The Manhattan Project

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Robert Serber's Interview (1994)

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Robert Serber was an American physicist. In 1941, Serber was recruited by J. Robert Oppenheimer to work on the Manhattan Project. Serber was tasked with explaining the basic principles and goals of the project to all incoming scientific staff. Moving to Los Alamos in 1943, he gave lecturers to members of the Manhattan Project about the design and construction of atomic bombs. His lectures were known as the “Los Alamos Primer." In this interview with Richard Rhodes, he discusses the decision to develop a hydrogen bomb. Serber also recalls Oppenheimer’s security hearing, the Chevalier conversation, and how the hearing changed Oppenheimer. Serber also explains why his loyalty was questioned by the government, and why the government was suspicious of his wife.
Manhattan Project Location(s): 
Date of Interview: 
Location of the Interview: 
New York

Robert Serber: Ernest [Lawrence] got overexcited about the Russian bomb. I imagine that [Edward] Teller called him and got him worked up. I warned him about Edward’s Super, that it wasn't a practical idea at the moment. I told him if he wanted to really find out he should talk to [Hans] Bethe, but he never did. He was all gung ho for the Super and he immediately went with more or less the action before he thought of what he could do, and the thing to do was to build these reactors to make tritium. He had it all figured out where to do it and who would be the director.

Richard Rhodes: But they had not in fact done any reactor work, either of the men?

Serber: No. They had not done any of the reactor work at all, never thought about it, even. When the GAC [General Advisory Committee] meeting was coming up, he asked me to present. The reason he asked me was he thought I would get a more sympathetic hearing from Oppenheimer than Willy would.

Rhodes: So Lawrence asked you?

Serber: Yes. Well, there are several reasons why I did it. One of them was of course that Ernest was a dictator and if he asked me to do it, you either did it or you to fired. But that wasn't the principal reason. It didn't seem like a bad idea at that point to develop some more reactors, to build some more reactors.

Rhodes: These were to make tritium?

Serber: Well, not necessarily.

Rhodes: To make neutrons?

Serber: To make neutrons, which could be used to make tritium or to make plutonium or whatever. It seemed to me like a plausible thing to do at that point.

Rhodes: Were you aware, or maybe I should say was he aware, that there had just been approved a major expansion in the whole plutonium AEC complex on October 10th?

Serber: I wasn't aware and Ernest didn't seem to give any sign that he was. He never indicated that in any of the discussions. Want to hear about the GAC meeting?

Rhodes: Just back up and say, how did you become to be at Berkeley? What was your position there?

Serber: I was the director of theoretical physics at the Radiation Lab.

Rhodes: Had you gone there after Los Alamos?

Serber: After Los Alamos. 

Rhodes: In what, '46?

Serber: Yes. In December of '45.

Rhodes: Oppenheimer had gone back to Berkeley too at that time?

Serber: Oppenheimer, he went to Cal Tech and then he came back to Berkeley, I forget how. Maybe in September or something like that.

Rhodes: How did you feel about their proposal? You said you didn't think it was a bad idea to have some more neutrons around if you needed them. So then onto the GAC meeting.

Serber: I went on to Princeton and went and stayed with Oppie that night before the GAC meeting. Oppie told me that he had just received the telegram or a letter or something from Jim Conant, which was essentially the resolution that the GAC passed, that the majority passed. He told me come and he showed me.

I was astonished, coming from Berkeley. I had no idea people were thinking anything except pushing weapon developments as fast as they could. Conant was the prime move on that. And the next morning he went down to Washington. Bethe and I went into the—before the formal meeting started, Bethe went to testify on his opinion of the Super because Edward and Lawrence were pushing for a crash program.

I enlisted of all the theorists in the Los Alamos effort, which wasn't very realistic since there really wasn't anything – you couldn't have a big effort until you had an idea on what to do. There wasn't any disagreement that Los Alamos should push and try to figure out what to do. They called everybody away from the universities. It didn't seem very sensible.

Hans and I testified, and I remember when I told Ernest’s idea about building reactors on the Pacific Coast, Fermi said to me, “Why Berkeley? I mean, one place that has no experience at all [with] that kind of thing?”

I said, “Well I think the point is that Ernest was stressing what he considered the importance of building more reactors, to the point where he is even willing to do it himself. If there is a better way of doing it, Ernest will be the first one to applaud it.”

The meeting started, and Luis [Alvarez] and Oppie and I had lunch together at the break of the meeting. Oppie told Luis about the resolution. I told him what was going on with Fermi. Luis was very unhappy. He was I think looking forward to being director of a big project.

Rhodes: Why was Luis there at all? If you had come back to represent Lawrence?

Serber: Luis was so anxious, he didn't want to wait for news. He didn't have any business there.

Rhodes: He describes forlornly waiting out in the lobby and watching all the generals go by. You had spent the night at Princeton - did Oppenheimer did you guys talk about the whole business? Was he impassioned about it? Where was he at that point?

Serber: He mostly was showing me what Conant had proposed. We didn't disagree at all about Teller and the Super. There wasn't any sense to do any crash program at the moment. I mean, when you say it like that, you have to dispose of it in five words.

Rhodes: One of the mysteries is that Conant’s communication—no one has ever turned up the document. If you read a letter that Oppie wrote to Conant on the day that he was supposed to have received a letter from Conant, he makes no reference to Conant's position at all. In fact, he tells Conant what is happening as if he hasn't yet heard. Which left me wondering if there really was a Conant letter. Did you see a document or did he tell you something? Everyone remembers a letter afterward. Bethe says there was a letter. Teller says there was a letter.

Serber: My recollection was that I didn't actually read it, but that he had paper in his hand.

Rhodes: Could it have been his letter to Conant? I don’t meant they didn't discuss it, I'm sure they did. It isn't clear - it sounds like the communication might have gone the other way.

Serber: I know Oppie told me that Conant had a proposal. And I think he said that he just received it, the formulation of it, from Conant. That is my recollection. I don't know what he had in his hand.

Rhodes: It is a minor point, but I just was struck by it. He was up at Harvard at an Overseers meeting about a week before then. There is some reference in his correspondence to having a conversation that had nothing to do with Harvard. And then the next thing is Oppie's letter to Conant, which seems to be informing Conant of the proposal to building a hydrogen bomb, to go for the thermonuclear.

Serber: What he was talking about wasn't about the proposal to build a hydrogen bomb. I mean, not directly with Conant’s version of the resolution the GAC passed. It might have very well been Oppie's letter.

Rhodes: Conant’s response.

Serber: Conant’s response.

Rhodes: It might have been a telegram, right? A telegram. Yeah. Okay. Were you surprised that the GAC—well you said you were, that was kind of a shock.

Serber: I had no idea that anybody was thinking in that direction. At the time I guess I wouldn't have appreciated at all the difference between what [Isidor I.] Rabi and Fermi said and what the others said. I don't think it is a practical matter that either of them would agree to anything of great consequence. I thought it would put us in a better moral position. It would be a good public relation. I didn't think for a minute the Russians would accept any agreement. Rabi and Fermi were eager to have an international meeting to discuss it.

Rhodes: To negotiate something.

Serber: To negotiate it, right. I didn't there was any chance that they would accept anything like that. I thought it was a good idea to try.

Rhodes: Was it Oppenheimer's notion that we really would forego—and Conant’s—developing thermonuclear?

Serber: Is that not what the resolution said?

Rhodes: It is how much Oppenheimer - for example, Luis told me that Dean Acheson says in memoirs, “I never could understand how you could disarm by example.” I always thought that was kind of a misconstrual of what Oppenheimer meant. He wasn't proposing unilateral disarmament.

Serber: No. I think the idea was that they—remember at the same time, the GAC was urging Los Alamos to go ahead with the project. I think the idea was to go ahead with the research and not any particular reason there was on how to do it and at the same time make a public demonstration. So you could take the high moral tone and you wouldn't do it essentially, unless somebody else did it. Meanwhile, you were trying to find out how to do it. I think it was moral. I didn't think it would be any great loss to postpone development because they didn't know what to develop.

Rhodes: This connects to something that I find confusing. Oppenheimer seemed to be so strongly concerned to end war with nuclear weapons. Yet his whole emphasis as GAC chairman over the years was to try to get essentially tactical weapons, smaller weapons that could actually be used. It is hard for me to reconcile those two positions.

Serber: Well the first one was an estimate of what was actually happening, given the situation. Oppie and I used to call the bomb used in Japan “a psychological weapon,” which we thought would end the war. Later on when the situation changed and it was a question of both sides having weapons and not wanting to use them against each other sitting, suicidally. Well, I mean, it was a particular tactical situation where the Russian ground forces were strong. The question was how could you protect Europe from the Russian ground forces?

Rhodes: Make them small enough to use in Europe, as it were.

Serber: It was a particular tactical situation.

Rhodes: That makes sense because the whole push of the Air Force was consistently for the biggest possible weapons.

Serber: With the biggest possible budget.

Rhodes: Yes. Did you get involved in the MTA project?

Serber: Somewhat in the beginning. In the beginning I was the Director of Theoretical Physics Division. And I had groups that did not only pure research but did machine design, and the machine design work working on the MTA. I was responsible for that part of it. I sat through a lot of meetings.

Rhodes: I bet. By the time I got to Luis, which was in the early 80s, late in his life, he expressed what I took to be pretty sincere unhappiness on having to have worked on the MTA. He attributed that work to his losing contact with the cutting-edge of physics, having to go back and sort of relearn to do the work that would eventually led to his Nobel.

Serber: That was a big diversion at Berkeley. Then I left before any construction really started.

Rhodes: Was Luis a sort of super-patriot in those days? Certainly the record looks like that.

Serber: Luis was different, mostly tight-knit and Luis was always logical. He didn't respond in an emotional basis. Whatever his assumptions were, he would argue reasonably and logically from them. They were all wrong usually, but he was willing to discuss it.

Rhodes: Rather than just assert that “This is the truth and you aren't a patriot.”

Serber: Luis was quite unusual in that respect.

Rhodes: After the H-bomb decision, did you have a lot of contact with Oppenheimer through all of those years? You continued to see each other and be friends, yes? After you came here?

Serber: After I came here. Didn't have as much as you might think. It is only forty-five miles but you don’t get down every week. We would see each other maybe several times a year.

Rhodes: I just wonder if he was aware that he was slowly being pushed out of the government by people who were opposed to his—what they took to be—his position. All of his cords were cut off one by one until he was left with just one affiliation with the AEC. One of the reasons that the whole security hearing seems so unusually cruel.

Serber: Could have just let it go, his term was going to expire pretty soon. They could have just let it go. Probably was at least [Lewis] Strauss, that backed it up.

Rhodes: I was going to ask you, was he aware that Strauss was gunning for him?

Serber: You know what is smarmy about his testifying? The business of sending -

Rhodes: Isotopes.

Serber: Isotopes to Europe. Yes. You would think he knew after that. On the other hand, Strauss was the chairman and the trustee of the Institute [of Advanced Study at Princeton]. They had to get along to some extent.

Rhodes: Apparently Strauss' favorite way of firing someone was to find a better job for him somewhere else. Which must have been a really delicious sense of superiority that he liked, that he could do that.

Serber: Yes. I think it was the Air Force mainly that was out to get him.

Rhodes: Actually, the record shows it is pretty clear that Strauss was too. After Borden's letter, Strauss is the one—the FBI made Strauss request the wiretaps on Oppenheimer's home, his lawyer's office. Strauss requested those. Strauss got regular copies of those discussions, and used them to plan the strategy that [Roger] Robb used in the hearings.

Serber: Oh yeah. The Air Force started it.

Rhodes: Did you talk to Oppenheimer about the security hearing during that time?

Serber: No, but one morning here at 3:00 am I got a phone call. The guy says, “I am a lawyer in [Lloyd] Garrison's office.”

He told me Oppie is going to have these loyalty hearings, and a request from Oppie not to communicate with him. He was sure the phones were going to be tapped and the letters. So I didn't communicate with him during that period. Later on, Kitty told me that it wasn't true that Oppie requested it. It all came from Garrison. He didn't know anything about it.

Rhodes: Was that because you had you been a member of the Communist party?

Serber: No.

Rhodes: It was your wife, Charlotte?

Serber: She wasn't a member.

Rhodes: She wasn't a member?

Serber: No. She was never a member.

Rhodes: Oh. I thought she was.

Serber: They had two things against Charlotte. One was that her father was an old time Socialist in the Spanish Wars, and he organized the medical aid for Spain in Philadelphia. Her brother was very left-wing and he sounded like a communist. I always heard that there was a certain amount of discipline in the Communist party. That wasn't her brother. I could imagine him giving them some money, but I can't imagine him doing anything else.

In Berkeley she was secretary of the medical aid of Spain and also an aid to Russia Committee, and aid to Britain Committee, she worked on all three of them. I think that it was her association with her father and brother that they were really worried about. They didn't have anything at all on Charlotte. The fact that she worked for—

Rhodes: What was her maiden name?

Serber: Leof.

Rhodes: Yeah. There is a reference in the FBI files on Oppenheimer to the “Leof family of Philadelphia” in connection with Charlotte. There is also, by the way, this is before 1950, there is one of those an informed observer things that the FBI does, that says the most left-wing member of Oppenheimer's group is Phillip Morrison, and second to him is Robert Serber. And the source of this information? Edward Teller.

Serber: Left-wing.

Rhodes: That they are considered “the most leftist among the physicists.”

Serber: Well. Yeah, I don't really know why they would consider me a leftist.

Rhodes: Why would Garrison have wanted to keep you from communicating with Oppenheimer?

Serber: I mean, again with the record of Charlotte, I imagine that they considered Charlotte left-wing. The only thing I can think of was that any left-wing connotation was a Teacher's Union in Berkeley, which Oppie was a member and I just followed him in. I don't know anything else I could have considered that way. Of course I was a good friend of Frank Oppenheimer. It was all, I guess, by association. I associated with Charlotte. She associated with her family. It was all that kind of thing.

Rhodes: It was. Very much so. With Oppenheimer too. The fact that Kitty had been a member of the party once was almost evidence to the FBI that he must have been too. You didn't testify at that hearing, right?

Serber: No.

Rhodes: Probably for the same reasons we are talking about, because your name comes up quite often. In the index there’s about ten entries for Dr. Serber.

You remember that a lot of the problem at the hearing for Oppenheimer turned on the question of his veracity about an espionage contact during the war at Berkeley?

Serber: The Chevalier one?

Rhodes: The Chevalier. They particularly brought forward the conversation that he had with Boris Pash, which I brought because I wanted to read you a paragraph.

Oppenheimer says, “I have known of two or three cases and I think two of the men were with me at Los Alamos. They told me they were contacted for that purpose,” meaning, for espionage. And then he gives the reason.

The background was, “Well, you know how difficult it is with relations between these two Allies. And there are a lot of people who don't feel very friendly to Russia. So that the information, a lot of our secret information on radar and so on, doesn't get to them, and they are battling for their lives and they would like to have an idea of what is going on. And this is just to make up, in other words, for the defects in our official communication.”

Then he goes on to say, “Of course, that is treason. You can't do that.”

This was the crux of what supposedly was his telling lies because either this version was supposed to be true, with two or three contacts or the other version was supposed to be true, where Chevalier came to him and said, “This other guy wants me to talk to you.”

Oppenheimer said that this was not true, the two or three contacts, but that the Chevalier story was true. Later in '46, the FBI interviewed George Eltenton and Haakon Chevalier. Eltenton told his story. He didn't say two or three, but he did give this estimation. It turns out that is the same kind of statement that the Rosenbergs used when they contacted people, Harry Gold used when he contacted people. It was the standard line for scientists, that there was a higher morality involved.

I am just wondering if this wasn't the true story, that the Chevalier story wasn't something that Oppenheimer made up to protect Chevalier.

Serber: To protect?

Rhodes: Chevalier gave the other story—not this one, but the other story—in '46 to the FBI. And when Oppenheimer then was—

Serber: The other story was that Chevalier he went to—

Rhodes: He went to Oppenheimer just to tell him about it, not to actually solicit information. After Chevalier talked to the FBI, Oppenheimer was then contacted about three months later, and he gave the Chevalier version from '46.

Serber: And that's the version I got from Oppie.

Rhodes: That's the version that he insisted was the real truth, that this was, as he put it, “a cock and bull story.”

Serber: Well the two or three people, I mean, I don't know who it was supposed to have been.

Rhodes: I don't either. I think there is enough independent evidence to indicate there were major attempts to contact people around Berkeley by [Peter] Ivanov at the Soviet Embassy. Probably by Chevalier, if he was in fact a part of all that. There is a case to be made because the same kind of contacting was going in other places too. And they also insist there were ten thousand pages of documents in Moscow.

Serber: I think my own impression was that, what's his name, Eltenton, was the guy that was trying to do it. And that Chevalier was—his role, what he wanted to do, was just tell Oppie about it because he thought he ought to know what was going on. That was my impression of the thing. Oppie didn't say that to me explicitly, but he implied that. He told me that Chevalier was innocent.

Rhodes: Did he?

Serber: Yeah.

Rhodes: Did he tell you that when? After the war?

Serber: After the war.

Rhodes: Yeah. Did any of this come up during the war that you recall? Were you ever contacted by anyone?

Serber: No, I wasn't. And in fact, I didn't know anything about this until it came out after the war.

When we were living with the Oppenheimer's and once we went in for a cocktail and the Chevalier's were there, and Oppie went out to mix a martini. And Chevalier followed him out into the kitchen. I was there with Kitty and Shirley and Barbara Chevalier.

After about fifteen minutes Kitty said, “What happened to our martini? Bob, go in and see what’s holding them up.”

I walked into the kitchen and I had this feeling that I suddenly really interrupted something. And they both looked embarrassed and Oppie started right away talking to me immediately, and I'm sure that was—

Rhodes: That was the moment?

Serber: That was the time that Chevalier was talking to him about it. I mean, that did happen. I'm pretty sure.

Rhodes: I'm so struck with this testimony that he gave in '43 because the pattern, the rationale is identical with the one that was used consistently throughout the country, as far as I can tell, by Soviet agents attempting to contact American scientists. They always appeal to one’s higher values. And I see how he might have concocted that, as he claimed later, whether there were two or three contacts or what. But it also doesn't make sense he would say there were two or three, just to make it up. It does makes sense that he was trying to help a friend whose livelihood he accidentally compromised.

Serber: Both things may be true, most likely. That wasn't the only attempt to reach him and in the course of it he learned he wasn't the only one. That is the most plausible explanation.

Rhodes: There was one other point that actually Lewis Strauss' biographer raises that I have never heard of before. That is, what Oppenheimer told the FBI in '46, which was the Chevalier version of the story, was still within the statute of limitations, whereas this was not. This is the story Oppenheimer said was not true. But he was protected from being legally liable for this statement, but not for the later statement. Is that the sort of thing he might have taken into account? I mean, he really was fighting for his life in '54, at least his political life.

Serber: I shouldn't think so. I mean it is, I shouldn't think that. I was thinking that could have affected what he said.

Rhodes: What’s really sad is that in both instances, whichever story is true, is that what is pointedly true about them is that he said no. The evidence is not of his disloyalty but of his loyalty. He was stuck on a dilemma of having to deal with these two different stories. How sad.

Serber: Yeah. Why would he mention it to Pash at all in the first place?

Rhodes: I am trying to think of how it came up. This was six months after it happened. I haven't gone back and read the earlier part of this very long transcript of their conversations. This may be the time when they were talking about [Rossi] Lomanitz. Oppenheimer wanted Pash to know about Eltenton; that is why he went to them. And as they talked Pash kept saying, “Well, we need to know more than just a name. How do we know about this man? What is the reason? What is the context?” That is when he gave this context, but refused to give any names.

Serber: Then later on he said the story of two or three was false.

Rhodes: That is what he said at his hearing. But that was apparently the real turning point of the hearing for him. He was apparently very much made uncomfortable by this transcript that he had forgotten about, being brought up all of those years later. And it was doled out to him at the hearing a piece at a time; he wasn't allowed to read the transcript. They would read a line and say, “Did you say that?”

And then it would be something else next that might contradict what he said before. It was really very cruelly used. But it was when he was presented with this statement that apparently he got upset and said, “That is a cock and bull story. Why did you tell that story? Because I'm an idiot?”

You remember those quotations?

Serber: It didn’t make any sense, I have to say.

Rhodes: I want to get the story right, especially because this sort of [inaudible] book has been such a slur on everybody. It is at least clear that Oppenheimer was contacted, maybe more than once, to give information. He has always said no. The only other question I had was, did the hearing change him as much as I have heard people say?

Serber: Yes. Yes, it did. It broke his spirit, really. As Rabi said, “He can run the Institute with his left hand.” He didn't really have anything to do. He spent about a year after the war being an advisor and being in high places and knowing what was going on. And they excluded him, and after that he had nothing that he wanted to do in life at that point.

Rhodes: What had he seen as his purpose in those years, when he as an advisor? How much was he involved with Bohr and Bohr's ideas? Being an advisor, did he have a larger purpose in doing that work, beyond the work itself?

Serber: Well, Rabi once said, “I had been an advisor to all kinds of things and ambassador. I don't know that anything I ever did was any good except the Atoms for Peace Conference and founding the CERN and Brookhaven Laboratory.”

 But he said, “I would hate to be excluded from it and knowing what is going on.” And I think it was even more true of Oppie, to be in on things. It gave a sense of importance; that became his whole life.

Rhodes: It's an amazing story.

Serber: Another strange aspect was that because of the hearings, he became a hero of the peace movement. For completely wrong reasons; very mysterious. Part of the reason was that he worded so obscurely you could read anything you want into it.

Rhodes: I have a hard time reading his foreign affairs papers. In fact, sometimes they sort of sound like Bohr.

Serber: That's right. They do. To be honest, a clue to Bohr is that he was dyslexic, which highly offends all of Bohr's ex-students. What did she say? Bohr showed all the classic symptoms.

Rhodes: She is right. Most of all that he had his mother and his brother writing his papers for him.

Serber: That's right. He always had somebody write them.

Rhodes: That's right. Yeah. That's interesting. That is probably the origin of complementarity.

It has been very interesting to have the Soviet side of the story now, about their work on their weapons and to match that up in time with what was going on over here. It is certainly true that they were working on their alarm clock when the H-bomb decision was being made. But if they had gotten their alarm clock, they wouldn't have had much. It would have been 400 kilotons from this thing.

Serber: Yeah. [Inaudible] nothing would have made any difference. That is really the point. Nobody was going to use one of these weapons anyway.

Rhodes: That's right. I really had the feeling, why Truman fired [General Douglas] MacArthur, I have a feeling that one of his reasons was, he didn't want that son of a bitch to have any atomic bombs.

Serber: Truman was a very practical character.

Rhodes: Last thing about that H-bomb decision time, though, it doesn't look as if Truman ever had any doubts about pursuing the hydrogen bomb. It sounds very much as if he at the beginning - certainly as soon as he talked to [General Omar] Bradley.

Serber: You wouldn't expect him to. I think everybody behaved in a way you would expect them to.