Lawrence Shepley

Ford:

To start out, please talk a little bit about your experience as a student working under John Wheeler's supervision at Princeton.

Shepley:

Well I'm not quite sure what you want. I was at Princeton from 1961 to 1965, and I took at least one course from John, relativity. The reason I went to Princeton, in fact, was because of John Wheeler. He had given a talk at Swarthmore College, where I went as an undergraduate, and that so turned me on to the idea of doing physics using geometry that I decided to go to Princeton.

When I was there looking around for a dissertation topic, I asked several people, including Johnny, for suggestions, and one of his suggestions was something that only very recently did a graduate student work on, David Henry (Harry) King. But the idea that I found most appealing was one that was suggested by Charles Misner having to do with spatially homogeneous cosmological models. Well, Misner left for Maryland during this period, and Johnny, very generously, I think, took me over.

I did the mathematical work, with some suggestions from him, but then when it came to writing up the dissertation, he was very helpful indeed. We went though it word by word, page by page, and in all cases he would ask penetrating questions, and I had to sharpen my reasoning and explain what I was doing, and it became a much better dissertation because of that. So I think his main contribution — well, the contribution that really lasted — was that in addition to inspiring me in physics, there was this business about being very careful about what you say and how you say it.

Ford:

Did you move directly then from Princeton to Austin?

Shepley:

No, I went to Berkeley for two years to work with Abe Taub as a postdoc, and again John was very helpful in getting me that position. Then in Berkeley I started working a bit with Ray Sachs, who was then on the faculty here, and he was the one who had me hired here as an assistant professor in 1967. I've been here ever since.

Ford:

Well, let's jump right on up to the Austin period then. You overlapped with John here for 11 years, I guess.

Shepley:

Yes.

Ford:

Are there any remarks you might want to make about his performance here as a teacher, as a researcher, as a departmental citizen?

Shepley:

Well, one of the things John did when he first came here that was quite innovative, although I'm not sure that it had a lasting impression, was to form a symposium for seniors in physics. Faculty members would nominate their best seniors who would come here and give a talk in a symposium that lasted a couple of days. The idea was that we would see who the very brightest young physicists were, and persuade some of them to come. He was very interested in building up the quality of the graduate students here. The effect of those conferences was somewhat minimal as a direct effect; that is, the students who came to the conference didn't come here as graduate students for the most part. A few did, but not very many.

Ford:

You got some who already had their eyes on Caltech or Harvard or the like?

Shepley:

Yes, that's right. But they saw a chance , you know, to come and talk to other students and visit Austin. But I think that he was pretty instrumental in helping the department improve its graduate students over the years. We now have a very good set of graduate students, whereas, when he first came, I would say that the quality was not nearly as good. Now, you know, there are lots of reasons for an improvement in graduate students, but I think Johnny was instrumental in that.

He also, I remember, taught electricity and magnetism at the graduate level in a way that was very effective. I'm not sure what else to say. He had his own center while he was here, the Center for Theoretical Physics, and he was instrumental in bringing Claudio Teitelboim and Philip Candelas, as well as a series of visitors of very, very good quality, including people like David Deutsch.

Ford:

It's clear to me from talking to John that he was very happy at Austin—happier than he had been in Princeton, really. Do you have some insights into the reason for that?

Shepley:

No. In fact I'm quite surprised. He was happy here, but I thought he was also very happy at Princeton. It was my understanding that the principal reason he came here was that he was basically forced to retire at Princeton. But one thing I do know—well, I don't know it for sure, but I have heard it—is that at Princeton he was not very successful in having some of his proteg‚s appointed to the faculty, Misner for example.

As I understood, he wanted Misner to stay at Princeton, and Misner was not able to. He was much more successful here. We had a very high regard for him, but I presume that Princeton would have had a very high regard for him too, so that's why I'm a little surprised to hear that he may have been happier here. Austin is a much more easygoing place. John is the type of person who likes to be on a first name basis with people, which is more Texan than it is Princetonian.

Ford:

Yes.

Shepley:

So that could be one reason. He had a marvelous house in Westlake Hills, just north of where my house is, with a beautiful, commanding view of the city. So that may have been one thing, but his house in Princeton was a wonderful house too.

Ford:

Through his whole career John has seemed to interact more with his own graduate students and postdocs, his immediate group, than he has with faculty colleagues, either at Princeton or here. Is that correct, or were there significant collaborative efforts here with other faculty members?

Shepley:

In the sense of doing research, I think you're right; he interacts more with students and postdocs than with faculty members. In fact, when we would go over candidates for postdocs, one of the things that Johnny always looked for was youth. I think he had the feeling that he wanted fresh input as opposed to people just sort of redoing things. On the other hand, he was receptive to visitors, faculty visitors, but I think his real enthusiasm was with students and young postdocs.

I know that he was always very open with people, especially students of all ages who would come and talk to him for hours on end about things, and that would often result in papers or collaborations, occasional senior theses. We don't have as strong a senior thesis program here as they do at Princeton, but he did supervise a few as I understand it. And he was able to work with people who, for instance, might have been a bit difficult to draw out. He recognized intelligence and productivity where other people might not have recognized it, might not have seen how good they were.

Ford:

He embraced teaching undergraduates as well as graduates?

Shepley:

Oh, most assuredly, yes. I'm not sure what courses he taught while he was here. The teaching load here, at least at that time, was one course per semester. I know he liked to teach a variety of courses, but I'm not sure exactly which ones he taught.

Ford:

Did you sense an impact on the intellectual life of the department in general by Wheeler's presence?

Shepley:

Oh yes, I don't think there's any doubt about that. He really was the sort of person who kind of insisted on, I don't know, drawing people out, giving people a chance. It's a different kind of insistence on quality than other people have, but it still is an insistence on trying to do the best that you can in the department, especially encouraging younger people. He was certainly very popular here, and he was popular with people outside the university as well as in the university. So, I mean it was just wonderful to have him. Even after he left here, we still welcome him back whenever he has a chance to come back.

Ford:

Well, why don't we jump to the physics? John Wheeler is physics. That's the core of his being. Writing about his life, you have to write mostly about his achievements in physics, and especially in the relativity and gravitation period, the latter part of his career, with which I'm personally less familiar than the nuclear period earlier. I need the benefit of assessments such as you could give as to what you see as the pinnacles of his achievement and/or the most interesting ones to describe for the general reader?

Shepley:

That's kind of hard to say for a general reader. For a physicist I think there's no doubt that as far as relativity is concerned it was his insistence that you really take relativity as a geometrical theory seriously and look at all of its implications, the geometric singularities—which is what I was working on when I was a graduate student. He likes to say that the reason he coined the term black hole was that a black hole is kind of like a disease, that you need to name the disease before you can cure it.

It was the idea that if you have a theory that's as good and as elegant and as kind of obvious in some sense as general relativity, that doesn't necessarily mean it's a true theory; but on the other hand, you should investigate all of its implications, all of them down to the ones that are the most uncomfortable. And so his work with Misner and other people on developing the geometrical foundations of relativity I thought was especially important. Then work he was interested in on quantum gravity—I'm not an expert on that—is, I think, also very important. You've already talked to Bryce Dewitt, I'm sure, about quantum gravity.

Ford:

Yes, I did.

Shepley:

Then in more recent years he became interested in the foundations of quantum mechanics itself, and also maintained a very strong interest in tests of relativity, so he's had impact throughout the field of gravitation and relativity and cosmology; he was very strong in that. Also in developing groups that really created, I think, modern quantum theory. In terms of what nontechnical reader might be interested, I think the book Spacetime Physics that he wrote with Ed Taylor at MIT is one of the very best examples of how to explain a difficult subject in very pictorial language. I was at one time slated to teach a course based on the sequel to that book, called Scouting Black Holes, which is an excellent book that uses calculus. The first book uses algebra.

Ford:

That is also by Wheeler and Taylor? I'm not familiar with that book.

Shepley:

Well, it's only out in paperback. Here [holding book] is the latest version, still a preprint version. It takes off where Spacetime Physics leaves off. In fact, the first chapter in this is, I think, Chapter 9 or something like that to correspond to the next chapter after the end of Spacetime Physics. What Spacetime Physics did was really talk about physics in a way that a lot of physicists are not used to, explaining it, talking about the concepts, reducing the calculations to a minimum so we don't do a lot of just busywork problems, with Wheeler's famous quotation that you should know what the answer is before you start the calculation, that kind of thing. So it aims at developing intuition about something. And I think that's the way to do it. I don't know that I'm as successful as Johnny is in doing things like that, but I think it's an ideal to work for.

Ford:

Let me ask a question related to hard calculations versus blue-sky thinking. My observations of John's work in nuclear physics in his early years is that he was almost too good at turning the crank on very, very difficult calculation—in his work on pair theory, in some of his early work in nuclear physics. In fact, on the collective model, Aage Bohr and Ben Mottelson got most of the credit and Wheeler probably had most of the good ideas. He may have been handicapped by pushing the nuclear wave functions and more formalistic approaches, and yet, paradoxically, I hear from people commenting on his later work that they see him doing too much qualitative blue-sky thinking and not enough hard calculating. How do you size up this issue?

Shepley:

Well, that's a very interesting question, because when I was a graduate student I had the feeling that he was the sort of person that did do what you call blue-sky thinking and conceptual work. On the other hand, it was the sort of thinking that inspired his students to do all the real calculations. Yet there was no doubt that he had the ability to do the calculations. I think that's probably what kept students and postdocs in line so that their work was legitimate in a sense. But he certainly was very encouraging about people doing calculations, even if he may not have done them himself.

For example, in my dissertation I did some numerical work to back up the theoretical work, and I think that was in part because I really realized that someone like Wheeler would not be satisfied with just sort of abstract functions floating across the page—that there had to be something somewhat more concrete. As I say, it was completely clear that he could do calculations and he could do difficult calculations and carry them through to a successful end. But there was also no doubt that he also felt that you really should know what you're doing before you just sit down and try to solve equations. I think you're right though, that the reputation he has is of just the thinker. But, as I say, it is clear that he certainly had the ability to do calculations.

Ford:

As a student of his myself, I knew, as probably every student of his knows, that his analytic ability is very high.

Shepley:

Yes.

Ford:

Is there anything else you want to add about his research achievements?

Shepley:

You are going to talk to Wojciech Zurek, I suppose, about the quantum mechanics?

Ford:

I'm hoping to, yes.

Shepley:

That's an area of his that I kind of watched from the outside, so I don't really know how big of an impact it has had. It's certainly one of his major interests, and I think that the biggest problem in this field today is the problem of what does it mean to quantize gravity. Wheeler had some very good insights into that right at the very beginning, and continuing through his life, but the problem is still far from solved, what even it means to a apply quantum mechanics to a geometric theory.

That is something that I think is a field that he's been very influential in, but as I say, it's a still unsolved field, whereas other fields in terms of, in which his work has been extraordinarily influential and successful has been in relativistic astrophysics— properties of black holes, cosmology, outgrowths in taking relativity seriously as a theory and looking at its implications even in very extreme situations. That has been enormously successful.

Ford:

How about any anecdotes? Do you have any Wheeler stories?

Shepley:

I don't know that my story is a true one, unfortunately, so that maybe I better not tell it. My dealings with Wheeler were always very friendly and I didn't think of him as particularly eccentric, although he had some foibles. For example, one time at his house here in Austin people were discussing the energy crisis and things like that, and he talked about how if you use solar energy what you do is you set up a collector that reflects solar energy in cylinders about this long and about this wide [holding up hands] made out of some kind of material that you can just combine with oxygen in your fireplace. Wheeler enjoyed physics toys, for instance, and unfortunately he also had a reputation for setting off explosions, but I never really saw him set off any of his famous explosions.

Ford:

Reportedly one was on this floor.

Shepley:

Yeah, but not very big ones. So I kind of missed out on that. As I understand, he also collected flags, which was interesting. Mrs. Wheeler was always a very gracious and very proper hostess, and that was very nice. It's sort of a style which I think was a bit more suited to Princeton than to Austin in one sense because she was always very proper. But on the other hand, she was very popular here in Austin.

Ford:

She too enjoyed it here.

Shepley:

We certainly enjoyed having the Wheelers.