Oral History Transcript — Dr. Sheldon Glashow
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Sopka:This is Kathryn Sopka speaking. I'm visiting today with Professor Sheldon Glashow in his office in the Lyman Laboratory of Physics. In the interest of compiling a history of the physics department in recent decades, Professor Glashow has kindly consented to share with me his recollections of physics at Harvard as he knew it first in the 1950s as a graduate student, and since 1966 when he returned as an associate professor. Professor Glashow, perhaps we can begin by asking you to tell of your pre-Harvard background leading up to your arrival in 1954.
Glashow:Well I think that I applied to Harvard Graduate School because of the reputation that Professor Schwinger [?] already had, and it was my intention to work with him when I would come to Harvard. In fact this was exactly what I did. And the way Professor Schwinger operated (???) in those days was very strange. He had in my year about ten or eleven students that wanted to work with him, and as I recall he brought us all into his office, gave us all a problem to do, and told us that he couldn't handle us all at the same time and requested us to go home and solve the problem and come in one at a time as we could solve the problem. He didn't know what students at that time were like. What happened is we all got together at one of our homes, did the problem, and came back again as a group of eleven or so people. And this made things a little bit complicated for him, but what he did manage to do was give us each separate things to think about, this time different problems for the different people, and in this way managed to get us to come back individually. And I do believe that most of these eleven people did get their Ph.D.s with Schwinger, and this was more or less a typical thing with him. He had this many students at a time. The biggest difference I noticed between Cornell and Harvard was social, not so much the courses. The courses were substantially similar at Cornell and Harvard, and I turned out to be taking the same courses at Harvard that I had already taken at Cornell — with the exception of Schwinger's courses. Socially it was a little bit different to live in a city rather than on a mountaintop, and it was a little bit disappointing that the university did not and does not to this day sponsor a place where faculty or students can get together to play ping-pong or billiards. I enjoyed Harvard very much. After about four years though I was happy to leave. Shall we turn now to what happens after? Do we just go on and on?
Sopka:I think if you just continue to reminisce.
Glashow:Fine. Yeah. Well finally, after a great deal of work, I wrote my thesis with Professor Schwinger which concerned itself with the intermediate vector boson and how it might provide a possible theory of the weak interactions. Actually we were going to write a big, thick paper on the subject toward the end of my days at Harvard, and I remember writing a sketch of a first draft, giving it to Julian, and his saying that he would expand it and correct it and write the final paper soon. But that soon turned out to be never, and the paper that we were to write together never materialized. When I left Harvard, winning a National Science Foundation postdoctoral fellowship, I intended to go to the Soviet Union to spend a year a Tom's institute, the Nebredev [?] Institute in Moscow. And the people at Harvard were very happy to support me in this endeavor to write all the letters that had to be written to Russia, to the State Department, and to the National Science Foundation. But try as we all did, it didn't materialize by the time I graduated and by the time it was time to take up my National Science Foundation fellowship. So I went to Copenhagen, where I intended to wait until my visa came through to visit the Soviet Union. At this point a very large and complicated correspondence, three-sided correspondence, developed between Russia, Harvard and me, with Russia insisting that Harvard accept a substitute for me in my stead — that is to say, if I would visit Moscow some Russian would have to visit Harvard that Harvard had never heard about and was not very happy about. Also the National Science Foundation developed qualms about giving me my fellowship in the Soviet Union. But meanwhile I had gotten to know the Soviet Consul in Copenhagen quite well, and he promised me that any day now my visa would come. And he would come to our parties occasionally and magically produce vodka out of thin air. I never quite understood how the trick was done. But the trick worked for vodka, but not for the visa. The visa never came through, and I ended up spending about a year and a half very productively at Copenhagen.
Sopka:With whom did you work at Copenhagen, or were you independently —?
Glashow:At Copenhagen there was — Copenhagen then was a little bit like Harvard now, with a lot of young visitors present, generally from many different countries, and I wrote a few indifferent papers with a Swedish collaborator and a Polish collaborator. I got to know a Chinese theorist quite well and found that we enjoyed the same sorts of things, like picking cherries from cherry trees. And he was kind of short, and would climb up on my shoulders to knock the cherries down from the tree. And I did one piece of work by myself based on my thesis which I think was one of the best papers I've ever written. It was on partial symmetries and weak interaction. Also in those days I thought I did something very important to prove that certain theories were renormalizable [?], that the gauge theories, and it was very quickly proven to me that that however was all wrong and was complete nonsense in fact. Then I was not working with any of the senior people there. Another person from Harvard was visiting at the same time, I should mention, Danny Clydeman [?], also one of these eleven people who working with Schwinger at the same time. Eventually he turned into a mathematician. He is at MIT now. He also turned into my brother-in-law, strangely enough, but that's another story. After about a year and a half at Copenhagen, I decided it would be good to go elsewhere and spent the remainder of my tenure as an NSF fellow at CERN, and began to worry about where I was going to get gainful employment, since I had only a few years. Incidentally the NSF fellowship paid very poorly by American standards in those days, but the way things were in Europe it was a veritable fortune, so that I was living quite comfortably.
Sopka:How much was it? Do you recall roughly?
It was $3600 a year, which in those days was not particularly generous in the States, but it was really double the amount that similar people had in Europe. Now of course it's the other way around. Graduate students in Europe tend to get twice as much as graduate students or postdocs to here. After CERN — well, what happened at CERN was that I eventually ended up getting two offers of jobs, one from David Finkelstein who is now at Ushiva [?] University and was building castles in the sky there; the other was from Murray Gilmond [?], who was under the impression that I was an East German. I don't know how he had this impression. And he had read some of my work, and it was written in a tongue that I learned from Schwinger, which was moderately obscure. He was able to translate it into a language that generally that other physicists could understand and thought a lot of it, and on that basis offered me a position at Caltech as a research fellow, which I took. I went then to Caltech for a year. I found the smog rather depressing, the atmosphere otherwise quite pleasant, and left after a year to accept an assistant professorship at Stanford where my friend Marshall Becko [?] was at the time. He was also one of these eleven as I remember, more or less, at Harvard. Marshall was just approaching the end of his tenure as an assistant professor and got himself fired. Realizing things were not very good for junior staff at Stanford, I decided to leave as quickly as possible and managed to get an offer at Berkeley.
So the next year I found myself at Berkeley, where I remained until January of 1966 when I came here — except I should say for a year that I took leave of absence, an important leave of absence as it turned out, from Berkeley. I came to Harvard for six months, where I did some work with Sidney Coleman [?], who I originally met incidentally at Caltech where I was in fact if not in name his thesis supervisor. We did some interesting work in '64 at Harvard, after which I went to Copenhagen for the spring of '65, fall or spring. I may be confusing my dates slightly. And it was at that point, I think it was the late fall of 1964 in Copenhagen where Buercane [?] was, James Buercane, at the same time that we wrote our first paper on charm, suggesting the existence of the charmed quark. After this semester or year of leave of absence I returned again to Berkeley and, as I say, after a few more years at Berkeley came back to Harvard in '66. Over these years I had been collaborating quite regularly with Sidney Coleman and I was delighted to return to Harvard where Sidney was already ensconced in order to continue our collaboration. I think over all the years from '66 to '70 were not particularly productive in my case.
Physics, my field of physics, elementary particle physics, was at its dullest point for years in those days and I don't think very much exciting work was getting done at all, but in 1970 we had the good fortune to have two very smart young foreign visitors at Harvard. These are Johnny Lee Opolis [?], who was a Greek and is presently at the Le Core Normal [?] in Paris and Ejono Myani [?], who is at the University of Rome today. And with these two gentlemen I wrote a paper again returning to the idea of the fourth quark, which turns out to have been very important. There was the invention of the so-called GIM mechanism. This — what was done here is interesting historically. What we did with this paper is realize that the charmed quark circa 1964 could solve a long standing problem in physics, the suppression of neutral currents which violate strangeness, and this problem was identified it turns out way back in 1961. I recently noticed this in a paper by Galmond and me written in that early year at Caltech — a paper which I had completely forgotten about in 1964, again in 1970, and only remembered much later in 1976. After that, for many reasons, physics became considerably more exciting elsewhere and particularly at Harvard, and this became incredible about two years ago now. Two years ago you remember was the time the J psi [?] was discovered. This was the particle that Teng [?] just recently won a Nobel Prize for discovering, and in those days our group at Harvard was tremendously excited. We had joint seminars almost continually. There was a great deal of progress being made, and this excitement, this productivity and this general flavor has continued to this day. The last two years at Harvard have been in my memory certainly the most exciting years since I've first been exposed to physics at Harvard. It hopefully will continue. We have a number of really very bright young people here, Politzer [?], Georgii [?], Darucula [?] and several others, and we hope that the situation will continue to the indefinite future. I've gotten myself to the current day. Maybe I should stop and start over.
Sopka:Well, maybe I can pose a few questions.
Glashow:Why don't you do that.
Sopka:I was wondering at what point in your education you decided that theoretical physics was for you — maybe even when physics was for you and then theoretical versus experimental.
Glashow:I think I could answer that one. I think that I got committed to physics at the age of — oh, it must have been 1942 — ten, when most countries were at war and children were interested in airplanes and bombs and such things. My brother pointed out to me once that if an airplane drops a bomb and keeps on flying that when the bomb explodes on the ground that the airplane will be right over the bomb. This struck me as a rather unusual fact and I struggled to understand it. I think I did and I think he helped me to. He's quite a bit older than me. Soon after he went to combat in the Second World War. And I remember being terribly interested in physics. I think around the time I was eleven — or, let's see, it would be junior high school, it would be, no, thirteen, I remember that a teacher was very impressed because I asked the teacher why is it that the man in the moon always faces the earth, that he doesn't turn around and face outer space for example. It turns out this is a difficult question, and I think I understand it now, but being interested in this question I think at a young age almost compels a person to be something like a theoretical physicist. I digressed a bit. I toyed with the thought of medicine. I did some experiments in biology and I remember winning the Westinghouse Science Talent Search — not winning it, but being one of the 40 finalists — and my project consisted of some silly thing in which I tried to grow tomato plants in a solution from which the sulfur had been removed and replaced by selenium. I don't think I succeeded in the experiment. However I did do a great deal of, in organic chemistry, synthesizing many of the halides of selenium and keeping them in small sealed glass jars — experiments which are so dangerous that I would not consider letting anybody do it in the physics department, let alone letting my child do it in my home. Real bad experiments. I had a tank of fluorine, in a large tank several kilos of fluorine in my basement. I'm glad I switched out of that to physics (???). So it was quite a little while ago that I was interested in scientific things. I used to make explosives.
Sopka:Were your parents sympathetic to and encouraging your scientific —?
Glashow:My father said I should become a doctor and do science in my spare time, which in retrospect might not have been a bad idea, but I wasn't interested in taking care of people's ills. My experience with my brother the dentist was compelling in this respect also. Some people came to him with pain in their mouths and wanted him to fix them and then got angry at my brother for fixing it. No, I didn't want anything to do with that. My parents, once I made it clear to them that I wanted to do science, they were totally sympathetic. And in fact as a high school senior, junior, I had a small laboratory built, rather unprofessional laboratory but involving a sink and gas for a Bunsen burner in my basement, in the closet in the basement in the large house we lived in. So I had the facilities to do that kind of thing, and I was encouraged certainly to buy a book, even if it were fairly expensive, if I felt that I could learn something from the book. So when I, one day I found a book, it was George Gallup's [?] book, one of the early books I read, 1-2-3 Infinity. I remember my mother had dragged me to Macy's at some tender age, I must have been 13, to buy a coat or a suit or some such thing, and I encountered this book. It was three dollars and seventy-five cents and it seemed a great deal of money, and I scrounged up the money or borrowed it from my mother and bought it, and felt very bad about it when I got home because it was so much money spent on one book, but I remember specifically my father saying that the value of the book is its value to me and has nothing to do with — if it's valuable to me, it's worth whatever I paid for it. That kind of backing was very, very helpful. I always had that.
Sopka:When you were an undergraduate at Cornell, was your training mixed between experimental and theoretical, or were you able to focus on —?
Glashow:Oh no, it was theory. By the time — Now we're skipping a few years. High school is more important than college I think. By the time I got to high school I had this laboratory at home that I was playing with, but more important, I had my friends at the Bronx [?] High School of Science who — Steven Reinberg [?] was next door, except that he's at Stanford at the moment, and Gary Feinberg [?], who is a professor at Columbia — we three were not quite peers, we were each one semester apart as I remember. Steve was one semester behind me, and Feinberg was one semester ahead of me, yet for our own reasons we all ended up graduating at the same time. And we would bounce ideas back and forth to each other, in a kind of nasty way. Like one day Steve would come to me and say, "Hey, I learned quantum mechanics yesterday. It was trivial." So of course the next day I'd come to him and say, "I've learned calculus and variations. It's even simpler." And in this fashion we taught ourselves, if not the substance the language of physics and mathematics. We knew the right questions to ask. We knew quite a bit. We lacked technical detail. It was college that supplied this. Feinberg stayed at Columbia in New York, and it was Steve and I that together made a trip to see various schools. We investigated Princeton — I don't know if he came on that part of the trip, but the both of us went to Cornell and MIT, and we certainly chose, independently both of us, Cornell, because it was so pretty and the people were so nice. It's still very pretty and the people are still very nice there, and we went to Cornell together. At Cornell we got of course the technical knowledge that we didn't have as high school students, but the motivation and the general idea about that the big questions are in physics I think we had picked up back then. And as far as experiment goes, we had no interest in being experimenters at any point in our career. It was theory from the word go, the compulsory laboratory course at Cornell certainly only served to make more definite our judgment that experimental physics was not for us.
Sopka:This is an interesting point historically, and with the development of physics in America over the period that I've been looking at in connection with the writing of my own thesis where at the time when first Campbell got his degree here, he was the first Harvard student to be allowed to write a theoretical thesis. He even had some experiments in an afterthought through collaboration with a fellow graduate student, one of Campbell's contemporaries, David Webster. You may know. He was out at Stanford. He regrets greatly that he was not allowed to write a theoretical thesis. He spent four miserable years here at Harvard trying to do an experiment that would be satisfactory for a thesis.
Glashow:Well, it takes another sort to be an experimental physicist. It's just a different type of person entirely. And one thing that bothers me a little bit is there's a test that I was a guinea pig for once which I forget it's name. You will know it. Kids take it if they don't know what they want to be, and you answer a zillion questions and then the computer works on it and tells the professions that this person is most interested in and least interested in by comparing the candidates' answers with the answers that physicists have made or policemen or other sorts of things. Well I took the thing and it's supposed to give you a rating of 0 to 100 on the basis of any particular profession. I got the grades on it too. As well as being input for the thing, they told me what I should be, or what the machine would have told me to be if I had asked that. They found that I scored, on the basis of 0 to 100, 120 to be a psychiatrist, and something like 70 to be a physicist, and something like minus 20 to be a policeman. It was a very skewed distribution. I don't know what I would do if I took the thing again, but the reason I think it gave such screwy results, because I think I'm better suited to be a theoretical physicist than a psychiatrist, is that it did not separate experimenters from theorists; it put them in the same bag. So what it decided is I'm not very interested in being an average physicist. That is to say, if you average experimenters and theorists. But if they ran the two categories as separate categories, which they should have done I think, it would have been a very different test. And I think a lot of people make this confusion of tending to identify the personalities and reactions of experimenters and theorists. They are different breeds. America tends to put them in the same department, which has been very healthy for American physics, but I don't think that just because they are in the same department they are the same kinds of people. They are very different.
Sopka:Well I believe that's true, and I think that in the early days when there was the bias against theoretical physicists as a professional entity, there were no doubt young men who were eliminated from a career in physics by virtue of the fact that they were so unhappy or inept in the laboratory.
Sopka:Professor Van Blech [?] says that he never could have learned how to blow glass, and that was one of the requirements.
Glashow:Well, he seems to have managed quite well.
Sopka:Conden [?] said that he broke so much glassware that they were delighted to have him turn to theoretical physics.
Glashow:Well, Newton didn't blow glass either, it should be pointed out, or Hamilton, and these were great physicists too.
Sopka:Oh yes. I think it was primarily on the American scene in the early 20th century that there was such a strong emphasis on laboratory work as being synonymous with physics.
Glashow:You know, for the record we still require a laboratory course for theoretical Ph.D.s. I'm not sure that's a good idea, but we do do it.
Sopka:Another question that you might want to comment upon is kind of the style of doing theoretical physics vis-a-vis the experimentalists.
Sopka:No, on your own perspective as to whether you are more interested in the kind of mathematical structure or with the direct correlation with laboratory results.
Glashow:I am very close to the laboratory. Not everybody at Harvard is. Sid Coleman is much more interested in the formal aspects of the theory than in immediately getting results which can be compared with experiment. I like experiment. It's not that I have anything against experiments, it's just that I don't want to do that. But they are part and parcel of my business, so I am on the phone with the experimenters fairly often, and I am interested in the day-to-day explanation of what they're doing and what they will do with the next machine they build, and so they are close together from my point of view, but physics is a continuum and there are all sorts. Sidney is a little further down the way from experiments and toward formalism, Arthur Jaffee [?] is another giant step toward formalism and the hope of his work being directly applicable to experimenters is thin. It will take many, many years before that comes to pass. That is a continuum.
Sopka:So of the spectrum represented here at Harvard, would you consider yourself to be closer to the world of the experimenters than your colleagues?
Glashow:I think at the moment, certainly of Steve and Sidney and Arthur and me I would be closest to experiment, Steve next, Sidney a little further, and Arthur further yet. Roy Glauber's [?] work has generally been very close to experimental things. (???) Martin [?] in solid-state theory has also been very close to experimental questions. And certainly at least as close in my work.
Sopka:Another question on the style of physics that you've already touched upon —
Glashow:Schwinger was too, was both. Schwinger was both very formal and at the same time very close to experiment. A remarkable conjunction of getting the right experimental number and using techniques that were at times incredibly formal and incredibly beautiful. But that man was, is, unique. And physics in those days was very different at Harvard than it is now, because it was quieter, there was no yelling in the halls, and nonetheless great things were getting done.
Sopka:Another aspect of the style of the way you do your work is to what extent you collaborate with other people or discuss your ideas, or do you tend to be an individualist?
Glashow:Oh, we all discuss our ideas to absolute — to nauseum. At Harvard at the moment, everybody discusses everything with everybody, and there are continuous seminars, and we are a very talkative lot. Many of the papers coming from Harvard, most of them, are collaborative. There have been something like 80 papers from our office, that is next door, this year, and I would offhand guess that three-quarters of them were collaborations. Except for conference reports and things of that sort, I haven't written a paper by myself in a very long time. Sidney tends to do things less collaboratively to an extent; on the other hand, a lot of his work gets published by his students rather than as joint papers between himself and his students. But aside from who signs the papers, everybody does discuss everything. We have a little private seminar which is really not so private because everybody knows about it, meets every week when people talk about what they had just done or hoped to do, and there is lack, there are no secrets. Everybody knows everything.
Sopka:You mentioned your own graduate work and that you were part of a group of almost a dozen students working with Schwinger. How do you find your contacts with students now in either formal course work or thesis supervision?
Glashow:You mean are they good?
Glashow:I think we had an exceptional year with eleven people or so, ten of whom made it. One was a Spaniard who got sent down, he became the head of Spanish physics: Louie Garido [?]. When he showed up with a thesis without ever talking to Schwinger, Schwinger said it wasn't any good so he left Harvard. But aside from him, everybody, most of these people turned into being rather exceptional physicists. Let's see, who are they: Ray Sawyer, myself, Danny Clydeman, it's hard to remember them all at the moment. Some have become mathematicians. It was an impressive lot of people. That year might have been a sort of funny point [?]. Probably an average number for Schwinger was still remarkable — something like five or six. But you have to remember, he was essentially the only person doing theoretical physics at Harvard in those days. Today we have half a dozen people who direct theses in theoretical physics. I don't think — probably we don't have as many — well, we probably have a similar number of exceptional students today as we had then. Quite recently there have been very good students: Claude Bernard, Hugh David Pulitzer, Eric Weinberg have come out of here. They have all been as good as anybody in the old days, maybe better. So we still very good ones.
Sopka:Do you enjoy working with students more in a seminar situation or in a classroom or on an individual —?
Glashow:My success is more with postdocs. I've been very, very pleased with the postdocs that I've had the pleasure of working with at Harvard, talking about Iliopolis [?], Myoni [?], more recently Georgii [?] and Darucula and Pulitzer. Working with these people has been very rewarding and been a lot of fun, and sometimes watching them change into better physicists as they spend a few years at Harvard has been very satisfying to me. But my students, either they stay in physics and have trouble getting jobs, or they switch out of physics and become famous in some other field. Except for Sidney. Sidney was my best student.
Sopka:Have you had any undergraduate teaching responsibilities?
Glashow:I'm teaching Physics I at the moment. For background Harvard has four courses in basically freshman physics. One is Physics for Poets, which I helped to teach last year which I thought was a lot of fun, with people that did not have to take a first year physics course but really took it because they wanted it for cultural reasons. They wanted to satisfy to distribution requirements at Harvard. In any case, they didn't really have to take this course. They enjoyed it, they learned a great deal. At the time of the pile is Physics for Smart Alecs or something like this, Physics 55, where the kids are very, very smart. A cut below that is Physics 12 for normal physics majors, which is also a very strong, very good course. And then in the middle there is what is essentially physics for pre-meds, Physics I, and there we have a bunch of people who are taking the course because they have to take the course. They are generally having trouble with the course, they are not interested in taking it, and that is the least satisfying experience I've ever had teaching physics. I will never do that again.
Sopka:We might just pause it. [tape turned off, then back on...]
As I was saying, there is one curious anecdote I would tell which has to do with my oral examination when I finished Harvard, final thesis examination. Strangely enough this took place in Madison, Wisconsin. Enrico Schwinger was visiting there at the time. And we had to make up a committee. The committee consisted of Professor Schwinger, Paul Martin, who was also visiting. The two of them were working on something at the time, and we needed a third person. The third person turned out to be Yang [?], Vee [?] Yang of Stonybrook. And the thesis examination was very strange, because it turned into an argument between Yang and Schwinger in which I played very little role. I started to explain the basis of what I had to say, which really wasn't very much, but implicit in everything I was saying was the idea that there were two kinds of neutrinos — the electron, as we would say today the neutrino comes with the electron. The electron neutrino is different from the muon neutrino. Now this was not an idea of mine, far from it; it was implicit in Schwinger's thinking. It was very difficult for him to conceive why nature would have it that the neutrino was the same. Built into his formulas [?] essentially was the notion that the electron neutrino and the muon neutrino were different, and I relayed this fact in my thesis as a matter of course.
I never thought about it in any other way than Schwinger had taught me. Yang however always thought that — as well, I think, as everyone else in the world — that there was only one kind of neutrino, the electron neutrino and muon neutrino were the same. And he could not understand that it could have any meaning to say that the neutrino was different. And this was not, as I say, this was not something that was directed to me. It ended up being directed at Schwinger, because I said this is the way I've been trained, come on, there have to be two kinds of neutrinos. That's the only sensible notation. And the debate was whether it was merely a question of notation or whether there was some substantive physical content to this idea. There was most certainly physical content to the idea, and Schwinger together with Paul Martin proceeded to explain in great detail with me as a voyeur what the difference was between a one-component neutrino, one neutrino theory and the two neutrino theory. It was not clear to me that they had succeeded in explaining the difference to Yang. He was getting rather irate during the course of this discussion. I was sort happy because I didn't have to answer any questions. I did end up passing the examination, but there was kind of an argument going on. It was then interesting that a year or two later Yang published a paper inventing the theory of two neutrinos, and he has always gotten credit for the theory of two neutrinos rather than one neutrino. And it always seemed strange to me that that credit was not Schwinger's, since it was so implicit in his thinking at the time. But I never remember Schwinger saying anything about that afterwards.