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Interview of Mary K. Gaillard by David Zierler on April 2, 2020,Niels Bohr Library & Archives, American Institute of Physics,College Park, MD USA,www.aip.org/history-programs/niels-bohr-library/oral-histories/XXXX
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AIP Oral Historian David Zierler interviews Dr. Mary Gaillard, Professor of the Graduate School, University of California, Berkeley and Affiliate Senior Scientist at Lawrence Berkeley Laboratory. Dr. Gaillard discusses her experiences as an undergraduate at Hollins College in Virginia, and as a graduate student first at Columbia University, then at the University of Paris at Orsay. She describes her subsequent research on kaons and baryon decay while working for the French National Center for Scientific Research at CERN, her year-long collaboration with Ben Lee at Fermilab, and her eventual return to the United States as the first woman to be a tenured professor in the Department of Physics at UC Berkeley, focusing in particular on the working environment at each institution. The remainder of the interview deals with the state of theoretical physics over the course of her career and through to the present.
OK. It is April 2nd, 2020. This is David Zierler, oral historian for the American Institute of Physics. It is my great pleasure to be here today with Dr. Mary Gaillard. I’m so happy that you are with us today. Thank you, Dr. Gaillard.
Can you please start with telling us your current title and affiliation?
Professor of the Graduate School, which means I don’t get paid but I have to be on committees [laugh] and I have students. I currently have one student at the University of California, Berkeley. And Affiliate Senior Scientist or something like that Lawrence Berkeley Laboratory.
OK, wonderful. All right. So let’s start right at the beginning. Tell us about your early childhood in New Jersey.
Oh, boy, well, I left New Jersey when I was about 5, so I don’t remember much. I remember the ocean, which scared me to death [laugh] and…
Where were your parents from?
Well, my father was born in Wisconsin. My mother was born in a tiny, tiny town in Ohio near Cleveland.
What brought them to New Jersey?
My father was teaching at Rutgers. He was a history teacher. But he was a pacifist, and he was involved in passing anti-war literature and stuff like that. And eventually he got fired. Well, he didn’t get tenure. And then he moved to this small town near Cleveland, Ohio, and that’s where I grew up.
And did you go to public school or private school as a small child?
And for high school as well?
Did you show an aptitude for math and science in high school already?
Oh, yeah, in fact, all my math and physics—physical science teachers were men, but they were very encouraging. That’s one thing that I’ve always appreciated.
And they were encouraging because you had already expressed an interest in pursuing a career in math and science?
Not really. They just saw that I was good at it. [laugh]
What led you to decide to go to Hollins College?
Oh, well, that was mainly money. We didn’t have much money because my father was a teacher in a small liberal arts college, and they gave me a full scholarship with books and everything. I mean, they gave me the biggest scholarship, so that’s how I ended up there.
So you weren’t primarily motivated to go to a woman’s college? That was not part of the consideration?
That wasn’t part of it, and I wasn’t even—I mean, I knew I was going to major in physics but I didn’t really think much beyond that because that was in 1956. Women didn’t do anything in those days. [laugh] But I was expected to go to college.
What were some of both the drawbacks and the benefits of going to a woman’s college?
Well, I guess—I mean, actually, here’s what I read [laugh]. The people—women do better at women’s colleges because they don’t feel intimidated. They don’t—they can just do their own thing, and nobody puts them down. I remember actually when my daughter was a couple of years at the international high school in Geneva. She was interested in science, but whenever she spoke up in class, some smart aleck kid put her down. [laugh] And eventually she just did something else. So I can see that—I think that’s an advantage. And disadvantages, I don’t know. I just—when I left there—well, it was a school with a lot of wealthy kids. It was a very expensive school. I mean, I wasn’t paying for it. And it was kind of—I had more in common with the professors than most of the students, although I still have a couple of very good friends that were there with me.
You mean, socioeconomically, you had more in common with the professors?
Yeah, and intellectually. I mean, a lot of the girls were there to find the right kind of husband, and that was it.
And you did not identify with that?
No. I left there and went to Columbia for graduate school, and I felt liberated. I think [laugh] especially going to New York City, it was an exciting change—and a lot of fun. [laugh]
Now when you entered Hollins, did you declare a major in physics right away?
I did, yeah. Well, I mean, you didn’t declare formally until your junior year. But I knew I was going to major in physics.
Why did you choose physics initially?
[laugh] I’ve thought about this recently because people keep asking me, and I think it was because I like math. I was good at math. But of all the sciences, physics was the most mathematical, but it seemed to me more relevant to the real world than pure mathematics. I think that was basically it.
At that early stage, did you already gravitate towards the theoretical side of things, or were you interested in experimental as well?
I didn’t really know. I mean, what happened was—well, this is a strange story. What happened was that there was a woman there that was—there was like one physics major every other year. But the woman who was head of the department had been at Yale, she was let go when her husband died. She was on soft money. But she had worked with Oppenheimer. I mean, she was somebody who had been active in the field, and she got me to go—well, I spent a year in Paris, and she got me into a laboratory in Paris. And then after my junior and senior year, she had me apply to a summer student program at Brookhaven National Laboratory on Long Island. And I worked with the Columbia group, and that’s when I really got excited about high energy physics. But I always assumed I would be an experimentalist because people were discouraged back then from doing theory. I remember the first—the orientation at Columbia. You were told, “Well, only a few of you are going to stay in the field at all, and don’t even think about becoming a theorist.” I mean, that was the message—and, you know, I was a woman. As such I didn’t have the gall to think about to becoming a theorist. And then [laugh] after my first year at Columbia, I got married to a Frenchman, and I moved to France. And at that time, he worked—well, he was working in a small accelerator lab south of Paris. And so I took courses in Paris, and everybody told me that I should get a position in an experimental lab. The courses were taught by the theory group. But everybody said nobody gets into the theory group, so get yourself into a lab. Most of the students were already affiliated with a lab. And so I did the rounds of all the labs, and got turned down by every one of them. It was a very—it was a horrible experience. They only took people from two elite schools, which were all-male at the time.
Which were those schools?
École Normale is one of them, and the other one is École Polytechnique. Now they’re coed. But at that time, they were all-male. And so I just kept on taking the courses, and I did very well [laugh] and I got accepted into the theory group, and so I became a theorist by default.
By default, OK. Well, so I haven’t left Hollins yet. Did you do a senior thesis at Hollins?
No, we didn’t have—
No senior thesis. And did you know right away that you wanted to pursue a graduate degree in physics? Did you go right to Columbia?
Yeah. I think I went to Columbia because I had worked with a Columbia group at Brookhaven.
And how did you get involved with Brookhaven initially? What was that connection? [unrelated conversation]
We will say, formally, we are back from our break right now, and my question was how did you originally get connected with Brookhaven coming out of Hollins before Columbia?
My physics professor, she recommended me, and I think she—I mean, she knew people, and she was influential—because she had been active before she went to that small girls’ school.
What was her name, your professor?
And she said there’s a program at Brookhaven, and she thinks you’d be right for it?
And when you got to Brookhaven, what were your impressions?
Well, I mean, I was going to—it was very new to me. [laugh] Well, I was assigned to Bob Adair from Yale, and he had—there was another woman who was a student at Yale who was there too as a summer student. And he gave us a nice little course on particle physics. So that was nice. But I actually worked with the Columbia group. I don’t remember exactly how that happened because I think Bob was maybe not actually working on anything or—I don’t know. But I ended up working with the Columbia group.
Now, had you taken a class in particle physics at Hollins?
No, they didn’t have anything that [laugh] advanced.
So this was new? This was new for you?
OK. And then so I understand the chronology. This is you went to Brookhaven after you graduated or this was a summer—?
Two summers. The summers after my junior and senior years.
And so then it was the connections from Brookhaven that got you to Columbia?
And why Columbia? Did you apply elsewhere or that was your only application?
Oh, I probably did but—I’m sure I did. But I was working with the Columbia group, so I knew them—and a lot of the summer students were also going to Columbia so I knew a lot of people. It just seemed like a natural thing to do.
So what was the Columbia group? What does that mean? It was students from Columbia at Brookhaven?
Yeah, professors. I mean, Brookhaven was run by something called the University—oh, gosh, I can’t remember anymore. [laugh] It’s a consortium of universities mostly around the east coast, I think, and they ran it, and they worked there, and brought students from their home universities. But each group had a staff member assigned to it.
And who were some of the people in the Columbia group that you grew close with?
Oh, the professors? Leon Lederman, Jack Steinberger, Mel Schwartz who unfortunately passed away some years ago.
And they encouraged you to come to Columbia?
I don’t think they encouraged me or discouraged me. And I also knew some of the students who were also starting at Columbia. [laugh] I felt at home.
Now, you described—when you got to Columbia, you described it as a liberating experience. What do you mean by that?
Oh, well, New York is very different from rural Virginia. [laugh]
There was an art theater that showed a lot of foreign movies just around the block, and stuff like that. I mean, it was a whole new experience.
And I assume also that you were being exposed to physics at a higher level as well.
Oh, certainly. Oh, yeah. I worked a lot, yeah.
And it was only a one-year program at Columbia?
No, it was—no, I went there intending to get my PhD.
Oh, you did?
Yeah. But then I married this Frenchman, Jean Marc Gaillard, who was a postdoc in the same group.
Oh, so you met him at school?
I met him at Columbia, right. And, well, I actually met him at Brookhaven. And then I married him, and left in the summer after my first year at Columbia.
But you did leave with the master’s degree completed?
Oh, that was another comedy of errors.
[laugh] Do tell.
[laugh] I was supposed to—you were supposed to take an exam to get a master’s. If you didn’t go on to a PhD, and you wanted a master’s, you were supposed to take an exam. And I took a French exam, which was no problem for me. And then somebody told me what book I should read. So I was studying this book. I went off on my honeymoon, studying this book. And then I got sick because of something I ate in the South of France. And I was miserable, and I hadn’t gotten my master’s yet. They were going to arrange for me to take the exam with a professor in Paris; I can’t remember his name except that it begins with T, but anyway.
So you had already left for France while you were still enrolled at Columbia?
Well, I had to get my master’s in order to start the graduate program in France.
I see. So there was no—you did not do a master’s thesis at Columbia?
They didn’t have a thesis. But you had to take—if you didn’t go on to a PhD, you had to take an exam. And so I was waiting to hear about when they were going to give me the exam. And finally I called Leon Lederman, I think, and he said, “Oh, didn’t they tell you? You’re exempt on account of your grades.” [laugh]
[laugh] Well, good. Now, when you went to France, did you go with the intent that you were going to build a life for yourself there? Or were you thinking, “I’ll just do my graduate work here, and then come back to the States”?
No, I went because I was getting married.
And your husband, I guess, he had no intention of staying in the States. He was only in America temporarily for school?
Yeah. Oh, no, he was a true Frenchman.
And what brought him to Brookhaven and Columbia?
Oh, just to have the post doc experience.
And so did you ever have any concerns that the quality of your education in France would not be as good as in the States? Or was that not true?
No, I did, I did.
You did? And so you enrolled at the University of Paris at Orsay
Yeah. Actually [coughs], I wanted to—I mean, I got engaged but I didn’t want to leave right away with him. [coughs] I had to finish my coursework, and then I could write a thesis somewhere else. But these guys, Lederman and Schwartz and Steinberger, they all said, “Oh, no, you should go with your husband.” And so they finally convinced me to go.
They said you should go with your husband. Did you ever wonder if you had been a man, and you had married a Frenchwoman, do you think they would’ve encouraged you to go?
[laugh] I had to ask. [laugh] So you went. How was your French at this point?
It was pretty good because I had spent a year in Paris [coughs] as an undergraduate, excuse me.
You did a study abroad?
OK. So now you enroll in 1964, and I see you have a doctorate in 1964, and a doctorate in 1968. So how does that work?
That was the old French system. The French system now is more like the American, just something like a PhD. But they had a doctorate, which was a level somewhere between a master’s and a PhD. And with that, you could get a nontenured job. And then it usually took a very long time to get what they called doctorat d’état—state doctorate. And that was beyond a PhD at the time.
Oh, I see. So the second one was sort of more like a postdoc?
No, it was—well, I don’t know. A lot of European countries had these kind of degrees that require a lot more publications than a PhD.
And for the initial degree in 1964, did you have to do any lab work?
No, I was only doing theory.
You were only doing theory. And what was the process of identifying your dissertation topic?
Well, I was at CERN, and somebody at CERN actually suggested it because it was—well, this is the first one, the little one. It was related to an experiment that was going on at CERN.
And what was that experiment?
It was measuring spins of resonances. Are those words OK? [laugh]
Yeah. No, I’m tracking with you.
That’s fine. OK. So that was the experiment, and then what was your dissertation? How did it relate to that experiment?
Oh, I worked out—gosh, long time ago. [laugh] I worked out you know, what they should measure—and suggested ways to measure it. I forget it. I can’t remember. It was a long time.
But it was directly related to the experiment.
And what was the process for defending that first dissertation? Was there an oral portion and a written portion?
That one I think not. I think you just—well, I wrote something, yeah, there was a written portion. I don’t think that one had an oral portion. The second one did. The second one had an oral portion, which was open to the public. And afterwards, the candidate had to throw a party, a wine or a champagne party. [laugh]
[laugh] That sounds pretty good.
And I remember my husband’s grandmother getting tipsy. [laugh]
[laugh] And what was your husband doing? What drew him back to Paris?
Well, actually, he had a post doc at Columbia but he wasn’t really—he didn’t have his actual degree yet. Well, for one thing, he didn’t want to live forever in the States. He wanted to live in France. And he had a job near Paris, and he also had to finish his thesis. And, in fact, he wrote his thesis on the experiment he had done at Columbia, which was a famous experiment, by the way.
What was that experiment?
Establishing that there were two different neutrinos. The three leaders—Schwartz, Lederman, and Steinberger got a Nobel Prize for it.
And so right after your initial defense, you started up at CNRS, the French National Centre for Scientific Research.
What was your connection there? How did that opportunity come about?
I mean, there were basically two tracks in France: one was in the university, and the other was in the research institute. And once I had the first thesis that was a requirement, I guess, for the first step, which is kind of like an assistant professor, I got that position, yeah.
And so this position, was it a joint position with your work at the university? What was the arrangement?
Well, I was officially tied to the university where the theory group was. At the time, they were in a town called Orsay, which is south of Paris. So you get a position in CNRS but then you’re tied to some place. And I was tied to that place.
And what were some of the big projects that were going on at CNRS at the time?
Oh, boy. [laugh] Well, Orsay had [pause] an electron-positron collider. I think they discovered some resonances there, like the omega, I think.
And what was your work? What were you involved in?
I got involved in kaon physics. Well, you know, I was at CERN, and my husband was working on kaon experiments, and so I just—there weren’t any other students who were theorists. [laugh] And so I talked a lot to experimentalists, and so my initial papers when I went to CERN were on kaon physics.
And was that what you did for your second degree in 1968?
Yeah, my second degree, well, it was based on that and some other papers.
Like what? What other papers were you—what else were you working on at the time?
[laugh] You’re making me remember a lot.
I think the work I did on kaons was the most important but I did do some other work on weak decays of strange particles, baryons.
And following the successful defense of that second degree, did your position at CNRS change?
I was promoted from Research Attaché to what they called research chargé—I don’t know—Chargé de Recherche--I don’t know how to translate it. But it’s more like an associate professor, I guess.
So was there an actual—?
Oh, wait, actually, no. It’s probably more like assistant. It doesn’t have tenure because I think it—but nobody ever got fired. [laugh] But, yeah, it’s probably more—the first position was probably more like an instructor, which doesn’t exist anymore I think here. And that second one was more like assistant professor. And then the next one is called master, and then the highest one is director. Master is roughly the same as associate professor.
At this point, are you directing your own research or are you still be tasked with research projects?
Oh, I basically always directed my own research.
And so how did that progress over time at CNRS? What was the process of taking on new projects?
Oh, to get an idea [laugh] of something to do, I guess.
And explain that process. Not all of us are theoretical physicists. How do you get an idea, and how do you act on it?
Usually by talking to somebody, and something comes up. And then you think, “Oh, I should look at that. Maybe I could work that out.” Or somebody—sometimes an experimentalist would just ask me a question, and I would work out something.
And in the early 1970s, and again in 1983, you visit Fermilab—
—as a visiting scientist. What was the connection there? How did you get yourself to Fermilab?
Well, the year before that, there was an international conference at Fermilab And my husband and I both gave—no, we—oh, wait. We were session organizers. And so that’s how—I mean, people—so the director got to know me and stuff like that. But it was actually Leon who was visiting CERN one day, and said, “Why don’t you spend a year at Fermilab?” And so we did.
And what were your impressions of Fermilab?
Oh, I loved it.
[laugh] It was new. It was still being built, and there was—I mean, they hadn’t had time to develop a terrible bureaucracy. [laugh]
The theory group was—well, Ben Lee was the leader of the theory group, and he was the only permanent member. Everybody else was either a postdoc or a visitor.
Now, were most of your collaborations with Ben Lee at Fermilab? Is that where you did your work with him?
Yeah. I mean, we were continuing—after I went back, we were continuing sort of to collaborate a bit by distance. But the most important work we did when I was at Fermilab.
So did you go to Fermilab knowing that you were going to work with Ben Lee, or that just sort of happened spontaneously?
It just happened spontaneously.
So how? Tell us the story. How did that collaboration start?
OK. Well, this was the early days of what’s now called the Standard Model. I mean, people had predicted neutral currents, and some experiments thought they saw them, and other experiments said, “No, they’re not there.” And Ben and I just started talking about the situation, and also charm had been proposed. And then I said to Ben—I asked Ben a question because in the so-called GIM mechanism which suppresses the decay rate of K to 2 muons for example there’s a cancellation between the up quark and the down quark and—I mean, up quark and charm quark--contributions. And then I think I asked Ben why the decay of K to 2 gammas is not suppressed, and we kind of worried about that overnight. And then he remembered, based on some work he had done with some other people, that the cancellation mechanism was different. And so then we decided to go systematically through all the rare decays of kaons. And by comparing neutral kaon decay and K,K-bar mixing predictions with experiment, we were able to estimate the charm quark mass. So that’s how that came about.
How long did that entire process take? Was this years, months? What was the duration of this?
Maybe months, I would say.
Now this is—
But we did it all when I was there, and I was only there for a year.
Right. I mean, it’s such a—in the history of physics, it’s such an important collaboration that I have to ask how did your personalities and your scientific styles complement each other to produce this work which seems like it could not have been produced as a solitary effort?
Maybe—Ben was—he knew a lot more formal physics than I did, and I probably knew more phenomenology than he did. And also—
And what does that mean that you knew more phenomenology than he did?
I knew more. Well, he had done some very formal work, for example, an alternate proof of the finiteness of the gauge theories. And I had done a lot of work more directly related to experiment.
And what about in terms of your personalities? Because clearly there needs to be that connection as well.
Oh, yeah. No, we just clicked. I mean, he was a person that I could talk to at the board more easily than anybody else. I mean, I’ve had a lot of collaborators, and we do a little bit of board work, but we often just do some things, somebody else does something else, and we put it all together. But Ben and I really worked at the blackboard together all the time.
What was the culture like as a—I mean, given the time that you spent at Fermilab, you probably had the opportunity to compare the culture of Fermilab to CNRS. My specific question, I guess, is as a woman, where was it easier for you to collaborate and—I don’t know if be taken seriously is the right word. But where was the place where it was easier for you just to be a physicist, and the fact that you were a woman was a secondary thought?
No contest: Fermilab. [laugh]
[laugh] Yeah. No, I mean, actually, I shouldn’t compare it with the CNRS. The CNRS is an institution. It’s not a lab. I was—I mean, physically, I was at CERN all the time.
Right. And CERN, that was an issue at CERN as well? There was a patriarchal feeling to it?
You know, they didn’t hire a woman junior staff member until, oh, around the time I left. Yeah, it was around the time I left in 1980. And they didn’t hire a senior staff member until the mid-90s when they hired Pippa Wells and Fabiola Gianotti. But they hired two women experimentalists. There still hasn’t been a senior staff woman theorist at CERN.
So you have this clear contrast between CERN and Fermilab, and yet you stay at CERN until 1981. Were you thinking about like trying to put something together so that you could stay at Fermilab?
We could’ve stayed. Well, actually, this was maybe—I mean, I spent a lot of summers at Fermilab just because I felt more comfortable there. And then at some point, maybe it was 1978 that Leon Lederman offered us jobs, my husband and myself. But my husband absolutely didn’t want to go.
This is the LAPP theory group leader opportunity?
Oh, at Fermilab., OK.
But your husband didn’t want to go?
So then what was that opportunity with LAPP as a theory group leader from January ‘79 until July 1981?
Well, somebody—the head of the lab—there was an experimental lab at Annecy. And one day, the head of the lab, I think Marcel Vivargent, asked me if I wouldn’t like to start a theory group, and I accepted because I was pissed at CERN. [laugh]
[laugh] Was that a better place for you?
Well, I didn’t move there, I mean, I commuted. It was—well, [laugh] I mean, I was the chief honcho. [laugh] And then I got—actually, I had a student. I had a student. Occasionally, I would get students sent to me from Paris, and I got a student about the same time I moved there, and he moved with me. And that was Pierre Binétruy, and he was very successful. He was running everything in France by the time—unfortunately he died a few years ago.
And then in the middle of this, you become the director of research at CNRS. This was in January 1980 to July 1981.
Yeah, and that’s equivalent to a professor in a university.
Right. So you were—it was not an actual tenure process. This was just the equivalent?
And what work were you doing at this point at CNRS?
This would’ve been—
And this was your last work in France before coming to Berkeley.
So what was that? Do you remember what that work was?
I was working with Bruno Zumino, who eventually became my husband, and this was on—I don’t want to answer because I’m going to get this wrong. There was a theory—oh, yeah. There was a theory called—well, sometime in the late ‘70s, well, supersymmetry was invented in ‘76. That was by Bruno and and Julius Wess and, independently, some other people. And the version with four supersymmetries was proven to be finite by Stanley Mandelstam. But, oh, no, this was later. Wait a minute. Oh, it was proven to be finite later because I—yeah. Stanley Mandelstam was at Berkeley, and he was a very sweet guy but he was very shy. And one day, John Schwarz, who had been a student at Berkeley, came to visit. And then a bit later, I saw him coming out of Stanley’s office, and he said, “Stanley told me that he proved that N equals 4 [laugh] supersymmetry is finite.” And none of us had a clue. [laugh]
Anyway, so then supergravity was invented, and the highest number of supersymmetry generators in that case is N equals 8. And that was speculated to be finite. Actually, people are now still working on proving that it’s finite, and there seems to be—it seems likely it is. But, anyway, so we were—I think Bruno and John Ellis Luciano Maiani and I were looking at that theory to see if it could be relevant for particle physics. And then there was an issue, and it turned out that—well, first Murray Gell-Mann had looked at it briefly. And the particle content of the—elementary particle content of the theory doesn’t contain all of the standard model particles. And some of them would have to be composite. So we took the point of view that the elementary particles we found and what we observe are all composite. But then we needed gauge bosons to be composite. And there was some doubt expressed that you can have a massless gauge boson coupled to the conserved currents.
Oh, why not? Well, there’s an argument by ‘t Hooft which actually I don’t find totally convincing. And there’s also something—a more quantitative argument by Banks and—oh, I don’t remember but some other people. But there are arguments. But what—we found a loophole to their argument. I mean, Bruno and I wrote a paper studying this kind of theory, and we found a conserved current but the conserved current that we found it not gauge invariant. So the argument says they have to be both conserved and gauge invariant to be impossible. And so we found a way around that argument. And then, I mean, actually that paper—I mean, we didn’t get it very far with the theory itself but the paper has turned out to have a lot of applications in string theory.
But you didn’t know that at the time? You would find that out later?
So in 1981, in July of 1981, you come to Berkeley. So what was the connection? How did that happen?
Dave Jackson, oh, [laugh] and Dave Jackson and a bunch of women graduate students. Dave Jackson was the chair of the department, well, just prior to—I mean, but he finished when I came, and then it was Leo Falicov. But Dave was the prime mover. There were a bunch of—a group of women graduate students, I think, led by Persis Drell. And they wanted to absolutely have at least one woman on the faculty. And so I was invited to Harvard as a Loeb lecturer in December of 1980, I guess. And then it was that—and then I got an invitation to Berkeley as a chancellor’s lecturer.
Is that where you met at Harvard? Is that where you met Dave Jackson?
No, no. No, I knew Dave Jackson. But, I mean, Harvard invited me for this one lectureship, and then David—well, Berkeley invited me for the other one, I guess when Dave was still chair. But actually what they had in mind was having me give some lectures to convince the faculty they could actually hire a woman. [laugh]
Now where did you know Dave Jackson from?
How did I know Dave? Oh, he—from CERN, for one thing.
Oh, from CERN.
Yeah, he did some stuff—he spent a sabbatical there.
Right. OK. So you come in. It’s this historic moment. You’re the first woman full-tenured professor of physics at Berkeley. And my question is how did this make you feel? In other words, if there were women graduate students who wanted a woman professor of physics, right, would you have rather been offered the job just because of your accomplishments in physics, and not because you were a woman? Did you dwell on that? Did you feel like you supported this, that you felt like you were breaking barriers? What was your feeling about this?
I felt they really wanted me because they thought I was good. I mean, they didn’t give me the impression—you know, I didn’t—I really felt appreciated.
Did you feel like you were really breaking a barrier?
Good question. [laugh] I might have. I don’t remember thinking about it that much. What I remember was that I was so glad to get away from CERN, where they didn’t want to hire me, to a place that wanted me [laugh] and—yeah.
And your experience at Berkeley was similar to Fermilab where you felt at home, and you felt comfortable?
And how were your relations with your fellow professors?
Fine. I mean, I think there was—oh, I mean, I think probably there were a couple of old fogies who weren’t enthusiastic. But, you know, I didn’t interact that much with them.
And you had from the get-go a joint appointment with LBL, with the Lawrence Berkeley Laboratory?
Yeah, but that’s standard. I mean, it’s not—well, I got some summer salary—sometimes summer salary from the lab, and sometimes from the National Science Foundation. But it was standard that all of the particle physicists and many other people who are in the physics department also have an affiliation with the Lab.
And how did you divide your time between the two? Was it a fifty-fifty arrangement or was it weighted one more than the other?
I think I did most of my—well, I was on campus to teach, and when I had office hours to see students, and sometimes seminars. But I think I did most of my research at the Lab. And most of the students used to come to the Lab. Now—when was it? Sometime around 2000—I don’t know. A few years before I retired from teaching, there was a renovation of the physics department, and so now it’s much better for the students down there now. So in recent years, I’ve seen my students on campus and sometimes I get them to come up to the Lab.
And was this the first time you were teaching at a university level when you got to Berkeley?
Yeah, first time I ever taught anything except summer school. [laugh]
And how’d you like it. How’d you like teaching physics?
It’s always an adjustment.
Well, yeah, and it’s also—well, it’s kind of—it always reminded me of when I had little kids because [laugh] you had to stop what you were doing, and keep to a schedule. [laugh]
Did you find it easy or difficult to convey physics concepts in a physics 101 kind of class?
I never taught 101. I taught graduate courses until the last few years when I taught some upper division courses. I mean, I’m good at giving lectures in physics conferences, even public lectures. But with students, it’s harder. It’s hard to—and for me, anyway. I mean, some people are naturally good teachers. It’s hard to know what they’re getting sometimes. And I encourage students to ask questions. But unless the class is really small, they’re often reluctant to because they don’t want to embarrass themselves, I guess, in front of other students by asking a stupid question. But it would be a lot more helpful [laugh] to the teacher to know what they haven’t gotten.
Now, these woman graduate students who had clamored for a female professor, did they all immediately become your students?
Well, most of them were experimentalists. But I think for the first five or so years that I was there, all of the women theorists came to me, except for one who did very mathematical—much more mathematical work than I did.
And did you involve them in your work at the Lab, or you kept those worlds separate?
No, no, they were all affiliated with the Lab. I mean, it’s still true.
And the work that you had done at CERN, did you essentially bring that and continue it at Berkeley? Or did you start to work on new projects at Berkeley?
Mostly new projects? I mean, there were some—there were a few things that sort of dangling over that hadn’t been completed. But I basically worked on new projects.
And you had multiple sabbaticals at the Institute for Theoretical Physics at Santa Barbara.
What attracted you to go there?
Well, not teaching [laugh]—
—a lot of people, I mean, you know, it’s a very active place. There’s a lot of interesting seminars.
Was it a place that was good for collaboration?
So what were some of the collaborations that you developed at Santa Barbara?
Well, actually, I remember Pierre Binétruy was there for a while. He was my former student, but we collaborated. Who else? I’m getting a little confused because I also went to Aspen several summers, and I think I actually started more collaborations in Aspen than at Santa Barbara. In Santa Barbara, I was more continuing what I’d been doing, I guess.
When did you begin your collaboration with John Ellis?
I think that was after I came back from Fermilab.
So that was mostly when you were still in France?
And how did you get to know John?
He came up to me, and he said, “Why don’t we look at”—oh, I had written another paper with Ben Lee about strange particle decay, and he suggested we look at decays of charm particles sort of using the same techniques to see what predictions we might make. And then that was the start. And we wrote a paper on the Higgs with Nanopoulos, and it just continued.
And you collaborated with him over the course of many years.
About six years, yeah.
And what were some of your most notable work with John?
Well, I think the Higgs paper, we predicted—among other things, we calculated the decay rate for Higgs to two photon, which was actually the discovery mode. And what else did we do? Oh, we predicted gluon jets, and that turned out to be a pretty important paper. And we calculated the b-quark mass, and we predicted the b-quark mass correctly. We still don’t know whether that’s—the fact that we got it right is an accident or not because it was based on a so-called Grand Unified Theory, a theory that is disproven but it still could have some meaning.
You feel that the Grand Unified Theory has already been disproven?
Well, the simple SU(5) theory we used certainly has because it predicted proton decay at a level that’s not been seen.
And the same question I asked with Ben Lee, how did you and John complement each other?
That’s a good question.
What was his training versus your training?
He was a—what was he? Was he Oxford or Cambridge? Hmm, can’t remember. I’m trying to think what he did before. You know, in some ways, it was almost the reverse of Ben and me [laugh] because I was more familiar with complicated calculations, and he was kind of a jack of all trades. I mean, he had ideas about all kinds of different things. He would often instigate a project. [laugh]
And he would rely on you to push it forward?
Now, back to—in the 1980s, you became group leader of the theoretical physics group at LBL. Was this a promotion? Was this a tenure—a temporary appointment? What was that position?
It was a temporary appointment. I mean, at the time, people—I don’t know. There was that—the appointment was limited to two years, three years, I don’t remember. But it rotated. And, now, I can’t remember if I—I think I just served one term. But it had an extra semester tacked on because I took a semester’s sabbatical at Fermilab, and so I made that up plus another semester to fill out a year. But I don’t know if you’d call it a promotion. Well, no, actually, no, what I said is wrong. Before that Geoff Chew had been the group leader forever, and they wanted to change that. [coughs] But then it sort of drifted back into being forever [laugh] when there were people who were willing to do it forever because everybody realizes it’s kind of a pain in the neck, so if you get somebody [laugh]—yeah.
Now, in 1991, you were in inducted into the National Academy of Sciences. And aside from that being—I’m sure personally you felt very honored to be recognized. But I wonder if the induction was also useful for your research. If being a member of NAS opened opportunities or created connections that might not have otherwise been available to you?
No, I don’t think so. I mean, I met interesting people, but it hasn’t really impacted my research.
Really? So it’s never been useful to you in that regard?
So what is it good for then, aside from being an honorific?
Well, I mean, it’s good for doing studies and stuff like that.
How do you mean?
Oh, I think there’s one being set up right now on, what’s it called, COVID-19.
You mean that as a—do you mean to say that as a member of the National Academy, you can be assured that your research reaches a wider audience? Is that the idea?
No, it’s just I think it’s—well, it’s an honor but it’s also—because some people—I mean, my—but it also sometimes serves a purpose in advising the government or doing projects with the government. I mean, the kind of research that I do is useless but [laugh]…
When did you start taking on advisory work for the Department of Energy?
Oh, boy, it’s—well, when I got back from—when I came to Berkeley, I think I moved in ‘81. And I think in—well, first, I got drafted onto the Committee on Women in Physics at APS. And then I got drafted onto this—what was it called? Oh, it was a Department of Energy task force, or whatever they called it, to examine physics departments around the country. I mean, DOE supported physics groups and labs, and so I got on that. And then, well, I guess I served on every possible—well, I served on Argonne Visiting Committee, and I served on Physics Department review committees such as at Harvard, every possible Fermilab committee [laugh]. I guess I was doing penance for not having gone there [laugh] [??].
[laugh] And what were your contributions to these advisory groups? What were the kinds of things that you were recommending?
Well, for example, whether or not they supported an experiment, basically. I mean, these were decisions about what should funded, for example the experimental program at Fermilab. I did that both with the Accelerator Program and also for the Astrophysics Program.
And what kinds of projects were you likely to support, and what kinds of projects were you likely not to support?
Well, it depended on the physics potential. I mean, if you thought this experiment —it’s also a balance between cost and physics potential. If you have an experiment that costs very little but is a long shot, you might support it. Whereas the same experiment, if it were expensive, you would say, “No, that’s too risky.” It really depended on the physics potential. And the hardest committee that I was on was on the 1983 “Woods Hole” Panel.
Why was that so challenging?
Because the question was whether or not—well, one was supporting the Super Collider but that wasn’t the hard part. The hard part was do you keep Brookhaven going, and that was very painful because it was—I mean, the community was very divided, and a lot of us thought it was too little too late. But the people who lived on the east coast had kind of—that was their bread and butter, and they wanted it—the process was very painful.
Yeah. Now, you joked earlier a little bit about how what you do is useless, right.
So obviously that’s not true, but you feel there’s probably a kernel of truth that nags at you there. So I wonder if you can explain, have you ever been concerned with how to translate the value of theoretical physics to a wider audience so that people who are not in your field who are not specialists can appreciate the value of what you do beyond the theoretical realm? Because it does have societal value. It does have scientific value. So have you ever thought about how to communicate these ideas and issues to a broader audience?
Well, I have given some public lectures. or I try to convince people that this is worth doing.
And what are your arguments?
Actually, that was part—well, I often did that when I was giving lectures supporting the Super Collider. That knowledge is some—seeking knowledge is innately human thing. That babies from the moment they are aware of anything start reaching around, and trying to figure out [laugh] what the world is around them. It’s just something that is what makes us human. And there are spin-offs, but, I mean, some people—they’re been important spin-offs like some radiation treatments and things like. But that’s not the thrust of my argument. That’s not what—but we don’t—it’s good to get a spin-off but that’s not why we do it. We do it because we want to understand nature.
And you feel that that is something that is satisfying to a larger group that might say, “Well, why should we support something just because you’re curious about it”? Have you ever felt like you needed to make that argument, or that argument doesn’t really need to be made?
Well, some people—I think some people will—some people understand it, and they think it’s great. And some people will always be skeptical.
How has support for theoretical physics from the government, how has that changed over the course of your career?
I guess it’s gotten worse.
It has gotten worse?
And, I mean, to state the obvious question, what are the impacts of that? What is threatened as a result of decreasing government funding for theoretical physics?
Jobs, jobs for young people. Yeah, I think for a long time, after World War II, high energy physics in general was carried along by this notion that, you know, it was going to do something like the bomb, something [laugh]—if you think the bomb is useful but anyway. [laugh] And physicists didn’t try to dissuade anybody of that because they knew it was—but then at some point, the politicians kind of caught on [laugh] that…
Yeah. In surveying the course of your career, how much overlap is there between the projects that you feel have had the—that you’ve been involved in that have had the greatest impact, and the projects that you’re proudest of? In other words, are those two things one and the same, or are there projects that you feel very proud of that might not have had as great a contribution as others, and are there contributions that are huge but that you’re not so proud of?
By huge contribution, you mean they had an impact on the field?
Yeah, I think it goes hand-in-hand.
It does go hand-in-hand?
It might be [??] clever but that you’re proud of that doesn’t really—yeah, you can be but—yeah, I can think of things like that that I did that I thought was very clever that didn’t have a big impact. But I’m just sort of pleased with myself. It doesn’t really matter [laugh].
So what does it mean that you did something that was clever? What does that mean?
Well, here’s an example. We did this work on N = 8 supergravity, and that theory has a peculiar symmetry, and there are infinite towers of bound states that are predicted. And I figured out a way to classify them or something like that, and that required some clever mathematical tricks. That’s an example. It doesn’t have any impact but it was [laugh]…
But it was satisfying to you?
Yes. And the weird thing is that I can’t—I worked out the argument on some scratch paper, and then I just gave the answer, and I’ve never been able to remember what I did. [laugh]
When you’re working on a theoretical problem, how do you define success and failure? How do you know that a theory is on its way to success, and how do you know when it’s on its way to fail? And if you see it going in that direction, how do you know when to jump ship?
Well, there are two possibilities. I mean, one is that you find a flaw in a theory that it can’t possibly work and—
What does it mean to find a flaw?
Maybe an internal inconsistency [coughs] mathematical inconsistency, or you see that you’re going to get a prediction that’s obviously wrong because it doesn’t agree with observation. Or somebody comes along, and does an experiment which rules it out. So there are various ways. I mean, if you think if what you’re doing is going nowhere, well, you just quit, I guess, well, except—well, at least I do. [laugh]
[laugh] And how do you know—how do you define success? How do you know that something is really working, and that it’ll be important?
Well, you don’t, actually. Although when I wrote those papers with Ben, the charm quark wasn’t confirmed until almost a year later. But, somehow, we felt that everything sort of meshed together. I think we felt that it had to be right, sort of, because—I can’t really explain it. But it just—
It had to be right because you had a hunch?
Because—not a hunch, but, well, I guess it’s a hunch. But it’s just that when we did all these calculations, everything was very consistent. There wasn’t any of what they call fine-tuning or fiddling parameters. Things just came out looking like they made sense. I don’t know how to quantify it.
Do you see yourself in a specific intellectual tradition in physics? Do you see your style and your thought process as coming from a particular intellectual heritage that you identify with?
No. I don’t think so.
Who are some of the physicists that you really emulate, or are heroes to you?
Well, Feynman obviously was a giant.
But I’m asking—I mean, everyone knows that Feynman was a giant. But who are the people that spoke like that you felt a connection to, an affinity to, the way that they did physics?
I don’t know.
You never thought like that?
No. I mean, in the beginning of my career, I was thinking just let me do physics. [laugh]
I mean, in those days, struggling to be able to do physics. I guess I didn’t—
Did you ever concern yourself with bigger questions beyond your particular fields or project? Did you feel like the things that you were pursuing had import beyond the specific parameters? That you were working towards a greater understanding of how the universe was created, and how it might end, you know, the really big questions? Did you feel like your projects were related to those big questions, or you kept your focus more narrow?
Well, I mean, I think I’ve always felt that expanding our understanding of the universe was in itself important. But, I mean, I don’t think that much about sort of more philosophical things.
So in that vein, are you satisfied that there are some things in physics that are simply unknowable? Or is it just a matter of time until they will be known?
I think I’m kind of agnostic.
Are there things that are—at the beginning of your career that were mysterious either to you personally or to your field that are now really well understood to the point that they’re not mysterious anymore?
Oh, yeah, I mean, well, the whole Standard Model. When I started physics, nobody understood strong interactions. They were just like a mishmash of sort of these postulates or speculations, and now they’re—I mean, they were in enormous contrast to quantum electrodynamics. But now we sort of see them all as one and the same. I mean, there are differences of course but the level of understanding is comparable.
And what was the breakthrough with the Standard Model?
Probably the discovery of asymptotic freedom.
And the flip side of that question is what were some things that were mysterious either to you personally or in your field that remain mysterious today, that are still really unknown?
What is dark matter? Well, what is dark energy is even more mysterious.
Why is dark energy more mysterious than dark matter?
Well, with dark matter you have something—some kind of bunch of particles or something. But dark energy is—it’s just harder to see what it is. I mean, well, you can assume it’s a cosmological constant, which it sort of looks like, well, then it—yeah, that’s—there are mysteries which are the mysteries of scale. And the cosmological constant is the most striking of those. How is this number so tiny compared to all the other numbers like the Planck scale, the strong interaction scale? And then there’s also the so-called gauge hierarchy problem. I mean, why is the symmetry breaking scale so small compared to the Planck scale?
What are the things that stand between the issues that you’ve just raised and our understanding of them? Are they technological limitations? Are they limitations of imagination? Is it simply a matter of time and more work on these areas before they’re understood? How do you understand these limitations?
That’s why I came in as an agnostic. I don’t know. I can’t tell. It’s possible that one day we’ll come to understand these things. But I don’t see a path to it right now.
Could the same be said about other issues in physics that have achieved that crossover into understanding?
You mean like asymptotic freedom and the strong interactions?
Things that were not understood and then—I mean, just in terms of extrapolating, what were—in the way that I’m asking, is it limitations in imagination or technology or genius? What were those things that allowed us to understand things that are now not mysterious?
Well, it’s everything. I mean, first of all, there were the experiments that discovered scale invariance and partons. And then there were theorists who showed that these—the strong interactions become weak at—well, first somebody had to realize—I mean, the understanding that the interactions, strong interactions had to be mediated by vector bosons. They interact with one another. That this implied that the theory got weak at high energy—weakly coupled. And so it was a whole combination of theory and experiment. And I think that’s always going to be the case.
Why is that always going to be the case?
Well, except I guess for Einstein’s [laugh] theory of relativity, I mean, I don’t know—other than Einstein, I don’t know of any progress that was made without a combination of observation and theory and interpretation.
What do you see as the future of theoretical physics? Where is the field headed?
Well, I think it’s headed towards insanity [laugh] by itself. I mean, no, if we don’t have experiments, people can let their imaginations run wild, and invent anything without it being verified or disproven. So I think it—I mean, if we want to understand more about what happens at higher energies, we have to have higher energy colliders. I don’t think—well, cosmology is tied to particle physics, and that’s probably something from—I mean, there is a lot of data coming from cosmology. And there is some data that will be coming from very low energy precision physics. But I don’t think that theory by itself—it needs to be kept in line by [laugh] experiments.
And that’s what you mean by “it’s headed towards insanity” if it’s not kept in line? Is that the idea?
Has that always been the case? Has the theoretical and the experimental, have they always had that relationship or this is a new historical development, do you think?
Well, I think they always have.
Well, Dr. Gaillard, I think for my last question, I want to ask another question that’s forward-looking but it’s more personal to you, and that is what are you personally most excited about? I mean, you’re still very active in the field. What motivates you to continue working in the field? What is it that you want to accomplish personally, and what do you want to see be accomplished in the field?
Oh, boy. Well, I guess, I mean, I would like to see some progress toward answering some of those unanswered questions. But I don’t see a clear path to getting there. I mean, it would be nice if we could find a way to know whether string theory is the right way to go. But…
As opposed to what? If there’s a choice between string theory and X, what is X?
Well, I don’t know. The only alternate proposal that I know about and I don’t know much—I know zero really about it---is what they call loop theory—advocated by Lee Smollin at the Perimeter Institute. I don’t think it’s very widely subscribed to. Actually, there’s been recent progress in proving that N equals 8 supergravity is finite. And if that’s true, that might be another path to be looked at again.
A path to what?
A path to try to understand better. I mean, I guess behind all of these things, string theory, N equals 8 supergravity, is a—yeah, I didn’t express this before. But we don’t really know how gravity fits with the other forces. But gravity couples to everything, so it’s important. And some understanding of the relationship between gravity and the other forces of particle physics is kind of a direction in which it would be nice to see progress.
Well, I can’t resist. I said that was my final question, but this leads so naturally into that. Obviously if these questions are going to be answered, they’re going to be answered by the next upcoming generation of physicists. And so what advice do you have sort of globally for people entering the field in terms of the kinds of things they should study, and the way they should study those things?
That’s a [laugh]—actually, I often advise people to go into astro-particle physics just because I think that it has more promise of getting data because I don’t—I mean, I strongly believe you can’t go forward without good data, and unless—well, of course, if they do have another generation of colliders, that would be great. I just don’t know if that’s going to happen. Well, there’s also good theory being done still on the Standard Model, understanding the details of what happens with strong interactions. I mean, that’s also good physics. And there is good physics with neutrino beams and underground—so there is—but I guess I would say…
Do particle—do astrophysicists who specialize in particle physics, do they need the next generation of colliders to do their work?
Not necessarily. I mean, they have—their data is—I mean, they have data from around us, but it’s not a reproducible experiment. So [laugh]…
And you express doubt that there will be a next generation of colliders. Is that a doubt in the technology or is that a doubt in the funding?
That’s a doubt in the funding, yeah.
So technologically it could happen?
Oh, I think so, yeah. And they are making progress I think in—I haven’t followed it that closely, but I think accelerator physicists are making some progress in trying to build machines that don’t cost as much per the electronvolt.
Well, let’s hope they get that done.
Well, Dr. Gaillard, I want to thank you so much for your time today. This has been an absolute delight speaking with you. You did a tremendous job plumbing the depths of your memory [laugh] to provide this absolutely interesting and delightful narrative. And I’m really appreciative, and it’s been an honor to spend this time with you.
OK, well, I enjoyed it too.
Thank you so much. So I’ll end the recording here.
[End of recording]