Interview with Howard Schnitzer

Interview recorded in Waltham, Massachusetts, 12 October 2001.

PoS

What we would like to do, in addition to learning about your personal trajectory in the field, is to focus specifically on how you learned renormalization theory, how you used it, and how that use has changed over time, and how you've taught it as well. Should we start from Rochester?

HS

You can start at Rochester.

PoS

If possible why don't we go back just a trifle.

HS

I was born in Newark on November 12th, 1934. I remember it well. (laughter).

PoS

You went to college at the Newark School of Engineering?

HS

Newark College of Engineering, which is now the New Jersey Institute of Technology.

PoS

And at what stage did you realize you wanted to study physics rather than engineering?

HS

Engineering seemed too practical, the people I was with seemed too interested in money. I was reading biographies of [Albert] Einstein and of other people, and I sort of had an itch for more fundamental questions. Also, I got a summer job at Brookhaven Lab when I was a senior -- which was in 1954. I there met people like [Enrico] Fermi, [Richard] Feynman, and [Keith] Brueckner.

PoS

When you say you were a senior, this was entering your senior year?

HS

Between the junior and senior year at college.

PoS

And who sent you to Brookhaven?

HS

Well, they had a program for students, and I was being hired as an engineering student to do some engineering work for the AGS, which was to be the next accelerator. Of course the physicists were behind schedule, so they had nothing for me to do, and they assigned me to Cliff Swartz to do some experiments. And I actuallydid some health physics experiments of measuring neutron background at the Cosmotron. Probably a lousy experiment. And Cliffforced me to give a talk in front of those guys,in front of Fermi, it was six months before Fermi died --,and Feynman and Bill Rarita, and Brueckner were there. In those days of particle physics, everybody who was in particle physics spent their summer at Brookhaven, there was no other center. It was a much smaller profession then.

PoS

And so, how did the talk go?

HS

I guess it was alright. They didn't kick me out. But I used to go to seminars and as an engineering student, -- mechanical engineering to boot,--I wrote down all the things, words, I had never heard before. I remember Feynman bawling me out. He said 'You can't learn by writing, you have to listen.' And Rarita said 'Oh, Dick, different people learn different ways.' 'No, no, you gotta listen.' He didn't appreciate the fact that I had no background in the field at all. I kind of felt that engineering really wasn't for me, and that this kind of stuff was more to my taste.

PoS

And by your senior year, were you a physics major?

HS

There was no physics major. I got a degree in mechanical engineering.

PoS

And how did you decide to go to Rochester?

HS

Well, Cliff Swartz, who I worked with, got his PhD at Rochester. And he suggested I apply there. I also had an NSF fellowship. And with the NSF I applied to Rochester, Cornell, MIT, and Harvard. Harvard accepted me but I didn't want to go there because I thought it would be over my head, and I still think that was the right judgment given the quality of people there. MIT would not take me. Cornell would take me on the condition that I would redo my senior year. They asked me what books I had studied. But I had already taught myself Quantum Mechanics, but they weren't interested. They said, 'Well, you have got to redo a lot of undergraduate stuff.' and I said 'Go to hell.' So, by default it was Rochester. Incidentally, I was also accepted to Johns Hopkins, which seemed very old fashioned. Who was the grand old man of Optics? He interviewed me there. They were still doing classical optics. Also Carnegie-Mellon but I didn't want to live in Pittsburgh. So, Rochester was it.

PoS

So you come to Rochester in 19--?

HS

1955. I graduated college in 1955. Summer of 1995. .

PoS

You came to Rochester in the fall of '55. Under whose aegis? Who are the people at Rochester at that stage?

HS

Well, it was Bob Marshak, and there were smart young people: Susumu Okubo, a student of David Feldman, a faculty member who was not going to get tenure. Mort Kaplan, who had just done important experiments on cosmic rays with emulsions, on the particles now called K-mesons. People were doing cyclotron experiments investigating pion-nucleon scattering. And George Salzman, with whom I worked during my first year there. I think the good class was the year after me. I think almost everybody in my class wanted to be an experimentalist, I think I was the only theorist in the class. My memory is hazy on that.

PoS

In the class after you there were people like George Sudarshan, Bunji Sakita, and Francis Troyon, who became head of the plasma program of Euratom.

HS

Sudarshan and Sakita. Tulio Regge was finishing his thesis. But he didn't do his experimental requirement. So he and George Sudarshan were lab partners. They spent the year trying to build a cloud chamber, or one of these little diffusion chambers with dry ice. I don't think they ever got it to work. Another professor there was Wolfgang Franzen, who has just retired from BU. I bump into him every once in a while.

PoS

So who taught you quantum mechanics, quantum field theory?

HS

Quantum mechanics: Bruce French, of Lamb shift and Feynman fame. Or anti-Feynman fame. He was a student of Viki [Viktor Weisskopf]. I also learned nuclear physics from him, I learned quantum mechanics from him, classical mechanics from George Salzman. The next year I learned field theory from Charlie Goebel.

PoS

He was there at the time, right?

HS

Well, he was a great underachiever anyways, even in those days. His drawers were filled with 3/4 finished calculations. He'd get bored, and go on to something else. He could never finish anything. He had a very good mind; was a child prodigy. He was one of the University of Chicago whiz-kids who graduated very young. I remember in the lab he'd come in with old Norse sagas, and I'd say, 'Charlie, how can you read that?' He said, 'Well, it's a simple transcription from old Gothic.'(laughter) So he was out of my league, intellectually. Sakita and I and Francis Troyon were the only students of Charlie Goebel. I don't know whether he had any students at Wisconsin. Francis Troyon just retired. He stayed one of my closest friends. Sakita you know about. These were the only people who could work with Charlie. Mainly, we worked by ourselves. Sudarshan was a student of [Robert] Marshak.

PoS

How did you choose your thesis, and what was your thesis?

HS

Charlie gave me a project. I mean, I was going to work with George Salzman who didn't get tenure, I did a project on dispersion relations. Analyzing experiments and ...

PoS

And this was under his influence?

HS

Under George Salzman. Well, he gave me a problem, he said 'It looks like the forward dispersion relations were not being satisfied.' If true, it'd have violated microscopic causality, which would have required a major, major revision. And my job was to look at the experiments, which I did. I was actually able to find a mistake in the Carnegie-Mellon experiment, because-- what I remember -- that such experiments had to satisfy a triangle equality, in order to satisfy iso-spin invariance. The set of Carnegie-Mellon experiments, which were crucial, badly violated the iso-spin invariance. You know who did the experiments? Jules Ashkin. The late Jules Ashkin. And he came to talk to me, and I guess he was somewhat flabbergasted because I was a kid. What was I, 21 years old? Ashkin was a terrific physicist and a particularly nice guy. And then I did one more thing on dispersion relations.

PoS

So let'sgo back to the previous question: In your field theory course, how far did you go? Were you taught renormalization, what kind of renormalization, what was your view? Who taught it?

HS

Charles Goebel, who then moved to Wisconsin. There was also a previous course of Marshak. Now, Marshak's course was really poor from the modern retrospect. He taught out of [Gregor] Wentzel and [Walter] Heitler’s books.And with 20/20 hindsight, you know, it was a handicap. There were no relativistic examples in these books. It was heavily dominated by Marshak's philosophy that you have to quickly get to experiments. Heitler was a massive treatise of how to do semi-classical radiation theory making use of atomic wave functions and the Born approximation. It addresses a huge number of phenomena, but it doesn't attack any issues.

PoS

It's a collection of examples?

HS

Bethe-Heitler cross-section, Compton scattering, Klein-Nishina, whatever. But always perturbation theory with your best atomic wave-functions. In fact, Marshak had a screening: To become his student, you had to calculate from scratch the Klein-Nishina formula. He'd say 'Go calculate relativistic Compton scattering.' If you could do that he would take you on. In those days, I guess, everyone was doing it with alpha and beta matrices -- with the old-fashioned Dirac notation and hole theory. It was a formidable calculation, which it would not be now.

PoS

You mean he was still teaching hole theory?

HS

Yeah, yeah. Goebel had no book, he just lectured.

PoS

So when was your introduction to things like Feynman and Julian Schwinger and Freeman Dyson?

HS

When I came to Boston.

PoS

Not before?

HS

No. My thesis was on the old Chew-Low theory. I did meson production and resonances. I came to Brandeis summer school in which [Joseph] Jauch lectured from his book, which was what everybody was reading, but we were not reading this at Rochester. Should I tell the story of what was being done in Rochester ? When I arrived at Rochester, John Greene (who later went into plasma physics) was working on his thesis. Hewas to try, using all the known Tamm-Dancoff calculation techniques and all possible meson-nucleon couplings -- pseudo-scalar, pseudo-vector -- to calculate the binding energy of the deuteron to fourth order. Nothing worked. And I don't know much about the rest of the field outside the Rochester community. That was the end of field theory there at Rochester. And so we bifurcated in two camps. One camp was the dispersion relation camp thatstarted with the old Chew-Low theory, and eventually moved on to Marvin Goldberger's stuff. So there was that form of the black box. The other form of the black box was the Marshak approach where you looked at group theory. But it was always a black box, and always skeptical whether field theory was right. So there was no field theory while I was there.

PoS

But you learned group theory from Marshak. You were introduced to symmetry notions.

HS

A little bit. Not SU3. When I came out of Rochester, my mathematical tools were analyticity and SU2. You could make a living as a particle physicist with very little technical mathematics.

PoS

So why were they teaching Wentzel?

HS

Because that's what he knew. He wanted people to quickly move into his machine to get numbers. He was a very, very smart phenomenologist. He was not interested in fundamental issues in my opinion. You know, he really wanted to fit data. He had one student, Peter Signell, who started mutilating ad-hoc nucleon-nucleon potentials to fit data. And the results were very impressive. It was a whole industry. You had a potential that could fit much of the nucleon-nucleon scattering data. A very useful technology, but I don't think it attacked any fundamental issues.

PoS

But it's a high level of phenomenology in the sense that it employs group theory and is kept that way all the way through.

HS

Yes, yes , yes. But I would never call Marshak a field theorist in the sense of the people that I met in the Boston area.

PoS

So is the following inference correct: that after you graduate in 1960 and you come to Boston, that renormalization theory is not part of your toolkit? I mean, would you have been able to do a Lamb shift calculation?

HS

Not in a million years.

PoS

When you came to the Brandeis summer school, were you still a student?

HS

Yes. I was a first year graduate student, so a lot of what Jauch said was over my head, but I sort of got an inkling of what happened, and I went back and read the book when I was able to digest it. That's what people were reading. I really learned field theory from [James] Bjorken and [Sidney] Drell. I tried Sam's [Schweber] book, but Bjorken and Drell was the most systematic one for practical calculations -- which was my mindset at that point of time. So it got you up and running, quickly. Did it displace Heitler? Oh, easily. Jauch and [Fritz] Rohrlich’s QED book, “The theory of photons and electrons,”displaced Heitler’s classic, “The Quantum Theory of Radiation.” Jauch and Rohrlich displaced Heitler except for some really stubborn people. When was Jauch and Rohrlich? I'll bet. 1956, 1957, because Jauch was saying he was going to read it from his book. That was the first textbook that did relativistic field theory with modern renormalization theory. Isn't that right?

And it was back and forth from the phenomenology back to the fundamentals, back to the phenomenology. And Jauch and Rohrlich set themselves a narrow task: to write down all the perturbative quantum electrodynamics known at that time. Reading that book was self-education.

PoS

I think Jauch and Rohrlich was published in 1955.

HS

That makes sense, because I cameat the end of my first year of graduate school to the Brandeis Summer school, and the book was already in existence. So it should have been summer of '56..

PoS

So this was your introduction to renormalization? At least renormalizing quantum electrodynamics?

HS

Yes. I started getting the gist of it but I didn't really understand it. There were all sorts of counter terms.

PoS

So you studied that by yourself at Rochester? Were there other people?

HS

No, I studied by myself when I came to Boston. In Rochester we were either doing dispersion relations or weak interactions.

PoS

So you didn't look at it between the time you were a first-year graduate student and the time you came to Brandeis?

HS

Maybe I had looked at it, but it didn't make much sense to me. I wasn't good enough. See, I was switching from engineering, I had a lot of phenomenology to learn, and I didn't want to spend my life doing my thesis. I wanted to get on with it. But I read it eventually. I read it when I came to Boston.

PoS

You come here in the fall of '60?

HS

Yes as a post-doc, for you [Schweber](laughter) in '61, as an instructor, I guess. I had stayed a year in Rochester after my degree.

PoS

You finish the dissertation, which as you say was primarily Chew-Low theory and you come to the Boston scene. What was your impression of Cambridge in particular. How did you get to know people like Sidney Coleman, Steven Weinberg, Sheldon Glashow?

HS

Glashow wasn't here. It was Jeffrey Goldstone and Sidney. How did I get to know them? I lived in Cambridge. So when I wasn't coming out here to Brandeis, I would stop at Harvard Physics. Sidney was then a post-doc. I don't know how I met Sidney. But Sidney and Jeffrey and I used to go out for coffee at 2 o'clock in the morning, 1 o'clock in the morning, in the middle of our work period in those days. Sit at the Cafe Pamplona , and talk.

PoS

That's where you got addicted?

HS

No, I started getting addicted at Rochester tocoffeehouses.

PoS

So, what was going on at Brandeis?

HS

Sam was here. Stanley Deser…I never worked with Stanley, all the years I've been here. In particle physics there were post-docs, Hugh Pendleton, the late Menasha Tausner, Saul Barshay, who is now in Germany, Ronald Rockmore. I thought most of these people had a heavy emphasis on phenomenology.

PoS

But not I [Schweber]. I was writing this Field Theory book...

HS

You were writing the field theory book, Stanley was always a relativist, I saw myself as a dispersion relation person at that time learning field theory.

PoS

Did you teach here?

HS

Yes. During my second year I taught E&M, mostly graduate E&M, and I taught Quantum Mechanics. I gave a special course on functional analysis, nuclear physics, group theory.

PoS

But you never taught Field Theory?

HS

Never taught Field Theory. I really like classical electrodynamic theory, and most people don't like to teach it, and I have a great deal of fun, because I sneak in group theory into the course. George Sudarshan was at Harvard; he worked with me while I was at Brandeis. And this reminds me, I had worked with him at Rochester. He was interested in indefinite metrics, and I found a dispersion relation example. You know, most of my stuff, up through 1963, is still heavily into the phenomenology/dispersion relation point of view, except for the one thing that I did with Wally Greenberg.

PoS

He was a post-doc at that stage with Francis Low.

HS

Yeah, we did a little baby thing on axiomatic field theory. But I don't see any real field theory here.

PoS

No, but you interact with Sidney, and you go to all the theoretical seminars once you're here. How does the world look different in Cambridge as compared to Rochester?

HS

I thought the people here were much deeper. I thought there was a very big ocean. That it was very intimidating.

PoS

And by whomwould you say the intellectual tone was set by?

HS

Schwinger at first. Yes. And I think Schwinger painted himself into a corner.

PoS

This was when he was doing all his unified field theories?

HS

Well, before. He was trying to find a symmetry group to describe hadrons, and he had some clever schemes, but none of them worked. That was a dead end, none of his schemes worked. Then he did source theory, he didn't believe in field theory. I think that's where he painted himself in the corner. He didn't want to take stuff from younger, and people less smart than him. The kiss of death for an aging scientist.

PoS

What do you mean he didn't believe in field theory?

HS

He thought field theory was not going to describe hadron physics, and he had a hybrid S-matrix field, that was his source theory. The calculations at the end of the day were field theory. But he wouldn't call them field theory. He got burnt on dispersion relations, so he didn't want to go into that. In fact, at a Rochester conference, [Gunnar] Källén and [Arthur] Wightman did a calculation correctly that he had done incorrectly. Namely trying to represent the analyticity properties of the vertex 3-point functions. Not only that, Källén was extremely rude to him at the conference, so Schwinger dropped it while everybody was proving things. Analyticity, field theory, dispersion relations, he never went near that again. I don't know Schwinger that well, but Schwinger was a dominant figure when I first came.

PoS

In what sense? How did he set the intellectual tone?

HS

Let me see if I remember. Did you attend his lectures, Sam? Not his courses, but his seminars. You know, when he gave a public colloquium, I would attend. Well, they were just sort of complete. Self-contained, no place to ask questions. You can nod your head, I could follow, but you couldn't go home and reproduce anything. There was no way to penetrate, it was a package. There were people, --I guess it was Charlie Summerfield,-- doing theses on quantum electrodynamics, also. I interacted with Paul Federbush because we went to the same high school. In fact, my mother knew his grandmother, so we had a long acquaintance.

PoS

He was at MIT?

HS

MIT.

PoS

And did you have contact with Francis Low?

HS

No.

PoS

So it was really much more the Harvard group?

HS

The Harvard group, the Harvard young people, the Harvard post-docs and I hung out together.

PoS

And what kinds of things would you talk to Sidney Coleman about?

HS

Politics. Sidney and I did some physics together, phenomenology. I collaborated with Sidney, you know, I don't have a huge number of collaborators in the Boston area. I think the most influential on me was when Steven Weinberg came. Which is later.

PoS

So at the beginning of the '60's, from your own personal experience, you have a sense that there was no clear direction in the field.

HS

That's right, there were a lot of options open. Dispersion relations, Weak interactions as a window on symmetries. Field theory was not going to do it as far as hadron physics was concerned andI was interested in hadron physics. Almost entirely. And the hadron physics I was doingwould look entirely phenomenological: looking at the data, seeing what the experiments told you.

PoS

Did see weak interactions as a window on symmetries?

HS

Yes.

PoS

Or symmetries as a window on weak interaction?

HS

No, I think the decay patterns told you about symmetries. (delta I) =1/2 rules, for example. Later, when [Murray] Gell-Mann got into the business, discussing V-A, and the analogies between electromagnetism and weak interactions. Weak magnetism, and PCAC. I think PCAC was the most influential inpushing me towards more fundamental physics. That was Steve Weinberg, and Steve Adler, who was a post-doc. Adler-Weisberger made a great impression on me. It was good for me, because it combined what I knew about dispersion relations with a more fundamental point of view, a more local point of view.

PoS

So, did you see the early '60's, and dispersion relations in particular, as a time of opportunity? It's not so much that field theory comes to a dead end. Did you have a sense that there were many problems to be solved, rather than hitting your head against the wall?

HS

There were a lot of things to do. I never thought myself good enough to give a world-view, like the smart people. There were a lot of problems to work on. And there was a lot of organizing to do. In other words, I could not have sat down and provide an eight-fold way, but given the eight-fold way, I kind of knew what things to be done, you know, more engineering type things, plumbing, as [Leo] Kadanoff would call them. But you wouldn't bang your head and say 'I don't know what to do.' There were lots of things to do, from organizing data, fitting cross-sections. It was not a frustration in a sense, it was just, to usea more precise word,confusion. Because it wasn't well organized.

PoS

It is interesting to me, that when looking back at Rochester at the present time, that it did give you tools to address problems. In other words, that you were in a position to realize that there were lots of problems to be looked at, to be studied.

HS

Right, but my training was not to look at it in any deep way. Nobody was saying then, 'this is only a way-station and a better description.' But rather, 'There's a huge amount of data, let's fit it. Let's do something about it.'

PoS

Let's fit with something in mind, whether it satisfies dispersion relations, or...

HS

Or (delta I) = 1/2 rule, or V-A. There was a point of view. Probably in retrospect, V-A was the most important success of the Rochester things, what Marshak and Sudarshan had done.
It was late in the 1960s, when Steve Weinberg came to Harvard -- 1966, 1967 -- that things started to make more sense, to me and to everybody else. The current algebra was more highly developed, and the thing I did with Steve, developed when he gave a lecture, and he said 'Well, there's a problem. I can't use soft-Pion physics in the problem of the A1 meson decay into a Rho and a Pi, and the Pi probably having about 4-, 500 MeV's, two or three times its rest mass in kinetic energy.' So at the end of the lecture, I proposed a way to do it. There was enough information from Ward identities that you could actually make a prediction. So we worked on that, but that was just Ward identities. Then what happened, wasthat [Bruno] Zumino and Schwinger and Weinberg all independently got effective Lagrangians for current algebras. Which superceded stuff that I had worked on.

PoS

Before then, in '63, you have a paper with Sidney Coleman.

HS

Yeah, right. What preceded that was the Coleman-Glashow tadpole theory. And that did not fit electromagnetic mass differences well because the tadpoles were isospin 1 only. And my contribution was that there had to be explicit electromagnetic corrections which were isospin 2. So, with the known experimental form factors, Coleman and I sat down and calculated all the electromagnetic mass-differences of the baryons. With that correction, it gave support to the Coleman-Glashow tadpoles, that there was explicit symmetrybreaking of isospin 1 tadpole contributions, which was in the same representation as the strong symmetry-breaking Lambda eight. So my contribution was the explicit electro-magnetic correction. That was thepaper on departures from the eight-fold way with Coleman and Glashow. That was an abstract, but the final version was the paper with Sidney on departures from eight-fold way.

PoS

Is that your introduction to current algebra -- Adler-Weissberger?

HS

No, something more specific.

PoS

Probably Murray Gell-Mann’s paper in Physics?

HS

No, it was more personal. Ok, I was married in '66, May. That spring I went to Caltech. Before that, I had Sloan foundation money. In a previous spring, and I went to Paris. I was very lonely in Paris, I wasn't making friends. And I knew that there was a spring program in Trieste, so I just packed up and went to Trieste, and I learned current algebra from [Sergio] Fubini. And Ben Lee was there.

PoS

That was your introduction to Ben Lee?

HS

Yeah, and Sidney and Shelley [Glashow] were there. And then I came back, and so I thought current algebra was a powerful tool. So I had another semester off, and I went to Caltech. And Gell-Mann would come in every week saying what he did at home that night before. [Roger] Dashen was very active. I worked with Fred Gilman on problems in current algebra. So, those two experiences, being at Fubini's feet, and then later atGell-Mann's -- Feynman was on sabbatical --, those two experiences made me a comfortable practitioner with current algebra. And also working with Weinberg. So, current algebra was my main interest for a long time after that. For a while I could keep up with the big boys on that one.

PoS

Still we don't encounter renormalizations or anything like that. So you can avoid all of these difficulties, except for anomalies.

HS

Anomalies were a little bit later, and I never worked on it. I listened. I learned what the message was: the message was about the counter terms breaking conformal symmetry. It's a linear divergence and you have to be careful when you shift the origin. Orif I have a triangle diagram, I can't keep all three legs of the triangle conserved. I learned the lesson, but I didn't contribute. So, in my world, there was no real opportunity to learn renormalization. Because, if you didn't have full blown Yang-Mills theory, what was there to do? Some people do radiative corrections, like Alberto Sirlin. You know, he did quantum electrodynamics radiative corrections to hadronic processes, which is, a little cottage industry, and you have to really know renormalization very well. I don't think it was the mainstream of the problems. You can do current algebra without ever talking about these things. What was being revealed was that we really were finally getting back again to local physics. And there was developing the point of view of effective field theory.

PoS

And that's Weinberg?

HS

Weinberg was the intellectual leader at that time, for a long time. Gell-Mann first, then Weinberg.

PoS

So, what was that point of view?

HS

PCAC; that you could have local fields; and that the currents were local, and that you could describe low-energy hadron physics with all this algebraic machinery.

PoS

Side question: how much do you keep up with condensed matter physics in the sense of superconductivity?

HS

At that time? Almost not at all. When I was a graduate student, in '56, I went to give a paper at an APS meeting,in 1956, in St. Louis. There I heard [John] Bardeen's talk, and I didn't understand a word he said. I heard Brueckner talk at Rochester and I started to understand, because it was in terms of annihilation and creation operators.

PoS

This was Brueckner many body theory, electron gas and things like that?

HS

Electron gas and nuclear matter, and I was interested in that, but I could never find a good problem. I followed a little bit Lee and Yang on hard sphere gases. I found it interesting, but I never really could find a problem that I could do. The problems I could do was stuff I told you about. But I guess Weinberg showed there was a great deal to do in current algebra, hadrons, and SU3. This had been very successful by that time.

PoS

Your first meeting with Weinberg was at the summer school here?

HS

No, I knew him when he became a professor at Harvard. And he posed some problems in one of his lectures, and I essentially proposed a solution, so he suggested that we work together on it, to write it up. And so we worked a little bit on that, and I worked with him and Glashow. I did a lot of work in current algebra with Ira Gerstein, and Ben Lee.

PoS

And Ben Lee was where at that time?

HS

At Stony Brook. You know, current algebra looked like the first window into short-distance physics. I think correctly. I guess there was still a school in axiomatic field theory going on, still being practiced by the mainstream, but I found it very unattractive. Because I could not possibly see how all those guys were going to say anything about experiment.

PoS

Did you go listen to Klaus Hepp and people like that when they came to Brandeis?

HS

Yes, I talked to Hepp, in fact, about the little note that Wally Greenberg and I had written.. We sat down, we discussed it. I tried to do something more, but it never worked out. The tools there were functional analysis. But that was not a good subject for me, in terms of what I could do. Group theory, analysis, and more recently, in the last ten years, geometry and topology, is better for me.

PoS

So, it would be fair to say that it was Steve Weinberg who converted you, made you a field theorist in some sense?

HS

Yes. I think that's fair to say.

PoS

And the specific problems that you start working on as a field theorist rather than a current algebra person were what?

HS

No, I think it's a mixed bag, because we're using Ward Identities. Time-ordered products, etcetera, etcetera. So, I was notcalculatingeffects from a fundamental Lagrangian, I was doing really long dirty calculations on Ward Identities, which were eventually simplified by effective Lagrangians. The stuff that I had developed was superceded within a year or two. But there were a whole bunch of calculations I could do, at that time, that people didn't know how to do. Or rather Steve and I knew how to do. But he was also developing other stuff.

PoS

Are we now talking 19--?

HS

Well, probably started in 1967. 1967 is the calculation with Glashow-Weinberg? Well, let's see. 1967. The current algebra hard pion processes. There were two earlier ones with current algebra sum rules with Steve and Shelley. More electromagnetic mass-difference calculations to 4th order with Ira Gerstein and Ben Lee. I think those were the best tools of the day. I don't think people were doing local field theory.

PoS

Let me ask you a slightly different question. At the time, you were aware of the papers of Steve and Goldstone on symmetry-breaking, which was earlier in the decade, '61, '62. Where does that fit into the scheme as far as you're concerned?

HS

The Goldstone boson and PCAC fit in as a necessary part of the toolbox for doing current algebra. You couldn't describe pions unless you know how to relate axial vector currents to pions. So it's part of the toolbox. I think the smarter people had, eventually, when field theory came along, a deeper notion what that meant, in terms of modern QCD, Quarks and Gluons. People didn't believe much in quarks. Gell-Mann used to make fun of the 'concrete-headed people that believed in concrete quarks.' I remember the words, because I was there. When did I believe in quarks? I had a friend who wore a pin that said 'Quarks will be found.' And he was wrong too, in some sense. I didn't believe in quarks until the J-Psi business. And that was another result that pushed me deep into phenomenology with potential models.

PoS

Which you did, too?

HS

I did a lot of that. Did a lot of spectroscopy.

PoS

Again in terms of the things that you remember,what you're saying is that symmetry-breaking for you becomes a practical matter in how to handle pions and...

HS

Kaons and things...(end of tape 1)

Continue reading part II of the interview.