the [laughs] waning days of the D0 experiment, it’s one of the main research topics that remains.
It sounds like you did not have an idea that the D0 experiment would go on as long as it did.
Three years, we thought. And we thought that the luminosity of the machine that measures — that tells you what the intensity is going to be would never exceed 3x10^30, in appropriate units. In the end, the experiment ran from 1992 to 2011, and the luminosity rose to 4x10^32, so well over a hundred times more intensity. No, the situation opened up in a way that was just not foreseen.
Now, another question about collaborations: were you mostly working with Fermilab physicists, or was it mostly other academic physicists who were sited at Fermilab on D0?
Well, at the peak, D0 had about 550 — 600 physicists, of which 50, I guess, were associated with Fermilab, and the other 500 from institutions around the world. And there were, at peak, I think 80-some institutions: some with one person, some with groups of 10 or 12. In the initial phases, the Americans were dominant — our collaboration was dominantly American. Then there was a major upgrade to the machine and to the experiment, which restarted the experiment in 2001. And at that point, we gained a very large number of European groups, and they constituted probably 30 percent of the collaboration, or maybe a bit more.
And what were some of the considerations and motivations behind that upgrade in 2001?
Well, first of all, the intensity of the machine was going to go up. And what that meant — and the repetition rates of the intervals at which the particles could arrive was going to be shortened dramatically. So, having built the experiment for a repetition rate of 3 microseconds and being forced, with the prospect of 200 nanoseconds, there was a whole lot that had to be done to the electronics. Also, in the original experiment, we were forced to be frugal at some level, and so there were things that we could not afford, and besides, we were playing catch-up. And we had undertaken this one major new thing, the liquid argon, and we didn’t want to undertake a bunch of other things as well. So, we did not have a central magnet, so that the particles came out on straight line trajectories. And so, we could not measure their momenta. And that is a major loss of information. So, the upgrade was motivated, in part, by putting a magnet in. We had a fairly small bore, or diameter, available inside the calorimeter, and we had to fit within it. We couldn’t rebuild the major calorimeter. So, that meant that we had to have very high-precision tracking detectors in order to make the measurement of the momentum in this limited space. So, all of that put together meant that we had to do a complete rework of everything inside the calorimeter and all of the electronics. And then there was more radiation to contend with, and so we had to add shielding and stuff. It was a big deal, and we proposed it, what, three years before we started to run, even. And the PAC, at that time, laughed at us. They said, “You can’t do the tracking that way, and you’re going to upgrade a detector that’s never even run.” So, we had three, four years of battle to finally get approval. But the basic motivation was: all the things that came with the higher intensity and the defects that we had built into the detector by not having the magnet.
Paul, what was your sense, especially by 2011 — I’ve heard it said that the Tevatron collider became so fundamental to the overall mission of Fermilab that post-2011, there were people asking, you know, really existential questions about what Fermilab would do next. Does that accord with your assessment of the centrality of the Tevatron to Fermilab, writ large?
Well, it was a large problem, because it was the dominant piece of the Fermilab research program. And it was big enough, and important enough, that it was clear that that program could sustain the lab and make it a first-rate player in the world stage. There were other experiments going on, and every so often, we would shut down, and they would run, but the dominant program was the collider, and it was just these two experiments: CDF and D0. Then, with the fall of the SSC in ’93, and CERN’s decision under Carlo Rubbia that they would build the LHC, which itself was a huge gamble. I mean, those magnets, nobody imagined you could build and make work. But as that project got going, it became apparent that there was no future for the Fermilab collider program. The ring wasn’t big enough to be a competitor for the LHC. And so, there had to be a rethink of the Fermilab mission, and there was a year — I think probably 2006-ish — where there was a long series of meetings and discussions and arguments: what will Fermilab’s role be? And I guess that was an existential question. And the decision that was arrived at was to build the neutrino program which is now being built. There have been many — several neutrino experiments, but the big neutrino oscillation — neutrino beam from Fermilab to South Dakota is the keynote part of the Fermilab program. Whether that’s a large enough program and sufficiently broad program to carry the lab, I think, remains a question. I think that it is possible that when that is achieved that Fermilab will face some kind of reduction or revision in scope. I don’t know. It seems to me that the neutrino program is not as fruitful, or not as broad a set of scientific questions, as was addressed by the collider. Which is not to say that the central questions in play in the neutrino program are not fundamentally important.
Right. To what extent do you think that the experience of SSC has essentially thrown a wet blanket over what Fermilab might have accomplished otherwise? In other words, just because of SSC, is there just a diminished appetite in the United States for larger and larger energies in these kinds of projects?
Oh, yes. I mean, certainly, the effect of the SSC continues to be felt. There is a fear of overreaching. There is the understanding that politics can intervene at any stage in the project in the United States and close it down, unlike in Japan or Europe, where if a decision is taken, they will carry on with it. I mean, it’s affected the community in the U.S. I’m not — the direct impact on Fermilab less so, I think, other than Fermilab could not talk about a major new expensive proposition. And this was illustrated — I mean, it’s not just Fermilab; it’s the U.S. For some years, the community has been engaged in designing and talking about the next step of electron-positron colliders, and there is this machine called the International Linear Collider. I worked on all phases of trying to bring that into existence. And there was a moment in 2005 when the Department of Energy, at the highest levels, felt that they had a go-ahead from Congress that they could host such a machine as long as the price tag was somewhere around $3 billion.
Which, of course, on the low side of the initial cost estimates for SSC.
Yeah. So at that point, I got dragooned into going to the DOE and managing the effort on the ILC and suchlike. And we set up the team that did the design effort and cost estimate. And it basically came in at a — weird for the U.S. style cost estimate. It was $7 billion in stuff that you purchase, a certain amount of labor at the collaborating institutions, which wasn’t funded, because that’s the way that costing is done in Europe and in Japan. It was a foreign method of doing cost estimating for the U.S. Anyway, the sticker shock for that was so severe that the notion that it was possible to build this in the U.S. completely vanished. I mean, now we’re into new phases of these long-range planning things, but it’s now understood that anything more than $2 billion spread over many years is not a saleable prospect.
Paul, is this the same to say that the United States has essentially ceded, for the indefinite future, its leadership in high-energy physics?
I think so, yeah.
Who do you see as most likely to take the mantle? Is it the Europeans? The Japanese? The Chinese? If this kind of project goes forward, what’s the most likely site, geographically?
To answer your first question, I think in the near term, the mantle is in Europe, the leadership. CERN has a budget which is twice that of the U.S., and they have the capability. It’s a treaty organization. I mean, the nations are locked into it. So, they define the broad outlines of the future of the field. The Japanese have had a capability on the scale of a medium-sized lab, and they’ve done some very good projects. Japan is the proposed site for the ILC. The site is known. And then, the Japanese politicians would like to see them become a world power, and I think it is in part because it brings in engagement from around the world, opens up Japan to be a more open science and technical society. They also see it as a way to pump money into the region that was damaged by the earthquake and tsunami of 2011. But it’s not clear that Japan is able, yet, to really manage a project of that size. There’s no track record. And the Chinese — well, the Chinese want to flex their muscles and say: we’re going to do a new project. And now, instead of having one possibility for the future electron-positron Collider in the form of the ILC, there are four. There’s another linear machine proposal at CERN, which I think is now pretty much doomed not to happen, and two circular machines: one at CERN and one in China. The Chinese have even less history of managing these large projects, but they’re audacious, and they’re technically savvy, and they’re going ahead, and they have the money. So, it’s a fluid situation. I probably haven’t described it [laughs] all that well in the sharp synopsis rambling.
Paul, I’m curious to what extent these nationalistic kinds of considerations are important to you. I mean, on the one hand, as a scientist, you just want these experiments to proceed. Right? And it’s better that they proceed somewhere else than not at all. And yet, perhaps as an American, you’re disappointed that they’re not happening in the United States. I wonder if you can reflect a little about the importance of national considerations in where and how these experiments proceed.
Well sure, I would like to see there be a major project in the Americas. Many of us would like to see a rational planning process for the world in which there are major facilities in Asia, the United States, and in Europe. And there are, in fact, three major topics requiring large facilities. One is the next large hadron collider, another is the next large electron-positron collider, and the third is the large neutrino facility. And if I were building the world, having three regions technically competent and three major kinds of projects, I would allocate one to each region, and we would all work according to our whims and desires at the place that suits our own research. This is not what happens, because now national politics get inserted, and each region wants to hedge their bets and try to build two or maybe even three of these things on their turf. So yeah, [laughs] we learn a good deal about how to try to work with the political systems around the world and learn how different they are. Scientists are not terribly good at doing that. They’re much too straightforward, and often naïve. It can turn into a semi-disaster if we try to drive the process. But we’ve at least become good at knowing how to talk about it.
Paul, what’s your reaction to this kind of idea that someone who would say, “We were so certain that we’d find the Higgs boson that it really doesn’t justify CERN taking on this project, because we were certain it was going to be there anyway”? What’s the counterargument to that kind of thinking, and how might that counterargument be useful in gauging the kinds of decision-makers in bureaucracies to support these kinds of projects going forward?
Well, if you accept that knowing more about the construction of the universe is good — all of the scientists would adopt that as a basic starting point — then you have to accept that there is an awful lot that we don’t know. There are these huge gaps and flaws in our understanding. Dark matter, the fact that the Higgs boson occurs at 100 GeV, but the natural place for it to live would be at 10^19 GeV. And these are all questions that bear on the construction of the particle universe. So, discovering the Higgs was not, in itself, the end of the story. Yes, we knew where it was going to be. We had been narrowing the window down. We knew where it was going to be if the theories were all correct, and then the frameworks that we were using to predict it, but I think we knew then — we certainly know even better now — that studying the Higgs boson and the way it decays into various particles and the way it interacts with things, should contain clues as to these missing elements in our understanding. So, that’s the hook that says: yeah, we know the Higgs exists. That was cool. What else have you done? Well, if you have enough of them, and you study these patterns, you can reveal the presence and character of the new physics. So, that’s the argument as to why you want the new facilities, as long as you buy the premise that knowing the answers is worth pursuing it.
So I guess — that’s a very useful thing to hear. And so, if you were given an opportunity to give testimony in Congress, right, for people in a much broader audience — obviously, who are not operating at your level of understanding — what is compelling about the gaps in our knowledge of how the universe works and how these large-scale research endeavors really would close those gaps?
I think the answer ultimately was down to the fact that we are a curious species of animals and would like to know the answers to: where did the whole thing start? How did it start? How did it evolve? And what’s it made of? It’s a little hard to make the argument that that knowledge by itself will provide material to change the pattern of society and the progress of society — but what will directly influence progress of society are the technical innovations that are made by the scientists who are trying to do these things, and which then pass into the common knowledge and general society. The web is often cited — superconductivity, the use of MRI magnets, levitations of trains, and that sort of thing, came about because physicists needed tools to do things that they couldn’t otherwise do. And so, they developed the capability then turned it over to industry, and industry made it really work. But the knowledge itself, I’m not sure I could make that case clearly, except in a general level of we are just programmed to want to know how things work.
It’s interesting. You mentioned our ongoing inability to understand dark matter, for example. Have you always seen that logical transition from knowledge in particle physics as a starting point to understand astrophysics better?
Well, there was a realization in the ’80s of the real tight connection between astrophysicists and particle physicists, and again, Leon Lederman was at the heart of this by bringing those communities together in one place. But for a long time, basic physics — particle physics, nuclear physics — has been key to understanding astrophysical things. So, how does the Sun work? How does it make its energy? Well, that’s a nuclear physics problem and a thermodynamics problem. Sorry, I lost the thread [laughs] of some of your questions, so let’s reset!
The idea that there is a natural trajectory from advances in particle physics to advances in astrophysics.
Yeah. Well, yeah. But the astrophysicists would agree. I mean, physics is the tool with which they predict and understand astronomical things. The specific business of dark matter — well, you know, the only evidence we have for dark matter is that you feel it in galaxies, but there is no other evidence for it. So, it’s not necessarily true that the explanation of it has to do with particles. It is true that nobody has any good ideas other than particles.
Paul, another thing that I wanted to ask you about is your work in neutrino-based experiments. When did you first get interested in neutrino physics?
I’ve never done a neutrino experiment.
But you are involved with certain projects, like at Los Alamos, for example. I’m thinking of the CAPTAIN project.
No. One of my colleagues at Stony Brook — there are neutrino physicists in our group.
Oh, I see. So, you’re part of a group. I see.
The Stony Brook group has two pieces: one is collider, and the other is neutrinos.
Oh, okay. I see. And what about —
We all know the main threads of what’s happening, and they connect at some level, but I’ve never done it.
And what about the ATLAS experiment? Were you personally involved in that at CERN?
No. I was going to get involved. By the time it came along, or by the time D0 was beginning to ramp down, ATLAS was started, and what I saw as what I would want to do would be to advise students, to help shape the analysis, but not to go spend a lot of time at CERN. I was at the stage in my career where that wasn’t going to be desirable. So, I was looking for that kind of engagement. I didn’t care whether I signed their papers or not. I wanted to be engaged in research and with our group. But ATLAS had a fairly strict policy that you had to provide some kind of dowry project. That didn’t seem to make sense for me, and so I said: well, fine. I’ve been there. I’ve done that. And there’s still a lot of interesting stuff to be done with D0, and this linear collider is sufficiently interesting and important to try to get it underway, that I’m going to put my effort there. I do remain close to the ATLAS work, because all of my colleagues are working on it, but I’m not.
Paul, I’m curious. You know, in thinking about what long-term a project like the ILC would accomplish, do you see operating at, you know, 500 GeV — is this something that’s necessary to either improve upon the standard model or even help to contribute to some grand unified theory? Do you think in those terms?
Yes. The ILC in particular, in order to be made palatable to the Japanese ministry cost-wise, has been scaled down to an initial stage of 250 GeV. And that’s good enough to make a good start on measuring these branching fractions of the Higgs boson and getting a sense of whether there’s something new beyond the Standard Model. That will become much better if it starts to run at 500. Moreover, that gets you to the point where you can study the top quark in a really precise fashion. It gets you to the point where you can study the way in which the Higgs boson interacts with itself. So, there are known things that will get much better when you go to 500 GeV. What’s not clear is whether or not you’ll be able — what the prospect is for uncovering unknown things. The LHC has certainly pushed the frontiers back, such that it’s less likely to find something there. Although still, the complementarity of the hadron machine and the electron-positron machines is such that there could be things that the LHC is unable to see that would be seen in e+ e-. But I think the major — for me, the major reason for the linear colliders, like the ILC, is that they are expandable in energy. You can add length, or you can add new, more powerful accelerating cavities and go up in energy. The circular machines that are being proposed, you cannot. Up against the rock of synchrotron radiation— the beams radiate their energy more quickly than you can replenish it.
What is the theoretical basis for knowing that as you go to higher and higher energies, there are new discoveries to be made? How do we even know, or how can we even prognosticate, that there will be new science to learn at higher and higher energies?
I think it’s extremely likely that if you go high enough in energy, there are fundamental things to learn. If you go to the point where gravity becomes strong and comparable to the other forces, something will happen that is new and unforeseen. However, that’s many orders of magnitude away. So, the question that you’re asking — suppose I were to propose a machine like the LHC, which is now at 13 or 14 GeV, that operates at 100 GeV. That’s what CERN is talking about at the moment. How do I know I’m going to uncover anything in that increase? And I would say that there is no assurance whatsoever. I guess the biggest weakness of the strategy that — if we’re going in that direction, and then CERN, I think, is doing it cautiously. They’ve certainly not decided if they’re going to go in that direction. But that, to me, is the argument that is tough to answer. And the question you just asked is one that is going to occur to our politicians and our government people who have to put up the money: “How do you know you’re going to find something new with these billions of dollars?” And I don’t think you can answer that in a clean way. The study of the Higgs, that’s fine. We knew that that’s a good thing to do, and it will tell us something. If there is a new force, a supersymmetry or something that begins to pop out, you know you want to explore that and study it. But in the absence of any hint, it’s a hard argument to make.
You mentioned gravity. Is it possible that, in addition to particles, that our understanding of gravity might also improve, operating at these energies?
No. No, it’s not a contender. You’re going to learn about gravity in a whole lot more by getting another 10 binary black hole coalescences. [laughs] That’s where that’s going.
Right. Paul, just to bring our narrative up to the present day: what are some of the research endeavors you’ve been involved with in the past few years?
For a while, I was doing three things. One is I’m the co-spokesman of D0, which is still publishing, just based on their accumulation through 2011. So, we have three papers at the moment which are in the stages of finalization for the summer virtual conferences. The other is in this management and planning for the ILC, which I think is coming to a critical stage, where the world has decided that it’s a good thing, and that Europe and the U.S. will participate. Japan says that they’re considering to go forward, and I think there has to be a decision from Japan, yes or no, within the next year, or “no decision” means “no.” Anyway, I’ve been working on that sort of as a planning and organizing — and for a while, I was the editor for the Reviews of Modern Physics for articles in particle physics. I stepped down from that in the past year, so it’s just these two other things.
If you had $10 billion, green light, whatever you wanted to do with it, what would you do?
You want me to spend it on a scientific —
[laughs] I realize I should have specified. Yes.
Oh, I might want to influence the election. No, in particle physics, I’m convinced that the next step is an electron-positron machine, and my favorite candidate continues to be the ILC, for the reasons of upgradability that I’ve just mentioned. There are clearly things that are important to do in astrophysics and cosmology, but they’re not yet at the $10 billion level. They’re at the up to $1 billion.
But ILC very much is in that $10 billion range.
It is. Yeah.
Yeah.
In U.S. accounting, it’s more than $10 [billion].
Right. Paul, one aspect of your career we haven’t touched on yet is your work, both as a teacher to undergraduates and a mentor to graduate students. And I’d like to ask first: for undergraduate teaching, what are your favorite courses to teach?
E&M is a beautiful subject, and coherent, and it’s amazing that four equations will tell you everything that we see and experience. And the other course that I enjoyed a lot was thermodynamics and statistical mechanics, about which I know very little. I was reading the text two days before I was teaching the stuff. But the fact that in that course, the first thing that you say is that a priori all things are equally likely, and that a whole science can be developed from that statement. Oh, it just struck me as wholly amazing.
I wonder: what are some of the challenges and opportunities of teaching undergraduates at a place like Stony Brook, where undergraduates are not necessarily — you know, they’re not coming from the kind of elite background that you would have at an MIT or a Princeton.
No, our undergraduates are typically — many of them are first generation in colleges. Many of them come from families that immigrated within the last 40 years. We have always seen a rise and fall of the cultures and ethnic backgrounds that reflect the immigration pattern of two decades before. So, we have had Vietnamese, we’ve had Haitians, we’ve had others, — no, it’s a different kettle of fish. The brightest of the undergraduate students we get are probably as good as what you find in the elite universities, and then there is this trailing off of ability and interest that goes way down the spectrum. But many of them are great and enjoy what they’re learning.
Right.
So, I mean, the pleasures are there in teaching.
To think back earlier in our discussion, when you realized in the mid-1960s that Stony Brook was a very promising place in terms of all the talent that were coming on, do you feel — is your sense that that initial push has been fully realized at this point?
Yeah. I mean, I think Stony Brook is lucky. There were several universities, several attempts, to build new universities in the ’50s and ’60s, and not all of them, by any means, have managed to make it to being credible sorts of places. UC-San Diego was one, and that clearly did. Stony Brook is another that did. But there are other places where these things didn’t jell so well. So, I think a lot of the promise has been fulfilled. I probably see Stony Brook differently from some of my colleagues, because the university grew strong quickly in the sciences, and partly, as we said before, because of its proximity to Brookhaven. It grew rapidly in music because of its proximity to New York, and the music faculty has been superb. But in some of the humanities in particular, not so fast. So, the promise is sort of not quite uniform, but I think it’s been fulfilled. On the other hand, in the early days of the university, when I was first here, there was a sense of adventure, and the members of the faculty were all young. We all knew each other. We socialized. We had sit-ins together. We had faculty meetings of the university faculty where everybody came. And now, it’s become a big, more impersonal, bureaucratic institution that isn’t so much fun.
Better to be at the emeritus side of your career, I suppose, for that reason. [laughs]
[laughs] Well, yeah. It was a nice experience, starting with a university that was just building.
And who have been some of your most successful graduate students and postdoctoral students?
Oh, we have professors at Ivy League universities, various midwestern universities various people in national laboratories. The person who is leading one of the major experiments to be built at the ILC was a Stony Brook student. I don’t know if the names would mean much to you, but I think we have been more successful than many of our peer institutions in producing people that have made their mark.
Right. In a sense, certainly punching above the weight of the department, in some ways, in terms of the students that it has produced.
Yeah. I mean, probably the same impetus that brought me to Stony Brook to be a part of the experiment, I think it played, at some level, with the students who came in the earlier days. They were attracted by something that was new and growing.
Right. Paul, I think for my last question, since we’ve worked up to the present day, we’ve touched on it before in terms of what your goals are for what might happen next in particle physics. But I wonder if I can refine the question a little bit. It’s one thing to really hope and push for these new large-scale programs to get off the ground, but it’s another when you’re working in an advisor capacity when students come to you and they say, “I want to pursue a career in particle physics,” and you have to give some advice — not just based on what might happen with programs, but in terms of, you know, how can I help ensure that this person is going to have a successful and impactful career. And so, my question is: with so much up in the air about what programs might come to fruition, 5, 10, 15, 20 years down the line, what advice would you have for graduate students who are — they need advice on what they’re going to do in three to five years, in particle physics. What are some things that you would say to them?
Let me answer that in a little bit of a roundabout way. In a three- to five-year period, I think it’s easy. We know what the programs are, and you can steer students to the things that probably are going to have a large impact. I mentioned before that when I came to Stony Brook, optical atomic physics was in the doldrums. It was one more property like all the others. And then came the revolution. We had lasers, which caused the revolution, and this understanding of new kinds of forms of matter, and interesting techniques had really blossomed. Nuclear physics was very big when I came, and then it went through a period where it, too, was just measuring one more nuclear transition, and it seemed pretty dull. And then, now it has a renaissance, because it purloined a part of particle physics and has done these heavy ion collider projects, and then found the quark gluon plasma. In my opinion, particle physics is in pretty strong danger of going into a period of not having a tremendous amount of excitement, because we don’t know how to build the facilities that would take us further, because they’re too expensive, and so we’re more and more dotting the i’s and crossing the t’s. So, my advice, I think, would be: think carefully about what’s going to be exciting in 20 years. For the last 10 years, I would have said cosmology is a place where that is surely going to be a growth industry and where there are tremendous, interesting questions. That could run out, too. But for the moment, that’s — but many things in astronomy or astrophysics are still of interest — binary black hole mergers, active galactic jets, and all this stuff. So, I would tell people, unless you are really bitten with the bug of studying particles, think twice about it. Now, my friend, Stan Wojcicki at Stanford, I remember years ago, positing this kind of “wave of the future,” is that we’ll build one more machine, and then we’ll price ourselves out of existence. And the fact is, four or five generations of new machines spawned since he made that declaration. So, I could surely be wrong. It may just be an old guy talking.
[laughs] And to be clear, the limitations that you see, in terms of these large-scale, high-energy physics projects, these limitations you primarily understand in political and economic terms, not in technological terms? In other words, the know-how to get up to 500 — it’s there. That’s not the concern.
Well, to get to 500 GeV, we know, but then that’s based on technology that’s been around and refined, and has been around for a while. If, however, you want to have a 5 TeV collider that is 10 meters long, there are ideas — and there’s R&D going on, on such things — but we don’t know how to do that. So, there’s the stuff that just isn’t ready.
And absent having any kind of commitment to building such a thing, there’s probably not so much engineering appetite to figure out how it would be built without the support for knowing that it would be built.
Well, that particular thread of very high gradient, very, very short accelerators, is unlikely to be driven by particle physics. We would be a beneficiary of it, but as you say, there’s no appetite for developing the large-scale application. On the other hand, if your neighborhood hospital had an accelerator that was fit on the table and would accelerate things to a GeV or 3 GeV or whatever, in order to zap tumors, that would be a major deal, and there would be a hell of a lot of money put into developing it. So, I think that’s where that particular technology is — how it would develop.
Right. Well, something to look forward to. [laughs]
We hope.
Paul, it’s been a pleasure speaking with you today. I really want to thank you for the time you’ve spent with me.
Thanks for the opportunity. I’ve enjoyed it. And enjoy your time in the Poconos.
[laughs] Okay.