Sidney Coleman

Sopka:

This is Katherine Sopka speaking. I am visiting today, January 18, 1977, with Professor Sidney Coleman in his office in the Lyman Laboratory of Physics. In the interests of compiling a History of the Physics Department in recent decades, Professor Coleman has kindly consented to share with me his recollections and perspective on the development of physics at Harvard since he first came as a Research Fellow in 1961.

Sopka:

Professor Coleman, perhaps we can best begin by asking you about your pre-Harvard background and the path that led to your becoming a theoretical physicist.

Coleman:

Well, I like to tell people I am at Harvard because I met a man at a bar. The detailed circumstances are this: I was a graduate student at Cal Tech. I had come there after an undergraduate career at the Illinois Institute of Technology, a justly little known school in Chicago, and I entered graduate school in Cal Tech in 1957. In the subsequent summer, the summer of ‘58, I decided that I wanted to do thesis research under Murray Gell-Mann, and Murray took me as a thesis student. But really I was sort of fiddling around. I didn’t have any definite idea of what to work on, and especially in my third year I was talking a lot with people like Dick Norton about possible things to do, and was feeling rather depressed because I was not able to get my hands on an attractive project. In my fourth year, Shelly Glashow came to Cal Tech as a post-doctoral Fellow. He had graduated from Harvard a few years before and had spent a couple of years in Copenhagen. We got along very well. We struck it off almost instantly the first day I met him. We got to talking about physics, and my thesis ideas were generated in conversations with Shelly. I met him in September or October of ‘60 and by the spring of ‘61 we had already published our first joint paper in Physical Review Letters based on some work that Murray had been doing. Murray invented SU (3) and Shelly and I applied it to electromagnetic processes. Later that spring, Julian Schwinger was visiting UCLA giving a sequence of lectures. Shelly had been a graduate student of Schwinger’s and saw him socially. Schwinger remarked that he controlled a post-doctoral fellowship and was looking for someone to fill the position the next year, that is to say the fall of ‘61. Shelly said I was very bright, and might be a suitable candidate...you see, things were much less formal in those days. They didn’t have to go through layers of committees to make sure no prejudice was involved. Shelly arranged for me to have dinner with him and Julian and Julian’s wife at the Beachcombers in Hollywood. So I met that at the bar — that’s the first time I met Julian — I met him in a bar. We had a very pleasant evening, and I think two days later Shelly told me Julian wanted to offer me the job, which, as I recall, paid what was at that time a good salary, $6,000 per annum. And he knew nothing about nothing - in fact, I did not have a thesis project, although I had done several things by that time and was fairly confident that I could put together a thesis if need be. I wasn’t worried about getting a job, I expected up until that moment to spend the next year at Cal Tech and finish up my thesis and then go looking for a job. But this seemed like a reasonable offer and I asked Shelly whether Harvard was a good place in which to work and a pleasant place in which to live, never having been there. And he said, yes, and it was a bird in the hand, so I said yes also. I came to Harvard a bit late; I think I came in November because there was some administrative fuss. Curry Street, who at the time was either Chairman, or Acting Chairman had written me a letter asking when I would be getting my Ph.D. and I wrote back that I had no idea since I hadn’t even begun writing a thesis yet. And he said it might be advisable if I had at least a thesis draft accepted before I took the job. So I said O.K., but that took me a little while and I think I did not get a thesis draft completed and preliminarily accepted by Murray until October of '61 and I came out here in November. I was two years a postdoctoral fellow and then I was offered and accepted an Assistant Professorship. I went out to Berkeley for a term; I guess it was academic '65-66, although I could be off by a year. I went out to work with Shelly, although in fact we didn't do too much collaboration. Shelly was at that time at Berkeley as either an Assistant or Associate Professor, I don't remember which. I came back here in January (I am trying to reconstruct the exact sequence of events). Well, shortly thereafter, I received a letter from Berkeley saying they were willing to offer me a tenured position. I went to the then Chairman of the Department (I'm not sure who it was — was Wendell Furry Chairman then?) and I told him, look, I have this offer from Berkeley and I'm thinking about it, do you people want to respond? They did, and offered me tenure here, and I accepted. In retrospect, I certainly didn't have any ambition at any stage of going to Harvard or staying on at Harvard. It's just something that happened. But of course I liked it here once I got here. Not so much for the Physics department, as for the general Cambridge life, which I found very pleasing. I had spent all of my life until the age of twenty, aside from brief trips, in Chicago, and then I spent four years in Pasadena. For two of those years I didn't have a car. I didn't know how to drive; I never owned a car in that period. The second two years I was able to borrow friends' cars, Southern California is not a very exciting place if you don't have an automobile. And I was very much drawn to the intellectual and social life of Cambridge. I liked it a lot; I was very happy to stay here.

Sopka:

Could I just ask you about the transition from an engineering school to graduate work in theoretical physics?

Coleman:

Oh, I'd always wanted to go into physics. I went to IIT just because I was dumb. I was a genius as a grammar school student. It's been a steady decline since then. In retrospect, I realize I could probably have gotten scholarship aid at any school in the country. Does that sound too egotistical? No, I had a terrific record. I was a real smart-ass kid but I thought I had to stay in the Chicago area, because my family certainly could not afford to pay my living expenses away from home. My mother had been widowed when I was nine years old. She lived on her savings for a while. My brother was just six months old when my father died. But after my brother got to be of an age where he could go to kindergarten, she went to work and she worked steadily from then on until retirement, about two years ago. Secretarial work. We didn't have a lot of money. And so I thought it would have to be a Chicago area school, someplace I could commute to. The University of Chicago came to mind and there was a day when people from various universities came to our high school to talk to students. I talked to I believe it was a young woman who came from the University of Chicago. I said, "I'm interested in studying physics" and she said "We don't teach physics. We teach the general liberal education", explaining the Hutchins' plan. I did not then realize that this had been a farce from its very beginning. Anyone with any wit got through all those courses in a year and a half by taking examinations and at that stage, the program was, in fact, in its ultimate decadence and would be formally abolished a year later. She gave me this great line and I said "to hell with all that bullshit" (slightly more politely because it was the nineteen fifties and we all spoke more politely) "and I'm not interested in that" and I went to the person from IIT who said, "you can take Physics courses from the very beginning" and I said "well, that seems like a good deal and I think I'll go to IIT". If I had had better advice I would probably have gone to the University of Chicago and gotten a better education, because IIT was a sort of crummy school, and still is. However, it wasn't that bad. Probably, going to IIT had a greater deleterious effect on my social development because it was a street-car school and full of creepy people and on my general cultural development. I am a linguistic idiot to this day, a monoglot — I speak only English. If I had gone to a decent school I would probably have been forced to learn some foreign language when I would have had the time to do it well. I probably lost a year or so in learning physics. There were some people who, although not outstanding physicists, knew what was going on. One man named Bob Malliot, in particular, took an interest in me and gave me essentially informal reading courses. He gave me books to read, like Dirac's book on quantum mechanics and he would talk to me about what I had read. So that was pretty good and then I went to a first-rate graduate school. But to do physics and theoretical physics in particular was in my mind from when I was eleven or twelve.

Sopka:

That's interesting to know.

Coleman:

As to high energy theory, though I didn't even know what it was when I entered undergraduate school and I barely knew what it was when I entered graduate school. But at Caltech I very soon learned what it was and decided that that was what I wanted to do.

Sopka:

Let's move on to your...own research.

Coleman:

Well it had been...my own research. I can't say I've ever had a systematic research program. I've worked on problems that seemed attractive to me and interesting. I've favored my weaknesses, I suppose most people do. I like well-formulated problems, problems that can be handled more or less by abstract reasoning, that don't require staying on top of the latest experiments and data. If you drew a continuum with a pure phenomenology on the right and pure mathematical physics on the left, the only person around here who is to the left of me is Arthur Jaffe, who is a real mathematical physicist. Shelly Glashow and Steve Weinberg are both to the right, although there is no one here who is a real phenomenologist, who worries a lot about data reduction or things like that. I have very little contact, other than social contact, with experimentalists. It's not important to me that I'm at the same department as Carlo Rubbia and Dick Wilson and people like that. I'd be just as happy if I were on the other end of the country. Well they're nice people, I shouldn't say that, but as far as the progress of my work goes. I don't like to get involved in big programs. I like to find the problem, solve it and go on to something else. There are, or may be, common themes in my work, but there is not a systematic development of a single thing.

Sopka:

Are you personally more partial to an abstract mathematical structure, or to a more physical model kind of theoretical approach?

Coleman:

You're talking about my tastes or what I've actually done?

Sopka:

Your taste and your style, I guess is what I mean.

Coleman:

My style tends to be more abstract and mathematical although as I say very, very far from mathematical physics in the pure sense. I'm much closer to what Shelly does than to what Arthur Jaffe does. But I'm in the Jaffe-ward direction of Shelly. The kind of high energy physics I think is best is, in fact, the kind Shelly does. Shelly is just about right. But the sort of things we do are determined by our talents as well as our tastes. And I don't think I have the talents to do the sort of stuff Shelly does as well as Shelly does them. But I do have the talents to do the sort of things that I do very well. That's, of course, retrospective. I don't claim that sort of analysis went into my decisions to do the kind of physics I did. It's what I think of as a possible explanation when I look back. Also, of course, something else should be taken into account. I think it's a natural human tendency to undervalue the things one does well and overvalue the things one does not so well. Because you say — "I wish I could do that" but if you could already do it, you — “well, that’s not much". But anyway that's the way I think about it. I don't think I've been central to development of high energy theory. I think Shelly has, and Steve has. On the other hand I think I've done some very, very decent things.

Sopka:

What's your favorite paper?

Coleman:

That varies from day to day. My favorite paper. Probably either the first paper I ever did, the paper in collaboration with Shelly, "Electromagnetic Properties of Baryons in the Unitary Symmetry Scheme", or a paper I did a few years ago called "The Quantum Sine-Gordon Equations as the Massive Thirring Model". I suppose they have a common style. Both are, in the context of the times, strikings papers. They produce unexpected results. They get in there quick and get out there quick. I sometimes say the kind of physics I like to do is more like guerilla warfare than an expedition. I like to find the problem, solve it, preferably in some snappy, elegant, striking way and then go on to the next problem.

Sopka:

How are your graduate students coming along?

Coleman:

Well it depends on the graduate student. I don't think of myself as someone who is particularly good for a graduate student. The kind of physics I do doesn't generate a lot of subsidiary or ancillary problems. I don't have some massive machine going that's trying to understand the structure of the helium molecule...(Does the helium molecule exist? Probably only under very special conditions...) or charmonium or anything like that where I can break the problem up into little parts and say you do this and you do that. So typically a graduate student who succeeds with me has to be something of a self-starter. When a bright independent graduate student comes along, we usually work very well together. I've had some very successful graduate students in recent years, people like Eric Weinberg and David Politzer who, I think, are two of the best theorists we've produced. They have both been my graduate students. But someone who's not quite up to that, I think, would find work with me a depressing experience because although I'm willing to talk with them, and comment on what they're doing, I'm not generative of things for them to do. I may suggest small problems but they may turn out to be insuperably difficult. I don't know. If a problem looks easy to me I do it myself. And sometimes problems I suggest turn out to be very useful and sometimes they turn out to be just impossibly difficult, certainly not worth putting a lot of effort into them. A student is liable to work on them for five or six months and feel he's wasted a lot of time. That happened with both Eric and David, before they got problems that finally paid off. Eric worked for a year on a problem that, to my knowledge, is still unsolved, and David also, but then we got something that worked and they took off.

Sopka:

I guess it's part of the education process to work with such a problem...

Coleman:

Well I have a feeling that someone that works for either Shelly or Steve has an easier time of it. They're — liable to generate the kinds of problems that are certainly do-able if you have the patience to go through all the calculations and work things out; they don't require a brilliant flash of inspiration. I don't seem, on the record, to generate that sort of problem for my students.

Sopka:

But you do enjoy working with students or do you?

Coleman:

No. I hate it. You do it as part of the job. Well, that's of course false...or maybe more true than false when I say I hate it. Occasionally there's a student who is a joy to work with. But I certainly would be just as happy if I had no graduate students. There are plenty of colleagues around here whom I can work with. There are plenty of research fellows; junior faculty. This is true all through the Cambridge area. There's not only Harvard, there are people to work with at MIT, at Brandeis, and there are some good people at places like Northeastern...places loaded with physicists to collaborate with, to talk about physics ideas with, who are ready and KNOW basically how to do research. You know who's good and who's bad. It's not a question of their being embryonically possibly good or possibly rotten. So certainly if I want physicists to collaborate with I don't have to have graduate students. Occasionally there is a graduate student who is a joy to collaborate with. Both David and Eric were of this kind, but they were essentially almost mature physicists. They were very bright by the time they came to me. In general, working with a graduate student is like teaching a course. It's tedious, unpleasant work. A pain in the neck. You do it because you're paid to do it. If I weren't paid to do it I certainly would never do it.

Sopka:

I guess your remark means then that you would like to avoid teaching undergraduate courses or even required graduate courses...

Coleman:

Or even special topics courses. Teaching is unpleasant work. No question about it. It has its rewards. One feels happy about having a job well done. Washing the dishes, waxing the floors (things I also do on a regular basis since I'm a bachelor) have their rewards. I am pleased when I have done a good job waxing the floor and I've taken an enormous pile of dirty dishes and reduced them to sparkling clean ones. On the other hand, if I didn't have to, I would never engage in waxing the floors, although I'm good at it. I'm also good at teaching; I'm considered very good at teaching, both by myself and others. And I'm also terrifically good at washing dishes, in fact. On the other hand, I certainly would never make a bunch of dirty dishes just for the joy of washing them and I would not teach a course just for the joy of teaching a course.

Sopka:

That's an interesting analogy.

Coleman:

What I enjoy doing is physics. I mean I enjoy many other things. But the part of my professional life which I enjoy is doing physics and if someone were to suddenly say to me, look you can sit in this office and talk and do physics with the same people, everything would be the same except you would never have to teach a course and never have to see a graduate student, and we'll halve your salary — I'd leap at the offer.

Sopka:

So I guess really you would be happier with the format of an institute of theoretical physics? Rather than a teaching institution like a university?

Coleman:

Well no. That makes it too abstract. Because that means, would you like to have a position at, say, the Institute for Advanced Studies? And then all sorts of other things would enter the picture. Like you'd have to live in Princeton which is truly an awful experience.

Sopka:

I was there as a young bride a long time ago.

Coleman:

Young brides get the worst of it. They're even worse off than the people who are at the University of the Institute because at least the people at the University or the Institute can fill their days by engaging in their professional interests from the moment they wake up until the moment they go to sleep. But if you don't have that, there is really nothing. Nothing. It's a terrible place. Dullest place in the world. No I wouldn't say that, but certainly the dullest place at which decent science or decent scholarship is done in the world today. The only advantage to Princeton is that it's close to Princeton Junction.

Sopka:

Which is then accessible to Philadelphia or New York.

Coleman:

Well I spent a semester at Princeton. And it was, in fact, a pleasant semester. I would get up Monday morning and do physics which I would continue to do with interruptions for sleep or eating until four o'clock Friday afternoon, whereupon I would hop the train to New York and not think about physics until Monday morning again. It was a little more schizy than the life I lead in Cambridge, but it was much the same proportion of physics and non-physics. I don't know if I'd like to live that way on a steady basis, but it wasn't unpleasant. But there's not even a decent bookstore in Princeton. Nothing. No place to eat decent food unless you have a friend who cooks . Well, it's terrible. Let's see. We've covered a lot of points I guess.

Sopka:

Yes, we have. We are almost down to the last one...talking about the physics department and your perspectives on it from within, and when you go away, from without.

Coleman:

Well, as a social entity, it's not like a physics department at a place like Princeton or a midwestern university or something like that. Or even at Caltech. We're not isolated; we don't have to choose the major portion of our friends from our colleagues. If I were asked to name my three best friends in the Cambridge area, well, probably one of them would be Shelly and he's from within. But the other two would probably be Jerry Lettvin who's a neurophysiologist at MIT and John Schrecker who's a historian at Brandeis. And if I were to go on I could mention people who are in the Biology department here before I got around to other physicists. That doesn't mean I dislike the physicists here. Some of them are people whom I feel very, very close to. I feel very close to Paul Martin, I see a lot of Steve Weinberg, etc. But they aren't my best friends. The Physics Department is not the pivot point of my-social life. That in a way has its disadvantages. The very openness and number of things to do means that things are not so tightly knit. I'm sure graduate students are much more aware of this. At Caltech where I was a graduate student there was much more closeness between the graduate students and the faculty. Caltech, at that time was (and still is) a much smaller school than this. There were something like a thousand students, graduate and undergraduate together when I was at Caltech. Also it was out in Pasadena so it was the Caltech students, the Caltech faculty and a bunch of little old ladies in tennis shoes. So everyone got to know everyone else. Graduate students would have parties and professors would come. Professors would have parties and students would come and not just from the physics department you know. I got very friendly with someone like Max Delbruch, who's now retired and off in Germany someplace, but at that time he was a molecular biologist at Caltech. That sort of thing doesn't happen here. Cambridge is the social equivalent of Brownian motion. People, like random molecules, just sort of wander off. Because it is so big, because there are so many interesting people, because there are so many interesting things going on, there is less camaraderie, within the department than there is in other department. The Princeton department is always having dinner at one another's house. What else is there for them to do? So. There's that.

Sopka:

Well I was thinking more in somewhat different terms, of the social aspect of the Physics department. Not so much what you focused on, as just the kind of interaction such as the faculty lunch on Monday noontime. That seems to be a rather unique institution.

Coleman:

Oh, yes. We are a department in which power is more diffuse than in any other department I know of. When Steve Weinberg was professor at MIT he said "I don't object to the fact that they don't consult me about new tenured appointments, but I wish at least they'd inform me". MIT tends to be, or at least was during Vicky Weisskopf's reign, a highly centralized department where a lot of power was in the hands of the chairman. He made a lot of decisions, unilaterally or with the aid of those people with whom he chose to consult. Other members of the department were not let in on it. In our department, however, the power is very diffuse. The chairmanship of the Harvard Physics department is a dreadful job, a killer job. The Chairman has infinite responsibility and no power.

Sopka:

Someday it will be your turn.

Coleman:

That's a way to ruin my day, reminding me of that. O.K. it's a killer job. Every decision is discussed by everyone. And this means this has its bad points and its good points. The bad point is that it is a terrible bore. It is uniformly agreed that our Monday afternoon faculty meetings are excruciatingly boring. The good point is that nobody feels he is frozen out. There is no bad feeling within the department. Everyone feels he knows more or less what's going on, what decisions are being made for what reasons. He may not agree with all of them but he does not feel there are conspiracies or foul plots or anything like that, in contrast to some other departments I know of. And the price you pay for it, as I say, is the sacrifice of Monday afternoons. I think the price is worth paying. I think it's a good way to run a department. As an intellectual entity: well in that sense we've never been a department with big groups. Shelly and Steve and I, I suppose, constitute a group as much as anything else. We all tend to go our separate ways, occasionally collaborating but not too often. We're very strong in molecular beam physics because we've got Norman Ramsey. When Norman Ramsey retires we may or may not ever be present in molecular beam physics. We're a world power in mathematical physics because we have Arthur Jaffe. If Arthur Jaffe goes someplace else, we may not even be represented in mathematical physics. Certainly we weren't before Arthur came. Our strategy has always been not so much to build groups...at least from the time I've been here, and in talking with other people who were here before. We've tried not so much to build up groups focused on subjects but to try and get the best possible people. And let things flow out of that. That seems to have worked fairly well up until now. I would say from the outside, that there are some fields in which we are arguably the best department in the country; mathematical physics and high energy theory. And there are others, from what I know. We certainly are a major power because of Carlo in high energy experiments and, as I said earlier, because of Norman in molecular and atomic beams, etc. I can see that as experimental physics gets more and more expensive this is going to be difficult to maintain. You've probably heard this from other people, because it's something we've been discussing for some while. It is difficult to maintain this sort of thing because it's difficult to get a young person in an experimental field, unless you can give him financial support for his laboratory work. Laboratory physics of almost every kind is becoming so expensive that University funds are simply not available on that scale. It has to be effectively government funds. A young person, just starting out has a very great difficulty getting a government contract. If I were a younger person just starting out, I would not look favorably toward an offer that said you can some if you want to but we won't give you money for laboratory. If you want to try and get a government contract, Mazel tov. That means that there's a narrowing process I don't see how to get out of. We can only make attractive offers to young people who work in fields that are already represented here, where they can become parasitic on the contracts of the senior faculty person. And in the long run that probably is going to be our greatest problem in maintaining excellence. Because a theorist needs very little support. If we suddenly wanted to go into some theoretical field in which we are totally unrepresented, such as nuclear structure theory or theoretical plasma physics, we would probably be able to pluck someone out and they would come or we would have at least a reasonable chance of getting them to come. In experiment that's a real problem.

Sopka:

Well I thank you very much for giving me your time this afternoon. You've been very informative.