Oral Histories

I recently ran across a recent interview with Mary K. Gaillard, which encouraged me to look again at the AIP’s oral histories site. For a review of her autobiographical book, see here.

She has the following comments on the current state of HEP theory:

Zierler:

What do you see as the future of theoretical physics? Where is the field headed?

Gaillard:

Well, I think it’s headed towards insanity [laugh] by itself. I mean, no, if we don’t have experiments, people can let their imaginations run wild, and invent anything without it being verified or disproven. So I think it—I mean, if we want to understand more about what happens at higher energies, we have to have higher energy colliders. I don’t think—well, cosmology is tied to particle physics, and that’s probably something from—I mean, there is a lot of data coming from cosmology. And there is some data that will be coming from very low energy precision physics. But I don’t think that theory by itself—it needs to be kept in line by [laugh] experiments.

Zierler:

And so what advice do you have sort of globally for people entering the field in terms of the kinds of things they should study, and the way they should study those things?

Gaillard:

That’s a [laugh]—actually, I often advise people to go into astro-particle physics just because I think that it has more promise of getting data because I don’t—I mean, I strongly believe you can’t go forward without good data, and unless—well, of course, if they do have another generation of colliders, that would be great. I just don’t know if that’s going to happen…

Another very recent interview I found interesting was that of Vipul Periwal. Periwal arrived as a Ph.D. student at Princeton around the time I was on my way out, starting his career right about when string theory hit in late 1984. He worked as a string theorist for quite a few years, ending up in a tenure-track faculty position at Princeton, but then left the HEP field completely, starting a new career in biology. Here are some extracts from his interview:

Zierler:

And what was David [Gross]’s research at this point? What was he pursuing?

Periwal:

String theory. He was just 100 percent in string theory. Right? They just did the heterotic string, and so everyone was — every seminar at Princeton at that time was all string theory. It was all string theory. Curt was working on it, David was working on it. Edward was working on it. Larry Yaffe was probably the only person — no, two people, Larry Yaffe and Ian Affleck were not doing string theory. Not that they couldn’t, but they just would not do it.

Zierler:

So you mean, despite at this point all of the work on string theory, there were still existential questions about what string theory was, that remained to be answered?

Periwal:

There still are.

Zierler:

Yeah.

Periwal:

No one has ever figured out what is string theory. I mean, if you go ask all the eminent string theorists, none of them can answer for you this one simple question. Can you show me a consistent string theory, where supersymmetry is broken?

Zierler:

Was it good for your research? Was it a good time for you [his postdoc at the IAS]?

Periwal:

I don’t think I did particularly interesting research. I did — I mean, I did okay, but I’m not particularly proud of anything I did there, except for one little paper I wrote, in which [laughs] — see, this is called the contrarian part — is I showed — people were very excited about the large N limit, so I took this toy model, and I showed that in the large N limit, it actually produced something nonanalytic, as in like, you could not, in any order of 1 over an expansions, ever see what the answer was that was exact at N equals infinity. So, in other words, it was to me a cautionary tale. Like, you think you’re doing large N and then getting an intuition for finite N. But here’s this very simple model where you can do the calculation exactly, and you can do all your 1 over N expansion as far as you want, and it’ll never tell you [laughs] about what’s going to happen at N equals infinity. But you know, it’s a — at this point, string theory was already at that time pretty much a sociological thing.

Zierler:

What do you mean “sociological”?

Periwal:

So, it’s something that was borne home to me gradually, that there’s no experimental proof. Like, are you a good physicist or a bad physicist? Who’s going to tell? How do you know? Right?

Zierler:

Yeah.

Periwal:

I mean, I’d go and give a talk somewhere, and I remember this very clearly. I went and gave a talk at SUNY Stony Brook, what’s now called, I guess, Stony Brook University. And at the end of the talk, I was talking to one of the faculty there who’d invited me. And he said, “So, what does XYZ think of this work?” And I was just taken aback. I was like, wait, you’re a physicist. I’m a physicist. Why do we need to know what XYZ thinks of this?

Zierler:

Yeah.

Periwal:

Right? That’s what I mean by sociology.

Zierler:

I see. It’s as much about what a certain group of peers thinks about the theory.

Periwal:

Yeah, and this really perturbed me. As far as I was concerned, after the string perturbation theory diverges thing, I was not interested in doing perturbative calculations. So, what the solution was that people did was: okay, we’ll work on various supersymmetric theories where there is no higher contribution, and under the assumption that there is supersymmetry, you can use holomorphicity to deduce things from the structure of the fact that there’s so much supersymmetry. And this really bothered me, as in okay, there’s this really amazingly beautiful structure, and lots of very pretty mathematical results that are coming out — mathematical results that are suggested by these correlations. But I just don’t get — as a physicist, I don’t to want to have to worry about, “What does XYZ think about what I’m doing?”

Zierler:

Yeah, because you’re pursuing a truth, and it’s either true or it’s not. It doesn’t really matter what other people think about it.

Periwal:

Right. I really don’t care. I mean, no matter how much I respect — and I do — Edward, or David, or whoever, I really don’t need to know what they think about my work. Right? I just — anyhow —

Zierler:

How does that attitude serve you in an academic setting, though? Right?

Periwal:

It doesn’t.

Zierler:

How does that attitude affect you in terms of tenure considerations and things like that?

Periwal:

Yeah, so when I was — no, so I actually — I mean, when I was — well, I have no — I’m really stupid sociologically, as in, I have no instinct for self-preservation. So, I could see I had role models in front of me of how people with tenure…

Zierler:

Succeeded.

Periwal:

…succeed, not just getting tenure at Princeton, but getting tenure at very good places after Princeton, too. And I paid zero attention to all this. So, while I was at Princeton, I tried doing some lattice gauge theory.

With this attitude, it’s not surprising that in Periwal didn’t get tenure at Princeton. He didn’t soon get job offers elsewhere in HEP theory, and decided in 2001 better to try another field than keep going in the one he was in. The interview ends with:

Zierler:

Alright. So, really, the last question. What does the big breakthrough moment look like for you? How would you conceptualize this in terms of putting all of this together? What does that big breakthrough look like?

Periwal:

If I could make a prediction that was clinically testable, that would make me very happy.

Zierler:

Do you think you’ll get there? It’s the thing that motivates you.

Periwal:

Yeah. I want — you know, I said this once. We had someone visiting when I was managing the physics seminar at Princeton once, as an assistant professor. So, this guy asked me, “So, Vipul, what are you working on?” And I was very jaundiced at that time about making a prediction. So, I said, “Well, lattice gauge theory,” which, you know, nobody at Princeton did lattice gauge theory. You were all supposed to be doing string theory. I said, “Yeah, I want a number before I die.” [laughs] People are looking at me like, “What kind of lunatic is this?” But you know, a number. That would be nice.

Looking through the old interviews, I found one of very personal interest, that of Gerald Pearson, who worked with my grandfather Gaylon Ford at Bell Labs. Some of his stories mentioned work with my grandfather (whose main expertise was in the design and construction of vacuum tubes) at Bell Labs during the 1930s. During this period both studied at Columbia, where my grandfather got a master’s degree in physics.

Pearson:

Gaylon Ford worked with Johnson. When Kelly was head of the tube department, he worked in that area. And then they had a big shakeup after which the job was no longer available. Much against his desires, he came over to work with us.

Hoddeson:

In 1938 you were moved over from Johnson’s group into Becker’s. In fact, you and Sears seem to have changed places.

Pearson:

Before that took place, I remember Johnson called me into his office one day and he wanted to know if I would like to work on… well, Buckley had sent a memorandum asking for temperature regulators for buried cable. Johnson wanted to know if I would like to work in this area. Of course, no one likes to change their jobs but I said, “Fine” and we agreed that I would spend a portion of my time on this problem and that’s where thermistors came from. This continued on and it was very successful. Then it was decided that the work fit in better with Becker’s area than it did with Johnson’s. And, well you asked me about Ford. He was the one who was brought from the tube shop to work on this. And then he later went to work on something else.

Hoddeson:

Let’s see if we can date that time. Ford wasn’t working with you yet. Ford is here with you in 1934. But this move didn’t take place until ’38.

Pearson:

Yes, that’s what I was saying. He first came over to work on change of resistance with temperature. And he was working with a sulfide compound. And then, let’s see, what happened to him. He went someplace else and Johnson called me into his office and asked me if I would like to carry on Ford’s work and we agreed that I should do it part time and still work on noise. But I said I didn’t want to work with sulphur, it smelled too bad. I said if I work in that area, I’m going to use some other materials. So I made a study of that. First I worked on boron and then on a combination of oxides. A lot of my patents are on such materials and devices. These devices are still used today in the buried cable system as volume regulators.

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7 Responses to Oral Histories

  1. Jesper says:

    Hi Peter,

    the interview with Periwal is spot-on right. I was a postdoc in HEP during the 00’s and I had very much the same experience and the same attitude as Periwal – not to pay attention to the sociological aspect of the game (which sure enough ended my academic career). I think, though, that what Periwal describes goes much deeper than just string theory. During my career I came in close contact with other fields like loop quantum gravity and noncommutative geometry, and what I encountered there was the same sociological structures – a very hierarchic system, where it is critical for your future prospects to be accepted by the few people “on top”.

    Its depressing, because the incentive structures in academia are in a way upside-down: you get rewarded for being a conformist and punished for being original. You build a career by sticking to mainstream and you kill a career by trying out ideas outside of mainstream. As long as the incentive structures are not fixed I am not sure that things will really change.

    The only place that I encountered a fundamentally different culture was in mathematical physics, among people doing axiomatic and algebraic quantum field theory. There I found a much less hierarchic culture where people were more open to new ideas. In fact, very much the same attitude that I have encountered among mathematicians.

    My field of research is an intersection between mathematics and physics and thus I have often given talks to mixed audiences. To me it is striking how different mathematicians and physicist react to new ideas. In my experience the mathematicians – and also mathematically oriented physicists – are much more willing to consider new ideas. Thus I completely agree with your view that HEP should look towards mathematics in order to learn how to deal with a situation where we have less experimental data to work from.

    – and by the way, it is possible to do research outside of academia. I don’t think that people should necessarily waste their time in a system that is broken.

    Best, Jesper

  2. Tess says:

    I find the “it’s sociological” comment really amusing, thought I’m not sure what it’s trying to imply about sociology. From sociology, there’s a subfield called Legitimation Code Theory, which talks about how knowledge is structured and related systems of power. The shift he refers to, from dealing with the research claims and evidence as written to asking “what does a particular expert think of this?” can be described within LCT as a change from a knowledge code to a knower code, where the authority of the speaker determines the perceived legitimacy of what is said.

  3. Jesper,
    I think you are right to point to the culture of mathematics as a good example of how progress can be made. In mathematics, people reject new ideas *after* considering them carefully, rather than before. Some years ago, there was a very interesting announcement of a proof that all finite projective planes have prime-power order. I won’t embarrass the author of this paper, who was and is a well-respected mathematician, by giving further details, but I found this announcement surprising, so I immediately got hold of the paper and starting reading it. I organised a seminar series in which I explained the argument. Not until week 3 or 4 did I find the crucial error, buried deep in a double induction, where one of the indices had slipped by 1, thus bringing the whole house of cards tumbling down. It would have been easy for me to reject the result as implausible without reading it, as seems to happen all the time in physics, but that is not the culture in mathematics. It would have been easy to say, there’s a mistake on page 1, the whole thing is rubbish, but that is not the culture of mathematics. The important thing is to engage with the argument, and to find not any old mistake – that is easy – but to find the crucial mistake which cannot be patched up. If experts do this kind of work before passing judgement, then the subject is in safe hands. If they pass judgement before doing this work, it is not.

  4. Thomas Van Riet says:

    Concerning: “No one has ever figured out what is string theory. I mean, if you go ask all the eminent string theorists, none of them can answer for you this one simple question. Can you show me a consistent string theory, where supersymmetry is broken?”

    That is not about the ‘what’ really. Rather about the ‘how’ to break SUSY. At which scale etc,…. Let me be clear that dynamical SUSY-breaking in QFT is also a nightmare (ironically string theory, through AdS/CFT, has given us insight in this issue) . Are we all negative about QFT because of that? I mean, imagine we could break SUSY like 123 and pull as many 4D EFTs out of our stringy hat as we wanted (“old school landscape reasoning”) people would have complained we cannot predict anything more than what QFT can. Once we start realizing that finding consistent non-SUSY 4D vacua is actually highly involved and constraining (“Swampland viewpoint”), we seem to be criticized for not yet having described the universe and everything within. So I wonder: is research on fundamental interactions only free of attacks once we solve all problems at once? I expect that this is not possible and that any healthy approach to a “theory of everything” is one that makes us confront ourselves with our limited knowledge of mathematics. String theory seems to make that clear to us. There is no reason, I can think off, to be less excited about strings, than we were 20 years ago. On the contrary, we have only seen striking ideas like holography emerge.

  5. Peter Woit says:

    Thomas van Riet,
    Periwal was a Princeton faculty member specializing in string theory, with his field of expertise non-perturbative string theory. He’s undeniably right that “No one has ever figured out what string theory is.” Do you disagree with that? The “SUSY breaking” reference was clearly just to rule out certain specific non-physical cases with a lot of SUSY where someone could point to a conjectural definition.

    As for whether there’s a good reason to be less excited about string theory than 20 years ago, you might want to consider asking all the IAS physics faculty why they’ve stopped working on string theory…

  6. Thomas Van Riet says:

    Dear Peter

    We must be reading different arxivs? To my knowledge they have continued working on it. It is certainly true that the hep-th community has gone in many spin-off directions inspired by string theory ideas (SYK being one). But no, stringy research is alive and kicking.

  7. Peter Woit says:

    Thomas Van Riet,
    I notice you didn’t answer my question, assume you agree that “No one has ever figured out what string theory is.” is an accurate statement. As you are well aware, the SYK model is a quantum mechanics model that has nothing to do with string theory. Yes, string theory “inspired” work on SYK, because its failure caused string theorists to stop thinking about strings and try and find something different and more promising to work on.

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