Edward Teller

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Interviewed by
Karen Fleckenstein
Interview date
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Interview of Edward Teller by Karen Fleckenstein on 1983 September 9, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/4372

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Early contacts with Maria Goeppert Mayer, collaborations with her on uranium explosives for Los Alamos at Columbia University and on stability of neutrons at University of Chicago Nuclear Institute, reflections on meeting with Joseph Mayer while she was terminally ill. Also prominently mentioned is: University of California at San Diego.



I met Maria the first time in Goettingen. I studied there.[1] As you know, she was the daughter of a Goettingen professor, but she had married an American. By the time I got to Goettingen, she was gone. I met her briefly on one of her visits back to Goettingen about which I remember very little.

I don’t think I need to tell you about her early work. I don’t know what her thesis was. I know it was a spectroscopic thesis, and then she wrote a beautiful paper, later, out of the thesis.[2]

When I came to the United States, in 1935, she lived in Baltimore, and we lived in Washington. There was quite a nice group in Baltimore, partly from Germany — James Franck, and then Joe Mayer, Maria, and (Gerhard) Dieke. We had seminars once every two weeks, and the Washington contingent went over, (Karl) Herzfeld and I. We discussed a great number of topics and visited with the Mayers. I don’t think that Maria and I collaborated at that time, although we talked about a number of subjects that came up in the colloquia.

Actually, you know, she had two children, and my impression is that while the children were small, she had a lot to do. Just at the period when I got to know her better, she started to pick up her interests (in physics) again. Then came the war, and we found ourselves at Columbia. I was there on a visiting professorship of a year, intending to go back to Washington, which I never did. Why the Mayers were there, I don’t know. But shortly afterwards, I left via Chicago to Los Alamos.

Then came the beginning of our first collaboration which at that time was secret. It is now declassified. Actually, it is quite an interesting project connected with atomic bombs. In fact, it was a peculiar collaboration. I was not allowed to tell Maria what she was working on. In a way, she worked for me. She did the work with two of her graduate students, who then got their degrees based on that work, classified, but later it was declassified.

I can now tell you what it was. She did not know at that time. How much she guessed I don’t know, because we took these regulations quite strictly. We were working on uranium explosives. The calculations were made with the assumption that the radiation that was produced in the explosion would escape. It’s not a very big object, and radiation moves fairly fast, so the assumption was not nonsense.

Furthermore, the main method of escape was at frequencies lower than the continuous spectrum, in the line spectral region. And lines are excellent absorbers, but between the lines a lot of radiation can escape. However, I noticed that we were working in a region where the number of lines was simply enormous.

I was allowed to tell Maria that I was interested in the opacity of uranium. At what temperatures? she asked. I mentioned how many thousand electron volts, at which point her eyebrows went up a little bit. So she obviously knew what I was talking about. But apart from her eyebrows going up, she did not tell me, “Now I know what you are talking about.” Quite a situation, you see. But there is collision broadening — there is this, there is that — she was a spectroscopic expert. It was a very natural thing for her to do that. She got herself two really excellent graduate students.

The work actually, according to the rules of the times, should have been performed in Los Alamos. However, we were much too busy at Los Alamos, and all of us, including me, guessed that this would be a correction and not an important effect. But I kept insisting, “It’s a correction, but maybe it’s not a correction. It’s better to look at it decently,” and Oppenheimer agreed.

I had some other reasons to travel to New York, which do not belong here, reasons connected with the safety of some establishment that they were putting up, so it was agreed that I would be put in charge of this work from the Los Alamos end, that the work would be carried out under proper secrecy arrangements at Columbia, and that Maria and her two students would work on it. So our first extensive collaboration was on that subject.

As it turned out, the correction was not terribly important and not negligible. Today, in appropriate laboratories, similar calculations in different spectral regions are being made by the shovelfuls. Sometimes they make a big difference, sometimes they make a small difference, but this was the first of its kind. It was a good piece of work and, as far as I know, performed with quite satisfactory accuracy. This is not self-praise because I didn’t do it. I only estimated that it would be something. They really carried it out and, incidentally, without computing machines. The way things were done in those days was just by pencil and similar, more classical instruments.

When the war was over, a Nuclear Institute was set up in Chicago, and both the Mayers and I accepted appointments there. I spent three very nice years there, and during that time a non-negligible portion of my work was done with Maria. The origin of elements was a popular subject. Now, I can easily tell you how much of that I remember.

Of course, what we did, we now know, was wrong for several reasons. However, I don’t think it is quite inapplicable, and I occasionally think about returning to it. The idea was that in the Big Bang, or at an early stage, you had an agglomeration of neutrons. Nuclear structures were not as well-known at that time as they are now, and we assumed that an agglomeration of neutrons would be stable. As you probably know, the present idea is that an agglomeration of neutrons is not stable without gravitational forces. But it’s close to stable — I mean, a 5 percent shift or 10 percent shift in the nuclear forces would make it stable. I do not know how big the change is, but we assumed it to be stable.

Then the idea was that, in spite of its stability and in a very natural way, it should disintegrate into smaller parts, and that these smaller particles would be more stable also, with a quite obvious role of the shape of the curve.[3] But the question was the mechanism.

We invented, for the mechanism, this process. First of all, an agglomeration of neutrons, a neutron nucleus, is not a neutron nucleus, because a neutron can transform into a proton, emitting an electron. Now, the proton would be more strongly bound to the neutrons by about 7 MEV. And the second decay could lead to an alpha particle, liberating all together, whatever it is, 28 MEV, and therefore, this process would go on, and probably less than a percent, maybe a tenth of a percent, I forget what fraction, would not be neutrons, but protons with the corresponding number of electrons present.

These electrons would then protrude from this nuclear matter and put their negative charge, on the surface, like an atom, only instead of having a small nucleus and a big atom, we had a big nucleus and a little surface layer, not much more than a couple of wavelengths of electrons. Then this protrusion of electrons from the nucleus would lower the energy, and from this it follows that this configuration now would be unstable in that if you increase the surface — for instance, by crinkling it — more electrons can protrude, and the energy would be lowered. And this process would then result in the nucleus throwing off smaller parts, and these in turn become smaller still, and by this repeated process, the heavier part of the periodic table would in the end be produced.

We could not find a decent quantitative verification of anything of this kind. Today, as you know, the Big Bang theory does not assume such a neutron mass — not only for the reasons that I give you, but also because if it’s assumed that there’s enough energy there to produce neutrons and protons and electrons and positrons and neutrinos, which then all will transform into each other, and these initial stages are even analyzed to some extent, and that probably is right. However, the kind of process that we discussed might occur in collapsing stars, in supernovae, and there, fractions of such neutron matter, partly contained by gravitation, might temporarily hold together, and the evaporation process might have some feature in common with what we discussed.

While I spent those years in Chicago, I still went back for some periods to Los Alamos, and in the end I returned for a longer period, the time when I worked on the hydrogen bomb. But in the meantime, I went back to help out. One summer while I was there, Maria, by herself, got interested in the greater abundance of the nuclei that have magic numbers. It was really not connected with her work, except that by our attempt to understand that part of the periodic table, it was natural to look for the abundances; and she had a little trouble with that. Then, possibly due to a suggestion by Fermi, I think he suggested it to her, she looked at spin-orbit coupling to get the right number. She then produced this exceedingly nice paper, which she actually wrote while I was in Los Alamos.

In the end, I went off to Berkeley whereas the Mayers worked at La Jolla. Not many years after, Maria got sick in a rather horrible manner. I think it was an infection of the nervous system, which wiped out her ability to speak. I don’t know if you know about that. And you know, we have too much brain, and if you lose some of it, you can substitute one part of it for the other. Maria learned to speak again, but it was very poor.

I was busy here. I saw her maybe two or three times a year for short visits. She wasn’t traveling. I was. She invited me occasionally to the seminars. I was very touched on one occasion when she invited me to give a talk, and she then introduced me –- a short, simple talk of a minute or two, but without stumbling over a single word. It is quite clear that she could now speak, but the only problem was the tremendous effort for her.

I sat down and talked with her, and it did not work. It was a horrible thing because, as I said, we were good friends. She was a good friend. I wanted to talk, and I’d say something, and she would mumble something. And I had to ask her, “What do you mean?” And after I had asked her three times, I got embarrassed and had to give up. It was not much of a conversation. But if she really concentrated and wanted to talk, she could do it. And very unhappy, and very mad at herself.

I could have changed it, and I just did not have the right idea. We had a mutual friend from Switzerland. I don’t know if you ever heard of him. He died a few years ago, a very nice guy, Bert Mathias.[4] A great expert in superconductivity. I am mad at him for only one reason. He took so much money away from me in poker. But other than that, I have no objections.

After Maria was dead, I was talking to him and told him of this horrible thing: I couldn’t talk with Maria. He said, “I don’t understand, I never had any trouble. It’s easy to talk to her. I don’t know why you can’t.” Do you know why?




He talked in German.




You know, she had had to learn English. In her native tongue, she was quite fluent, but in English, no. Now, my German is about as bad as my English. I might have just as well talked with her in German. And I would have, had I had that idea. But we usually talked in English because we talked English to everybody else, so it was the natural thing to do. And had I only once happened to talk German. Well, many years lost, and then she died. Any questions?


You covered almost all of the things I was going to ask you about. When did you start the work on the opacity project?


We got to Los Alamos in spring, 1942. I believe it might have been the early fall of ‘42. That was from ‘42 to ‘45. And you could look it up, I don’t remember now, but two students, nice guys. One of them died.


Was that Harris Meyer?


Oh, Harris Meyer. Harris Meyer was the one. And he’s still alive, and I thought yesterday of the name of the other, he was up at the University of Washington.[5]


One thing I would like to hear you say a little bit about is the seminars at the Institute for Nuclear Studies, in Chicago, because I’ve heard some things of them being legendary. Were they?


Yes. They were nice. Well, look, after all, there were some nice people there, including Enrico and some others. But I don’t remember all the names. You know, the other day, there was this book by Freeman Dyson, have you read it?




Disturbing the Universe. And he talks of one of the seminars there, in the Institute. I did not remember it, but the spirit sounds right.


OK. So the atmosphere was — well, I think that’s it, you’ve covered all the important points for me.

[1]Actually, I had finished my Ph.D. at that time and was working as a research assistant with James Franck and Fritz Eucken.

[2]The thesis and the paper were concerned with double beta-decay.

[3]What is meant is a slightly unstable equilibrium with small perturbations giving rise to increasing changes as explained below.

[4]Bertel Schmidt-Mathias

[5]Boris Jacobson was the other of Maria Mayer’s students.