Louis Witten

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ORAL HISTORIES
Interviewed by
Dean Rickles and Donald Salisbury
Location
Cincinnati, Ohio
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This transcript is based on a tape-recorded interview deposited at the Center for History of Physics of the American Institute of Physics. The AIP's interviews have generally been transcribed from tape, edited by the interviewer for clarity, and then further edited by the interviewee. If this interview is important to you, you should consult earlier versions of the transcript or listen to the original tape. For many interviews, the AIP retains substantial files with further information about the interviewee and the interview itself. Please contact us for information about accessing these materials.

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In footnotes or endnotes please cite AIP interviews like this:

Interview of Louis Witten by Dean Rickles and Donald Salisbury on 2011 March 17, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/36985

For multiple citations, "AIP" is the preferred abbreviation for the location. 

Topics discussed by Louis Witten in this interview include: Peter Bergmann, childhood and background, being drafted during World War II, meteorology, radar applications in weather, Glenn Martin Company, Johnrass Hopkins University, Franco Rasetti, Theodore Berlin, Gilbert Plass, Lyman Spitzer, Stellarator, Atomic Energy Commission, Martin Kruskal, Martin Schwarzschild, University of Maryland, Elliot Montroll, statistical mechanics, Massachusetts Institute of Technology (MIT) Lincoln Laboratory, George Trimble, Research Institute for Advanced Study (RIAS), Solomon Lefschetz, Robert Bender, gravity, Roger Penrose, Gravity Research Foundation (GRF), unified field theory, John Wheeler, Stanley Deser, quantum gravity, Bryce DeWitt, and general relativity.

Transcript

Rickles:

Okay, so, what I’m working on is quantum gravity in the very earliest days

Witten:

I’ve never worked on quantum gravity. Well, actually not such much. In the early days I didn’t.

Rickles:

Kind of, though. But the reason I wanted to speak to you was to talk about RIAS and your work behind the scenes, funding people who were working on quantum gravity as well. So, that’s my main interest today.

Salisbury:

We actually met many, many years ago.

Witten:

You look familiar, but I can’t remember where. Do you remember where?

Salisbury:

Here in Cincinnati. I was still a graduate student and I came to the workshop on asymptotically flat space-time.

Witten:

Oh yes.

Salisbury:

I was a student at the time of Peter Bergmann’s, but I was just a beginner at the time. That was also many years ago.

Witten:

That was about 1974.

Salisbury:

Yeah, right. But I did my graduate work in Syracuse with Peter, and I now teach at a small college in Texas, Austin College is the name.

Witten:

Do you know Ivor Robinson?

Salisbury:

Of course.

Witten:

How’s his health?

Salisbury:

He’s doing well. In fact, we interviewed him the day before yesterday. He’s doing well, but he is suffering from Parkinson’s disease. But nevertheless, it hasn’t debilitated him. We had a conversation in which I was very much reminded of Ivor’s character. The usual humor is still there.

Witten:

Yes, very good.

Salisbury:

Lots of anecdotes. We talked to Johanna, too.

Witten:

Did you interview Schucking in New York?

Salisbury:

I have interviewed Schucking, but we don’t have that on our current schedule, although we are going to be in New York tomorrow, Friday and Saturday.

Rickles:

We’re seeing Jim Anderson and then Josh Goldberg, so they’re the last two on our list.

Witten:

Give them both my high regards.

Salisbury:

We will certainly do that.

Witten:

There’s going to be a festschrift for Josh Goldberg.

Salisbury:

Oh there is?

Witten:

I just submitted an article to it.

Salisbury:

Oh, I see. Who is producing that?

Witten:

It’s going to be an issue, I think, of the Journal of General Relativity and Gravitation. Two people really are getting it all together: one is Ed Glass and the other is David Robinson from London.

Salisbury:

I see. Well, he hasn’t told me about that. Well, he’s not who’s responsible I guess, so…

Witten:

And Glass, I think was a student of Bergmann’s.

Salisbury:

He was a student of Bergmann’s, right. In fact, we had a memorial workshop — I guess it was more of a meeting than a workshop — a year after Peter died, and I saw Ed again there. I hadn’t seen him for many years. That was in 2003.

Witten:

He had a severe accident some years ago, which put him in a coma for a while, but he has recovered.

Salisbury:

Oh, I didn’t know that. I’m going to try to record here also, but we have lots of backups. We want to reassure you also that the standard procedure here is that when we get a transcript produced and then we send it back to you then so that it can make whatever changes you deem necessary.

Rickles:

Should we make a start? [Yes.] So, what do we have for the date? We should put the date on that. The date is 17th of March 2011, and this is an interview of Louis Witten conducted by Don Salisbury and Dean Rickles. So we usually begin these things with some brief biographical details; not too many available for you on the Internet. I know you were born April 13th in 1921 in Baltimore. Beyond that, I don’t really know much more, other than that your father’s name was Abraham and your mother’s name was Betty Bessie.

Witten:

That’s all correct.

Salisbury:

And we’re anxious to learn more.

Rickles:

We are, so we’d be keen to know what your parents did and what kind of…

Witten:

My father was usually an unemployed paperhanger, and we were in very stringent circumstances financially. I had an older brother and sister, and my brother graduated from senior high school at the age of 16 and got a scholarship to Johns Hopkins University. I followed in his footsteps and at the age of 16 also graduated and got a scholarship to the Johns Hopkins University in the Engineering School. I studied civil engineering.

Salisbury:

How did both of you manage to accelerate your high school education?

Witten:

It was not unusual in those days because if you did well in the early grades, like first through second grade, you skipped. That’s against their principles now because they think that socially you need to be with your age group. Now, that was not a problem then because enough of us skipped that we were still in our age group. So, that’s, I think, a completely fallacious thing reason to hold people back, but at any rate.

Rickles:

Was your father or mother mathematical? Did they have interests in math and physics?

Witten:

My father and mother both emigrated independently as teenagers in 1909 from Eastern Europe. My father was from the Ukraine, and my mother was in the Russian Empire, though I don’t know if it was Lithuania or Latvia; it’s just about on the border. They had no particular general education, either one of them. My father was 14 I think and my mother was 19 when they came.

Rickles:

So how did you begin to get into mathematics? Or was it mathematics in the beginning or tinkering?

Witten:

Civil engineering was what I did first. I was in civil engineering.

Rickles:

So were you interested in fiddling with mechanical things?

Witten:

Well, as I told you, we were in stringent straightened circumstances, and I don’t think any toys were ever bought for me. We never had anything but toys tools to fix the house. I did a lot of carpentry and electrical work at an early age, fixing things that needed fixing around the house.

Rickles:

Curiously, Dieter Brill tells a similar story. He grew up just after the war, and they had that.

Witten:

Well I grew up in the middle of the Depression, which was a long time for me.

Salisbury:

So you have a civil engineering undergraduate degree?

Witten:

I have a civil engineering undergraduate degree, and I worked as a civil engineer for two years, and then was drafted into the Army, and I was in the Army for four years.

Rickles:

Did you have a sort of engineering position in the Army?

Witten:

No, I did not. I was drafted and put in the Air Corps, and the Army did tests. I don’t know what the tests were, personality or intelligence or whatever. And after the tests, we had an interview with the sergeant, who told me that my score was good enough that I could do anything I wanted to do. I said, “Well, what do you suggest?” He said, “There’s a good school in meteorology that you have to apply to be an air cadet.” And so I said, “That sounds good,” and I became a meteorologist.

Salisbury:

So, you received training, then, in meteorology.

Witten:

I was in meteorology school for nine months. At that point they were beginning to think of radar applications in weather, so after the nine months of meteorology I was sent seven months to electronic school. And then I did radar weather type of things.

Rickles:

So, where were these schools? Were they military establishments?

Witten:

The meteorology school was at NYU in the Bronx, and the other one, the electronics, was half at Harvard and half at MIT.

Salisbury:

So, we’re talking here of early 1940s.

Witten:

We’re talking 1942, because of the war. Our war started in ‘41.

Rickles:

Well, you got your degree in ‘41.

Witten:

No, it Meteorology school was in ‘43. Not ‘42; ‘43.

Rickles:

Were there any other physicists who were being put into these schools as well?

Witten:

I wasn’t a physicist.

Rickles:

But people who later became physicists.

Witten:

Yeah, because one, the only one I know, I forget his name, but he became a professor at St. Louis in condensed matter physics.

Rickles:

So, were you picking up any other… ?

Witten:

At the end of Bedoremy military career, as I say, I worked in civil engineering. I was very happy there; I wanted to go back. I worked for the Washington Suburban Sanitary Commission, which is water purification and sewage treatment. And I worked on the design of a dam and water filtration plant, and a couple of other things. So I really enjoyed my work, but after four years of not doing civil engineering but doing radar things, I decided that I wanted to study physics. I also made another decision. I wanted to have some money before I started to study physics. So after I got out of the Army in 1946, I worked for the Glenn L. Martin Company on pilotless aircraft, which used my electronics training.

Rickles:

So pre-PhD you were already with the Glenn Martin Company?

Witten:

Yes, until 1948. And then I thought I had enough money, both to get married and to go to college, back to school.

Rickles:

What were you working on at the Glenn Martin Company?

Witten:

Pilotless aircraft. One of the things became the Titan, which is what sent a lot of things up into space later.

Rickles:

Interesting. So were you picking up some decent mathematics along the way here that was useful?

Witten:

No, I wasn’t. I completely I had lost whatever mathematics I had studied.

Salisbury:

So what technical expertise was required to work on this pilotless aircraft project?

Witten:

Well, electronics. I did the control systems, which were electronically servo-mechanisms. I learned a little bit about analog computers.

Rickles:

Were you trying to teach yourself on your own at this stage now?

Witten:

No.

Rickles:

Do you remember what books you were reading?

Witten:

No, I don’t.

Rickles:

I’m sorry, that’s a ridiculously hard question.

Witten:

I don’t remember. They were not scientific books, though. I had been trying to learn by reading non-scientific books what Einstein had accomplished, without any success whatsoever because it’s too scientific. I mean not in general; I wanted to know the details of what he accomplished.

Rickles:

It’s interesting, both Deser and Brill mentioned a book by a husband and wife team that was an almost a cartoon introduction to general relativity by Lieber and Lieber.

Witten:

No, I didn’t… I had no guidance at all.

Salisbury:

And you weren’t satisfied with what you were able to pick up from that reading?

Witten:

No, I decided to learn for myself and see. So then I went to Hopkins graduate school, which was an unfortunate choice because in those days the faculty at Hopkins was still living on its glory of the early days. It was very, very good at spectroscopy and early subjects of that kind, and had nobody who really knew modern physics.

Rickles:

So when you went into Hopkins, did you have a thesis topic in mind or were you just waiting to be assigned one?

Witten:

No, I didn’t know any physics. I had no thesis topics.

Salisbury:

How did you come to select Hopkins?

Witten:

I lived in Baltimore. I didn’t want to be away from my parents anymore. I’d been away four years.

Rickles:

Did you do many courses to catch up while you were at Hopkins?

Witten:

The first year I took about 12 courses. I was also going out with the woman I was engaged to, so I was asleep all the time. [Laughter]

Salisbury:

So that’ll be six courses per semester.

Witten:

No, twelve.

Rickles:

Twelve at the same time?

Witten:

Maybe it was ten, I don’t remember. But I took every undergraduate course in physics and mathematics that I hadn’t taken. I also had a course in quantum mechanics with Ronald Gurney, who is a rather well known physicist. He was a visiting professor. He was the only one who knew really modern physics that year.

Rickles:

So what were the courses being taught?

Witten:

I don’t remember. Mathematics and elementary electricity; magnetism as well as graduate electricity and magnetism, dynamics and analytical mechanics, both undergraduate and graduate in mechanics and both undergraduate and graduate in electricity. Then a couple of mathematics courses, differential equations. I don’t remember the sequence.

Rickles:

And you were registered for them or you just sat in?

Witten:

No, I registered.

Salisbury:

And I would suppose the way you characterized the faculty there, there was no exposure to relativity, special or general.

Witten:

No, no. We had one very good professor there who did know modern physics. I spoke badly. That was Professor Franco Rasetti. Rasetti. Franco Rasetti was on a team that worked with Fermi in Italy, and during the war, he refused to continue to do physics because he was a pacifist. And he went to Canada and worked in geology, and became a famous geologist. Then he came back to Hopkins and he taught physics, and he was a great teacher. Some people say that he was better than Fermi in the group of Fermi and so on.

Salisbury:

You don’t perchance still have notes from your graduate experience from those classes?

Witten:

Yes, I do. Would you like to see them?

Salisbury:

I’d love to see them.

Witten:

I’ll get them. [Leaves room to retrieve notes.] The top one is an example of why I didn’t remember the names of all my courses. I took something called Stochastic Time Averages.

Rickles:

Everybody needs to know Stochastic Time Averages. [Laughter]

Witten:

That was taught by a very good professor, Arnold Vintner Aurel Wintner.

Salisbury:

1950. You have notes — you think you could identify them — from Rasetti?

Witten:

Rasetti, this was Rasetti. He taught statistical mechanics.

Salisbury:

You ended up writing a thesis on statistical mechanics.

Rickles:

So Vintner Wintner wrote with Wiener, is that right? Is that was I see there, Norbert Wiener’s name? Did Vintner Wintner write with Norbert Wiener?

Witten:

I don’t think so. Could be, I don’t know.

Rickles:

Not a book. MIT Journal, 1939.

Witten:

I think this is also Rossetti. I must have saved this.

Salisbury:

This is fall of 1949. What’s the subject matter of that?

Witten:

This is Dr. Plass. This is quantum mechanics.

Rickles:

This was two years in to Ph.D.

Salisbury:

It’s apparent that it was your experience with electronics in the military that got you interested in pursuing meteorology. [Yes.] How do you explain that you enrolled in 12 courses at one time? Is that a reflection of enthusiasm in your field?

Witten:

No, I wanted to catch up. I had decided that I would take only three years to get my Ph.D, and I was able to keep the schedule, which was very remarkable then and still is quite remarkable.

Salisbury:

And you got your PhD in three years? [Yes.] That is remarkable.

Rickles:

So, how did you end up with Theodore Berlin?

Witten:

He was the only one who did fairly modern things in theoretical physics. I knew I wanted to do theoretical work, and he was doing statistical mechanics. He did extremely young. He died at the age of about 40, I think.

Rickles:

I take it this was one of your teachers. Was that the person teaching the course?

Witten:

Yeah, Prof. Cox. He taught that course.

Salisbury:

Did you have a quantum mechanics course?

Witten:

Yeah, from Gilbert Plass. Gilbert Plass was interested in climate change. He’s the first person probably in the country to be interested in climate change. He’s now in Texas someplace, and he’s well known in that field.

Rickles:

That rings a bell, actually.

Salisbury:

The text referred to here is Dirac.

Rickles:

Were you working through Dirac’s Principles of Quantum Mechanics book?

Witten:

No. I did that on my own at some point, but that was later. What happened is Gurney was not a good teacher. He was a good physicist, but not a good teacher. So the next year we repeated the course with Plass. Well, that’s not quite what happened. What happened is that in the middle of the year, while Prof. Gurney was lecturing to us in the classroom, right before us he had a stroke and he had to go to the hospital. Then Plass took over, and then we made him repeat the course from the beginning.

Salisbury:

Well it looks like what I would view as a standard material for today, but this is 1949.

Witten:

It is today. He had just gotten his Ph.D from Princeton. And by the way, he didn’t get tenure at Hopkins, and that’s why he left. We also had a very good nuclear physics teacher Stanley Hanna who didn’t get tenure at Hopkins, and ultimately became a very well-known professor at Stanford.

Salisbury:

The relativistic wave equation! But still, any general relativity?

Witten:

I never had a general…

Salisbury:

Never had a general relativity course.

Rickles:

Did you do any differential geometry or anything in the maths?

Witten:

No. I’m completely self-taught in those subjects.

Rickles:

So did you have any sense of what you wanted to work on?

Witten:

Yes. I wanted to work on modern physics, but there was no modern physicist to guide me there.

Rickles:

You didn’t have a specific thesis in modern physics?

Witten:

I didn’t even know what it was, so I didn’t have any specific thesis. [Laughter] I mean in those days, they were just discovering new particles, and I didn’t know what they were talking about.

Salisbury:

So I guess there wasn’t a seminar program?

Witten:

There was a seminar program, but the people invited other people to come talk, like spectroscopists. The head of the department was Gerhard Dieke, who was a spectroscopist.

But I wanted to tell you something about Richard Cox. You mentioned Richard Cox. He did a lot of things, but he also did some experiments in condensed matter physics. He discovered an anomaly which wasn’t consistent with physics. It couldn’t be explained. It wasn’t at all consistent, and he was told his experiment was wrong, and he knew that his experiment was right. So he published it, and it was an anomaly in the literature. Some years later, it was discovered that parity wasn’t conserved, and his anomaly was non-parity. It’s well known now by many people that his experiment was the first experiment that would have shown parity wasn’t conserved if they had interpreted it correctly.

Rickles:

But he didn’t give that interpretation; he just thought there was something strange.

Witten:

That’s right. But he knew that his experiment was right and that people were trying to tell him that his experiment was wrong.

Salisbury:

I’m so grateful that you saved your notebooks.

Rickles:

So, how did you choose your topic? Was that assigned by Theodore Berlin?

Witten:

More or less. He had done a well-known thesis. I don’t know if that was his thesis, but he had written a well-known paper with Mark Cutts Kac on the spherical model of ferromagnetism, and the paper is well-known chiefly because it predicted a phase transition, but there were not very many examples in the literature of analytically showing a phase transition. And he was interested in other examples, and he never then tried to develop a spherical model of the condensation of gases into liquids. So he suggested I work with that, and I did, and I had a fairly good model — not good but fairly good. And just when I finished my thesis, Yang and Lee published their theory of condensation, which was much, much better than mine, so mine never took off.

Rickles:

Well we saw one of your first papers was on Yang and Lee’s model.

Salisbury:

Where you went from the hard sphere repulsion to…

Witten:

That’s right. I talked to Yang about it after I made that calculation, and he said that he and Lee had tried very hard without success to remove the hard sphere, so I was happy about that.

Rickles:

Should we move on to postdoctoral research? Are there any other significant…?

Salisbury:

Yeah I guess, because the natural follow-up would be to wonder whether you continued in statistical mechanics.

Witten:

No, I didn’t. My first postdoc was with Lyman Spitzer to work on the Stellarator. I don’t know if you know what the Stellarator is.

Salisbury:

I’ve heard the term, but I’m afraid I can’t describe it.

Witten:

It was to make controlled fusion. In other words, controlled thermonuclear reactions for energy. It’s a tremendous project, international now. I forgot what it’s called, but I think they’re building a great big plant in Spain some place I think. But it was unfortunately classified at the time. It was supported by the Atomic Energy Commission and it was classified, so Lyman Spitzer and I did publish a paper on ionizing and heating a plasma.

Salisbury:

How did that appointment come about? You simply applied?

Witten:

Well, I graduated in ‘51, and during the years I’ve been a physicist there have been periods when it’s been difficult to get an academic job and periods when it was very easy. In fact, I was offered an academic job in 1946 when I left the Army. So I could have become a member of the physics faculty at that time.

Salisbury:

That would be an undergraduate teaching institution then?

Witten:

I would have been teaching undergraduates, yeah. But in those days (1951) it was hard to get an academic job. I don’t remember how I got in touch with Lyman Spitzer, but I interviewed at Princeton.

Salisbury:

But you had no prior experience with plasma physics?

Witten:

No, because nobody did. That was a new field at that time.

Rickles:

So did you do anything between Ph.D. and postdoc, or was it just straight transfer?

Witten:

I went just from Ph.D. Formally I graduated in December and started there in October.

Rickles:

Were you funded by the Atomic Energy Commission? Did you get your salary from…?

Witten:

From Princeton University. Lyman Spitzer had a grant with the Atomic Energy Commission, meaning through the university, so I was funded by the university.

Rickles:

So, who else was working on this project?

Witten:

Well, Martin Kruskal.

Salisbury:

What date would this be?

Rickles:

‘52, maybe ‘51 if you said you went straight in. You said you ended in December, so ‘51, ‘52.

Salisbury:

This is a bit earlier than the Berkeley Radiation Laboratory.

Rickles:

Yeah, that was started in ‘52.

Witten:

Yeah, more or less the same time, but I don't know.

Rickles:

I suppose, because NSF funding would have just started then as well maybe.

Witten:

Well, they had a lot of money, the Atomic Energy Commission. I don’t know, I really wasn’t involved.

Rickles:

We could investigate that.

Salisbury:

They were doing secret fusion research. Yours was secret also?

Witten:

Yeah, that’s what I said, it was secret. That’s why I left ultimately.

Rickles:

So you say Kruskal as in Kruskal diagrams?

Witten:

Yeah, and Martin Schwarzschild.

Rickles:

Really? Wow.

Witten:

There were four of us when I started. Lyman Spitzer, Martin Schwarzschild, Martin Kruskal, and I.

Rickles:

I was going to ask how you got into general relativity…

Witten:

No, no, no, Kruskal wasn’t interested in general relativity at that time.

Rickles:

Really? So were you discussing…?

Witten:

No, we weren’t general relatively — you’ve got a long way to go. [Laughter]

Rickles:

But that is interesting. Do you remember the kind of discussions you had with Schwarzschild and Kruskal?

Witten:

Yes, I told you it was about to ionize and heat… how to make the plasma and how to heat it. Spitzer and I wrote an early paper on the subject, but I told Spitzer that the whole idea wouldn’t work.

Salisbury:

How did no one listen? Why?

Witten:

Well actually, my mathematics was, it still is weak, but it was weak at that time, and I didn’t know how to prove that it wouldn’t work. I didn’t even know what (omit) I’ll tell you what I knew. Spitzer’s analysis was correct. It was based on individual particles tracing the paths of individual charged particles. And from that, he predicted what a swarm of particles would do. From my civil engineering days I knew something about the flow of water, and you can't imagine turbulent water being described by looking at the individual molecules. So I told them I thought it would not work. But I didn’t know what I was saying, how to show it but Kruskal and Schwarzschild did. I mean, I didn’t tell them, but they did know that what you had to look for was where that flow that he predicted was stable. So they proved that it was unstable. See, and that’s the problem to this day, everything they try is unstable.

Rickles:

So they focused on a kind of cross-grained aspect rather than the individual?

Witten:

No, they made a slight departure from his trajectory, and instead of coming back to his trajectory, it flew off in all directions.

Rickles:

I’m just trying to wonder if this was an early piece of… collective phenomena?

Witten:

It is a collective phenomena, of course, but what they did was a very simple calculation showing that the individual phenomena was unstable, and so they would go to something else. But they didn’t know what it would go to.

Rickles:

So how long were you on this project?

Witten:

Probably a year.

Rickles:

Just a year. And was that the same for Schwarzschild and Kruskal, or did they stay on?

Witten:

They stayed on. But there was another problem, and that was that the pay was very low, and I had now one child and I wanted to have another child, and I didn’t have any background money. Kruskal was wealthy from his father, so he had no problems financially, and Schwarzschild was a professor, so he had no problems either.

Salisbury:

Would you say you were in part involved with this project, for lack of better alternative?

Witten:

No, I enjoyed it, but I wanted to move on. So I went to the University of Maryland.

Rickles:

As a postdoc again?

Witten:

We didn’t call them postdocs in those days. They were all called research associates. So I was a research associate.

Rickles:

Do you have a supervisor on these?

Witten:

Well that was a very interesting situation, too. My supervisor was Elliot Montroll. I don’t know if you know that name. He was then a very well-known person in statistical mechanics. But the year I got there he was on leave of absence, and he was at the National Science Foundation but in charge of getting grants of which he had one at the University of Maryland. In other words, there was a grant from the National Science Foundation and I was paid through that. I stayed there for a year.

Salisbury:

And what was the focus of the research there?

Witten:

That statistical paper by Yang and Lee, so I was doing statistical mechanics.

Salisbury:

So you were working independently?

Witten:

I was working independently.

Rickles:

Did you do any teaching or anything else?

Witten:

I started teaching nuclear physics, but I only taught about a half year. I didn’t know nuclear physics. I read the book by Blatt and Weisskopf the day before, and then taught it. [Laughter]

Rickles:

That’s a good way to learn something.

Witten:

Then after that year, I went to MIT, Lincoln Labs.

Rickles:

Statistical mechanics again, or something different?

Witten:

I didn’t do anything that year. It was a wasted year. We were in a group and we had no boss and nobody was telling us anything. We just…

Rickles:

Enjoyed yourselves?

Witten:

Enjoyed ourselves. We were joined, however, by Irwin Shapiro, who was there during the last part of the year I was there, and Irwin Shapiro proved that if you’re on your own and worked hard you could do something, because he became famous there.

Salisbury:

I wanted to say this was your first exposure to someone working with relativity, but no it was not, no that came later. [Laughter]

Witten:

He did it after I left. So then I went back to the Martin Company.

Rickles:

So was that easily done? Was it a phone call?

Witten:

That was easily done because I knew the people there. One of my bosses became president of the company.

Rickles:

Trimble, what that Trimble?

Witten:

That was a different George. I didn’t know Trimble at that time. Trimble wasn’t there on my first tour. I can’t remember his name. The first name is George, but I don’t remember his last name. He wasn’t president for many years. Anyway, I was in the Nuclear Division and they gave me the job of selling pigs. You know what pigs are?

Rickles:

I assume it’s not an animal.

Witten:

Pigs were… I didn’t succeed them selling any. They’re big cans with big cobalt source of gamma rays in it and you’re supposed to sterilize food by putting it in the can.

Salisbury:

Is that an acronym?

Witten:

I don’t know. They just called them pigs! I don’t know. I only sold them for a short time. But then, that’s when George Trimble came. George Trimble was the vice president of the Martin Company in charge of special projects or special thought — he was supposed to think of new things. And there was a new thing in the wind at that time which was anti-gravity, so he also thought well anti-gravity would be a nice thing.

Salisbury:

So it was in the wind — in what sense was it in the wind?

Witten:

Well, a lot of people were talking about it in the country. There was a guy in North Carolina, Agnew Bahnson, doing experiments on it.

Salisbury:

So it was in the popular press, is that correct?

Witten:

Oh, it was international press, not just the American press. A guy in France was discovering that on the night of a new moon a pendulum swung faster or slower. A guy named Townsend discovered that there was a type of bismuth that was repelled instead of attracting. I can’t remember all the people, but it was…

Rickles:

But it was Babson, too, of course.

Witten:

Babson, yeah. And also was the Air Force. And probably Josh Goldberg. It was before his time there, but I’ll come to that.

Anyway, so everybody left but laughed at George Trimble; all the scientist left laughed but George Trimble. I guess he said, “I’ll show them.” He had a lot of influence at the Martin Company, and in those days, the Martin Company was very, very successful financially. So they decided, based on his record, they should start a laboratory to do fundamental research. And they hired another engineer to be the director of the laboratory. His name was Welcome Bender the IV.

Rickles:

I would have probably stopped at the first! [Laughter]

Witten:

I asked him who was the first Welcome Bender, and he told me the story. He said the first Welcome Bender, of course, was four generations up and he was the last son of about six sons and no daughters. So when he was born and he was another son, the father said, “Well, he’s Welcome, too.” [Laughter] And that’s how the first Welcome got the name. So, Welcome Bender IV became the director of this new research laboratory that was to do fundamental research.

Salisbury:

Glenn Martin Corporation is in Baltimore.

Witten:

It’s in Baltimore. It’s not the Glenn Martin. My first tour it was the Glenn L. Martin Company. My second tour it was called first the Martin Company, and then the Martin Marietta Corporation, and now it’s Martin-Lockheed. So not for a long time has it been Glenn L. In my first tour, Glenn L. was alive, and he used to go around the company wearing admirals things around with his suit.

Rickles:

Was he an admiral?

Witten:

He was an airplane builder.

So anyway, Welcome Bender started this thing, and he immediately made a decision, which I knew meant that the lab was going to be unstable. This decision was not only was it going to do fundamental research without applications, but it was going to do it making a profit. I laughed, too, but unfortunately I couldn’t laugh. I couldn’t convince them that it was stupid.

Salisbury:

So how did he envision that the company would make a profit?

Witten:

Well, how did the parent company make a profit?

Rickles:

Oh, by building propulsion systems or something.

Witten:

No, by contracts with the government that were cost less plus, so profit. The amazing thing is, for example, I had a contract with the Air Force, which brought a profit.

Rickles:

So you paid for your own salary?

Witten:

No, I paid for about 5% of my salary, but on that 5% there was a profit.

Salisbury:

So would you say it was primarily this effort by the Martin Company that persuaded the Air Force that there might be…?

Witten:

No, no, no. It was in the wind. When I say it was in the wind, it was in the wind. I was invited to give talks in Seattle and all over the country, and I quickly learned that I should talk about gravity and they would ask me about anti-gravity, I’d say, “Well, we just learn about gravity. If there’s anything to anti-gravity, it’ll come along.” [Laughter]

Rickles:

Presumably if you’ve just had the atom bomb and you’ve shown that something can be done with nuclear energy, the next natural thing to look at would be gravity.

Witten:

Anyway, when I started there and I had a meeting with Bender. Since I was in the company, I knew these guys. I was the first person to be hired. They called it RIAS, the Research Institute for Advanced Study, RIAS. They were looking for an acronym, which I have to laugh about because I asked Welcome Bender where they got the name RIAS, and he said, “Well, they were looking for an acronym that didn’t sound like a soap, and RIAS, it stands for Research Institute for Advanced Study.” So I have to tell you that since that I can’t help when I take a shower thinking, “Rinse with RIAS!” [Laughter]

Salisbury:

But the acronym wasn’t intended to represent anything else. It just was not soap.

Witten:

No, just research, just the acronym.

Rickles:

Was it based on the idea of the Institute for Advanced Study, Princeton? I read somewhere that it was supposed to be based on an industrial version of…

Witten:

You can’t really say. It was meant to do fundamental research without applications. Now if you analyze it, let’s analyze it for a moment, which I did, but not with them. When the Martin Company at that time had contracts with the government, each contract was cost plus a percentage, and they could include in the cost a certain percentage of the cost to do research and development. So this was research and development so that they not only paid for their RIAS but they got a profit on it because they got a profit on the — contract. We kept our own books, so Welcome Bender wanted us to make profit keeping our own books, because he didn’t realize that this was accounting tricks.

Salisbury:

Did the government realize that it was an accounting trick?

Witten:

The government wanted it to happen because they knew that it was an honest development. The amazing thing is that the effort was successful. They went into applied math. I don’t know if the name Lefschetz means anything to you.

Rickles:

Yeah, Solomon Lefschetz.

Witten:

Solomon Lefschetz. He became and advisor and he brought in a guy named Joe LeSalle who started a group on non-linear mathematics. I forgot what it was called, but it was on differential equations and mechanics, that kind of thing. I forgot what it was called. And they were extremely successful, very well known. And ultimately, after Bender left, the guy who became the director was very ambitious within the company, and he wanted to make a profit. He slowly took it away from the fundamental research to being applied. And so the Math Department left as a department and became totally, as a new department, became the Department of Applied Mathematics at Brown University. That Department was transported person by person, every person from RIAS in that department went there. Also RIAS they became very well known in photosynthesis, which was a complete accident. So, it became a great group.

Rickles:

Was it Robert Bass who hired Lefschetz?

Witten:

Bob Bass was in the math group. Did you interview him?

Rickles:

No. I’ve had a couple of email conversations with him.

Witten:

Anyway, I don’t know where I was going. But when I first started with Bender, I really wasn’t doing anything in modern physics, and we talked about what I should do in this lab. I told him I was interested either in particle physics or theory of gravity, and naturally he chose the theory of gravity as what I should concentrate on because that’s what they started with, was an interest in gravity.

Salisbury:

What date would this be?

Witten:

I don’t know. You’d have to look at the history of RIAS. It was approximately ‘55.

Rickles:

I discovered some early papers of Welcome Bender, and he had some papers on space-time coincidences.

Witten:

He couldn’t have — he wasn’t a scientist.

Rickles:

Really? The method of space-time coincidences by Welcome Bender.

Salisbury:

Where did they appear?

Rickles:

I’ll dig them out. I’ll email them to you.

Witten:

The fourth? [Laughter]

Rickles:

Maybe it was a different one, there are so many. [Laughter]

Witten:

I would like to see them. That’s very interesting.

Rickles:

Whichever Welcome Bender it was, they’re from 1939. They basically pursue Einstein’s line, the idea that you should go for the invariants

Salisbury:

39, so it could have been the III?

Witten:

No, couldn’t have been.

Rickles:

Was he too young? I’ll send them to you. You might be interested.

Witten:

I can tell you one thing, for example. I told you I worked on the control system for some of the pilotless aircraft. One of the pilotless aircraft was called the Gorgon. The Gorgon was intended to test ramjets, so it was released from an airplane and it’d fly around in a circle, and I was in charge of the controls. But instead of ailerons we had what were called spoilers.

Salisbury:

This was your first stint at Glenn Martin?

Witten:

Yes. Instead of the ailerons we had what were called spoilers, little fingers that stuck up out of the ring, and Bender was in charge of that kind of thing. And the fingers sticking out, he said they weren’t subject to forces so you didn’t have to make them strong. That seemed like nonsense to me. The first Gorgon we launched went right down. So we took them to a wind tunnel to test, and when the spoilers came out it went back down because the wind was so strong.

Rickles:

Which is what you’d expect, really?

Salisbury:

Which is what you’d expect. [Lunch Break]

Rickles:

So we were still at RIAS, were we? [Yes.] Well maybe you could connect it to the Institute of Field Physics. There’s a bit in an interview of Bryce DeWitt on the archive I just mentioned [AIP archive: https://www.aip.org/history-programs/niels-bohr-library/oral-histories/2... where he says he’d just been to meet with the Bahnson company, and he’d just been to visit either you or Welcome Bender or George Trimble about you trying to hire him or get him to run some civil institute? Remember this? So, I think it was in 1955. I think you maybe tried to headhunt Bryce DeWitt, is this right?

Rickles:

For RIAS, were you in charge of hiring?

Witten:

Pretty much in charge of hiring for everybody, but to recommend physicists, yes.

Rickles:

So do you remember briefly meeting DeWitt? Apparently you flew into Baltimore.

Witten:

I think so, yes. I don’t remember but I believe that’s true. I mean, you’re reminding me. But it was obvious that nothing would come of it, so that’s why I forgot.

Rickles:

So, he wasn’t interested in pursuing that.

Witten:

Yeah.

Salisbury:

But when we left off, you mentioned Bahnson had expressed an interest in pursuing antigravity.

Witten:

Yeah.

Salisbury:

And that was an opening, we thought, into an engagement with relativity for you.

Witten:

No, no, no, it had nothing to do with it. I was already doing the study of relativity. But where we left off, I think, I had had the interview with Welcome Bender, and he decided that of the things I had mentioned as possible interests, he wanted me to study gravity. So I proceeded to study Einstein’s theory of relativity.

Salisbury:

And that was the first engagement with general relativity.

Witten:

Yes. The first thing I tried to do was read Bergmann’s book, so I worked my way through Bergmann’s book. Bahnson came a couple years later. I don’t remember exactly the sequence. I was already doing quite a bit of relativity by the time Bahnson came along. But I don’t know what you want to know about Bahnson. He claimed that he had an antigravity thing, and Welcome Bender sent me down to see what he had.

Rickles:

Did he claim to have built something?

Witten:

Yes, he had a laboratory. I went to visit him and visited his laboratory, and the basic idea of his laboratory was he had a strong electrostatic field, which was about 150,000 volts over a distance of about like that, about a meter. And he had an operator operating this thing. But I knew enough about experiments to know that this was not a very happy place, because I knew that for strong electrostatic fields, there shouldn’t be any sharp points around. Everything should be curved, and nothing was curved.

Salisbury:

Oh my goodness.

Witten:

And the operator was working on it, his hair was standing up. [Chuckling] And then Bahnson took a long cylindrical pipe, and he smoked a cigarette, and he blew through the pipe into this central place where the electrostatic field was, and low and behold, the smoke rose. Explain it. [Laughter] Just at that moment, there’s a table with a sharp corner, and I was standing with my back to it, about a foot away, and there was a spark from my backside to the corner of the table. So I said, “Let’s go down into the hall.” [Laughter] And I said it’s nothing worth explaining. It’s completely understandable. You all explain it. It’s not worth explaining. You had an electric field, you got ionization, you get motion. I said look at the operator, his hair is standing on end! [Laughter]

Rickles:

Antigravity too!

Witten:

And I didn’t talk to him much; I just left.

Rickles:

But how interesting, though, that he suddenly was able to…

Witten:

This guy was a millionaire, multimillionaire. He owned a tobacco company, half of the RJ Reynolds or whatever tobacco company. So he started the institute for Bryce. He started, I don’t know what they call it, the Bahnson Field Institute. I don’t know what they call it.

Rickles:

The Institute for Field Physics.

Witten:

Yeah. And Bryce became the director. I don’t know how much money Bahnson gave. But Bahnson flew his own airplane around. Crashed into electric pole, electric wires, killed himself.

Rickles:

Yeah, in ’64. Okay, so he wasn’t very impressive as a…

Witten:

I had so little contact with him. I don’t know why you bring it up, but it’s fine.

Rickles:

Well, it’s an amusing story.

Witten:

This is also an amusing story. There was this guy who I told you I forget his name who claimed that bismuth was antigravity.

Rickles:

A French guy?

Witten:

No, he’s from either Indiana or Illinois. He wasn’t French. The French guy, he had the moon and stuff — that’s a different guy. Anyway, I had a meeting with the vice president, and with Welcome Bender, the vice president, who brought up this bismuth thing, and I told him everybody knows the properties of bismuth. But he’s a smart guy and asked me, “Did you every think there might be an isotope of bismuth?”

Rickles:

[Laughter] That could make all the difference.

Witten:

So I said no, but to find it you’d have to test every bismuth nucleus in the world. Anyway…

Salisbury:

Was there, in fact, much comprehension by Welcome Bender and by others, of the nature of what you were actually doing at the Institute?

Witten:

No, no.

Rickles:

I supposed it shows how little understood gravity was, as well. Hmm. So what kind of research were you were doing at RIAS?

Witten:

Well, first I was studying gravity, so I did research in relativity, mostly looking for solutions of Einstein’s equations and things like that. But there are two things that I am sort of the most pleased with. Misner and Wheeler and the group there were working on what they called geometrodynamics, which they called an already unified field theory. You probably know about that. They were trying to show how all physics might come from it. And I think I showed a fundamental difficulty, which essentially put them on a different track, because geometrodynamics has in that respect some problem, and I think I showed that is one thing. And the second thing I did was introduce spinors into the analysis of relativity. I wasn’t a very good mathematician, so after introducing it, I did try to do the wrong things with it. But Roger Penrose, who is an excellent mathematician also introduced spinors, and did the right thing with them, so he became well known for it. My contribution isn’t particularly known.

Salisbury:

Actually, it would be nice to address each of those one by one to get some more detail. The problem: first of geometrodynamics.

Witten:

Well, you can see my paper. The thing is if you try to give geometry on an initial surface, hypersurface, by giving the metric and its first derivatives. There are some circumstances where you can’t uniquely from that tell what the electromagnetic field is.

Salisbury:

Yeah, I’ve actually just looked at that paper, and it wasn’t clear to me how you were identifying the change in the geometry. What did you actually mean by “a change in geometry”?

Witten:

You could have different electromagnetic fields on an initial hyper-surface. That will have the same geometry on that hyper-surface.

Salisbury:

So the same three metrics, same extrinsic curvature…?

Witten:

Yes, will not determine the electromagnetic field uniquely.

Rickles:

Okay, so it applies to the electromagnetic field as well as the geometry.

Witten:

Right.

Rickles:

So we already know that the geometry…

Witten:

If there’s no electromagnetic field.

Rickles:

Yes, so your result was that it also applies when you put…

Witten:

It does not apply.

Rickles:

Yeah, but you can’t determine the electromagnetic field…

Witten:

Yeah. And later, other people did it for fluids also.

Salisbury:

Sorry, I didn’t go into this in as much detail as I should have before our conversation here. But when you say different electromagnetic fields, you’re talking about different electric and magnetic fields, that is gauge invariant quantities?

Witten:

Yes.

Salisbury:

Because I had the impression that a portion of this had to do with the gauge freedom in electromagnetism, but that’s not true.

Witten:

No, no, no. Also, I showed that you could have magnetic poles in that theory, and they tried to not have them.

Salisbury:

I see.

Rickles:

Was that in the same paper?

Witten:

I don’t know if it’s in that paper or if it’s mentioned in the chapter of the book, in my book that I edited. The other paper about spinors, I know that Sciama was with me the summer I worked on the spinors

Rickles:

Where did you learn spinors from?

Witten:

From a book. [Chuckles]

Salisbury:

Do you remember which book?

Witten:

No. And then Sciama went back…

Salisbury:

Were you the first, then, to apply spinors to general relativistic context?

Witten:

Yes.

Salisbury:

You were?

Witten:

Yes. And then Schama Sciama, as I say, was with me when I was working on these spinners, and he told Roger Penrose about it, so at GR2, which was held in Royaumont. Penrose approached me to ask me what I was doing with it. By that time I hadn’t done anything more than he knew. But as I said, I was not a good and I’m not a good mathematician now. I guess I started learning it mathematics when I was 28, essentially, and Roger is very good.

Salisbury:

This is the paper in which you first employed spinors was the one in which you were looking at identification of independent invariants. Is that right?

Witten:

That’s right. Yes, that’s one of the things I was looking at. I was also looking at the classification of spaces, the Petrov classification. And there, that’s where I got very badly off, but Penrose got it right.

Salisbury:

But you were the first, then, to undertake a Petrov classification, but from the perspective of spinors?

Witten:

Yeah, but I did it wrong. It’s not worth mentioning; I did it wrong. Penrose is…

Salisbury:

But you had the idea, which, in many cases is already significant.

Witten:

Yeah, but it was stupid, though. I didn’t know enough to get it right! That’s the…

Rickles:

Was Penrose working on it independently?

Witten:

Yes, yes he was in England. That was in Baltimore. How much Sciama transmitted from me to him I don’t know, but zero from him to me. You could ask Penrose; he would know. I’m sure he remembers.

Rickles:

He’s on the list, actually. I almost interviewed him last year. When did you become involved in the GRF, the Gravity Research Foundation? Was this early on or much later?

Witten:

Well, George Rideout came to visit George Trimble, and George Trimble naturally turned him over to Welcome Bender, who equally naturally turned him over to me. I think it was about 1956 or ‘57, something like that. It was after the Deser-Arnowitt thing. So I didn’t read a Deser-Arnowitt paper. I never saw it until you showed it to me, and I’m not going to read it — I can't make anything out of it. However, I did read Bryce DeWitt’s paper. That makes sense. It’s not at all like this one.

Salisbury:

Well, because it’s dismissive of the idea.

Witten:

His is a serious paper.

Salisbury:

Yeah.

Rickles:

Did his paper trigger anything at RIAS, this paper?

Witten:

No.

Rickles:

Did they read it there?

Witten:

No. Who’s the “they”? I was the only one that could possibly read it.

Rickles:

Well because obviously this thing was set up to pursue antigravity and these types of ideas.

Witten:

It was set up to do fundamental research without…

Rickles:

Just in gravity?

Witten:

No, I didn’t say that. It was set up to do fundamental research without regard to applications.

Rickles:

Okay, in any field?

Witten:

That’s right. So it started in chemistry, material science, and biology and physics. Those were our first four things.

Rickles:

And who did you hire eventually? How many were there?

Witten:

Well I don’t know. Eventually there were about ten in the applied math department, and in the photosynthesis there were about a half a dozen. In the mechanical materials engineering there was about ten or so, and in physics there were a couple of and in chemistry about six or seven. What does that make, about 40 all together?

Rickles:

Were you the only general relativist?

Witten:

Yes, except for two summers I… No, there was another guy, John Moffat was there for a while.

Rickles:

Oh, he was?

Witten:

And there was Ian Gatland who went to Georgia Tech. Oh, and there was another relativist for a while, Otto Bergmann. Not Peter, but Otto Bergmann.

Rickles:

No relation.

Salisbury:

Yes, I noticed you have a publication.

Witten:

I think I do. I’m not sure, but I think so. He wound up at George Washington. Moffett wound up in Toronto, and Gatland wound up at Georgia Tech.

Rickles:

There’s a letter where you try to hire Schild, Alfred Schild.

Witten:

We had an interview with him, yeah.

Rickles:

What happened? Do you remember what happened?

Witten:

He went to Texas instead.

Rickles:

Was he just not interested?

Witten:

You’d have to ask him. I mean obviously he was more interested in Texas.

Salisbury:

There actually was another technical matter in that list that you gave me, if we could return for just a moment, and then I’ll get back here. This has to do with your difficulty that you found in the Misner-Wheeler program. You did a paper, I think this came a bit later, I wonder if in this paper you actually address this difficulty, in which you do unified field theory in the Rainich manner.

Witten:

Yes, that’s it. That’s the paper.

Salisbury:

What was the fundamental objection to their program that you identified in this?

Witten:

I tried to tell you, you can’t uniquely…

Salisbury:

Oh that’s it. I’m sorry, I see. Another aspect of this paper, I’ve forgotten when this paper appeared. Was it ‘59?

Witten:

About that, yeah.

Salisbury:

But you also used that procedure, the unified approach to actually develop solutions…

Witten:

Oh yeah, I found some solutions. The theory is good, but it’s just not the theory of everything. But I found some solutions, one of which is now called the Melvin’s Universe.

Salisbury:

Very good, very good.

Rickles:

What was the motivation of the unified field theory work? Because you mention at the end you’re only dealing with electric and magnetic fields, and you can’t…

Witten:

That was their work. My motivation was to try to understand it.

Salisbury:

And there’s another related paper that is of the same period where you’re looking at topological properties of cosmological models.

Witten:

Oh yes, that’s in GR1.

Rickles:

That’s with Bass.

Witten:

Yeah, I felt very strongly that topology should be an important part of relativity, but I didn’t know topology. And Robert Bass, whom you mentioned, was a well-trained mathematician. So I talked to him about various aspects, and then we wrote the fairly short paper, which unfortunately I discovered later had some errors in it, all of which could be corrected, but at that time I didn’t know enough topology to really recognize the errors. I was depending on him more. However, I do think I was one of the first of this generation of relativists who understood the importance of topology. But again, I was followed by very good mathematicians, namely Penrose, Hawking, and Robert Geroch.

Salisbury:

Right. Of course Misner-Wheeler did a wonderful introduction to many of those topological ideas in their paper from ‘56, right? But you most likely did look at their paper, too, though, didn’t you?

Witten:

I don’t remember. Probably I did because I followed almost everything Wheeler did.

Rickles:

But in the Wheeler paper there aren’t cohomology issues. Your paper introduced the concepts from cohomology, which definitely doesn’t appear before that in the physics context. I mean you never see the Betti number.

Salisbury:

No, no you do. Betti number is in the Misner-Wheeler paper. Betti number and Euler characteristics are both in the Misner-Wheeler paper.

Rickles:

So what were your recollections of the Chapel Hill Conference? One of my main interests is in the Chapel Hill Conference.

Witten:

Well, Feynman was there, and he spoke. He introduced what were then the original ideas, he expanded them, but I haven’t really read the later papers that he wrote. That was interesting, Feynman — that was the first time I ever saw him, so that was great.

Rickles:

Because he was heavily behind the idea that we needed to quantize gravity.

Witten:

Everybody was.

Rickles:

Except Rosenfeld. Do you remember the discussions over whether it ought to be quantized?

Witten:

Well there was some minor discussion that you put the expectation value on the right-hand side. I don’t know who had that view, but it was minor. Almost everybody was pro-quantizing. And Bob Dicke was there, and he always impressed me. I think he should have won the Nobel Prize, in addition to whatever Dicke got. And you may not know, but I did an experiment, too, the Ives-Stilwell experiment, for which I was the thesis advisor for a student at Hopkins and he got his PhD for that experiment.

Rickles:

Was that around this time?

Witten:

It was a little later, maybe a year or two later. I don’t remember the dates exactly.

Salisbury:

How did that come about that you became the thesis advisor?

Witten:

Well, I said to myself these guys are not satisfied with not understanding what I do without a laboratory. I better do an experiment. So I decided I would do an experiment, and that was one I knew could be done because it had already been done. And I was then permitted to hire somebody, and I hired Hirsch Bandelberg Mandleberg for the summer. And when the summer was over, his formal thesis advisor who was the head of the department who knew me, and who then gave permission that I should be the informal thesis advisor. And we then kept him on as an employee, and he finished his dissertation with that experiment.

Rickles:

Did you ever go to the Stevens meetings?

Witten:

I went to the Stevens meeting. That’s really where I learned relativity.

Rickles:

Do you remember which date they started, they began, and who began it?

Witten:

Jim Anderson was the spark plug behind it. Jim Anderson had been at the University of Maryland when I was there, and he started this thing at Stevens. And when did he start it?

Rickles:

Was it pre-Chapel Hill?

Witten:

No, it was later. I don’t remember, but it was later, but not much later. About 1958 I think.

Salisbury:

How frequent were the meetings?

Witten:

Once a month, I think, for two days maybe I think.

Rickles:

Oh, so they were proper conferences. We thought they were just brief two-hour sessions.

Witten:

No, at least one full day, because I think I used to — I don’t remember. I didn’t sleep overnight, so it was one full day. I’d go up in the morning and come back at night.

Salisbury:

Did you take notes?

Witten:

Unfortunately, no. But you have these good notes!

Salisbury:

We do — they’re amazing. [Laughter]

Witten:

But really, that helped me a lot to learn relativity because of the different discussions and the different ideas.

Rickles:

Did you notice was there any position that seemed to be the leading position, canonical or covariant?

Witten:

Yes, Peter Bergmann at his school and John Wheeler at his school. It all centered about one of them.

Salisbury:

But the discussions were amiable?

Witten:

Oh, absolutely.

Salisbury:

And still they would freely dispute their…?

Witten:

There were no disputes. One presented their side and the other presented his. Peter Bergmann was very interested in quantization by the Hamiltonian method, and John Wheeler was more interested in other problems. He was not doing quantization. He was doing this unified field theory, and he was doing imaginative ideas like geons and all this.

Rickles:

Oh, so this was pre-Wheeler-DeWitt kind of stuff?

Witten:

Yes.

Salisbury:

So they would talk. There was no attempt, then, to come to some mutual understanding of the issues?

Witten:

No, it was just everybody gave…

Salisbury:

But there was a discussion?

Witten:

There was plenty of discussion. Anybody wanted to say something, it was allowed. They told Jim Anderson in advance, and he put it on the schedule.

Rickles:

So, do you remember a talk by Arnowitt and Deser when they presented their linearized…

Salisbury:

It was Deser, I think, who gave the talk. In fact, we know there was a date. It was March 18, 1958, in which Deser presented his work on linearized gravity.

Witten:

I don’t remember that particularly. Because I knew because they had been publishing a series of papers, so I don’t remember what I read heard there.

Salisbury:

Actually this was even before they published the first paper.

Rickles:

We’re trying to pin down the beginning of the ADM kind of work.

Witten:

Well then you have to ask him about it. I don’t know the history of it; you have to ask him. If it was March whatever, 1958.

Salisbury:

Right, March 18, 1958.

Rickles:

That’s when Deser gave the talk.

Witten:

Now Deser once complained that I reduced his name to an initial. [Laughs]

Rickles:

Were you the first to write ADM?

Witten:

No but it’s in my book that it comes from.

Rickles:

Well, most people when they think ADM think of just that paper in your book, and nothing else — not the other 14 papers that are ADM as well!

Well, we’re almost done with my Chapel Hill questions. Can you think of any more technical questions?

Salisbury:

Well, I’d love to try to get more insight into the dynamic of these discussions, but you…

Witten:

It was just like a conference. For instance, it was there that the emphasis on the fact that relativity involved looking for invariants came up so strongly. That was impressed in my mind chiefly as a result of my Stevens experience, because having studied relativity alone, it didn’t strike me that that that’s…

Salisbury:

But that was the emphasis of the Bergmann group, not that it was shared by you.

Witten:

No, everybody’s group. That was no difference of opinion. Everybody’s group.

Rickles:

But it was the Bergmann’s group who thought you had to solve those problems before you could quantize. Were there others…?

Witten:

Could be that the others weren’t doing quantization at that time. DeWitt was. He was always doing quantization, but he wasn’t coming to these meetings. He was in North Carolina.

Salisbury:

Who were some other people you recall who participated in the meeting?

Witten:

Joe Weber. He was a regular participant. The reason I remember him, he’s from nearby. He came from Washington and he had to go to Baltimore. Frequently I was on the train with him.

Salisbury:

Wheeler came. Wheeler’s graduate students, all of them?

Witten:

Oh yeah, yeah. Well basically, it was Joe Weber and me from the south, Wheeler and his graduate students from Princeton, Jim Anderson and…

Salisbury:

Art Komar?

Witten:

No, Art Komar was with Bergmann’s group. He wasn’t at NYU then. But John Statchel. He was from Syracuse.

Salisbury:

I didn’t realize he had gone to those meetings.

Witten:

Yeah.

Salisbury:

There’s a physicist, Banesh Hoffmann,

Witten:

Banesh Hoffmann, he came. And there was another guy from Queens, but I forgot his name. He’s not that well known.

Salisbury:

I know who you’re thinking of, but I can’t recall his name either.

Rickles:

So, it wasn’t heavily quantum gravity?

Witten:

No.

Rickles:

It was mainly classical theory.

Witten:

Well even Bergmann’s work could not really be called quantum gravity. It was Hamiltonian. There was a wish to do quantum gravity sometime. And his group, Arthur Komar would come with that Bergmann group. I really don’t remember who else, the others.

Salisbury:

Another, I suppose, related question. Did you attend Dirac’s Yeshiva lectures in quantum mechanics?

Witten:

No.

Rickles:

I wonder if you remember a guy called Paul Weiss turning up to any of these.

Witten:

No, I don’t think he did.

Salisbury:

Do you know the name Paul Weiss?

Witten:

No.

Rickles:

We tried to trace this former Dirac student.

Witten:

No, no.

Rickles:

We’ll find him one day!

Salisbury:

Now, the recollection you have of the search for invariants as being of primary importance, but apparently approached from different perspectives, depending upon who…

Witten:

It wasn’t an approach to looking for invariants; just the idea that if you did a calculation, the answer should be an invariant. That was the idea. Or you should be able to give it an invariant characterization or description.

Salisbury:

One thing that came a bit later, well no, it wasn’t so much later, but when Komar and Bergmann started to investigate the use of the Weyl scalars as candidates for invariants, and then actually managed to display them as phase space functions. Now I would imagine, I don’t know, they must have presented this material in these meetings.

Witten:

Yeah. I don’t remember it, but they did.

Salisbury:

It would be very nice to know how the Wheeler school responded to those computations.

Witten:

I don’t remember. I couldn’t answer questions like that.

Rickles:

Are we ready to move on to the gravitation book?

Salisbury:

Yes, let’s do that.

Rickles:

Because you hadn’t been doing gravitation for that long.

Witten:

I wasn’t doing only gravitation, by the way, there. I did other things, too. But that’s not what you’re interested in. For example, there was this woman chemist who came who did some things with launching the length of hydrocarbons, which the results of which we could explain with statistical mechanics. I did a little statistical mechanics, but that’s a different story.

Rickles:

I wonder what you think of the recent attempts to try and use statistical mechanics on general relativity?

Witten:

I haven’t followed it.

Rickles:

So the gravitation book. How did this come about? Was it just you came up with the idea, you approached authors, gave them some things?

Witten:

Well, John Wiley wrote me a letter asking if I would like to write a book on relativity, either scientific or popular. So I wrote back I would think about it.

Salisbury:

Did you know him previously?

Witten:

That’s the publishing company. So I wrote back and said I’ll consider it and let you know. And I started writing a popular book on general relativity and gravity, and I discovered I couldn’t do it. And Felix Pirani was there that summer, and I told him my general idea, and he said, “That’s a good idea.” Then I started outlining to him how I was going to do it, and he said, “That won’t work.” So then I wrote back to John Wiley and said I can’t write a popular book; let me think about writing a scientific book. So I outlined a book, and I started to write that book, and I said it would take me a year to do each chapter, so that’s ten years — I don’t think I’ll ever finish it. So then I said, well I better not try that. I better ask somebody else to write the chapters. And so I wrote to Wiley asking if they’d like to do that. They said yes. So I picked people that were not well known. Bryce DeWitt was just beginning to be well known; he’s the only author that was a little bit famous. Everybody agreed to write the book, and so it became sort of a best seller.

Rickles:

Did you give Bryce DeWitt any word limit? [Laughter]

Witten:

Let’s not go into that! You probably know the answer. [Laughter]

Rickles:

It’s the book on gravitation theory.

Salisbury:

It is, it is indeed.

Rickles:

Still use it.

Witten:

I wrote to John Wheeler. Before I started, I asked what he thought of the idea. He said yes, it was a good idea. And before I named it, I asked him whether he thought that was a decent name. He said yes, that’s exactly describes what it is.

Salisbury:

Did everyone that you asked to contribute did do so?

Witten:

Yes. And they worked hard. The guys that wrote the chapters on the experiments, they had never even thought about experiments before, and they met, I don’t know, sort of every day for months to do it. Each chapter is sort of a gem, I think.

Salisbury:

It is, it is indeed.

Rickles:

Probably because they’re forced to think about it to present it to a general audience.

Witten:

I did insist that it be a pedagogically written chapter, and I did give them a length guidance, and I gave them a short outline of what I wanted in the chapter.

Salisbury:

And this is actually the first occasion in which researchers in various different fields of general relativity were asked to write a summary of the current status of their work, and try to relate it to the other fields. And that was the intention.

Witten:

Yes, right.

Salisbury:

That was a significant event.

Witten:

It came just at the right time, because that’s when a lot of people were coming into relativity.

Salisbury:

The Jablona Conference was exactly the same time, I suppose, at it appears, ‘62.

Witten:

What conference?

Salisbury:

The Warsaw Conference.

Witten:

Yeah, yeah, yeah.

Rickles:

So it was just before.

Salisbury:

But that was not designed as an effort to summarize the state of affairs in the discipline. So you received expressions of gratitude from participants in having…

Witten:

Everybody was happy, I think. Actually, I believe they got paid something. I think $5 a page or something.

Rickles:

That’s a rarity. You don’t even get a copy of the book these days. You get an electric copy, an e-copy.

Salisbury:

That’s right. Since we are ostensibly doing the early history of quantum gravity, is there anything that comes to mind that we might not have covered that might have anything to do with, even indirectly, with efforts in that field?

Rickles:

You’ve seen a good bit of the history of quantum gravity, and you’ve been slightly standing back from it, so you’ve got a good perspective.

Witten:

Now, in the last couple of years, with a colleague, Cenalo Vaz, I’ve done a little bit of quantum gravity, but very restrictive; the spherically symmetric, collapsed, things like that. But I never had a course in quantum field theory, and I never really learned it until I taught it here when I was in my 50s, so I didn’t follow quantum gravity until…

Salisbury:

Did you use functional techniques or canonical approaches?

Witten:

Canonical.

Rickles:

So the first time you did quantum field theory was in your 50s.

Witten:

Yes.

Rickles:

Wow. It goes to show you that there’s something to be said for teaching.

Salisbury:

That’s definitely true! There you go, now you have your rationale.

Rickles:

Do you have any impression of how the field has changed? How particular approaches…?

Witten:

Well I think you might say I have a vested interest, but I think that string theory is the direction in which ultimately they will discover the right path.

Salisbury:

Why would you say that would be a vested interest? [Laughter] I think I can conclude, okay. [Laughs]

Rickles:

Have you tried learning bits of string theory yourself?

Witten:

Yes, I actually — You know there’s a book on string theory by Green, Schwarz, and Witten. I taught a course here on that book before it was published.

Rickles:

That was the first book produced in LaTeX, I think.

Witten:

I don’t know if it was the first book or not.

Rickles:

I think it is. I’m pretty sure, actually. And it’s still a very good book, actually. It still reads very well.

Witten:

I think you’re right. I remember doing it. Somebody was teaching. I think you’re right.

Rickles:

So string theory is the way to go.

Salisbury:

String theory is the way to go — an objective evaluation. [Laughter]

Rickles:

Okay, well thank you very much.

Salisbury:

Yes. This is very valuable information. We really are grateful that you could take the time to talk to us.