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Interview of Maria Goeppert Mayer by Thomas S. Kuhn on 1962 February 20,Niels Bohr Library & Archives, American Institute of Physics,College Park, MD USA,www.aip.org/history-programs/niels-bohr-library/oral-histories/4770
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This interview was conducted as part of the Archives for the History of Quantum Physics project, which includes tapes and transcripts of oral history interviews conducted with circa 100 atomic and quantum physicists. Subjects discuss their family backgrounds, how they became interested in physics, their educations, people who influenced them, their careers including social influences on the conditions of research, and the state of atomic, nuclear, and quantum physics during the period in which they worked. Discussions of scientific matters relate to work that was done between approximately 1900 and 1930, with an emphasis on the discovery and interpretations of quantum mechanics in the 1920s. Also prominently mentioned are: Max Born, Pau Ehrenfest, Enrico Fermi, Laura Fermi, James Franck, Samuel Abraham Goudsmit, Werner Heisenberg, David Hilbert, Ida Noddack, Robert W. Pohl, Victor Frederick Weisskopf; Universität Göttingen, and University of Cambridge.
Okay, I think that will just go ahead and work for us.
One thing, was that Born was quite unhappy that he went to America when he did. I mean, he gives you the date, ‘25 or something like that… They rushed that Born, Heisenberg, Jordan paper through. That was just the wrong time to go. And Born felt that he’d lost, gotten behind a great deal by taking this trip, and this I have heard him say several times.
And at the time he said that.
Yes, when he came back. He wished he hadn’t gone. Not that he didn’t enjoy it, but that he just lost ground. And the other thing is that when I knew him as a student he was quite sick. I mean just what was wrong I don’t know.
This went on really for a considerable period of time. He speaks of having had a small breakdown at the end of the summer of ‘25, I think, he places it…
Then I am talking about a later time when he left for a semester, and since I was taking his courses you see, I know very well. And he went away — I don’t know where — to recuperate for a semester, and Heitler gave his lectures. And just what was really wrong I don’t know.
But you had seen signs of this before.
Oh yes. He was nervous you see, and occasionally —. I know once we intended to go skiing — his wife and I and some others. We were already on the train. Born said he couldn’t go, left the train and went back, I don’t know why he said it, there wasn’t any disagreement in talk or anything. There was nothing. He suddenly said he didn’t feel like it — he couldn’t. Of course he also worked quite hard on his book, Quantum Mechanics, which he said was not a success. At first I learned my quantum mechanics that way, but it probably wasn’t a success. It was clear that it should have had the Schrodinger equation in it.
You think he is probably right in attributing the decision to leave it out largely to Jordan?
I don’t know that. I asked him once, “Why don’t you have the Schrodinger equation in there?” And he picked out a formula and said, “This is the Schrodinger equation.” But it wasn’t a differential equation. It is the Schrodinger equation in the specified sense. I never had a lecture about the Schrodinger equation. Heitler did that when Born was away.
You actually started hearing him lecture at what point? Before the trip to America?
Yes. I had known him personally longer than that, because he was a friend of my parents. He was at our house socially quite often. And then I was back there once — I came here in 1930 — in 1931 or 32. He wanted me to write with him the new edition of the Handbuch article on Kossel’s structure. At that time he was not interested in Kossel’s structure at all anymore, but he had to write this article.
I guess the first seminars and colloquium for you would have been in ‘27, ‘28?
The seminars? ‘27 or so. You see I started as a mathematician, and switched into physics, I remember the seminars very well. They were held in the mathematics building.
How large were they?
20 or 30 people, something like that. It was very nice, because usually after the seminars we’d go for a walk with Born — the whole seminar — anyone who wanted to come along, and go somewhere in the hills and have a rustic supper in one of the village inns. On those trips I even went before I was in the seminar. I was a student and Born said, “Why don’t you come along?” So I met more people even earlier than I was in the study of physics.... I remember meeting Johann Von Neumann once in the hall. I had a beginning mathematics course and he had Heisenberg’s lecture. And Johann Von Neumann said to me, “You know it’s very exciting, Heisenberg tells us what he thought about last night.” This is Johann von Neumann’s statement. I knew Johann von Neumann very well. That was the time, I think, when Born was somehow not there. I’m not sure I can’t date it, I think so. Well I learned my quantum mechanics a la Born, partially by proofreading his book, but he lectured that way too. When he was away and sick, Heitler talked about the Schrodinger equation, Heitler and Nordheim....Incidentally, the so-called Born approximation was never called “Born approximation” in Gottingen. Once after several years here somebody mentioned the Born approximation and I said, “what is it?” I knew what it was, but I didn’t know it by the name.
What were the relations at Gottingen between Hilbert and the physicists?
Oh, very cordial. Hubert was very cordial, say with Courant, the mathematician, and with Born, and Franck. Definitely friendly. Social relations were also friendly. Hilbert you see was very much interested in the whole atomic development…Hilbert had a habit of giving on Saturdays, from 11 to 12, semi-popular lectures. And I was still in school, and he said, “Won’t you come?” And of course I had school, but I excused myself from school and did go. And this was about atomic structure. It was the first time that I heard anything about atomic structure. I hadn’t learned it in school, so that was probably ‘23, ‘22 or ‘23. And how much earlier he had become interested in it I cannot tell you, but he gave a lecture course one hour a week, semi popular — I mean descriptive. Also some nuclear physics — beta decay and alpha decay — which I learned first from Hubert. Courant had the philosophy, and I think Hilbert had the same, that mathematics is stimulated by physics. They always kept their interest in physics. Hilbert certainly very definitely did, Courant also. So that connection was very strong. Hubert of course was very old.
Did Hubert come to the physics seminars?
Did the physicists go to hear him, to the mathematical seminars?
I’ve had some lectures from him. I have not been in any seminar that he attended as far as I remember — no, I haven’t. But you see, he was fairly old, he had pernicious anemia, and it was sort of a foregone conclusion that he would die. Then this liver extract came out. It came out when he was already very sick, and the first shipment that came from here to Germany went to Hilbert, and that made all the difference. I mean, he would have died in half a year or so without that, and he lived I think four or five years longer…It was quite dramatic that it came just at the last moment… He was a very broad mathematician, extremely broad. He had a large garden. In the garden there was a blackboard the whole length of the garden, with a roof over it so even in the rain you could be out. And he would walk with his assistants up and down, and whenever they wanted to do something on the blackboard, there was the blackboard. It was a very long garden. It happened to be right underneath our house. In his last years he gave his lectures at home… May I talk about Ehrenfest? You see Born was really very mathematical, and he had brought us up much more as mathematicians, never looking much at the physics. He was rather (shocking) in his teaching. Ehrenfest used to come every summer to Gottingen, and Ehrenfest taught us the physics. We could tell Ehrenfest interested himself in what was going on. When you talked to him you knew. Then he would say, “All right, don’t write down an equation, what are you doing?” He was a wonderful complement to Born, for all of us I think; Weisskopf particularly. It was the time when Weisskopf was there and (Tiza) and (Martin Sturmann). And we learned an awful lot from Ehrenfest. Just the things that we had not learned from Born.
Did Franck also supply additional physics?
Oh, he gave lectures on atomic structure; we learned some physics from him, and from Hertha Sponer and various other people. There was a big physics colloquium in which Franck and Born were. It was finally decided — Born decided — that he was not going to have theoreticians speak, because Pohl always tore into them in such a way. Most people couldn’t stand up against that, even under Born’s protection. So at the time I was there there were theoretical talks.
The colloquium was always addressed by students, was it?
Yes and no. Mostly. Sometimes there were outsiders — I mean when somebody from America was around. I remember Pohl talking about something which turned out to be complete nonsense. What was it, micro-genetic rays, or something like that? It is forgotten. The faculty might speak also if they had something interesting which should be reported. Yes, I remember the Davisson-Germer. Also, another effect which did not exist — no, I don’t remember the name… It was the kind of experiment that had to be done in darkness, and Pohl’s point was this: that if an electron goes by an atom at the velocity that it has in the K orbit then it will be captured. Now this was nonsense, because by the time it gets in it has an entirely different velocity. But Pohl gloated about it, and said, “Now you see, you can really talk about velocities, you fancy theoreticians.” — Born wasn’t there at that time.
Who had discovered the effect?
Bergen-Davis effect. I mean it was just wrong, and I think they just kidded themselves into seeing something that wasn’t there. Somebody tried to repeat it, and of course couldn’t. I didn’t know Pauli at that time at all. I was definitely in the Gottingen atmosphere, and I met Pauli, but that was all. I don’t remember him ever being in Gottingen when I was there. Another person who complemented Born later was Edward Teller. He is also a physicist, and had a different attitude than Born’s. And that was a very good combination, even though Teller was in the physical chemistry department.
Where did James Franck himself fit in to this?
The Franck-Hertz experiment was of course one of the crucial experiments, and he had lots of very good students doing various — — …Franck was somebody who was liked by absolutely everybody. When the Nazi doctrines came in everybody said, “Franck is an exception”, even the anti-Semites. Franck of course is something entirely else. You know that Franck resigned. On the basis of the first regulations, he could have stayed. He could have stayed for several reasons, because he had been Professor before a certain date, and because he’d been in the war. But he resigned with an open letter that he was not going to be in the University with discrimination against his race. He thought at that time he would go into industry. He didn’t, he left the country. There was a furor in Gottingen. A number of people wrote an open letter against Franck. We looked at the signatures. There was no well-known name among them. They were all ones who were second in line, you know, and hoped to get on by this method. It was a shameful affair, I mean even in history, and so on, it was not the top people. It was some lower people who hoped that by being friends with the Nazis they would get somewhere. And that I think contributed to Franck’s leaving.
He was offered, at a certain stage, early in the time of the Nazis, to have his own institute not the University institute but his own institute. And he debated it very much, and he said, “If I do that, the first man whom I’m getting into the institute will be Edward Teller. He’s a Hungarian Jew and they have to swallow that. Otherwise I wouldn’t do it.” Well, he didn’t take it anyway because by that time it was clear that it would be better to leave. I remember the discussion. That was in ‘33. The difference between Franck, Born, and Pohl. It’s like this. I was once in the experimental laboratory. I came down the steps. Franck, Born, and Pohl were standing talking to each other. They were all friends of my parents. Pohl just nodded; Born said hello; and Franck stretched out his hand. This was sort of typical. Pohl didn’t do anything, he didn’t nod. He said one doesn’t nod to a student. One doesn’t acknowledge the existence of a student…To greet a student whom you know personally anyway, not done. So I was very much amused to see Pohl in this country. He acknowledged that I was a physicist — a very different attitude. But he was just rude to all students. And he referred to the students as (die Pohlierten, die Franckierten, die Bornierten). Franck of course is really a wonderful person… He was at Johns Hopkins while we were there. This was very exciting, because we had a seminar, to which all the people from Washington came — Teller, and Gamow, and so on.
This was an interesting seminar, in the evening, not students, but just anything. We started with astrophysics, I think for a while; Nuclear physics — with Franck. And everybody came to Johns Hopkins because Franck was there. Later it was most of the time in Washington when Franck had left. But at that time it was at Johns Hopkins. And then he was in Chicago when we were there. He has had several heart attacks. After one of his heart attacks he wasn’t supposed to have visitors, but then his daughter called me and said “He’d like to see you. Don’t tell anybody, because he is not having any visitors, but he asked for you.” That visit was a revelation. The peace with which Franck said, “Well, all right if I die, so what. I have had a wonderful life. I have had two wonderful wives…” No mention about the trouble he has gone through in Gottingen. That was wiped out, he was thinking only of the pleasant things in life, and how ‘he had gotten more recognition than he had deserved. He was really not a good physicist, but he had gotten a tremendous amount of recognition and this was after all gratifying and very nice, although he did not deserve it’ — a completely peaceful attitude. They told him he should not do any more science. He said, “This I will not do, I will walk a little slower and all that, but they cannot tell me not to think about science.” You didn’t know that Born was sick most of the time, I mean that he was not well?
No, No. I knew that there had been some sort of breakdown. I did not realize that it had gone on…
You see, also he went to Russia, and he left early again because he wasn’t feeling well…It was the trip on which Fritz Houtermans met his first wife — in Russia. I have a letter from Russia — it is hard to date. ‘28, I would say… I think he is much better now, age helps us somehow. He seems to be all right now. Of course he has this sort of paralysis of his face — that was ‘32 or so…I knew him only socially at my parents’ house before about ‘25. I also remember him saying at my parents’ house once, “You know after all one gets old. I have a brilliant student now. I must say I have difficulty understanding what he is doing.” It was Heisenberg.
I talked briefly the other day in Berkeley with Michael Polanyi, who said he remembered a conversation with Born — he didn’t remember just when it occurred — about the state of quantum mechanics and what was going to happen. Born said “I’m too old now, it will have to be one of the younger men.” Is that a likely statement from him in ‘22 or ‘23?
I think so, yes. ‘22 - ‘23? .... But he was not giving up. He said “I have trouble;” and he didn’t give up.
Were he and Heisenberg quite close personally?
Yes…Heisenberg was very much liked by Franck also, as well as by Born. So Heisenberg would of course be a good source of information.
And we have a very nice letter from him. Sam Goudsmit wrote him.
Sam Goudsmit; that is strange.
Apparently they have been in regular touch since the war. Sam of course saw him right at the end of the war on the Alsos project.
And wrote a not very kind book about it.
True, true. Though — you think it’s a bad book?
It’s not kind. Incidentally, you mentioned Fermi’s being in Gottingen, and that Fermi was not too happy in Gottingen, which was true. Laura Fermi wrote in her book that what Fermi needed was a slap on the back and a little friendliness. Born wrote me a letter and said, “Will you tell Laura that she misunderstands, that it was I who needed the slap on the back. This brilliant young Italian disturbed me and I was depressed; I needed the slap on the back.” That letter I have.
There were remarks in there that just astounded me. For example the remark that Vickie Weisskopf, whom I knew in Cambridge, was shy.
Vickie? How astonishing. That’s entirely wrong. He came — we sat next to each other (in physics). I remember when he first came. I didn’t by any means know everybody in the class, but I met Vickie the first day, and he just talked. Vickie was not shy. It is true that he was once considering giving up physics, and that was when we had gone to a conference in Hanover. Everybody was so smart. They were all older than we students. He came home (desperately depressed. We felt also that they were unpleasant too to) us, and both of us considered giving it up. Vickie was more serious about it than I.
No, I’ve known Vickie 10 or 15 years. Never terribly well, but I found it hard to accept that he was a shy student.
It is not true. Look, Vickie came when Born was away. His first appearance was in the year that Born took a semester leave of absence.
Is the Oppenheimer story true?
I don’t remember it. It’s a lovely story, it may be true. Oh, it’s probably true, but I’m not so sure that I instigated it. I don’t remember, of course I might have instigated it, if I’d been a student then…But keep the story anyway, it’s a nice story. The spirit in Gottingen was so different at that time than anywhere else. I remember that Born would go for walks with his students a whole group of students talk of science or anything else.
You did all of your training at Gottingen, didn’t you?
I was at Cambridge for one semester, that’s all…I was 25 then I think.
Who did you hear there?
Rutherford. And I don’t remember the others.
Did it strike you — the English situation — as being very different from the German situation?
Yes, very. There was so much drill. You see we were completely free at the University, to go to lectures or not go to lectures, to do exactly what we wanted. In Cambridge you had to go to your lectures. There were these horrible examinations that they had to take every semester — I didn’t take them! We didn’t have any examinations. All you had to do was to convince someone that he ought to take you on as a Ph. D. Student, that was all. Write your thesis and be examined.
Did you find different attitudes toward physics in Cambridge?
Yes I did, but I can’t tell you why. (I had mechanics) It was formal — extremely formal. Now of course, probably they were just about as formal in Gottingen. Still it seemed to be a little more alive… You know my husband of course worked with Franck for a year, and then published a paper with Born…He was in Gottingen from 1928 to ‘30, and then every so often after that.
I have no notion of whether you were ever involved much in the background of the discovery of fission. Were you involved with that at all?
No, I learned about it at that occasion of which I have the picture.
Did you know anything about Ida Noddack?
Yes, I have met her.
Can you tell me anything illuminating about the extent to which her suggestions were ignored?
I think it was just a suggestion without any substantiation. That’s what I thought. I hadn’t read her paper, but I mean anyone can make such a statement… You see, the Noddacks have of course done some very good work, and have also done some very poor work. So generally — determination of isotopes — one does not necessarily (trust the Noddacks so far.) This probably plays a role. She was remarkably uncordial when we met her in Germany. Certainly rather surprising. We were there in ‘34, then in ‘50 we were over — for the State Department with the job of visiting various people — and we visited her. We didn’t see Mr. Noddack. And everybody was extremely pleasant. It was really a very pleasant trip. The only person who was not was Mrs. Noddack.
What about the relation of chemists and physicists, or nuclear chemists and physicists, the relation of the two professions in this period?
Well, Hahn was of course a chemist by training. The distinction between chemistry and physics is not very easy to draw actually. I think the only clear distinction is whether you were in the chemistry department or the physics department. And that is just about all. They were always different buildings, you see. Chemistry was somewhere and physics somewhere else and physical chemistry is still another place. In Gottingen when (Ortmann) came there was contact between physical chemistry and physics. Under Tammann, who was there before, there was none.
When in the development of nuclear reactions there became important areas which needed both the techniques of the physicists and the techniques of chemists, were these contacts hard to make? It had not been typical that physicists and chemists should work hand in hand...
Well look. Franck is a physicist, all sorts of people who came from America to him came out of chemistry departments... A large fraction of the people he had came from Gilbert Lewis and physical chemistry. My husband did. And everybody who was — (Latimer) and so on were there. And they were chemists. Surely Franck’s interests were somewhat towards chemistry. In fact Franck always insisted that every student should have taken chemistry courses, he felt this was essential.
Organic as well as inorganic?
Once you are to take chemistry courses, you had to take a minor. No one went into physical chemistry at that time because Tammann was a tsar, you know, — really difficult to work with. So then you had to take chemistry as a minor and you had to have organic chemistry also. I’m sure Franck was not interested in the organic chemistry.
You couldn’t take chemistry courses at all unless you took a full minor?
No, you could, but at the time of your Ph.D. you had to have two minors, so you might as well take chemistry as one minor and mathematics as the other...