The Manhattan Project

Charles Critchfield's Interview

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Charles Critchfield was a mathematical physicist assigned to work on the development of gun-type fission weapons, and eventually implosion-type weapons, at Los Alamos. He returned to Los Alamos in 1952 to work on the development of the hydrogen bomb. In this interview, Critchfield explores the personalities of his fellow Manhattan Project scientists, including Edward Teller, J. Robert Oppenheimer, and Niels Bohr, as well as their personal and professional conflicts. He also discusses the difficulties he faced first in the design of the atomic bomb, then in the design of the hydrogen bomb, especially regarding the Initiator.
Manhattan Project Location(s): 
Date of Interview: 
June 11, 1993
Location of the Interview: 
Los Alamos
Collections: 
Transcript: 

Charles Critchfield: Is that your book, by the way?

Richard Rhodes: Yes.

CritchfieldMaking of the Atomic Bomb?

Rhodes: Yes.

Critchfield: I’ve always heard it, Making of the Bomb. No, I didn’t know it was your book. Rubby Sherr sent me that, and he also sent me excerpts from two or three other books on the bomb. Rubby was my main man in my group for making the Initiator.

Rhodes: Did you get directly in Initiator development?

Critchfield: I was the group leader.

Rhodes: Ah, all right.

Critchfield: And, I’m the one that had to report to Hans Bethe all the time, and his committee, which had Kenneth Bainbridge and George Kistiakowsky, and Niels Bohr when he was here, and Cyril Smith and Dick Dodson, and like that. But my group was the operating group for making that device, testing it, designing it. My other main man was Milo Sampson, he was in charge of my test site down there on the truck route, where the truck route is now. All together, we had about sixty men.

Rhodes: Did Bethe design the Urchin? We saw him last month, and he once again said, “I never get credit for designing the Urchin.”

Critchfield: Well, Bethe has that problem. You know, he and I years ago wrote a paper separately on the P-P [Proton-Proton] reactions in the sun. At first, it was our paper, now it’s his paper. So, well, we don’t worry about that.

Rhodes: I ask, because one of the things that I found in Russia last year, where I’ve been working on the Russian story, the development of their bombs, early development. I found the document, a copy of the document that [Klaus] Fuchs gave them, describing in great detail the initiator, which you know is still classified here.

Critchfield: There’s a classified paper by Critchfield and Fuchs on how it’s supposed to work.

Rhodes: Well, Fuchs passed the exact measurements of all the way the parts assembled.

Critchfield: No, we, together, Fuchs and I worked it out, the theory of it.

Rhodes: So, but the Russians—

Critchfield: Bethe gets the credit.

Rhodes: Yeah, right, well, anyway, but the Russians used your design, I’ll tell you.

Critchfield: Yeah, well, they’re still using it.

Rhodes: No, I mean, their first bomb was absolutely Fat Man from beginning to end, the exact measurements.

Critchfield: Absolutely. And Fuchs knew every detail of it.

Rhodes: Yes, yes. But, that’s when Bethe said, “Oh, there’s my design.”

Critchfield: Well, he’s pretty old now, you know. He’s sort of subject to systematic delusions. Oh, yes, I really owe a lot of credit to him. Did I ever tell—no, I haven’t seen you before.

Rhodes: No.

Critchfield: Bethe was very scornful, disdainful of astrophysics back in ’37 saying, “You can’t prove anything in no laboratory.” But he was the leading author of the “Bible.”

Rhodes: Yes, “Bethe’s Bible.”

Critchfield: And, of course, again, he takes credit for it. He never mentions [Robert] Bacher—it’s always Bethe. And, so he was invited to a conference we had in Washington in ’37, I guess it was, no, ’38 conference.

Rhodes: ’38, yes.

Critchfield: [It was] on energy sources, nuclear energy sources of stars. And when he came to Washington, he told [George] Gamow and [Edward] Teller that he thought maybe the P-P reaction would be important, and they were very embarrassed. Because a couple of weeks before, I said, “Why don’t I work on this P-P reaction,” and they said no, because Carl Friedrich von Weizsacker has looked at it and he decided it won’t work. I’ve talked to Carl Friedrich about this, too. He was quite aware of the idea that Gamow and Teller had had, that the spin could change in the collision. I was, of course, because I was his student.

So, when Bethe said he thought it was important, they said, “Well, Critchfield, our student,” you know, I was getting my degree at that time, “He suggested that, but we turned him off.”

And, Hans said, “Well, why don’t we both do it?”

Of course, he was in Cornell and I was in Washington—

“And post together?”

I worked it out and sent him my work. He added a few paragraphs at the end of the paper, of some analytical work that he did, and typed it up and sent it back to me, signed “Critchfield and Bethe.”

And I wrote back and said, “At Washington, George Washington.” We always go alphabetically, so it came out ‘Bethe and Critchfield’, which was fair enough. But, anyhow, I was very grateful to him for even including me, because a graduate student is the lowest form of life, you know, especially in European universities.

Rhodes: Yes.

Critchfield: And, so all that in meantime, he wrote to us and said, “It turns out that the problem is more complicated, and so I think I’ll publish part of this paper by myself.” And, of course, that was the carbon cycle and he had worked that out. We knew from the tone of his letter he discovered something, but we didn’t know what it was. And that’s why this P-P reaction was published separately. So, that’s, briefly, that’s the story of it.

Rhodes: I’m curious to know your work around Los Alamos, or with what was happening here after the war.

Critchfield: Oh, I see.

Rhodes: You were back here, what—

Critchfield: Well, I came back every year in the summertime.

Rhodes: Were you working on thermonuclear things or on fission?

Critchfield: I wrote some papers related to the primary part of the H-bomb, which is still highly classified as far as I know. I haven’t ever followed it up. My main interest here in addition to that was to try to establish a feeling for supporting basic research.

Then when I left the University of Minnesota to go into industry, I had that job in the airframe industry establishing a basic research laboratory at Convair Scientific. This was supported very actively by the Air Force and General Hoyt [Vandenberg] was enthusiastic about it, and I had a nice laboratory there. But, actually, my main job there was to be a spy for Johnny von Neumann, because he didn’t trust Convair when they were developing the Atlas missile. That was the only thing we could get into the air or into orbit, or, well, into Russia, before they got a real weapon. See, the Atlas missile, you know, was just a big stainless steel balloon, and it’s not anything you’d ever send to the Army without somebody going with it. But it was the only thing we had.

After the test in the Pacific, the engineers at Convair continued to work on the five-engine Atlas, which we wouldn’t need. So Johnny got suspicious that what they were doing was padding the income. Of course, it was more expensive to work on a five-engine device. Then he convinced Convair, well, John Hopkins, I mean, Hopkins, yeah, Jay Hopkins, and General [Joseph] McNarney was the president of Convair, to take me on as a senior officer in the company. My title was Director of Scientific Research. But, the main problem was for me to decide whether they were cheating or not.

Rhodes: How many engines did the one that—

Critchfield: Three.

Rhodes: Three.

Critchfield: And what I found out was that these were very honest engineers, but they were very interested in space travel, going into orbit themselves. And so they were very reluctant to go back to three engines. Of course, General McNarney knew what I was there for. Every time I’d go to Washington, he’d call me in his office and say, “What did Johnny say?” And I’d tell him.

Then I’d go to Washington and Johnny would say, “What did Joe,” I mean, “General McNarney say?” So, it was kind of funny that way.

But I enjoyed being there for five years in Convair, and I still retain my consultantship here, so I had clearance in both places. Then the last year, I switched to a plastic company as vice president and was just starting what we now call the Stealth bomber. This is 1961. You realize it’s that old?

Rhodes: Really? No.

Critchfield: I stayed there just one year and decided to go back to the campus, because I didn’t really have anything to do, and besides, the president of the company wanted my clearance and they wouldn’t give it to him. The people who were paying for this program were super-secret, of course. I still officially don’t know who they were. You know who they were. And, they simply told him, “No, Critchfield’s cleared, you don’t need to be, because he’s your vice president.”

Rhodes: Were you consulting with Los Alamos around the time of the H-bomb decision and the work that went on here with Mike?

Critchfield: Oh, yes, oh, yes.

Rhodes: I had the feeling that there was a lot of turmoil and conflict that went on around that time, among the people at Los Alamos. I mean, Teller certainly remembers it that way.

Critchfield: Well, he wasn’t here, was he? He, mainly, he was at Livermore.

Rhodes: No, this was before that.

Critchfield: No, this was before that.

Rhodes: Yeah, before that.

Critchfield: Oh, yeah.

Rhodes: Really, ’50, ’51, up to the Mike shot.

Critchfield: Yeah, well, Teller didn’t get along too well with [Norris] Bradbury, unfortunately. He complained, and rightfully so, I’m sure, of course, because I was just here in the summertime. But that Bradbury was dragging his feet on this H-bomb, and that may be partly true to John Manley, too. I don’t know, I wasn’t too aware of what was going on here fulltime, except in 1952 and ’53, I was here fulltime. I was here halftime and halftime in Minnesota. That was more continuous than being here just in the summertime. And, finally, Teller got so fed up that he got the Air Force’s support of the Livermore thing.

Rhodes: One of the things that he says is that there wasn’t enough theoretical help through the late ‘40s up to the development of Mike.

Critchfield: Well, yeah, that would be part of his complaint, I’m sure. But, well, there’s a point in there in which the theoretical studies were just nonsense. I mean, there was no possibility of doing the bomb, the Super they called it, until [Stanislaus] Ulam’s idea.

Rhodes: You call it Ulam’s idea. Teller calls it Teller’s idea.

Critchfield: Well, there again, this European paranoia. I mean, you have to deal with these people and there you have it. We had dinner with—actually they were our guests at dinner the other night, and we’re still very good friends. Of course, he’s my old professor. So was Robert Oppenheimer and Stan Ulam.

No, you can’t work with Teller unless you do what Teller says. A couple of times he and Ernest Lawrence tried to get me to come to Livermore from the university, and then when I left industry, they wanted me to come up there. I wouldn’t work with Teller. I mean, he’s a nice guy, but you do what he says and that’s it, and that’s not my style. And, of course, Edward always says that’s not his style either, he wouldn’t work with Bethe, he wouldn’t even work with Oppenheimer there for a while. And, for thirty years, he didn’t speak to Stan Ulam.

Rhodes: Really?

Critchfield: Absolutely.

Rhodes: It got that angry between them after the—

Critchfield: After this Teller-Ulam paper, and Stan never made any claims of sole authorship. Well, what do you do with people like that? I don’t know. Just live with them.

Rhodes: Work around them, I suppose.

Critchfield: Well, that’s a question. With the idea of using the radiation implosion, things really got going here and especially under Carson Mark. Now, you know Carson, though.

Rhodes: Yes, and I haven’t talked to him yet, but plan to later.

Critchfield: Oh, please do, yeah. He may be able to tell you a little more detail, because I haven’t followed the declassification of what, well, the small contribution I made in that program, but I do remember writing some papers on it.

Rhodes: Well, I asked about the amount of time that theoreticians gave, because you were coming as a consultant and you’re a theoretician, right?

Critchfield: Right.

Rhodes: So, did you have a sense that there wasn’t enough help for these problems to be worked on in the late ‘40s?

Critchfield: Well, not after Carson took hold of it, no.

Rhodes: Carson has suggested that one of the things that paced the development of the hydrogen bomb was the need for computational, like computers.

Critchfield: Well, yeah. The development of computers was commiserate with this problem, and we didn’t have any computers in the old days for the A-bomb, as you know. We had Marchants and what was the other, Monroes.

Rhodes: Monroes, yes, right.

Critchfield: Which, incidentally, were kept in order, working order, by Dick Feynman and Nick Metropolis. 

Rhodes: We talked to Nick the other day. He was telling us that.

Critchfield: And typewriters. The typewriter would break down, they’d call Dick Feynman.

Rhodes: That is high quality help. Well, but look, when I—

Critchfield: No, I didn’t detect any trouble. It was limited by the speed of computers and their capability, of course.

Rhodes: But when I talked to the Russians and I said, “You didn’t even have computers when you worked on your bomb. What did you do?”

They said, “We used theoretical physicists.” Could that not have been done here?

Critchfield: Well, yes, that’s what they did do, isn’t it? The papers I wrote were analytical papers, which—I am no computer person. But Carson can fill you in much better.

Rhodes: I was just interested in a different perspective, because in a sense, Teller’s version of the problem and Carson’s conflict with each other.

Critchfield: Oh, those two don’t get along together at all.

Rhodes: Carson feels very much that there was as much effort given to the Super as could have been given to the Super.

Critchfield: Carson didn’t think about anything else. And, in fact, that’s one reason they wanted me to come here. I wanted to leave industry. Look, I’m trained as a professor. I’m not an executive or anything like that. But I happened to come through Los Alamos and I was on my way to Wisconsin. This would be early ‘60s, no, ’61. And, of course, it was the end of the ‘60s that they blew Wisconsin up.

Rhodes: Oh, yes.

Critchfield: So, I’m glad I didn’t go there. But, when I was here, Norris and [Cornelius] Everett said, “Well, look, if you’re going to leave industry and your high salary and all that stuff, come here. We’ll pay you a little salary.”

I said, “Well, I can’t, because I promised Lawrence and Teller that I will delay my decision until the end of July.” Because they wanted me to go up there.

Rhodes: To Livermore?

Critchfield: Right. And, they said, “How long are you going to wait?” And, since I had already made up my mind, really, that I didn’t want to work with Edward—well, I like Lawrence. I mean, Lawrence, see, would’ve gave me more of a free hand. But at the end of July I decided to come here. And the reason they, especially Carson, wanted me to come here was that he was spending so much time on the Super, on the H-bomb, that he wanted someone to take care of his rebellious men. People wanted to do their individual, self-motivated research. That’s what I’d been doing in industry, too. I used to give speeches to businessmen about the importance of having at least a handful of people who knew what they were doing in these big programs. They were mainly interested, of course, in anti-missile missiles and things. So that’s why I came here was to be Carson’s assistant. I was associate division leader or something, to handle our basic research people.

Rhodes: And, again, when was that?

Critchfield: 1961.

Rhodes: ’61. But, you were also here in ’52 and ’53?

Critchfield: That was an arrangement with the University of Minnesota, that I could be here halftime and halftime [inaudible].

Rhodes: And, that’s when you were starting some basic research work here?

Critchfield: Well, that was one of my main interests here. No, I was also interested in the tests, especially the Mike shot in the Pacific. In fact, by that time, of course, Robert had lost his clearance.

Rhodes: Yes.

Critchfield: I remember being in my office, for some reason, and this was one of those periods in which I was here instead of Minneapolis. I got a call from Robert and he had heard about the Mike shot, and all he would say on the phone, he says, “Critchfield, can you give me a number?”

I said, “Fifteen.”

He said, “Thank you.”

He knew what it meant, of course, and I guess it was around twelve or fifteen megatons, wasn’t it, something like that?

Rhodes: I think it’s put down at 10.5 these days.

Critchfield: It’s now 10.5? Anyhow, I gave him fifteen, and he was satisfied. Of course, I knew I was breaking the law, but Robert was an old friend of mine and I wasn’t about to tell him, “I can’t tell you.”

Rhodes: Exactly.

Critchfield: And, it wouldn’t mean any, and of course, I realized the phones here are tapped, so he probably just didn’t want to—but it didn’t mean anything except between Robert and me.

No, I was very interested in that program, but again, I kept telling, especially Carson, that we should have people who are on the frontiers of these general problems like equations of state or opacities for radiation and things like that. To keep them here, you had to give them some free hand to follow their own desires. Carson agreed, but he didn’t have time.

Rhodes: There was a lot of pressure to develop the hydrogen bomb once you had the principle tested?

Critchfield: Yeah, there were very challenging problems, of course. Just like in the A-bomb, there were things that we had no idea what to do about, like transport of radiation and high temperatures, high pressures and all that sort of thing. No, I never lost my interest in that, but I didn’t do more than a few papers of my own.

Rhodes: What was the push after Mike? Was it to get a deliverable design?

Critchfield: Oh, of course. And, I mean, that thing was a huge piece of machinery. As I remember, and there again, these guys have such a convenient recollection, you can’t get them to admit it now. It was the first Russian test with using radiation implosion. I forget when it was now.

Rhodes: ’55 was the first radiation implosion. They had a test before that was a kind of Alarm Clock. It was concentric spherical layers of lithium deuteride and uranium. That was their ’53 design.

Critchfield: ’53, it was after ’53 that we finally got the idea you had to use lithium, or you know, boosters in the thing. I don’t think you’d get anybody to admit it now, I don’t know, maybe.

Rhodes: You mean, got it from the Soviet test?

Critchfield: Well, I mean, that’s where the idea came.

Rhodes: Ah.

Critchfield: No, we got, Hans got the idea, of course, but he got it from the Russians.

Rhodes: That’s a funny story.

Critchfield: Now, that’s my recollection. I think Carson can—if he can talk about it, he could straighten you out on it.

Rhodes: Well, because then there’s the understanding that you could use lithium to breed tritium was not new.

Critchfield: No.

Rhodes: No, but the idea of putting it in. Well, I tell you, the Soviets have said a lot more about that particular design. They say it was twenty percent fusion, they say it was about the size of Fat Man. When I told Bethe that, he said, “I don’t know how they did that.” He said, “We couldn’t that kind of squeeze with the high explosives on our Alarm Clock design like that.” So he said, “If it really is as they say, that was quite an achievement on their part.”

Teller, of course, says, “Ehh.”

Critchfield: Well, I became disenchanted with Teller’s memory a couple of years ago. He sent me, Jean and me, the first twenty-one chapters of his autobiography. Have you seen it?

Rhodes: No, no, of course not. I’d like to.

Critchfield: And, we were just astonished at how selective his memory was. I’ve challenged him a couple of times now, since I see him once in a while, and he can’t remember. “I don’t remember that.”

Rhodes: Yes.

Critchfield: One of the worst things, matter of fact, one of the few comments I made about that manuscript before we sent it back, is—actually, it was Judy Schoolery who sent the thing to us. Do you know Judy?

Rhodes: His assistant, I think, isn’t she?

Critchfield: She was the historian for Edward at Hoover. At the end of one of his chapters, he said, “I never knew Bohr as a human being.” Now, when I was a student, both Gamow and Teller had studied with Bohr and they thought he was God, or at least his son. They were always so enthusiastic when Bohr came to see us, and especially here during the war. You know, he’d come and everybody’s eyebrows were long, like Bohr used to, and all that stuff. They just adored him. They worshiped him.

In this autobiography, he recites several incidents in which Bohr more or less scolded Edward, and at the end of that chapter he said, “I never knew Bohr as a human being.” Can you imagine anything as hypocritical as that? I told Judy, and I haven’t really asked Edward about that, as soon as I see him. Because I know that he won’t remember.

Rhodes: When we met with him this week, he did not speak kindly of Bohr.

Critchfield: I have a suspicion. Jean and I were at a party in La Jolla when Mr. and Mrs. Bohr were there, and that would be about ’55 or ’56. It was the first visit back here since Oppenheimer lost his clearance. My suspicion is that Bohr gave Edward hell for his part of the testimony. Ed was very thin-skinned, you know, and he wouldn’t forgive something like that. Which is very distressing to me, to hear him talk about Bohr that way. But that’s just a guess on my part.

Rhodes: Well, I think it was clear in my conversations with him that Bohr, in his mind, is allied in some way with Robert Oppenheimer, and that put him on the other side.

Critchfield: Well, look, Edward’s testimony in that great board hearing was just preposterous. He was the only scientist of any credibility that didn’t support Oppenheimer. Just a few months ago when we had dinner with Edward, he said that he didn’t think it was the H-bomb controversy and that Robert may have guessed it, and Edward thought that lost him his clearance. He thought it was his association with Haakon Chevalier.

I said, “Edward, I don’t think it’s either one of those things.” I said, “Your controversy with Robert and the H-bomb thing is peanuts compared with the testimony that Leslie Groves gave, in which when he was asked if he would hire him again he said ‘no.’” Of course, three stars on each shoulder have a lot more weight than any bigoted scientist, of course.

Then Edward said, “Well, what did Groves say?”

I said, “You don’t know?”

He said, “No.” Well, you know damn well he knew what he said. So, his memory is very selective.

Rhodes: Well, you know what Bethe said about all this when we saw him, he said, “Swiss cheese” about Teller’s memory, “Swiss cheese,” he kept repeating.

Critchfield: Oh, Bethe has the same disease.

Rhodes: Well, as it turns out.

Critchfield: And, if you talk to, well, I never got to talk to [Leó] Szilárd about these problems, of course, but he probably had the same problem, I don’t know. Szilárd, he was just a horsefly, you know.

Rhodes: Yes.

Critchfield: Stir you up.

Rhodes: Horsefly, good, yes, absolutely.

Rhodes: I missed part of what you said about Bohr coming back and talking and scolding Edward. When would that have been?

Critchfield: It was either ’55 or ’56. He just happened to be in California, visiting with [Lothar] Nordheim. Lothar Nordheim and his sister lived there. The six of us got together one evening. I personally always liked Bohr, and he was there on a visit and that’s when I suspect he scolded Edward. I next saw Bohr in Copenhagen in ’61, the year before he died.

Rhodes: Just before he died, yeah.

Critchfield: Bohr was very upset about the indifference that Churchill and De Gaulle had shown toward his efforts he kept there in support for international control, international agreement on how to handle the weapons, or chain reaction in general. Because its unique power, you can also make bombs.

Rhodes: Yes. Upset about something that had happened earlier or was happening around that time?

Critchfield: Well, no. That year, he’d tried very hard and it was both Churchill and De Gaulle. I happened to be in his office one afternoon, the day after the Bay of Pigs—

Rhodes: Oh, my God.

Critchfield: —in ’61. And, oh, he says, “It’s nothing. You can’t win them all.” But then he would jump on De Gaulle and Churchill. That’s all we talked about from then on, the whole afternoon.

Rhodes: So Bohr was still actively trying to do what he’d been trying to do during the war.

Critchfield: Yeah.

Rhodes: Ah, I didn’t know. The last thing I saw that he’d published was his open letter to the United Nations in 1950. So he was continuing through all those years?

Critchfield: Working, trying to work secretly without publication, with both those men. Of course, there again, you’re dealing with people who have their mind made up and know what’s right for everybody else and all that stuff.

I had the same trouble in industry. We had high-powered consultants, including Henry Kissinger, by the way. And [inaudible] and of course, Bethe and, well, Gamow was on the staff, not my staff, but the engineering staff. They couldn’t agree with each other.

One afternoon, I had Teller and Kissinger and myself in the board room. As I say, here are a couple of guys who were supposed to be giving us advice. Both of them knew exactly what was right, and neither of them, they couldn’t agree. So they just yapped at each other the whole afternoon. That was when Kissinger was a professor of history.

Rhodes: At Harvard, yes, right.

Critchfield: Yeah, the first thing Edward said the other night at dinner, he said—we finally got a table. We ate at the inn. I didn’t want to eat at the inn, but they did. He says, “Charlie, what do you think about President Clinton?” Because he thought he was going to put me on the spot, because he probably knew I voted for Clinton.

I said, “Well, the only thing I suppose I can think of is he hasn’t pardoned anybody yet.” That’s the first time I’ve seen Edward speechless.

“What did you just say?”

I said, “I think he’s going to do it soon, because of General [Harold] Campbell.”

When I was his student, I’m talking about Edward now. He and Gamow had this idea of nuclear forces being caused by an emission of pairs, of direct type particles, you know, spin particle. And that was my thesis, was to develop that and get the spin dependence of nuclear forces. The first paper we wrote violated parity and strong interactions, which of course, we don’t do yet, as far as I know. And, of course, he got that letter in there, that letter from Eugene Wigner, in which—and Edward’s interpretation was a rebuff, because he should know better than to violate parity.

So, in this autobiography that he sent us, and this was a very important paper, by the way. It started the whole research on strong coupling in nuclear forces. Robert Oppenheimer used to congratulate me. He said, “Why don’t you and Edward advertise? I mean, you don’t brag about your paper.”

I said, “Well, you know about it and Wigner knows about it, and [inaudible] knows about it. What more recognition do you need than that?” But, Edward doesn’t even mention it, because somebody scolded him. That’s my interpretation.

Rhodes: Thin-skinned man.

Critchfield: I mean, something that everybody else in the world that I knew congratulated him on, and of course, I was a student when I was a part of the paper, too. But it was his idea. So he won’t mention it.

Rhodes: Tell me this. I’ve tried to look up a lot of Teller’s papers to try to make some primitive assessment of what kind of scientist he is. I couldn’t see any patterns, I couldn’t put anything together. How was he as a scientist? How was he as a physicist?

Critchfield: He was first-rate.

Rhodes: He’s published sort of all over the edges, though, right?

Critchfield: Yeah, well, his early work was aimed toward the atomic, molecular physics. Some of that was very fundamental. When he came to Washington, he was brought there by Gamow, who was, of course, famous for his work on alpha, the theory of alpha decay and all that. So he switched over into nuclear physics, and he knew practically no relativistic wave mechanics, direct theory and that. That’s why he made the mistake with parity.

Finally, work in Washington in that frontier was the work of [Merle] Tuve at the Department of Terrestrial Magnetism at the Carnegie Institution. So he got into the nuclear field when he was just a beginner. That is where he published with a lot of different people, and, as you say, a lot of different subjects.

One of our papers, when I was a student, was on nuclear reactions and using the Breit-Wigner resonance type theory for a basis. That was just a kind of a superficial student paper, which as you say, was on the level of being of a dilettante and not an expert. But he was very expert in molecular, and especially hydrogen. Of course, that fits with his enthusiasm for the use of fusion in the bomb. No, he was first-rate.

Rhodes: Because, you know, I asked him, “Why did you stick with the runaway Super design, which really turned out, at least in the short term, not to be the best approach?”

He said, “I didn’t understand,” he said. “I had looked at what would happen if you compress the fuel, and I thought that heat and compression and the other components of the reaction all scaled up together. And so compression wasn’t particularly important.” He said, “I had neglected a rather obscure process,” and what did he call it? The three-body—I’m sorry, I don’t know the physics well enough to be precise, but—

Critchfield: Well, the inverse Compton effect, or something like that?

Rhodes: I think he’s probably talking about, he said the electron—

Critchfield: The electrons would soak up all the energy and—

Rhodes: Yeah. And, he said, “I realized that although that was a very weak process, that at the kind of temperatures and so on that we’re talking about in a thermonuclear reaction, it became important.” He then attributes the realization of implosion to having made this previous understanding, rather than that Stan Ulam walked in one day with the idea. That puts the change in Teller’s view in 1949.

Critchfield: Have you talked to Françoise [Ulam]?

Rhodes: No. We’re coming back in the fall to do some more interviewing.

Critchfield: Yeah. No, she’ll tell you the other side of that coin much better than I can. Or, Carson certainly knows it, too.

Critchfield: Yeah, I think your description of Swiss cheese brain is very appropriate. I can’t understand it, because my background, my family, ever since the middle of 1600s have been farmers, and we don’t look at things the same way Europeans do. Why it’s so important to be important, I don’t know. But it sure is. I guess their substitute for immortality or something.

Rhodes: Yes. What was it someone said to us the other day, that there was a whole body of problems. Someone was saying Teller was never interested in controlled thermonuclear fusion, because he’d made a decision that that was a problem that wouldn’t be solved in his lifetime.

Critchfield: Oh, I hadn’t heard that one.

Rhodes: This is someone who worked with him and who was in fact a friend of his, but it’s like—you can’t be famous working on something that you won’t solve.

Critchfield: Well, it’s obvious that he virtually wants to be known by everybody. He has a messianic complex.

Rhodes: Yes, yes.

Critchfield: That fits so well. Four years ago, the university, the George Washington University invited those of us left to come back for the 50th anniversary of Bohr’s announcement. Edward gave the luncheon talk, and that’s the one in which he proposes a defense against bolides, comets and things and you deflect them.

Rhodes: Oh, right.

Critchfield: Which he put in his speech again the other day, I understand. I didn’t go to that either, of course.

Rhodes: I didn’t stay. We had to leave, so I didn’t hear that part.

Critchfield: But, Edward was obviously so proud of himself for saving the universe, I mean, the earth from the threat of a collision with a large meteor.

Rhodes: Do you think it took someone with a messianic complex to push the hydrogen bomb through?

Critchfield: It probably did, when you consider what happened with the A-bomb. Well, I mean, look how long it took from ’39 to ’42 to get some action, and with people like Szilárd and Teller, and even Wigner, who was not very aggressive, but he was forceful, working on it. People like Lyman Briggs and even Jim Conant and people saying, “Oh, no scientist has ever contributed to a war during wartime,” and all that stuff, the arguments they had.

Rhodes: Well, I always try to imagine Teller, Wigner, and Szilárd fresh off the boat, going to Washington in 1940, ’39, and saying, “We can build a bomb that will destroy a city.” I’m sure they looked like crazy people to the military at that time.

Critchfield: Oh, of course.  

Rhodes: I know what Merle Tuve called them, “The Hungarian conspiracy.”

Critchfield: Well, it was a conspiracy, of course. But some conspiracies are good.

Rhodes: Yeah, yeah.

Critchfield: And they finally prevailed, but the threat that really held us together here during the war, of course, was Hitler and the Thousand-Year Reich idea. A lot of the people here hated Oppenheimer in Europe, because he was sort of a snotty know-it-all, very precocious, and most of those guys are, too. Edward is really quite precocious, and Gamow. So the reason they stayed here and worked for him was that they had a common cause.

Critchfield: Robert [Oppenheimer] was very content to say, “Well, if we can’t do it, then Hitler can’t do it and that’s all we have to prove.” Well, it soon became evident it was no problem to do it if we could get the material. And, of course, [inaudible] was U-235. And, then the real challenge came, of course, with the plutonium 40.

Rhodes: Spontaneous fission of 240.

Critchfield: Yeah, yeah. Yeah, we had these code names for the elements. We had code names for everything, of course, and plutonium 240 was just called “40.”

Rhodes: One of the reasons the hydrogen bomb didn’t get done sooner probably was that there wasn’t that pressure. There certainly was not agreement that this thing should happen.

Critchfield: Well, beyond, that’s something about Robert I never really understood. He was even opposed to finding out what we could, on the basis that it’s a terrible thing. But, most of us, I would say, I could speak for most of us, agreed with [Albert] Einstein when he was young and said that the responsibility of scientists is to tell the rest of the society what can be done, not what ought to be done. Of course, Albert changed his mind later, too. But that’s part of getting old, I guess. Of course, I’m eighty-three myself, I should talk.

Rhodes: You know, I should ask you this, because I asked Teller this as well. It isn’t clear to me whether Oppenheimer’s resistance to the hydrogen bomb was a technical conviction that Teller’s runaway Super would work, or whether it was political, or whether it was both. Was there a technical component to Oppenheimer’s resistance to all this?

Critchfield: Robert gave me the impression that he just thought it was wicked.

Rhodes: Did he?

Critchfield: But then I also had a suspicious of my own, although I was very fond of Robert, that there was some proprietary jealousy involved in this, too, that he didn’t really want anything more terrible than the A-bomb. I’ve mentioned that to some other people who’ve interviewed me and they tend to think I’m just making things up.

Rhodes: Well, no, he said as much, in a way.

Critchfield: Well, yeah, and so did Jim [James] Conant. In fact, when Sam Schreiber was here a year or so ago, he said that he was pretty sure that Robert got this idea from Jim.

Rhodes: The idea that—

Critchfield: The moral responsibility was not to develop it. I used to argue with Robert over the phone after he was kicked out, that that’s not what a scientist is supposed to do. He wouldn’t agree until, as you say, he realized it could be done. That’s when he said it was a “technically sweet idea.”

He was always quoting things from the Old Testament and the Bhagavad Gita and things like that. In fact, my main interaction here with him was, he used to give me private lectures on what he called the recondite side of life, which I always pronounced recondite. And he would quote from the Bhagavad Gita.

Rhodes: At the drop of a hat, as it were?

Critchfield: Well, in English, of course, but he had his own translation.

Rhodes: Yes.

Critchfield: In fact, that thing he said down at Trinity, I’d never seen any other translation as what he said, but it’s in there. “I become death, the shatterer of worlds.”

Rhodes: Yes. It’s not translated that way in other versions now.

Critchfield: No.

Rhodes: But, similar.

Critchfield: The words are, as I remember it, it’s Krishna striving to Arjuna, who God is, who Krishna is, because in the poem Krishna represents all three of the Hindu Trinity. What he says is, “I am Time.” But, the Sanskrit word is “kāla” is used the same way use Father Time. So, “I am Time, the destroyer of worlds,” is the way I’ve read it, other people’s translations. But Robert had a different—well, he always did things different.

Rhodes: Exactly did.

Critchfield: You know that famous quote of his, “May the Lord preserve us from the enemy without and from the Hungarians within.”

Rhodes: No?

Critchfield: Oh, he’d think that one would be so funny.

Rhodes: That’s wonderful.

Critchfield: That was Robert’s downfall. His sense of humor was to make completely extravagant absurd remarks. Well, like the one I just told you. And some people like [Lewis] Strauss and Edward Teller took him too seriously. Then when I told Edward about this Hungarian thing, Edward said, “Well, he never said that to me.”

I said, “Well, I’m not surprised.”

He said, “He must have been talking about Leo.” Leo Szilard. And, just the other day, Edward reminded me that Leo tried to visit here when Robert was still director, and Robert wouldn’t let him come up, although he had a clearance at Chicago, of course. He stayed down in La Fonda. Those two men couldn’t get along anyway, with their temperaments.

Rhodes: Yes, right. I never thought of that, but, yeah.

Critchfield: And, for some reason, Robert didn’t like [Eugene] Wigner.

Rhodes: That surprises me. Wigner is such a sweet man.

Critchfield: Well, he certainly was. But I remember, I was supposed to work with Robert, well, I was supposed to go to Copenhagen. And, then when Hitler went into Poland, I cabled Bohr and told him that we wouldn’t come. I was married then, and he wrote me back and said he didn’t blame me.

But, I applied for a national research fellowship to work with Robert in Berkeley, and in the meantime, I got started on a problem with Wigner in Princeton. I asked Robert if I could switch my designated master from Oppenheimer to Wigner, and he very graciously agreed. The man who took my place at Berkeley was Weinberg, Joe Weinberg. Robert put him on the problem that I’d already solved. I heard about this the next spring, and I went to Wigner and I wrote up my work and I published it, of course, and told Eugene that Weinberg was working on this problem. I could publish mine and beat him to it, or I could send him my work and help him out. Wigner said, “I can’t help you with that,” which I thought was kind of funny.

So, what I did was write it up and sent it to Robert, and Robert, of course, was very grateful for that. Joe published his version, which was the same result, but an entirely different method. So, from then on, Robert and I were very good professional friends. We knew rather casually as social friends. Our families, they didn’t grow up together or anything like that, but we were always very close personally, because of our mutual training, of course, and because of this courtesy that he extended to me and I extended to him.

So, when Edward and Robert fell out, I was caught between them.

Rhodes: Was Oppenheimer, after the war, guilty about the bomb? You know this famous remark that he supposedly made to Truman, “Mr. President, I have blood on my hands.” Which sounds like one of those extravagant remarks you’re talking about.

Critchfield:  Exactly.

Rhodes: Yeah. It pissed Truman off, you know. He said, “He didn’t make that decision, I did.”

Critchfield: He [Truman] told [Dean] Acheson that, “You got to keep this guy out of here. I made the decision and I gave the orders.” No, I think it’s true. It sounds so much like him.

Rhodes: He wasn’t going around wringing his hands because he made the bomb, was he, after the war?

Critchfield: Robert was always saying things like that. I say, it was his sense of humor. Another famous thing he used to say in his speeches was, “Physicists have no sin.”

Rhodes: Yes, right.

Critchfield: Well, now, what is that supposed to mean? Well, if you read the Bhagavad Gita, you know, one way to eternal bliss is to work hard and make money and invent thing and do, again, the Karma. But if you take pride in it, then you have to be reborn, because that’s a sin. That’s what Robert meant.

Rhodes: He meant, taking pride in it?

Critchfield: Well, look, the physicists didn’t do the major part of the bomb.

Rhodes: Right.

Critchfield: They’re the ones who really believed that you could get twenty thousand tons out of a golf ball size piece of plutonium or something. But the hard problem was in the explosives and the chemistry, the metallurgy. In fact, all the work that Hans did here in his theoretical division wound up with [Robert] Christy’s idea of just employing a solid ball. That’s why Initiator wasn’t supposed to be important, because the hollow shell type implosion was worked with a strong source. But, if you use a solid ball, you had to have an instantaneous source of neutrons, and that’s the Initiator. So, that’s when Hans invented the Initiator, see.

Rhodes: That’s why it was developed so late in the— 

Critchfield: Well, it was developed for the gun, and what my group did was to adapt it to the implosion. And the particular design, Rubby [Sherr] in one of his letters says that he’s not quite sure that the design is his. But he is sure that the name Urchin is his. Rubby was our main experimental man to really decide on the proportions. And it was my job, and I’d take Rubby with me to this committee to convince them that this was going to work, was going to be strong enough and would go off in time enough, I mean, at the right time, which Robert wouldn’t believe until the actual test, of course. He was very skeptical. [Isador] Rabi and [Niels] Bohr both told him it would be a miracle if it didn’t go off at the right time.

Rhodes: Well, I must say, when I saw the little description, what surprised me was the use of the Munroe effect. That was a surprise. I didn’t know that there was essentially shaped charge structures built into that.

Critchfield: Yeah, there was grooves inside.

Rhodes: Grooves inside, yeah, right. That was, wow. Someone said that was Bohr’s idea.

Critchfield: So far as I’m concerned it was Johnny Von Neumann’s idea to use the shaped charge physics, and originally, of course, he was applying it just to getting a symmetrical impression. But when we came to the Initiator, what we wanted to do was to break the nickel barrier between the polonium and the beryllium, and that’s why the screws are nailed in there.

But in those days, we didn’t really care who thought of what. We just worked as hard as we could to get the thing done and try to match it with the supply of material. It turned out to be bad economics, but it worked.

Rhodes: Well, I don’t know if you know what the Russians have announced lately about—they’ve announced they used a copy of Fat Man. They made the decision in ’48, after they checked everything out to be sure that [Klaus] Fuchs’ information wasn’t disinformation. The reason they chose to do that, even though they had better designs on the drawing boards, using presumably less plutonium, was because [Joseph] Stalin and [Lavrentiy] Beria were watching and wanted a bomb, and they wanted to be sure it would work. They knew that Fat Man would work, because it had been tested.

Critchfield: Well, were they using plutonium?

Rhodes: Yes. But, they could’ve used less in a more sophisticated design.

Critchfield: Well, of course.

Rhodes: Of course. They used up all the plutonium they had, actually.

Critchfield: And we used up all the U-235 we had to test the gun. After Trinity, that was a disgrace, because we knew we had at least a half a dozen bombs right in that gun design if we did it, an implosion. But, there again, we had two line officers in the command of what we were going to do. One was Deak Parsons, of course, in the Navy, and the other was Leslie Groves. They just wanted to be so sure, those things got dropped, because their stars depended on that, of course, I mean, two stars. That was really a disgrace in a way, because if the Japanese hadn’t quit, we had already wasted maybe more than a half a dozen bombs in that one bomb.

Deak was a funny guy in this. I first worked with him when I came here, and very fine man to work for. But he didn’t like that implosion.

Rhodes: I guess he didn’t.

Critchfield: You don’t use explosives to blow things together.

Rhodes: That’s amazing. Did he come around eventually?

Critchfield: Well, what Robert did was to remove responsibility from him.

Rhodes: I mean after the war, did he come to understand that implosion was indeed effective?

Critchfield: Well, when it worked, of course.

Rhodes: Yeah, right.

Critchfield: But it’s too late to change your mind then. The decisions had been made. I heard indirectly that when he first started here that June, Deak had come and on his staff was Ed McMillan and [inaudible] and Seth Neddermeyer, and Jim Bainbridge, I think was here then, I’m not sure. And, of course, all here to work on the gun at that time.

He went back to Dahlgren and talked to Tommy [Thomas] Olmstead, who was an ordnance man, I mean, just a technician, actually, a young man. Tommy told me later that Deak [Parsons] came to Dahlgren and says, “I have to work with a bunch of eggheads out on this program. We need somebody who knows what he’s doing.”

About using big guns, you know, or as Roger Meak put it, “Somebody who knows enough to put cotton in his ears.” But I can’t verify that. I know what Tommy told me, of course.

And, of course, Leslie—according to Laura Fermi—Groves always called us “crackpots.” Another case of Swiss cheese memories: when we first came here, the theorists, Bob [Robert] Serber and Oppenheimer, I guess, too, referred to the idea of blowing uranium together. They called it “The General.” Because the first thing that Groves said when he heard about this was, “The way to do this bomb is to make a hollow shell and blow it together.”

The only verification I have for that is that after Johnny was here and convinced people of the importance of the implosion, Groves came out, and he talked to our coordinating council. Of course, I was a member of that and also Deak and all the other group leaders and division leaders. Groves’ first statement was, “I expect my field officers to keep me well informed on the important developments.”

That was, of course, Deak he was talking to, and Deak was sitting right in front of me. He just turned red. He said, “I’ve been trying to tell you guys all the time, the way to make this bomb is to take a hollow shell and blow it together.”

Of course, Groves always talked that way. But apparently, it was his idea, and as far as he was concerned, we were just making work for ourselves to prove it.

Rhodes: I helped Bob Serber recently put out an edition of the Los Alamos Primer, helped him edit it. You may have seen it.

Critchfield: Oh, sure.

Rhodes: But Bob says that [Richard] Tolman originally had the idea.

Critchfield: Originally, back, way back in those—that’s the first summer.

Rhodes: I had the feeling Bob wanted to withdraw some of the credit from Seth Neddermeyer, actually. But Seth was after—

Critchfield: Well, independent, because Seth was at the Bureau of Standards. Seth’s idea was to make a cylindrical thing and just blow it together so it’d stay together. He wouldn’t buy the compression. That’s why he was removed from the command of that program. He just wouldn’t buy it. He thought it was such a neat idea to just blow it together and keep it, which, of course, would be like the gun. It would be very wasteful of material.

Rhodes: Yeah, right.

Critchfield: But, anyhow, to come back to this, the General’s design, I didn’t talk to Serber and I meant to do that, too, because I had to give a talk a couple of weeks ago and it might come up, but it didn’t. I called Christy and I talked to Edward and several other people, if they remembered the General’s design, and they don’t remember. But, the General reminded us of it, you see. It was kind of a joke there that first—even in April, when he came out here in April, 1943, they were talking about the General.

Rhodes: Bob didn’t remember that?

Critchfield: I didn’t talk to Bob. You mean Serber?

Rhodes: Yeah, Serber.

Critchfield: I meant to call him before I gave this talk a couple of weeks ago to—the Manuscript Society was here. But nobody brought it up so it didn’t matter.

Rhodes: Well, this is wonderfully helpful. Thank you. It’s very hard to get someone to talk about the people, and you’ve done that so much today. That’s great.

Critchfield: Well, I’m probably the oldest one now. No, Edward’s older than I am, and so is Hans. But I can afford to talk about it. A lot of people ask me why don’t I write my memoirs. I say, “I can’t do it until everybody’s dead, because I’ll get sued.”