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Interview of Robert Serber by Anne Fitzpatrick on 1996 November 26, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/25100
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Discusses his early career and his relationship with Oppenheimer, his work at Los Alamos on the atomic bomb, and later, the development of the hydrogen bomb. Prominently mentioned are: Norris Edwin Bradbury, Emil Konopinski, Ernest O. Lawrence, Robert Oppenheimer, Edward Teller, Robert R. Wilson.
All right. Let me just set this here and pick up this. For the record we are here today in New York City with Professor Robert Serber, and today is Tuesday, November 26, just before the Thanksgiving holiday, and usually I like to start off for the record of course with the tape— Dr. Serber, if you would please discuss a little about your personal background, particularly your educational background and undergraduate/graduate study and how you came to Urbana, that kind of thing.
Let me say I had an uncle who was a chief engineer for the Atlantic Refining Company and he steered me into engineering, and I went to, on his advice I went to Lehigh which was a good engineering college the new curriculum they had just established called Engineering Physics. And I graduated. I got a national research fellowship and went to Berkeley and had gotten an assistant professorship at Urbana on but jobs were rare.
Yeah, during that time.
And let me see, just after Pearl Harbor Oppie asked me to come back to Berkeley and work with him on the Atomic bomb project.
Let me make a note of that, because I want to ask you about that later. You started the Van Vleck was at Wisconsin but didn't he later go to Harvard after he left?
Yes, that's right.
I thought he did.
It was a year after I went.
He went to Harvard and Wigner came to Wisconsin
In deciding to go to Urbana didn't Rabi convince you to go — Rabi convinced you to go to Urbana?
Yes, that's right.
You wanted to stay at Berkeley, though didn't you?
Yes, I wanted to stay with Oppenheimer. Rabi convinced me that if was time to become independent.
But also in the Primer I noticed you mentioned that you wanted to with Eugene Wigner [?] as a post-doc, is that correct? But you chose Oppenheimer instead, if I understand.
Well, when I got the fellowship Van Vleck advised me to go to work with Wigner. I had never met Wigner and I didn't know him, I decided to drive east, where Wigner was now at Princeton, and then I met Oppenheimer.
You met Oppenheimer in 1934 at a summer conference, is that correct?
In the summer. It was a summer school at Urbana held every summer.
On theoretical physics, you said?
This is how you meet Oppenheimer, but you're going to Berkeley to study as a post-doc then, but then you go back to Berkeley again of course before the war, and but at that point Oppenheimer comes to you in Urbana and kind of recruits you, doesn't he?
Yes, that's right.
That was just after Pearl Harbor.
Just after. This was still in, what, December of '41 that he does this?
Yes. I think.
I have been watching at Los Alamos of course—when you were there in '93 they were doing the class classified video series for the 50th anniversary of Los Alamos and you gave a lecture, and I was watching that just the other day in fact. So you said something about Oppenheimer wanting you to come very much and he actually drives all the way down to Urbana to persuade you to do this. So— But you don't go out until the spring of '42.
Because you are teaching. Mm-hm [affirmative]. And another topic I would like to talk about today is the 1942 Berkeley conference of Oppenheimer, Teller, Bethe, Felix Bloch and Van Vleck comes to this, right? And—
Konopinski and Nelson and Frankel too, right?
So they are post-docs at that time, right?
Yes, that's right.
At the Rad Lab- the Radiation Lab?
Well, you know Oppie had a group working on orbit calculations for Ernest Lawrences's separator and they were part of that group.
But you must have known Lawrence then when you were at Berkeley the first time, right?
So you knew him for quite a while. Because this is — some of the events at the Berkeley conference I'd like to get into a little more in detail, in the lecture at Los Alamos a couple years ago you mentioned that when you arrive in Berkeley in April of 1942 Oppenheimer has assembled some British papers on the treatment of critical mass by elementary diffusion theory. And the thing I was wondering, what British scientists had been working on this up to this time and what papers are you referring to?
Well, of course, Peierls and Frisch had written a memorandum and I imagine that it would have been Peierls who wrote on this.
It was something that came out of Physical Review or one of these journals.
No, these were all secret documents.
Okay, okay. I didn't realize that. I didn't know if it was something published, publishable or not, so—
Peierls and Frisch had started the British on it; as soon as the British got interested they kept everything secret.
In the same lecture, (you noted) that up to this time there wasn't a single American paper on the treatment of critical mass by the diffusion theory? And do you mean there was nothing published or there was just no work being done it?
Well if there was any work being done nobody knew what it was.
Gregory Breit has been in charge of the theoretical aspects of this all in secrecy and security and I think he may have known something, but he never wrote it down, he never told anybody. And I have no information. I heard—
So you recruit Nelson and Frankel then from Lawrence's group to work on this particular problem. Because I think you asked Nelson and Frankel to try and improve on the simple diffusion theory that the British had used, and then I think you said in the 1993 lecture that they actually did much better than you expected, and I was wondering what they did?
What I set them to doing was essentially what Marshak did later.
Yeah. This was expanding the distribution and the harmonics. They kept doing that by they wrote down the integral equation, the exact integral equation, and then in the literature they found the Wiener-Hopf solution.
Uh-huh [affirmative]. How did you choose, why did you choose Nelson and Frankel out of Lawrence's group?
I guess they were the most advanced. They were post-docs. I think the rest of them were all graduate students.
Okay, and they were the only two post-docs?
Yeah. As far as I remember.
They complete all this work before the summer conference begins then, or are they working on it throughout the summer?
They didn't, um, they didn't complete it. They had enough done so they had it pretty good, it turned out to be a pretty good estimate of critical mass. And then later on they did more complicated models with several low-energy groups instead of just one.
For most of the group that Oppenheimer assembles then— so you believe that Nelson and Frankel's work was pretty accurate then at this time? Because I think I've read in the Primer that you thought you had the whole atomic bomb problem licked or close to that, because then you know the discussion sort of turns towards the super, which is another thing I'd like to discuss in a little while too.
Yeah, well, only as far as uranium goes, it looked as if the problem was straightforward, and the problem was to get the U-235 and then of course there was the question of —?
But you yourself, in the spring of '42 you're not working on the neutron- diffusion problem. You are working on things like efficiency and hydrodynamics?
Some of this you were doing personally though as an improvement on the work of Dirac, Paul Dirac, isn't it, or based on some of his earlier work?
Yeah. But it was independent work.
I remember stating to work on the shockwave problem and somehow it didn't go right, and Oppie and I went for a meeting in Chicago, and in the end it came down to and at that point we got or did get a paper.
You also mention I believe in the Primer different kinds of schemes proposed by Teller, and that—
In that summer?
During the summer conference I mean.
On another note, I mean, besides the super-and that's really well known, but you said that Teller was always presenting his wild ideas, and I quote you. But one in particular I was a little baffled by this, that you say Teller presents an autocatalytic scheme which doesn't have high enough efficiency to be worth anything, and the way I read this, I do have a clearance and I've looked at some of the later designs he proposes after the war, and it looks like it's something to do with compressing nuclear materials, but I'm not sure, and I was wondering if you can remember what it was.
Yeah, well, it was putting in an absorber, and an amount of nuclear material. The idea was to improve upon the assembly problem of a large mass of materials and shooting two pieces together.
And I assume this is using plutonium still, so—
Also possibly plutonium. And the idea was just to have a lattice of holes and fill the holes with something like boron that absorbs neutrons and it was barely more critical, and I suppose he decided that the pressure was suppose to compress the boron to increase the efficiency.
I was just curious because I had— Something he comes up with later. I may be way off, but I think he doesn't want to entirely drop this, because I think his original idea for the alarm clock is kind of similar. You know, that's for another form of thermonuclear but I have to be careful what I can say on this tape, [laughter] but I almost think he may have taken off on this idea that was proposed during the Berkeley conference. You said he had brought up a number of wild ideas. I was wondering if you could recall what else he proposed or what else other people proposed for that matter, besides the gun or—
Well, I think I mentioned everything that was proposed in the Primer lectures, implosion-
Yes. Also I think its come up in the history about this meeting that more time is actually spent discussing Teller's idea for a super. Is this true and is this something to do with? Because you all thought that you had the fission theory all set.
Yes it's true. And fairly remarkable that we started out talking about it and I think there had been a discussion about damage. Then Teller brought up the Super.
How long after the meeting started was this happening?
Maybe two days.
And then everybody jumped on that, you know. The A-bomb was a settled issue now and then we went up to Chicago two or three times, during the meeting we wwent to Chicago, and we taken some job like-
But there were no people to work on this problem throughout the war and even after, so—
Well, I think Konopinski did.
Konopinski's suggestion. I mean during the Berkeley conference, was of adding tritium into the mixture. This is an interesting one too, because this is going to be something, as I have dove through my reading, it's going to be something that's going to really plague the super configuration throughout it's theorized, for years after the war, because you know you can't produce enough tritium— As I was saying, the Atomic Energy Commission later has a few hundred grams on hand, and I think for possibly developing super it's going to take something like a thousand grams. So this is interesting too. I mean the super idea must have been taken somewhat seriously though; even despite you know Bethe's reservations and others. Because Oppenheimer I think, Oppenheimer decides to build a hydrogen liquifier at Los Alamos when Los Alamos opens. So they took it seriously.
Well Teller certainly took it seriously.
Yes, of course, Teller. I think other folks later on did too, though.
Yeah imagine. I mean I thought the super was hopeless and wouldn't work.
There are still people that think that it will work though, so— Some folks at Los Alamos think that.
It was my opinion that Teller always cheated in his calculations.
He cheated in his calculations?
Yeah. He made them overly optimistic, and he never ran them- never made an honest estimate-
Well in the ENIAC calculations, which I'll hold on until later, that's interesting when you say he cheated. I mean I think his initial calculations were too simplistic too. One, I don't think— I don't know if he realized, maybe you could tell me, just how difficult these calculations for such a device are, you know, and they do this thing on the ENIAC, but you know I not—
No. I, as far as I know, they never really did a serious calculation anyway, and it was all biased by Teller's enthusiasm.
Carson Mark told me that Frankel kind of suffered from the same problem too, over-enthusiastic about doing these kind of calculations.
Yes, I think that was true too.
But I'd like to get back to that a little later, before I get way off, but— One other question I want to ask you is about building this, if you know about this, building this hydrogen liquifier at Los Alamos right when it opens and why, if there's a reason I don't know why Oppenheimer didn't ask Giauque at Berkeley, who was a Nobel Prize winner in chemistry. Hammel suggested to me that Giauque had already built a liquifier at Berkeley but Seaborg didn't like him and Seaborg didn't want him on the project. I don't know if there is any truth to this or not, but-
I never heard of any of that.
But I was just wondering why he chose Earl Long to come and do this and— Because I gather it was decided sometime you know between the Berkeley conference and the first part of '43 I'll get into the war a little bit. Bethe has written that the neutron diffusion, the gun was of course still one of the biggest problems facing Los Alamos when the laboratory opens. How to carry out neutron diffusion calculations in some very complicated shapes, you know, a cylinder of uranium, and they ran into trouble. And I have come across a T Division report, among the ones that are still around that I can get my hands on-where Frankel and Nelson report in October of -43 that they cannot find a way of transforming the integral equation for the infinite cylinder geometry into a form for which they knew a solution.
Then he was with the problem, the theoretical group, and—
What group were you head of, again? I've forgotten?
And one at the moment actually was the shock wave, the exponential shock wave.
There's something that I've wanted to get back to as well of course because with computers— these things are either insolvable by the hand computers or they take too long, because that's an interesting problem you know because it's, believe it's Dana Mitchell is the one who suggests ordering these punch card machines. What group is he in or what—?
Mitchell? He was in charge of procurement.
Yes of course, but did he work in T-Division? He didn't? Okay. So it is his idea or is somebody in T-Division who originally suggested they try—
I don't know.
I think Dana Mitchell had worked — in part he'd worked here at Columbia, in Wallace Eckert's laboratory, his astronomical laboratory, and see it's Thomas Watson of IBM who lends the machines to Eckert's laboratory to try and automate some of these difficult astronomical calculations. And I think Eckert's—
Eckert worked for IBM.
And they had a little laboratory here on 116th Street.
I know Metropolis or somebody says that somewhere in the literature I'm fairly sure. I just can't remember where I saw it, but during the time that you start to focus on implosion, and the program focuses on implosion again because of. I think it was — when did I see it? It was something like April of '44, I think they are ordered by the end of '43 around December, but they don't show up until the late spring or middle of spring.
That would be just about that time.
Another thing that — this is more to do with your own work. Another thing I really had a tough time finding any documentation on, is what evolved out of your work at Berkeley then originally?
Serber-Wilson, the Serber-Wilson.
You mean, what Wilson did?
The general efficiency formula for this is now called Serber-Wilson I believe.
You mean, at my end and what Wilson did?
And I'm not even sure what role did Wilson play in this, putting this thing together. Because I—
—can't find anything written on this. I'm a little stumped.
On that, I was working on the diffusion theory—
—on and off the whole time, and I thought of that modeling method, and Bob Wilson was the one to actually do it and-
—and that was the method selected
How did you come up with this thing?
Is there any manuscript out there?
I can't find a thing on it. I can't find anything. The T-Division reports I think have disappeared, but there's nothing—
I have also discovered one of the more unreliable parts of the memory is time and things get mixed up.
It's used then for a neutron diffusion model essentially, is that correct?
Serber-Wilson is then used for this model?
And it's used, if I understand — I have documentation on this — it's used all the way up to the early '50s until Bengt Carlson introduces the SN method.
I wouldn't know about that.
But you knew Bengt, right? You knew Bengt Carlson, right? He was there during the war. Carlson. He's Swedish.
Serber-Wilson is used on the punch cards machines then, so it's possible to do that work on this, because — I know it's hard to recall what different weapons designs are being pursued, and you know that the gun versus the implosion is well known. However, in a footnote in the Primer you mention that once you saw a last of ideas for weapons on Teller's blackboard.
And there is one so large that his method of delivery was called "backyard" in quotes.
Yeah, that's right.
What was this? Was this — what is he saying? This is referring to the super configuration or—?
Now that was using a bomb to make a lot of radioactivity.
I don't remember more than that — what was supposed to be the initiator?
Well that's an interesting thing too, because at this time that's another problem how would you— when later on Richtmyer, Teller, George Gamow, all these people are trying to come up with some kind of scheme to serve as an igniter for the super, and this is, I believe one of reasons that the atomic project is pursued instead of a super at first. Ulam proposes the use of jets. I was just wondering if you recalled the list of ideas for weapons or different types of things.
No, I don't recall anything but generally.
And Richard Rhodes doesn't have enough, really doesn't go into it enough either I don't believe, so— And then some of this stuff I think is classified in parts so that's always a problem.
Well I think Teller went on a separate track from the rest of us.
There were claims that at the end of the war, sometime in late '45 after the end of the war he and Oppenheimer got together and agreed to hold this conference, in the spring of '46. But Teller implies it's actually more Oppenheimer's idea to hold this conference to kind of preserve the work that's being done and put it on paper for the future in case anybody wants to go back to it. On the other hand Bethe and Nick Metropolis have claimed that this was strictly Teller's idea. Do you have any idea, do you know?
No, I don't know about the origin. I was at the conference.
Right. I remember seeing your name on the report. I would guess it's more Teller's idea, but I'm —
[laughter] I would think so.
The thing is — Von Neumann — sometime I think in the summer or fall of '45 Von Neumann introduces Los Alamos to ENIAC, which I think less than a thousand words of memory, is little by today's standards you know, but I think that in the super, in the report on the conference, and then there is a separate report on the ENIAC calculations, they said it would ignite, the prediction was that it would probably ignite using something like two or three hundred grams of tritium. That's what I'd like to hear what went on and how it got started and —
Well, I mean I don't really remember much about the discussion, but my main memory is at the end when Edward wrote up a report on the conclusion of the conference, and the report was incredible, and there was a conclusion point that said it was almost certain that it would work. I don't know if it was to make a record for any future work. I didn't want to discourage Edward from pursuing what he wanted to do, and I thought to tell him what was to more closely the truth than the report, so we went over it and then modified the more extreme statements. But it was pretty optimistic. I went back to Berkeley. A couple of months later it came to me undamaged and it had my name on it.
I read the report too, and there's a version that's still classified— most of it's still classified— and there's a version that isn't, but there's a list of participants and then the list of people who wrote it up, and I think in the list of people who wrote it up, it's Teller, Metropolis, Frankel, then, so Teller didn't write it by himself I assume.
I don't know.
There are several other people, who helped, Turkevich, Anthony Turkevich is—
Yes. Well Teller certainly wrote the conclusion!
Yes. Because what I'm trying to sort out is then like you say— I think it's an optimistic report too, you know. I think it ends with something like it is likely that the super will work, but further calculations required a machine that is at least as powerful as the ENIAC and you need to pay attention to developments in high speed computing. And sure, it sounds very optimistic and the thing is, in what ways— I mean, it is optimistic in the ways that he — that it seems to indicate that the device won't require much tritium as indicated?
Well, no, well, my opinion was that it wouldn't work under any circumstances.
A lot of people feel that way too.
I remember, but it didn't seem to bear it out the possibility that it would work. And I thought Teller was fudging this, at every point Edward might think of something, which of course is what happened finally. I remember Bradbury was very mad at him.
I knew that they didn't agree on this; I know that after the war that Bradbury— I think Teller asks Bradbury, everybody knows this, — but he asked Bradbury if he could do something like 12 tests a year and have a kind of 100-person division working specifically on the Super, Teller would agree to stay on not go back to Chicago. Of course Bradbury says, "There's no way we can do this." "There's not enough manpower."
I don't know. I wasn't there.
A lot of people don't remember this.
What I heard was that Bradbury was really mad at Teller.
Is this immediately after the war then?
I don't know exactly, if it's later or not.
Maybe around '48 or '49?
When was Livermore assembled?
Oh, not until '52. I think it's proposed in '52. See, Teller resigns from Los Alamos in the end of '51 because —
Because Marshall Holloway is put in charge of the thermonuclear project, after the Russian bomb and all of course it becomes a serious thing, and Teller wanted to be in charge of that, and I think he got mad at Bradbury because Bradbury appointed Marshall Holloway head of the project, and once again Teller is not, he's not put in charge of T-Division during the war so he's sore at that, and then after this he is not put in charge of the thermo project, and with good reason he's mad I'm not sure Bradbury would agree.
Well, you know, undoubtedly some of this had to do with what I heard which was Bradbury essentially threw Teller out because he'd been misled when they discovered the work was misrepresented, the results of the calculations which were done by Teller.
That's interesting. I think there is truth to that, because a lot of Livermore's early tests are on different variations of the super design and a lot of them of course are fizzles which Los Alamos is technically very happy about, but I think maybe what you're referring to, when I again think about between '49 and '50 a lot of folks, including Ulam and Von Neumann's were involved in this too— Let's see, who else was involved? They start to put together more machine calculations to determine, the two part of the super problem, and one is the ignition and then propagation. And so another calculation is run on ENIAC in about 1950. This one is very negative, you know, it's negative and indicates it probably is not going to go. In the meantime though I think perhaps if Teller indeed was misleading anyone, was that there are two big sets of hand calculations that are done and in the first one they try and study the ignition problem, and this is about I think the spring of 1950. They do this at Los Alamos, and they suddenly realized that, two or three hundred grams of tritium is not going to do it. If at all it's going to require a lot more. In fact they just quit the first calculation on that because they realized it's not going to go, and then they start again. Ulam writes back to von Neumann who is now at Princeton that this thing looks bad. And then I think in the summer after that Fermi comes out. They are all consultants and Fermi and Ulan again says this is not going to work. And Teller didn't want to believe them. Maybe that's why Bradbury got angry and so-
Yeah, yeah. That's the time from what I remember was that Bradbury didn't like what he'd done.
The super conference, this conference really takes place in '46 but according to the Los Alamos report it's dated 1950. Did you make your comments that much later, or was this right after the meeting that they were writing it up ad you commented on it?
I don't remember.
Were you ever a consultant to T-Division after the war?
No. I just came back for that conference, I think that was the only time I was back at Los Alamos.
I think Frankel too, they all go back to Chicago and they just come visit in the summers, and for the conference.
The general impression of the conference that I remember was not good.
Because there was a lot of people at that meeting. Fuchs was there.
Actually Fuchs and von Neumann file a patent I think for some scheme of initiating the Super. It raises the whole question of what Fuchs gave to the Russians, or if they pursued a device like Teller's, the super device. Did you know Fuchs?
I wouldn't say very well, but I knew him.
Yes. Because I think one of the justifications for using ENIAC was T-Division's implosion problem.
And Teller is I think angry because he can't use the machines on hand, and even he begins to make arrangements I think to do calculations back here at Columbia in Eckert's laboratory. And then von Neumann comes into the picture.
I didn't know about that. Eckert's Lab was here.
Okay. Yes, at least that's what I was aware of. I don't know the exact location, but I know it's on Columbia's campus, right? So, and it's interesting too because I think Eckert's work really starts to push that too and I think it does, it influences IBM even a little later to kind of orient to more scientific computing.
Why did you choose not to stay on as a consultant to T-Division?
Oh, we were very busy at Berkeley building several accelerators.
And so right after the war you go to Berkeley?
You don't go back to Urbana?
Okay. I guess I hadn't realized that. Were you in the physics department?
No, I was hired by Lawrence not at the university but at the Radiation Lab, not at the physics department, as I had been with Oppenheimer before.
Okay. Yes, he goes to Princeton, right? He goes to the IAS, to be director of IAS?
And I've forgotten what year. I don't remember.
In '47 I think.
Okay. Okay. At the radiation lab then you were working on building accelerators? Is that correct?
Teller to this day still I think has a consultancy at Los Alamos and I saw him not this summer but last summer. For years he worked on the super theory in the summers and breaks, if at all.
[laughs] Edward probably was mad at Bradbury. Because—
Well, I know he was certainly mad at Oppenheimer.
Was there really that much tension between those two though? I often wondered.
Oh, yes. Yes. During the war he started his own group at Los Alamos.
If they accomplished anything during that. Because only the last year of the war too that I think that that group existed, so— I don't think what they proposed was viable essentially the one I think presented at the super conference. When you — skipping ahead again — when you went to the radiation laboratory I, believe, Frankel didn't go back. He went to Chicago; I think he want to Chicago.
Yes, he went back at that point.
That's interesting. What was it like to work for Lawrence?
Well, he was like a benevolent dictator.
Is that right?
I mean so long as you didn't disagree with Lawrence then Lawrence was great.
That's interesting too because—
Then what I guess happened after the war Lawrence became more and more conservative as time went on.
Really? Why? Was he fairly liberal when you first met him—?
Yes. He was liberal. He associated a lot with liberal people.
In order to get support for his machines, to build his machines—because he went— I know he went through the state and through the federal government for support?
Well it was a social thing really.
I see. Okay.
Whether that may have caused, or maybe the other way, Lawrence influenced Teller.
Just about the political aspects of the Oppenheimer case.
And then gradually they diverged and friction developed.
Yeah, that's kind of what I was getting to was that do you think Lawrence had anything to do with this division between Oppenheimer and Teller?
People have asked you about this ad nauseum; because you know the Oppenheimer and Teller issue and it's still a curious thing because there are so many ways this seems to tie together and the way that I think that Lawrence and Alvarez actually go and testify before the Joint Committee.
Lawrence had always tried to work in the background.
Is that right?
And in a way the Senate committee in no time at all convinced Lawrence it was it for him.
When you were still in Berkeley, then, at the radiation laboratory, did Lawrence spend a lot of time in Washington? — Did he not consult for Los Alamos at all then?
Uh-huh (affirmative). You didn't participate at all in the Greenhouse tests or any of that? I don't think I have any other questions for you?
I can't remember things accurately.
I can't remember what happened yesterday, so I understand.