The Manhattan Project

Robert Christy's Interview

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Robert Christy studied under J. Robert Oppenheimer at the University of California, Berkeley while earning his PhD in theoretical physics. He joined the Manhattan Project in February 1942 at the University of Chicago, and later relocated to Los Alamos when Oppenheimer personally recruited him on a visit to Chicago. At Los Alamos, Christy worked on the design of the water-boiler reactor. He was then recruited into the implosion group, where he designed the Christy gadget, the solid-core design of the plutonium bomb. He also witnessed the Trinity test. In this interview, he recalls what Oppenheimer was like as a professor and lecturer, his love for martinis, and his relations with graduate students. Christy discusses Oppenheimer’s role in the field of physics as a stimulator of ideas, and how it changed after his security trial. He also discusses Oppenheimer’s impact in emphasizing the value of theoretical physics in America. Christy remembers sharing a house with Edward Teller in Chicago and working with Klaus Fuchs and Rudolf Peierls.
Date of Interview: 
March 30, 1983
Location of the Interview: 

Martin Sherwin: This is Martin Sherwin. I am on my way to interview Professor Robert Christy in his office at 423 Downs on the Caltech Campus in Pasadena, California, March 30th, 1983.

You were a student of his?

Robert Christy: I was a graduate student of [J. Robert] Oppenheimer’s from the fall of 1937 until the spring of 1941 when I got my degree, my PhD degree in theoretical physics in Berkeley.

Sherwin: What did you do your dissertation on?

Christy: My thesis was on the calculation of gamma ray bursts. Well, it was the calculation of a cross-section for bremsstrahlung of mesons, and the subsequent calculation of the cosmic ray bursts that gamma rays resulting from mesons interacting in matter, the number of bursts they would make. The object was that the number of bursts have been recorded, a large burst of ionization, and it was thought to be due to the gamma rays resulting from the interaction of mesons. It was thought that one might learn something about the mesons by calculating this.

Together with another graduate student, Shuichi Kusaka, we basically independently calculated and compared results. We calculated the bremsstrahlung cross-sections for mesons of spin-one. That was the primary object. And then calculated the burst production from mesons of spin-one. It was essentially one of the first difficult calculations for a spin-one particle.

Then, just for insurance, we compared the observed burst production with the production for spin-zero mesons—that cross-section was already known—and for spin-one-half mesons. It was generally assumed at that time that the meson was a spin-one or spin-zero particle.

It turned out from our work that the observed bursts disagreed quite violently with our calculations assuming the meson to be spin-one. It agreed, however, with the spin-zero calculation, but it also agreed with the spin-half calculation. At that time, it was then assumed that it must be spin-zero, but it turned out subsequently that it was spin-half.

Sherwin: Why was it assumed to be spin-zero?

Christy: The meson in cosmic rays was thought to be the same particle that mediated the nuclear forces in the nucleus, which is now known as the pi meson. But the cosmic ray meson was thought to be the same particle. 

The meson that mediates nuclear forces, according to theory, should be integral spin. That is why the cosmic ray meson was thought to be integral spin. It was learned later, as a result of [Cecil Frank] Powell’s work during the war. This was learned after the war, that the cosmic ray meson is quite different from the—that is, the cosmic ray meson is the mu meson and the nuclear meson is the pi meson. The mu meson was found indeed to be spin-a-half after the war, but our work was the first hint that that might be the case.

Sherwin: How did you get onto the topic?

Christy: Oppenheimer. The meson was a popular subject at the time when we started this, which much have been around 1939, I would guess. The subject was suggested by Oppenheimer.

Sherwin: That was rather usual in terms of—?

Christy: That was a normal arrangement. It still is the normal arrangement that the supervising professor normally suggests the thesis topic. It is not always true, but it is the normal thing.

Sherwin: Now, in those years ’37 to ’41, let us see, I am trying to think of who else was there as graduate students. [Joseph] Weinberg was there.

Christy: Yes, Weinberg was there. Phil Morrison was there, Sid Dancoff, George Volkoff, I mentioned Kusaka, Eldred Nelson, Stanley Frankel.

Sherwin: Rossi Lomanitz?

Christy: Rossi came—

Sherwin: A little later.

Christy: I forget when he came. I know that I met him, but I certainly did not know him well. He may have come in ’40 or ’41. I do not remember. Bernard Peters was there. I knew him a little better than Rossi Lomanitz.       

Sherwin: Melba Phillips was gone by then?

Christy: Melba Phillips was gone, yes. Have you heard the famous story about Oppenheimer and Melba?

Sherwin: Oh, yeah, the one with the car?

Christy: Yeah.

Sherwin: I talked to her.

Christy: Oh, I see.

Sherwin: She did not want to talk about that.

Christy: I do not know. I have heard the story. That is all I know.

Sherwin: Let us see. Are there any others?

Christy: Well, maybe. If you name them, I will tell you whether, because I do not have instant recall of everything.

Sherwin: What was the relationship between, let us say, Morrison and Robert Oppenheimer at that time?

Christy: Oh, Morrison was another one of the graduate students, somewhat more politically sophisticated, I think, than most of us at that time. But I am not aware of any special relationship. We all were more or less friendly with Oppenheimer. That is, we were invited to his house, and it was kind of a large family, in a way. But I am not aware of any special relationship outside of that kind.

Sherwin: Could you talk about that? That is an interesting term to use, sort of the large family, or extended family, or something like that. How frequently did you get together?

Christy: Well, probably every couple of weeks or something like that, there would be an occasion. I am not saying that we were a part of his everyday life.

Sherwin: I understand.

Christy: I did not mean it in that sense. But rather, it was every once in a while a group would go out and have dinner or something like that. Frequently there was some kind of political occasion, support for the Spanish Front or something like that. There would be a cocktail party, and people would go to that.

After a while, they started the organization of a teachers union in Berkeley. The involvement I had was through a—there was to be a graduate teaching assistant branch of the teachers union. That got going for a while, and Oppenheimer played some part in that. I am not sure exactly what.

Sherwin: I just spoke with, when I was up in Berkeley, Joseph Fontenrose. Do you remember him?

Christy: Joe Fontenrose?

Sherwin: He was a Classicist who was very active.

Christy: In the teachers union or something?

Sherwin: In the faculty, teachers union.

Christy: I may have known him at the time. It does not ring a bell.

Sherwin: Okay. So you actually joined the teachers union?

Christy: I think so. It is a little bit vague in my mind. I do not know. I think so.

Sherwin: How would you describe the relationship of the political activity to physics to the group of graduate students? I mean, some of you were clearly more active than others.

Christy: Some were more active than others, and others quite inactive. I would say, my own activity was kind of peripheral. I went to various affairs. I was not an organizer of anything, but I did go to affairs and things like that. I do not remember exactly when this was, perhaps around 1940 or so, I had the impression that there was a group that might be, you might say, organizing people for introduction to the communist party, or something like that. I went to a couple of meetings of this group. This is the impression I have, was that it was kind of a preliminary indoctrination of some kind.

Sherwin: What gave you that impression?

Christy: Just by the activities, the reading material provided and so forth.

Sherwin: For example?

Christy: Well, whatever, Communist Manifesto and so forth. My memories are not very clear. But this was my feeling that this was a group that was being kind of approached with the thought of joining the communist party.

Sherwin: Was this—?

Christy: This was graduate students I am referring to.

Sherwin: Would someone like [Haakon] Chevalier have been sort of particularly—?

Christy: No. Some of the other physics graduate students who were closer to the party than I probably were involved in it. But I say I now do not really even remember who.

Sherwin: Like Lomanitz or [Joseph] Weinberg?

Christy: Or Weinberg, or Peters, or something. I do not precisely remember who. I think it was probably these that brought me to it because I knew them, and I think they were probably involved.

Sherwin: For example, Frank Oppenheimer down here has said that he and Jackie and joined the party in ’36.

Christy: Yes. I did not see Frank very much because he was normally here [at Caltech]. I saw him occasionally when the group of students with Oppenheimer would—commonly in April and May, they would come from Berkeley down to Pasadena when he came down to teach here. So, at least two years, I accompanied the group down here in April and May and met Frank and Jackie at that time.

Sherwin: That was when?

Christy: It was probably ’38 and ’40 or something, but again, I do not remember exactly.

Sherwin: What was that migration like?

Christy: Oh, quite exciting. People would get whatever cars or anything they had and drive down. I remember one occasion when there was a strange woman who was a part of the party. Her name was Malaika, I think. Have you ever heard of her?

Sherwin: Malaika? No.

Christy: I think so. Maybe Barkley or something was the last name?

Sherwin: I have heard a name like that. Go ahead, tell me the story.

Christy: As sometimes people do, she attached herself to one or the other of the graduate students. I think at the time she was attached to Burt someone, an Australian. I have forgotten him. She had a strange tale, which was presumably fictional, about having escaped from the German occupation of Belgium.

I remember her because she was a rather odd person, but she was along in the group on that occasion. It probably was 1940 or something like that. I remember, I think it was on that occasion, that I tried to go swimming in the ocean at Carmel, and concluded it was a little bit cold. Another occasion, I remember driving Oppenheimer’s blue Cadillac convertible down here. This probably would place it, I think. He was not driving because Kitty was pregnant, and that places when it was.

Sherwin: Yes.

Christy: So he asked Eldred Nelson and me to drive his car down, which was an exciting experience for me since I did not own a car. At that time, we stayed in the guest house behind the [Richard] Tolman’s, house, which is now Bob Bacher’s house.

Sherwin: I was there yesterday.

Christy: Kitty and Robert were in the main house.

Sherwin: I see. What was that Cadillac like? I have heard it talked about.

Christy: He had a black Chrysler convertible, as far as I recall. This was kind of a powder blue Cadillac convertible with leather. He always had leather upholstery in his cars. Quite a nice car, very, very nice.

Sherwin: A new vintage, like a year or two old?

Christy: Yes. I do not precisely recall. I am sure it was not very old.

Sherwin: Now, when you finished your dissertation, this was about 1941, right?

Christy: Yeah, I got married just after that.

Sherwin: And then what?

Christy: Well, my wife and I, after being married, we came down and spent the summer here in Berkeley. I guess Kitty and Robert were there. We saw them a certain amount. Then I had gotten a job.

Sherwin: By that time, he had moved to the new house on Eagle Hill?

Christy: Yeah. By the way, the conventional drink, Oppenheimer’s standard drink was a dry martini, as you no doubt know. I, among quite a number of other graduate students, I learned to drink martinis. So you do not only learn physics, you learn other things, too.

Sherwin: Yes.

Christy: I still enjoy martinis. In the fall of ’41, probably around September, my wife and I took off. I guess we were driving a friend’s car, the friend having a baby or something, it was Joe Keller. We drove his car to Washington University, St. Louis, and then we went on to Chicago for I had a job at Illinois Tech starting in the fall of ’41.

Sherwin: Then were you called by Oppenheimer to Los Alamos?

Christy: Well, no, that came a little later. I found things a little bit quiet, you might say, in terms of physics at Illinois Tech. I, however, went to seminars at the University of Chicago, which was a convenient place to keep in touch with physics. That turned out to be useful, because as a result of my being in seminars there, the people there knew me. When they started recruiting for the Manhattan Project in Chicago in early of ’42, they recruited me. I found that work more interesting than teaching twelve hours a week at Illinois Tech. So I joined the Chicago project.

Sherwin: You were with [Enrico] Fermi’s group?

Christy: I was mostly with [Eugene] Wigner’s group on the theoretical design of reactors, but I did spend some months assisting Fermi on measuring the exponential piles, preliminary to building the first chain reaction. So I was on both.

Sherwin: You must have gone there in what, late ’41 or early ’42?

Christy: No, it was in probably February of ’42.

Sherwin: February of ’42, okay.

Christy: I was allowed to go there by my school, providing the Manhattan Project found a replacement for me. The arrangement was that I was employed by the Manhattan Project at the same salary I was getting at Illinois Tech, which was twenty-four hundred dollars a year.

Sherwin: What did you do with all of the extra money?

Christy: That was my salary, yes. The Manhattan Project recruited someone to take my place, and they had to pay them twice as much to take my place.

Sherwin: I see.

Christy: In mid-year. It worked out that he got paid a lot more than I did, but I enjoyed the work. That was the important thing.

It was then in probably either late December or January of ’43 that Oppenheimer came around recruiting for Los Alamos, and he knew I was there. He asked if I would join him in Los Alamos. I said I would be delighted because like most of his students, I would more or less follow him to the ends of the earth. I was very pleased to be able to go and help him.

Sherwin: Well, what was life at the end of the earth like?

Christy: Los Alamos? When we arrived there, there was no housing on the Hill. We were housed in various dude ranches in the vicinity of Santa Fe, and driven up each day on a rather hair-raising ride. But that lasted only for a month or two. Then, some kind of crude housing was available up on the Hill. I remember there was one house that had bunks all over the place, double-decker bunks, and there were people everywhere. Dick Feynman was—I remember stepping over him to get into where my wife and I had one little alcove. We had a double-decker on what used to be a porch. Like I said, there were double-deckers all over the place. That was our first housing up on the Hill.

After a while, some regular housing became available, and we were very fortunate and had a one-bedroom apartment. The apartments were made as really a duplex. We had one that was just across the street from where the Oppenheimer’s house was on Bathtub Row. Very, very convenient location.

Sherwin: Did you have much socializing with the Oppenheimer’s, beyond the work? Which division were you in?

Christy: Theoretical.

Sherwin: So you worked in— [Hans] Bethe was the—?

Christy: There were some, although he had all sorts of responsibilities. I would say perhaps my wife saw Kitty more than I. That is, Robert was at certain parties. But I say, not much socializing just us, you might say.

Sherwin: Yes.

Christy: It was other, bigger parties. I saw him there.

Sherwin: Yeah, everybody has talked about the very special nature of Oppenheimer’s leadership at Los Alamos.

Christy: Yes, yes.

Sherwin: How would you describe that?

Christy: Basically, I did not have any real contact with him as a leader because he dealt primarily with the division leaders, or whatever it was they were called, and I was the next layer down. The actual leadership activities I was not involved in, that is, the meetings where things were settled and argued out. I occasionally got to argue my points, but I was not involved in the general leadership activities.

Sherwin: Who did you work closest with? You worked on the implosion device.

Christy: After [Rudolf] Peierls came, I was in Peierls’ group. Peierls had two associate division heads, you might say, or assistants. One of them was Klaus Fuchs, and I was the other one. But before he came—I am trying to think. I know some of the things I did; it was not implosion. For example, I designed the water boiler, did the theoretical design of the first enriched reactor actually that was built anywhere.

Sherwin: That was designed to do what?

Christy: In part, it was a reactor source of neutrons. It used U-235, and gave people experience in working with critical assemblies. That is something that they were going to have to deal with much more later. It was kind of an initial experience at a reacting assembly. I think that was probably the main motivation.

Later, I was in the implosion group, and my work there was primarily interpreting the implosion calculations and their relations to all of the experiments that were being carried out to test them. Essentially, my job was to try to see whether the experiments were confirming the calculations or not, and if so, where did they differ and so forth.

Sherwin: What was Fuchs doing?

Christy: I think it was more on the basic hydrodynamics problems of implosion, but I confess that I am not so clear. I am much clearer in what I was doing.

Sherwin: He was probably paying more attention to what you were doing than you were paying to what he was doing.

Christy: Possibly, yes.

Sherwin: You just mentioned him. This is sort of on the side, but in the nature of things of intrinsic interest, what was he like?

Christy: I always thought he was somewhat of a cold fish, but did not know him particularly well. He was not the kind that was, I felt, very easily approached. On the other hand, I think he was well-known to the Peierls, and he probably had a much closer relationship there than with me.

Sherwin: In other words, there was this clear division as it went down from Peierls into these two divisions?

Christy: I, more or less, always was a largely independent worker. I did not have a large group working for me. I sometimes had one assistant working for me.

Sherwin: Who did work with you and for you?

Christy: I had an SED at one time. I have forgotten his name. But often I was usually just working by myself. I was not head of a group.

Sherwin: Where you at the Trinity site?

Christy: Yes, yes.

Sherwin: What role did you play there?

Christy: Observer. Because of my fairly close association with the design of the weapon, I was invited along with quite a number of others, to view it from a distance.

Sherwin: Who were you with?

Christy: Well, Fermi was in the same general area, all sorts of people.

Sherwin: Is that story true about Fermi, sort of ripping up—?

Christy: I believe so, I believe so, yes.

Sherwin: Anyone else in that immediate area?

Christy: Oh, there were lots of people. I think there were two or three busloads of us. We were bused down in the late evening and the night. I have not a clear recollection, but it was all of the observers, basically, were in this one area.

Sherwin: Oh, I see.

Christy: I would say there were 50 to 100 of us there.

Sherwin: You were not involved with the assembling of the bomb?

Christy: No. I was there purely just as an observer.

Sherwin: When did you leave Los Alamos?

Christy: I left Los Alamos in the early spring of 1946.

Sherwin: And you went where?

Christy: I went to the University of Chicago where I had been offered a job as, I guess, an associate professor. I had not been there very long—well, curious living arrangements I might mention. It was not easy to find housing immediately after the war. So two of us who were going to the university rented a quite large house, a mansion, really. The other man who rented the house was Edward Teller, he and his wife Mici, and me and my wife. We had one baby at that time. He has to have had either one or two.

The arrangement we had was that they used the kitchen as their kitchen and the living room as their living room/dining room. We used the butler’s pantry, which was quite sizeable, as our kitchen, and we used the dining room as our living room/dining room. They used two front bedrooms on the second floor, and we used two back bedrooms on the second floor. That left the third floor vacant, which had many small bedrooms in it. Many, many people who were coming to Chicago from Los Alamos and needed a place to stay stopped and spent a week or two there. It was a general stopping point.

Sherwin: That must have been exciting times.

Christy: Mm-hmm.

Sherwin: How long did this last?

Christy: It lasted for probably four to six months or so.

Sherwin: What was it like living with the Tellers? He plays piano a lot?

Christy: He plays the piano. More or less we kept separate, as I tried to indicate. We had really our separate spaces and we just kept separate. Just life was simpler that way, if we go about our business and they go about theirs.

Sherwin: Okay. What contacts did you have with Oppenheimer after the war?

Christy: Limited. He came here, to Caltech, after the war. It was after he had been here six months as a professor, he realized that that was not going to work.

Sherwin: Why did he realize that?

Christy: Well, I never asked him, but it seemed obvious that A, he was always having to go to Washington. He had very, very many ties in Washington, and you cannot be a professor if your main interest and activities is in something else. It does not work. If you are going to be a professor, that has to be your primary interest. He could not return to that, for obvious reasons.

He suggested to [William] Fowler and [Charles] Lauritsen, who were the head of the Kellogg Laboratory here in nuclear physics, that they might recruit me here to come. Willie Fowler called me up in Chicago sometime in the spring of ’46 and asked me if I would come here. I was kind of on-the-fence. I was not sure, because Chicago is a first-class place, but my wife very much preferred the climate in California. She decided for us that we would come here, straightforward.

Sherwin: Yes, it is.

Christy: I came here. I did not have very much contact with Oppenheimer for some time, in that I was not going East very much. I did not see him very much for quite some time. That is about all I can say.

Sherwin: You were not involved at all in any of the hearings, the Oppenheimer hearings?

Christy: No, I was interested because quite a number of my colleagues here—Charlie Lauritsen was testifying, Bacher testified, Lee DuBridge testified. These are all Caltech people.

Sherwin: Yes.

Christy: I was very interested in it. Of course, just a fascinating thing altogether. Although I was also basically very upset that someone like Oppenheimer would be subjected to that kind of treatment. Basically, I was very upset, very deeply upset. I was so deeply upset that I took some actions there after that I would not probably normally do.

There is a fairly well-known incident at Los Alamos shortly after that. When I was visiting there and I saw Edward Teller, the first time I had seen him since this hearing of Oppenheimer’s. I saw him in public at the Fuller Lodge there at lunchtime. He put out his hand to greet me, and I refused to shake his hand. I say, this was an instinctive reaction, because I was so deeply upset at the treatment of Oppenheimer. This was noted by various people, and I think it did upset Edward. I say this is not a normal way for me to behave. But nevertheless, that was the way I felt, and that was the way I behaved. So relations with Edward were a little cool for quite a while. They are still cool, basically.

Sherwin: Let me go back and ask you a question about Oppenheimer’s teaching.

Christy: Yes.

Sherwin: Could you tell me about what it was like? First of all, why did you go to Berkeley? Was he the attraction?

Christy: Yes.

Sherwin: You did your undergraduate work where?

Christy: At the University of British Columbia.

Sherwin: You’re Canadian?

Christy: Yes, and I went to Berkeley because the year ahead of me at B.C., there was a student, George Volkoff, that I knew quite well.

Sherwin: He’s back there now, isn’t he?

Christy: Yes, he’s back. He’s retired as Dean, yes. He was a very thorough person then, always was a very thorough person. He researched as to who was doing the most active work in theoretical physics. He found out that Robert Oppenheimer and the group of students working with him was clearly the most active group, and so he applied there because of that. Since I was following a year behind him and to the same basic interests, I did the same. We both were pleased to be accepted there. Basically for the first time in my life, when I got there, I found the work hard, particularly Oppenheimer’s course.

Sherwin: Was this the famous course of quantum mechanics?

Christy: Yes. Well, he basically taught two courses at that time. There was an introductory course in theoretical physics, and then a course in quantum mechanics. I think these were—whether it was intentional or unintentional—these courses were made very difficult. I am not quite sure. It is either Oppenheimer did not realize that people did not absorb information as fast as he put it out, or he did it intentionally, essentially as a trial by fire to see who would survive. I do not know.

In the years prior to my going there, it had been customary for his students to take his course, the same course, two years in a row, and only then did they fully understand the material. But this meant that he always saw people in the class who he recognized as having had an introduction already, because they had been in his class the year before. I think it made him even make the material harder. But he put an end to that. He did not allow that, starting the year I went there.

Sherwin: In ’37?

Christy: Yeah. It was a very difficult experience to keep up with the material of his lectures and do the work that he required.

Sherwin: By ’37, had he become a skillful lecturer, even though he did not make the material easy? Was he audible, at least?

Christy: He was audible, yes. There was no problem there. I would say, not as polished speaker as he became later, but nevertheless, he spoke in sentences. He just put a great load on you, that is all. But it was not hard to understand him, as I suspect it may have been in the years before that.

Sherwin: Yes, according to the earlier students. But surely what was so difficult about it was not just the quantity of work, it was the level of the work?

Christy: The level, yes, that is right. Well, for example, the problems that he gave, some of them were very, very difficult. I learned later that some of these were research papers that he had published, and after he had worked it out and published it, he would assign it as a problem to his students. That was the level. The homework problems were research papers, except they had already been published.

Sherwin: Did he grade his own papers?

Christy: Yes, he looked at them. He looked at them, yeah, definitely.

Sherwin: Was there daily homework?

Christy: No, we have to hand it in every month or so. We would hand in a batch.

Sherwin: I see. And he would go through them?

Christy: Yeah.

Sherwin: How many students were in a class?

Christy: I guess there must have been ten or fifteen, something like that.

Sherwin: So there was quite a bit of grading work.

Christy: Probably. Some of the students did not succeed. Basically, they found, I think, the work too difficult, or they did not get along with Oppenheimer, or something. Some of them were turned off and ended up very unhappy at having studied under Oppenheimer. Basically, they, in a sense, failed and were unhappy.

Sherwin: Yeah. Surprisingly, all of the people I have interviewed—I guess, what comes from interviewing survivors only—nobody has mentioned that. For example, Max Friedman, did you know Max Freedman?

Christy: I do not think so.

Sherwin: He came a little bit later. He said that he was really not at that level, and so barely survived. But he worked very hard, and Oppenheimer knew it. He often got A’s, but not because he really understood the work, but because he was striving so hard that Oppenheimer noticed this and was very kind to him, even though he felt he never was on top of things.

Christy: Well, no one felt they were on top of things. You were struggling to survive all of the time.

Sherwin: Who were some of the people who fell by the wayside?

Christy: Did you ever here about Pete Peterson? I think that he was not very happy.

Sherwin: No.

Christy: Did you ever run into that name?

Sherwin: No, is he still?

Christy: He is an executive in an outfit in Albuquerque, I think.

Sherwin: Could you just repeat that name?

Robert Christy: He was known as Pete Peterson, but his name may have been Robert Peterson. He was very large, nearly as tall as I, and quite, quite broad, fairly heavy. I would guess about six two or three, and fairly heavy. He had been a Boy Scout, and he was still basically a Boy Scout. But I think he was sour on the experience with Oppenheimer.

Sherwin: Are there any others?

Christy: Let me think. Have you ever run into the name Gilbarg?

Sherwin: Nope.

Christy: I forgot what happened to him.

Sherwin: I must have interviewed fifteen Oppenheimer students. As I say, nobody, except you, has brought this up.

Christy: Well, I believe that of the order of twenty percent of the students or so did not make it. They would drop out, or go away, or something.

Sherwin: Did any of them stay with physics?

Christy: Oh yes, they stayed with physics. They got out of theoretical physics with Oppenheimer. That is all. They ended up doing experimental thesis or something like that.

Sherwin: Was there another theorist there?

Christy: Basically, no.

Sherwin: Did any of them go off to other schools?

Christy: I forget.

Sherwin: Off to other schools?

Christy: I say I forget. I do not know.

Sherwin: Oh, I see.

Christy: I do not really remember, but I do remember that there were some people who were not too happy.

Sherwin: Okay. Are there any things that I did not ask?

Christy: I saw Oppenheimer off and on, more or less, after the hearings. I was at the Institute for Advanced Study, I think, in the 1960-61 on sabbatical.

Sherwin: Oh, okay, could you tell me about that?

Christy: I was exploring some new ideas, which I developed while there, in astrophysics, and had a very successful time. Saw Robert and Kitty certainly much more than I had previously since we were right there. But his life was more strained.

Sherwin: Some people tell me, who knew of him those years, that the hearing had, in a sense, if not broken his spirit, then sort of taken a great deal—

Christy: That is my impression, yes.

Sherwin: Out of him. This is a quote from someone, “That he had not done any serious physics since the beginning of World War II. By the result of the hearing and that gap of time from ’40 to ’55, let us say, he just never was able to get back into doing serious work.”

Christy: I suspect that is true. I guess I did not expect it of him at that point. He was encouraging to people, and that encouragement was helpful. But no, he was not doing physics himself, basically.

Sherwin: Was he still on top of it?

Christy: I felt that he was. Yes, he was certainly aware of what was going on. He attended seminars. He read things. He was quite conversant with what was going on.

Sherwin: He was still able to really deal with people on their own level, if they were doing serious work?

Christy: Well, I think he could hear it and understand it. I do not know whether he was able to give advice as to how they might proceed, which is something he would have done before.

Sherwin: Now, you mentioned astrophysics. He had done some of that in the ‘30s.

Christy: Yes, he had always had very broad interests that covered basically anything that you could do in physics. Certainly my own taste was similar, and I probably got it from association with Oppenheimer that physics is very broad, and anything that you can use your physics to understand nature, that is a worthwhile activity. It does not have to be elementary particles, although a lot of the most abstruse activity is in elementary particle physics.

Sherwin: How would you characterize Oppenheimer’s work as a scientist?

Christy: I would say that he was probably best known as a critic and as a stimulator of others, than as a, you might say, inventor on his own. Everyone would bring things to him to listen to his comments and criticism.

Sherwin: You were saying that Oppenheimer was basically a stimulator.

Christy: Yes. I recall seminars in Berkeley before the war, and often there would be visiting one of the leading theoretical physicists, [Hans] Bethe, or [Edward] Teller, or Bloch, Felix Bloch. I remember that everyone always, you might say, waited for Oppenheimer’s comments on whatever the subject was. Basically his view was practically the last word. There would be discussion and Oppenheimer could summarize it, and people would accept his view in the end. He clearly had the facility for understanding, synthesizing, and expressing that was—it was generally recognized.

Also as a critic, of course, he was no mean critic. People who got up to give seminars with him in the audience would be shaking because of the criticism that they expected to get, which could be scathing.

Sherwin: Do you recall any particularly?

Christy: Oh, I remember once when he criticized me unjustly. I remember that very well, because he had not entirely—and this was in public at a meeting—and he had not entirely understood my point, and he attacked it.

Sherwin: This was when?

Christy: Oh, this was after the war, at a Physics Society meeting. It was not an occasion in which we could enter into a long debate, so I had to just bear the attack.

Sherwin: Can you describe it?

Christy: Well, he just said that I was wrong. Coming from Oppenheimer—I say, I do not remember the details. I remember that I was very upset.

I was going to say that I remember Dick Feynman having the same reaction, when he first proponed at his ways of calculating Feynman diagrams and things. [Niels] Bohr was in the audience, and Bohr said that “The man does not understand physics.” Well, you cannot argue with Bohr in public. So I say Feynman was very upset.

Sherwin: Yes.

Christy: Because Feynman’s approach was very different.

Sherwin: It was very intuitive.

Christy: Yes. So I say when you are attacked in public by a great man, it is a little bit hard on you, especially if the great man is wrong.

Sherwin: Yes, well, it is better that way than if he was right, actually.

Christy: Perhaps better that way, yes, all right. But I am just saying, I think many people will recall the fears they had in expressing things in front of Oppenheimer.

Sherwin: What would you consider his most important work?

Christy: Well, do you mean in physics?

Sherwin: In physics, yes.

Christy: I find it hard to put my finger on it, to tell the truth.

Sherwin: Did you ever do a paper with him or anything?

Christy: I do not think we ever did anything jointly. That is, I have always felt that his most important work was the body of graduate students that studied under him. This is a little bit different than what you are asking, perhaps.

Sherwin: Yes. Well, so the major fields of his interests—although he did not make any sort of major breakthroughs—

Christy: His work was at the forefront of particle physics for approximately ten years. But my own background covers only the last three or four years of that. I know what was going on. He was interested in cosmic rays, because they were a way of getting at high-energy particle interactions for understanding relativistic particles. He was interested in nuclear physics. But I do not know what history judges as his principle contribution. What has other people said? Do you know?

Sherwin: Well, it is interesting—not something very different than what you say. Those who were sort of in the period, let us say, ’32 to ’36, when he did some of the work on which has now become black hole.

Christy: Well, he did it with Volkoff.

Sherwin: Yes.

Christy: He worked on that with Volkoff. I thought that was the first time he did that, was around ’37 or so.

Sherwin: No, ’36, ’37.

Christy: Okay. Oh, Snyder was another student there at the time, by the way, who worked on that. Oppenheimer, Snyder, and Volkoff. Hartland Snyder. I do not know whatever happened to Hartland. Have you run into him?

Sherwin: No, I have not. It has just been interesting to me—I mean, my confidence in this area is limited. Although I am able to understand it enough, I hope, to write about the excitement of physics clearly and some of the issues, I am not confident enough to make any judgement.

Christy: I have never run into something that clearly had his name and was considered a major thing. I say it is a whole collection of things, but no one thing.

Sherwin: Yes.

Christy: This is in my mind. But nevertheless, even among the elite and theoretical physics, his leadership was acknowledged as a critic, as someone who understood what was going on and so forth.

Sherwin: Would it be fair to say, and someone has pointed out, Oppenheimer was the first person to really have a school of physics?

Christy: In this country, certainly, yes.

Sherwin: Now, I am moving from here. Tell me if this is too much of an exaggeration. That it is because he was capable of understanding such a broad range of physics, and accommodating so many interests, and seeing the relationship between the various interests of different students, and seeing physics so much as a whole. This school of theoretical physics had a very broad approach, and that certain, let us say, advances were made, simply because of that. Because there was somebody conducting the orchestra and everybody was not sort of playing off on their own. Is that an analogy that makes any sense whatsoever?

Christy: I would say that I do not know. It seemed to me that he set a style, and that style stuck with the people who worked with him. That had a very significant effect on them and their approach to physics. I think it was Oppenheimer’s style. The person who worked with him over the longest period, you may well have talked to, Bob Serber.

Sherwin: Serber, I have talked to him.

Christy: He was Oppenheimer’s kind of right-hand man for many years.

Sherwin: Yes, I have talked to him at some length. Let me ask you a question that is sort of a hard one. Let us say, Oppenheimer had not existed. In some way or another, one has to assume quantum mechanics would have made—

Christy: Quantum mechanics, oh yes. I think that basically physics would have advanced much the same, because the mainstream and theoretical physics was not in this country anyway. He helped introduce it to this country, but there was plenty of activity that was not in this county.

Sherwin: Yeah, so what difference would that have made?

Christy: I think that there would be much less theoretical physics activity in this country. I think that he greatly enhanced the prestige and the amount of activity in theoretical physics in this country. I think there has been a major impact. He made a major impact on theoretical physics in this country.

Sherwin: Sort of almost a domino effect, in the sense that he attracted so many good people, and they went out and did work, and in turn—that kind of thing.

Christy: Yes, yes, right, yes.

Sherwin: Now, if there was less theoretical physics in this country during this period, again, what would the difference had been?

Christy: Well, I think this country had always been, you might say, very strong in the gadgeteering approach to physics. But that approach did lack something. It lacked the theoretical background. For instance, it has been commented many times that [Ernest] Lawrence’s lab in Berkeley missed out on really quite a number of fundamental discoveries that were basically there, but they were not made there, although they could have been made in Lawrence’s lab.

Sherwin: But Oppenheimer was there?

Christy: Oppenheimer was there, yes. But there is something underneath the surface in experimental physics. It is the people who are there who see the data, are the ones that has to see that. That is, a person who is in another building and who occasionally talks to you, will not see the things that are lurking under the surface.

Sherwin: So Oppenheimer was not intimately involved with all Lawrence’s—?

Christy: Well, I would say he was not there sitting while the data was coming in and trying to figure out what in the world does this mean, and so forth. That is where the discovery is made, is trying to figure out what is going on. By the time someone has misinterpreted it or failed to see that there was an effect there that should be pursued, if that is not caught at the beginning—for instance, the discovery of the neutron and artificial radioactivity. All of these things were basically there, but they were not found in Berkeley first. The people right in the lab would have to find them, and I think if their training has more theory associated with it, they will perhaps be better at understanding the strange things that go on. I think that physics was enhanced in this country because of adding a greater measure of theory to it.

Sherwin: Okay, now I see what you are saying, that the work that was being done, the people who were working with Lawrence in the 1930s were products of the education in the 1920s.

Christy: That is right.

Sherwin: Most of the experimentalists were educated in the United States. They had a very thin theoretical background.

Christy: More or less, that is right.

Sherwin: They missed so much of it.

Christy: Well, I am not sure. See, this is maybe one reason why.

Sherwin: But for the post-war period, most of the experimentalists, or a lot more experimentalists, were educated in the ‘30s when there was more theory.

Christy: That is right, or in the ‘40s. I say, I think the character of physics was gradually changed by bringing more theory in. I think Oppenheimer—

Sherwin: Oppenheimer was very much responsible.

Christy: I think so.

Sherwin: Across the country in the ‘30s, who were the really important theorists? Not simply in contributions they made. Bethe did his work that he got a Nobel Prize for in the mid-‘30s. Oppenheimer brought quantum mechanics to America, supposedly, or did he just bring it to the West Coast? Did Bethe do the same thing on the East?

Christy: Well, Oppenheimer was here long before Bethe.

Sherwin: Bethe came in when, ’36 or ’37?

Christy: Must have been ’37 or something like that, ’36, 37, somewhere in there.

Sherwin: Yeah.

Christy: There were a few others who were here earlier, Ed Condon.

Sherwin: Where did Condon teach?

Christy: He was at the glass company.

Sherwin: Oh, yes, Corning.

Christy: Yeah.

Sherwin: He never had an academic position?

Christy: I do not know. There was someone who was at Chicago, and then at the Marine lab in La Jolla, a theoretical physicist, and the name escapes me. But there were just a very, very few. But he never had much impact, never had students. He did not have an impact.

Then there came a flood of refugees, and Bethe, and [Victor] Weisskopf. I remember [George] Placzek, Teller, and these came in the late ‘30s, more or less. But there just were not very many. Oppenheimer was just one of the rare ones that started a group.

Sherwin: Well, that is very interesting. Good, now, last question. Do you, by any chance, have any letters from Oppenheimer, from especially the—?

Christy: I do not. I am not one to keep things.

Sherwin: You are a physicist.

Christy: All I can say is that I have not seen one lying around for a long time, and I am not about to turn over all of my papers to see if there is one.

Sherwin: All right, there is no files? Okay, I just thought it was important to ask. He kept very—

Christy: He was quite a correspondent, I know. Physics was done by correspondence in the ‘30s, and I know he corresponded with quite a number of people.

Sherwin: He and Serber. For example, every Sunday, he would set aside Sunday, a part of Sunday every Sunday. He was a very organized person, that is Oppenheimer, and answer correspondence.

Christy: I see.

Sherwin: He and Serber would write letters to each other on Sundays. The letters would cross. Serber told me that before he went to Los Alamos, he burned all of it because there were a lot of politics in them. So the stuff during the war and afterwards, Oppenheimer’s papers are at the Library of Congress. There were carbon copies of most things that he has written. But for the stuff during the 1930s, it is very hard to find anything.

Christy: Yeah.