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Oral History Transcript — Dr. Eugene P. Wigner

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Interview with Dr. Eugene P. Wigner
By Thomas S. Kuhn
At the Rockefeller Institute
November 21, 1963
open tab View abstract

Eugene Wigner; November 21, 1963

ABSTRACT: This interview was conducted as part of the Archives for the History of Quantum Physics project, which includes tapes ard transcricts of oral history interviews conducted with ca. 100 atomic and quantusl 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, arid 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: Richard Becker, Niels Henrik David Bohr, Max Born, Gregory Breit, Richard Courarit, Paul Adren Maurice Dirac, Freeman Dyson, Albert Einstein, Enrico Fermi, Ferdinand Georg Frobenius, Werner Heisenberg, Walter Heitler, David Hubert, Friedrich Hund, Ernst Pascual Jordan, Max Theodor Felix von Laue, Fritz London, Herman Francis Mark, J. Robert Oppenheimer, Wolfgang Pauli, Michael Polanyi, Ratz, Riemer, Erwin Schroedinger, G. Schur, Leo Szilard, John Neumann, Victor Frederick Weisskopf, Hermann Weyl, Wigner (Eugene’s father), Enos E. Witmer; Berlin Technische Hochschule, Princeton University, and Universitaet Goettingen.

Transcript

Session I | Session II | Session III

Kuhn:

If you are willing, I would like best of all to start with your telling me about how you started to get interested in the sciences; I’m particularly interested in this in your case, as I said, because of your participation in the ‘Hungarian phenomenon’.

Wigner:

I don’t know whether there is a ‘Hungarian phenomenon’. There may be a phenomenon of foreigners. If you come to another country you are not at home, and as a result you want to excel more than if you bad an established place in the society, an established place in the set-up, and felt at home. Look at the ‘Chinese phenomenon’ in America—there are Yang, Lee, Wu, and many others—and it seems to me more likely that it would be a phenomenon of foreigners than a phenomenon of Hungarians.

Kuhn:

I think it is both, but there have been large Chinese colonies in the United States for a century, or if not for a century, at least for much longer than this recent phenomenon. Now this is something about people who are coming from China to America in this period, already wanting to get this sort of education; it is something also about China.

Wigner:

Yes, it is something about China, something about America, and also something about not being in a community of their own.

Kuhn:

I think that is surely a part of it. But let us not decide whether there is a ‘Hungarian phenomenon’. Tell me what Hungary was like and what group in Hungary you were part of.

Wigner:

When you said I should begin with the past, I realized that I told, much of the time, a falsehood to myself; namely, I thought that my interest in mathematics was evoked by my high school teacher Ratz. He was an excellent person—taught Johnny von Neumann and gave him private lessons. He recognized that Johnny von Neumann was a phenomenon, which is in itself an unusual activity since, when you have only a few students, how do you know bow they compare with others?

But just today I recognized that this was not quite true. I was sick when I was thirteen, which was before I had any contact with Ratz, and I had to be in—in Hungary we call it a sanitarium, but it had nothing to do with my brains, but rather with my lungs. I had terribly much leisure time because I had to lie in a deck chair for days on end, and I worked terribly hard on a problem of constructing a triangle if the three altitudes are given, the lengths of the three altitudes. Thinking of it now, it’s a perfectly obvious problem and you can do it in your dreams, but I had an awfully hard time with it and solved it after several months of concentrated thinking, which certainly supports what I always think distinguishes people in science.

It is not so much their ability as their perseverance and true interest. Johnny von Neumann was an exception; he had a brain which was phenomenal and a true miracle. But most of the rest of the people whom I know, including Einstein, did not have phenomenal brains—they were bright, certainly—but, endowed with a normal intelligence, had more interest in learning and science, more pleasure in inventing, than the others who do not become interested in science. I think this is probably not new to you. I now realize that I had such an interest in science even before I came under the influence of Hatz.

At the same time I was very much interested in botany; I had a botany book and learned about plants, particularly the evergreens, the gymnosperms, and I enjoyed that very much. I don’t think I know that as well now as I did at that time. But then I returned to Hungary after having been cured... I don’t know if I really was sick—I think it’s a bit doubtful.

Kuhn:

Where were you, in Switzerland?

Wigner:

No, in Austria, (Breitenstein), a little place. [At home again] I promptly contracted typhoid fever. I remember I had to take my examination for the year in the fall and that’s when I first met Ratz. I must say that he at once made a great impression on me, but I must have been interested in [mathematics] before, because I could have done many other things besides trying to construct a triangle out of three altitudes.

Kuhn:

What was the school?

Wigner:

The Lutheran High School.

Kuhn:

Was it a local school?

Wigner:

Practically all the so-called high schools—-of course they call them ‘Gymnasien’—. Most of them were, in a sense, private; this one was maintained by the Lutheran Church and it was very good, in most things excellent.

Kuhn:

Not, however, restricted to Lutherans.

Wigner:

No, not in the least. Ratz gave me the examination and of course I passed. There was little question whether I would pass. My grades in earlier years were good and I don’t think they would have wanted to put me back or anything like that. But Ratz asked me many questions and I got a very vivid impression of his interest in mathematics.

Kuhn:

Was this your first year at that school?

Wigner:

No, I had three years in that school; then around February I dropped out and went to this hospital or ‘sanitarium’, as they called it. Then I came back and I got over my typhoid fever around June, so I was out of school for four months or so. I did not go back to school because by the time I could, I couldn’t walk—being in bed for four months tires one awfully. Anyway, I took the examination in the fall and I remember that it was a very friendly examination, especially the mathematics part, and I had already gained the impression that this man was one who had interest in the subject, interest in his students, and was a “fine guy,” if that means something to you!

Kuhn:

Before you go on with the school, and I’d like to know more about how much science and how much mathematics you did there, would you first supply me with some further background for it? What were the interests in your home? What were your parents’ interests and activities? Were there brothers and sisters? This sort of thing.

Wigner:

I have two sisters and neither of them was interested in anything like natural sciences. I myself had a great deal of difficulty in starting to read; not that I could not read, but I just didn’t want to read a book. I had great conflicts with my father because he wanted me to read, but I think it was partly the particular book he wanted me to read which was very boring!

Kuhn:

Were you the oldest of the three?

Wigner:

No. My older sister, just one year older, loved to read, but my younger sister, who is two years younger, and whom you know, is not interested in learning, so to speak. She is too natural and very impulsive.

Kuhn:

She is a great supporter of learning, shall we say?

Wigner:

She is, but not so much of learning as of her husband [P. A. M. Dirac] whom she loves. .

Kuhn:

What about your father? What did he do?

Wigner:

He was director of a leather factory and also had some share in it. He was very much interested in that. You know, I have never realized as much as I have in the last few years how much wisdom I learned from him; once I remember asking him, “Why do people want money?” He said, “Because it provides influence and power;” and that influence and power are the main motives of mankind, I found out, I am afraid, only ten or fifteen years ago. I learned an awful lot from him which I did not realize at that time.

Of course if I think back, one does not realize in one‘s early years how much one Iearns from one's teachers; from Ratz I probably learned an enormous amount, but also from many many other people whom I could not even quote. But my father I remember very well now that he is no longer alive. He was not interested in mathematics however. I remember one occasion on which be was quite surprised and, I might say, pleasantly amused: I noticed that if you take the fifth power of any number it ends with the same number as what you started out with; for instance, if you take 7, the fifth power ends again with 7, but I did not find out the reason for that until many years later. I told it to my uncle who had a slight interest in mathematics and he told me it was contained in Pascal’s triangle, which is entirely incorrect, but it set me at rest. Actually it is a consequence, and a not entirely trivial consequence, of Fermat’s small theorem.

Kuhn:

You discovered this by induction?

Wigner:

Yes. Well, I took 1,2,3 and so on, and I knew that if you go beyond ten it’s always the last digit which counts—.

Kuhn:

How old were you at this time?

Wigner:

I think this was still in the pre—Ratz stage because in the Ratz era I would have gone to him and asked him about it. I would probably not have asked him “is this known,” but rather, “are there similar theorems in other number systems,” and so on.

Kuhn:

But this meant you experimented a lot with numbers; if you found out things about the fifth powers, you were experimenting a good deal with numbers.

Wigner:

Quite possibly, but I don’t remember this very clearly. In our high schools, of course, you start when you are ten and not twelve. We had a lot of Latin—in fact six days a week; calculation.For exaniole, calculating 5% interest or how to work with decimals, how to work with continued decimals such as .3333 and all that; geometry probably came first in the third year. This incident was either in the third year or, more probably, in the fourth. It was not when I was in the sanitarium because then I could not have told it to my uncle. But the family was not interested in it; on the other hand, they made only very perfunctory attempts to discourage me, very perfunctory. “Oh,” they said, “he’s a queer child, but it doesn’t matter much.”

Kuhn:

What did they want you to be interested in? What in your circumstances—?

Wigner:

They did not really press it, not really.

Kuhn:

But the normal thing for a son of your father to do would have been to continue in the tannery?

Wigner:

Yes.

Kuhn:

But was there value placed on learning as such, though, in your family?

Wigner:

Yes, I think a considerable amount. My grandfather on my father's side was not living when my father married, nor were either of my grandmothers.. But my grandfather on my mother’s side was a physician and, I believe, a very good physician. He did not live in the city. But this circumstance, nevertheless, had an effect. Oh yes. My father was a cultured person. He had a high regard for the brother of the principal owner of the factory who was a university professor. The situation of this brother had an adverse effect on our thinking of an academic career because he was an assistant professor and he remained that for his entire life.

Kuhn:

When you say ‘assistant,’ you mean Dozent?

Wigner:

Yes, Privatdozent. That was not his failure, though I don’t think he was really a genius. Probably not. There was a clique system at the Hungarian University and since there was only one university at that time he could not advance; it was an unhappy thing. And this of course was something to scare us away from an academic career. The first time I discussed my not going into the leather factory with my father was during the communism; and of course the leather factory was taken away from the owner and he was put out.

Kuhn:

Your father remained as director?

Wigner:

No, he was put out.

Kuhn:

Was he actually the owner?

Wigner:

No, the principal owner was a person named Mauthner. I am sure that my father had a fractional interest, but the principal owner was from another family, whom I knew of course. The first time I discussed not becoming a successor to my father was during the communism. I told him: “Well, if this is the situation, there is little point in my becoming a leather tanner,” or rather, going into this business, because my father did not personally tan the leather—it was a factory with perhaps 400 employees altogether——”I would prefer to be a teacher in a high school.” He did not say anything; he must have been badly hurt by, so to speak, having his life interrupted. I did not understand that at that time, but he said, “Well, if this is the world we have to live in maybe that isn’t such a bad idea, but you shouldn’t make a decision now.” This was in the seventh grade of high school.

Kuhn:

The seventh, then, of how many?

Wigner:

Of eight. But even before that I was very much interested in mathematics, you see. Ratz lent me books; for instance, Hesse’s Geometry and a book on infinitesimal calculus which I did not completely understand I now realize. It was rigorous but whether it was really rigorous and whether its arguments really followed from the principles of logic was not entirely clear. But it was interesting, very interesting. Ratz lent me several books; one of them was one in which Fermat’s theorem was given and then it slowly dawned on me that from this you could derive my rule on the fifth power with very little trouble, I had a little book in which I made notes on what I had found and what I learned. Then when the choice came, after high school, to really do something— I remember that after high school there was a terrible let-down; I lost all these friends, all these acquaintances, Latin was of no use anymore, and so on. I wanted to continue studying and my father agreed quite happily.

Kuhn:

If you had gone ahead with the original plan to go into the business, would you have gone in directly from the ‘gymnasium?

Wigner:

I think so, but there was no outspoken plan.

Kuhn:

But the normal route for somebody following your father’s footsteps would not have included the university.

Wigner:

Probably not, but I can’t tell.

Kuhn:

Had your father himself been to the university?

Wigner:

No. He finished high school at a night school, He also came from a leather tanning family, but in a small town. His father died when he was very young and he came to Budapest with his mother, went to work in this same factory right away, and worked himself up slowly. There was some acquaintance between my father’s mother and the owners of the factory and if my father didn’t act the way he was expected to, my grandmother was called in. At the same time my father also finished high school at the same school, the Lutheran High School, although it was not at the same location. But he did not go to the university because he was already working.

He was not at all opposed to it, however; you may in fact say that—things are becoming clearer to me now—he rather favored it. However he said, “You should become a chemical engineer because you can use that in the factory and that’s a good thing, a practical thing, and not something like a mathematician.” And he was right! At that time there were only three positions for a mathematician in Hungary. Particularly from having known Johnny von Neumann, I realized what the difference was between a first-rate mathematician and someone who could not do that simple problem of the altitudes in three months.

Kuhn:

You had really gotten to know von Neumann well?

Wigner:

Oh yes. He was one class behind me in the same school; we often took walks and he told me about mathematics and about set theory and this and that. It was amazing. And he loved to talk about mathematics—he went on and on and I drank it in, I must say. He probably contributed greatly to whatever I knew. I went to the Budapest Institute of Technology for one year.

Kuhn:

Before we get into that, what else in school had you done with the sciences particularly?

Wigner:

We had physics, and botanics. We had botany in the fourth year and I was quite impressed with it; I worked on botany after the triangles when I had lots of leisure. We then had zoology which I didn’t like particularly; geography, one year of chemistry, and two years of physics. The physics teacher was also excellent although entirely distant; he came in, gave his wisdom very well, and then left, I never talked to him privately, never; he was a little gruff but had a good heart—not a taskmaster. In fact he was so interested in his subject that he wrote books, just as Ratz wrote books. Ratz wrote books not of advanced mathematics but of high school mathematics. He organized a journal for high school students, too. Very excellent people. Of course we had only two years of physics.

Kuhn:

What was the name of the physics teacher?

Wigner:

Mikola (Sandor). He wrote a semi-philosophical book which was very good. We had a self-educating group—I don’t know what you would call it in this country—and practically everybody was a member of it; I once gave a lecture in it on relativity theory, although I don’t think I understood relativity theory except in a very vague fashion. Well, I understood it as one understands it having read it a month ago, As Dyson pointed out, it takes six months to really understand anything after having understood it superficially. Mikola called me in and asked me why I believed in relativity theory. I told him about the Michelson-Morley experiments, the absence of objective aberration, and he said, “Well, everybody believes in the green pastures (beyond).” There is a Hungarian word for that. He wasn’t very encouraging, but he was not discouraging either. He said that there were many important problems in nonrelativistic theory, which of course is extremely true; nobody could have been more right than he was. But you see he took some interest and he taught physics wonder fully because I went to college then and passed all the examinations easily without having to take any physics courses.

Kuhn:

How advanced was the subject matter and how mathematical in this Gymnasium course?

Wigner:

In that I helped myself a little. I remember I once proved the energy theorem myself and I was pleased with it of course. There’s nothing easier, but I was not a genius and I was 17. So I added a little [to the curriculum]. I remember that I read a number of physics books and reasonably advanced ones such as Graetz.

Kuhn:

Were these all Hungarian books or would you also have been reading some German ones at this point?

Wigner:

I think this book was German. I could speak German—probably made mistakes, and it was not German but Austrian—you understand. It didn’t cause me any difficulty to read it. I also read chemistry and mathematics books; there was one, Hans von Mangoldt‘s Hoehere Mathematik in three volumes, and I read those three volumes with great interest, I also had some physics books, chemistry books. It was considered a little bit queer in school but it was not discouraged, not even by my schoolmates. They did not feel that Wigner was trying to get ahead of them. But altogether I really learned so much that I never really doubted that I would pass the examination in college. Hence I never went to physics classes; it was not compulsory to attend. I remember when I took my exam in physics in Germany in the Technische Hochschule there were four of us waiting for the teacher to come in and, each time somebody came in, I stood up suddenly, thinking be was the teacher, [Laughter] (???)

Kuhn:

That’s a lovely story. Now you are not the first person I have talked to who has in fact read very widely in the sciences and in mathematics before getting to the university, but I don’t off-hand remember anyone else who has had that much science in school. This scorns to me to be more science—in Gymnasium and not Realschule—than would have been in the curriculum of a good German Gymnasium in this period.

Wigner:

The curriculum was not farther-reaching; these books were given to me by my teacher in mathematics. The physics ones I got from the brother of a friend; in fact, I’m not sure that I didn’t buy them, but he pointed them out to me. This friend was also interested in chemistry and studied with me in Berlin at the Technisehe Hochschule there. I went one year to the Hungarian T.H. and then I went to Germany. I wouldn‘t have gone to Germany except that my father thought it would be a good idea if I studied in Germany, which was partly because he thought that the German colleges were better, and also that I should see the world, and all that. But he encouraged that; I wouldn’t have thought of it. So he must have had some genuine interest in it. He wanted me to be a chemical engineer, to be sure, but that was reasonable.

Kuhn:

Was he back in his job by that point?

Wigner:

Oh, yes. Communism was overthrown in Hungary after about eight months.

Kuhn:

And he went right back to his job.

Wigner:

Yes, soon forgetting that there was ever Communism. In Berlin I got acquainted with a number of people: one of these was Szilard, who had a great influence on me; Neumann was there some of the time and we often gathered on Saturday in my room.

Kuhn:

He was there even then off and on? He wasn’t, I think, a student in this period. He seems to have studied simultaneously at Budapest and at Zuerich.

Wigner:

He was at Zuerich but he never studied at Budapest. He only took the examination.

Kuhn:

He took a degree in Budapest though he seems to have attended courses on a different subject in Zuerich.

Wigner:

Yes, in chemical engineering in Zuerich, pure chemistry perhaps. Then he came to Berlin and we saw each other practically every Saturday afternoon and discussed this and that. Already I had become interested in parts of science which were more nearly on the border-lines.

Kuhn:

Borderlines to physics?

Wigner:

No, borderlines of knowledge. I was most interested in physical chemistry and then I started to learn physics. I went to the physics colloquium where I did not understand a word, but somehow it had a fascination for me and soon enough I understood. For instance, Nobody told me what ”ionization energy” meant, but eventually I caught on, I read, and it was very interesting. I did several pieces of independent work which never got published under my name; as a matter of fact, some of it got published by as famous a name as Pauli. It’s not one of Pauli’s good papers—it’s a valueless paper and it had no significance whatever—but still—.

Kuhn:

What was it on?

Wigner:

It was on equilibrium of a piston with black—body radiation; the piston is moving-—well, it is a fluctuation phenomenon.

Kuhn:

Did you do it with quanta or did you do it with electromagnetic—-?

Wigner:

With quanta, and the result was of course Wien’s radiation law, which is incorrect—. It was a puzzle: “Now how is this?——It does not seem to work.” You can determine in this way a black-body radiation law, but you obtain Wien’s law rather than Planck‘s law. That was a puzzle.

Kuhn:

You quantized the field in the box, you didn’t quantize the oscillator?

Wigner:

Yes, I quantized the field in the box.

Kuhn:

Do you remember when you did this? How long had you been in Berlin then?

Wigner:

This was in the third year.

Kuhn:

The third year in Berlin, so this was the fourth year [in a Technisebe Hoehschule.] Where had you gotten this problem? Had you gotten it from the school or from the colloquium or from reading?

Wigner:

Either I thought of it myself, which is probably true, but Szilard was very interested in fluctuations and may have had something to do with it. I knew about Szilard’s interest in fluctuation phenomena at that time. Szilard also mentioned this to Einstein and Einstein pointed out that there was a paper by someone named (Kamka) on double quanta that brings the resolution. So I went to the university library, read (Kamka’s) paper—I’m not at all sure his name was (Kamka) —and thought it was a very unclear thing because nobody ever observed double quanta.

Kuhn:

This is ‘photon molecules’?.

Wigner:

Yes, which was a substitute for Bose statistics. Well, I took my Diplomarbeit with Hermann Mark, whom you probably know, on a reasonably routine thing, namely, the lattice structure of sulphur. Then I went to work with Polanyi.

Kuhn:

Now we’re going too fast. Excuse me if I slow you down, but you have a better memory than most and I’m terribly interested in what was going on both educationally and in discussion. I’m very much interested in this problem you worked on yourself; what were some of the other problems?

Wigner:

I don’t know if I remember. I sort of constantly had something that occupied my mind, but this I probably remember because Pauli published it and that had a certain effect on me; I thought that “after all it wasn’t so stupid.” I became interested in the chemical constant and I wrote a paper on it; I found a new derivation for its value, This may not have been entirely new but it pleased me no end because I read in every book that there is an N factorial in the formula for the chemical constant, as calculated, and the problem was how to get rid of the N factorial. But I realized that there is no N factorial in the formula if you derive it logically and consistently.

I attended Einstein’s seminar on statistical mechanics and that fascinated me. I read Wassmuth’s book, which fascinated me. A few times I tried to buy it, but it was out of print. Then I came back to Germany about ten years ago I saw it and bought it. I read it again and now I see it’s rather mediocre, but this did not strike me at that time. We had many many discussions; other participants in this seminar were Szilard, who introduced me to it; Kornfeld, whom I don’t think you know. He is now in Hungary and he changed his name to a Hungarian name. He visited the United States not long ago and wanted to visit me also, but did not; Gabor, an excellent British engineer whom you may know— I just read the other day that he had a substantial part in the discovery of the electron microcope, which I did not know These were the people whom I knew.

Kuhn:

Almost all Hungarians.

Wigner:

These were not ‘almost’, as I come to think of it, but all Hungarians.

Kuhn:

Were there a lot of other people in the seminar?

Wigner:

Oh, yes, perhaps twenty-five altogether.

Kuhn:

Of whom about five were the Hungarians in Berlin!

Wigner:

Yes. Szilard always had a great ability for getting acquainted with prominent people. He went up to Einstein and got acquainted with him. You probably know that they invented a refrigerator together.

Kuhn:

I didn‘t know that.

Wigner:

And they even took out a patent; they sold the patent under rather confused conditions.

Kuhn:

This must all have been over and above your curriculum as a chemical engineer. Were you again not going to classes?

Wigner:

I went to practically no classes. It’s not necessary in Germany. I worked extremely hard in the laboratory. I loved inorganic chemistry and still know it better than most present day chemists who instead of chemistry learn electronic orbits and what not. I like facts; I mean, I liked it because I like facts.

Kuhn:

And you have a good memory.

Wigner:

Not like Neumann’s.

Kuhn:

That, I must say, must have been a shattering experience—to have grown up with Neumann, however bright one is.

Wigner:

I am not a great man and I never have any illusion about that; on the other hand, I am a modest man and I don’t want to excel. I’d much rather be a soldier than an officer. It is not my ideal to excel and I took leadership only, if I felt it was necessary, that it was imperative. Well, I then did my doctoral thesis with Polanyi. I now know that he had a tremendous influence on me in philosophy. There is an, amusing incident which comes along later: I made an observation which Polanyi was not familiar with; namely, that an association reaction is not possible because the relative motion of the two particles is a continuum in energy and the final state of a molecule is a discrete one. Hence, the probability that it should just fit is impossible. This observation I made and told to Polanyi; Polanyi listened but, as he later on told me, he did not understand it. He said, “How about the kinetic energy of the molecule?”

I told him that the kinetic energy of the molecule is determined by the momentum, or look at it from the center of mass. Well, I understood it, but somehow he didn’t; I did not press my point home. Fundamentally I was a somewhat too modest a person beause this was a significant observation. But one day Polanyi came back and said: “Well, I am very sorry; this point which you always told me about I just heard in a paper by Born and Franck, and I am very sorry they have it. I told them you had the same idea, but they have sent in their article and nothing can be done. I am very sorry, I don’t know why I did not understand you.” I think the reason he did not understand me, as I now come to think of it, is that one doesn’t understand a young man who says something akin to revolutionary. Actually it was very good that he did not understand me because then I started to think: “Now how is this? After all, they do react and they do associate.” Then Polanyi and I—I think it would be honest to say this was mainly my work and I'm sure Polanyi would support that.

I wondered how it was that they reacted just the same; I developed a theory that there is a certain width of the line and this width I estimated by a queer and entirely incorrect method, but the result was accidentally correct. I estimated it in two ways and they gave the same result. Both estimates were unfounded and there was no basis to estimate the width of the ener level at that time, but I convinced myself that this was the right value. The two estimates also had nothing to do vith each other! I decided that the angular momentum limitation does not exist. This was taken entirely from the blue, but turned out to be entirely correct.

Kuhn:

The angular momentum?

Wigner:

Yes, you see, in order to associate they should really meet so that the angular momentum has a value h, or (multiple) of h, but the probability for that again is zero. I decided, however, that this was not so, that somehow the angular momentum gets filled up to the next integer or emptied down to the next lower integer and the probability is given in this way. Then I computed it and found that this was in consonance with the theory of the equilibrium; that is, at the equilibrium concentrations, the rates of reaction in the two directions were equal. This was my doctoral dissertation; at the end Volmer reviewed it and he was skeptical, but I was convinced that this theory was correct.

Kuhn:

What was he skeptical about?

Wigner:

Well, a young man comes with his thesis: a theory of reaction rates: angular momentum is filled up-now why should it? And then Volmer corrected my thesis and where I put in about the level width “estimated in two ways,” and so on, he said, “Im Ermangelung besserer Unterlagen,” which was correct, but I didn’t think it was. But he was right.

Kuhn:

Did Born and Franck react to this work, because of course you took issue with them on the fundamental point as to whether this was a spontaneous process or not?

Wigner:

I don’t know whether they really took issue. I did not meet them; they were only images, two big people, far away—four hundred miles. I was convinced.

Kuhn:

But this work was published?

Wigner:

Yes, but (they) did not contradict it; they said, “Who knows, who knows, maybe so, maybe not so.”

Kuhn:

Somewhere in here it had also become clear that you were not going to go back and be a leather chemist.

Wigner:

No. After I had finished and gotten my degree, I went back and became a leather chemist; and I was a leather chemist for two years.

Kuhn:

Were you? Now tell me what years these were—.

Wigner:

Oh yes! I can tan leather for you, perhaps not as well as people can tan it now, but I was in leather factories recently.

Kuhn:

What years were these? This is something we have missed in your biography, these two years. You took your degree presumably in what year?

Wigner:

I don’t know—I have a very poor memory.

Kuhn:

I believe you took your degree in ‘25. This however doesn’t leave two years.

Wigner:

No, ‘23 or perhaps ‘24....[But] that I was back in Hungary is not a question.

Kuhn:

For two years?

Wigner:

For two years. I subscribed, though, to the Zeitschrift Fuer Physik; I read the Born-Heisenberg-Jordan paper with tremendous interest and was terribly excited about it. I read that in Budapest.

Kuhn:

Your thesis paper was submitted in June, 1925.

Wigner:

What was the title of that?

Kuhn:

Polanyi and Wigner, “Bildung und Zerfall von Molekuelen,” Zeitschrift Fuer Physik, Volume 33, 1925. It was signed from Berlin-Dahlem; now this doesn’t mean you were there, but—. In the next year you begin the regular publication of what’s, about to be group theory.

Wigner:

Something is wrong here. It could be that—. I can’t be wrong that I was in Hungary.

Kuhn:

Perhaps it‘s one year instead of two.

Wigner:

Perhaps one year. My memory of such things is very poor. But that I read the Born-Heisenberg-Jordan paper in Budapest cannot be questioned; I remember the room. I don’t see how that is questionable. I did not get along very well in the factory; I did not feel at home there and though my relationship with my father was outwardly cordial, I did not find my place in the factory. I did not feel that this was my life, and I also felt, as I now know, a certain repulsion from the way people acted toward each other. I remember I once corrected somebody who wanted to buy some leather from my father. He gave some false information, I corrected him, and he was mad and bawled me out; I was a meek person and somehow the situation did not appeal to me. I don’t know whether this was sound or unsound. One day I received a letter from Weissenberg that he wanted an assistant and why didn’t I come there. He was a crystallographer at the Kaiser Wilhelm Institute. He told me he wanted to find out why the atoms occupy positions in the crystal lattice which correspond to symmetry axes, symmetry planes and so on; and he also told me that this had to do with group theory and that I should read a book on group theory and then work it out and tell him.

Kuhn:

This is terribly interesting because in the first paper in which you mention group theory you say that von Neumann has told you that—

Wigner:

That is so, You will see that it is not a contradiction.

Kuhn:

Before you go on with this, I really want to go back into this period in Berlin where you were talking with people attending the colloquium and find out more about what physics and chemistry looked like. I know you could do this because I remember one very interesting remark you threw in when we were talking with Professor Dirac.

Wigner:

You have a better memory than I.

Kuhn:

No. You see, I am alerted for this sort of thing. Unfortunately we are not quite sure what years you were in Berlin, but you were there from ‘20 or ‘21 and you were there for, would you say, four years?

Wigner:

At least four years. I am sure that I did nothing for two years as far as scientific work is concerned; for two years I worked in the laboratory and analyzed.

Kuhn:

Presumably would these be the first two years?

Wigner:

Yes, of this I am certain.

Kuhn:

Did you get your first degree immediately at the end of those two years?

Wigner:

No. I couldn’t have. What I did then is not very clear, but I took. some examinations although I don’t know how long they took, and then I went to work, I think, with Mark on sulphur. When I finished that I think I went to work right away with Polanyi; when I finished. with Polanyi I thought I went back to Budapest. In fact I am sure of it. We can ask Polanyi.

Kuhn:

Yes. But one problem about that Born and Franck article is that it was published in 1925. Of course it may have been late in ‘25. It’s all right. Let me say this: we create some confusion at this moment but that is much better because we can go back and check the records at Budapest and Berlin as to the date of your matriculation, but nobody would do that unless we knew that certain of the information in the biographical dictionaries must be wrong.

Wigner:

We can’t do that.

Kuhn:

Not at either one?

Wigner:

In Budapest possibly, but not in Berlin because I asked them to send me a copy of my diploma; they said it burned and is gone. But we can try again.

Kuhn:

In any case, it is perfectly useful to upset existing information.

Wigner:

I may be wrong, but now I was born in ‘02 so I should have finished high school in ‘20 because it’s 18 years. ‘20 to ‘21 I was in Budapest. No, you are right. ‘22-’25 at least I was—

Kuhn:

‘20—’2l in Budapest and the fall of ‘21 to Berlin.

Wigner:

To Berlin in ‘21 until ‘25—that ‘a four years.

Kuhn:

You took your doctorate with Polanyi in ‘25.

Wigner:

Yes, we could check when that Gitterstruktur paper was published, because that can be checked. No, this checks.

Kuhn:

It leaves you ‘25-’26 perhaps to be back in Budapest, but in ‘26-’27 you’re in Goettingen. When are you going to get back to the Kaiser Wilhelm Institute as an assistant?

Wigner:

Another person whom we could consult is my sister, my older sister.

Kuhn:

These are not dated; I have some Hungarian titles of articles that I can’t read, but unfortunately I can see that there are no dates on the journals.

Wigner:

I may have dreamed this, but I can’t believe—. You know, that is an important event in your life when you read the Born-Heisenberg-Jordan paper.

Kuhn:

And you also have recollections of having worked at the factory. We will leave this puzzle for the moment, but you must have been in Berlin for most of the time between ‘21 and ‘25. Could you have worked in the factory in the summers?

Wigner:

I am sure I did that.

Kuhn:

But of course you have to be there in the Winter to get the Born— Heisenberg—Jordan piece because that appears right about the middle of the winter; it was submitted, I think, in about November of ‘25.

Wigner:

I should check that. Excuse me, I am sorry, but you told me rightly (the idiom) “memory will deceive.”

Kuhn:

It ‘s also quite useful, you know, to have things that are in the literature contradicted; we can figure it out later. Now this is a very exciting period in physics. Some people who lived at that time didn’t know quite how exciting it was; I think in Berlin it must have been fairly clear.

Wigner:

Yes, it was very clear. Weissenberg was a very excellent crystallographer but he did not understand it. I told him about my solution of his problem, which was very easy. I think I had it after three weeks and most of that was spent in reading Weber’s book on algebra. I told him, but he didn’t like it. I still don’t know a better way to prove it. He said that it was not general enough. I could not do it better—I can’t do it better now.

Kuhn:

But now we’ve got you back to Berlin. I want to go to the earlier period, your years in Berlin as a student. . . The remark you made: I had asked Professor Dirac, “Were you conscious of the deep unresolved problems?” He had contributed the Helium atom but had said in general any notion that there was anything radically the matter had not existed in Cambridge. You said at that point, “In Berlin, I remember we were talking again and again about space quantization.”

Wigner:

Yes. I had the idea that possibly the quantum condition is that every angular momentum is always an integer multiple of h, and I asked Johnny von Neumann to work out whether this is possible or whether it has inner contradictions. Johnny von Neumann came back saying, “No, it has no inner contradictions; if all particles are at rest, then—”

Kuhn:

Immediately he came back?

Wigner:

No, after about a day! “If all particles are at rest, this should be the situation.” He was right, of course, in a way, but what I had in mind was a more general solution. However, I realized that if this was Johnny’s answer, evidently this was a difficult problem. I don’t know whether it was ever solved. In Hungary I had some big ideas—and as a matter of fact this was very closely connected, eventually, with the type of group theory which was needed in quantum mechanics. Namely, the electronic orbits are not orbits but are spheres and the electron is not in an orbit but is on a sphere which is something like plastic. This expression ‘plastic’ I did not know at that time; I don’t know what I called it, but I remember something shiny and transparent.

And it has some properties like spherical harmonics. This is close to our present picture—but of course—there is no shell. And what made me think about this principally was the sum rules and the intensity rules of Kronig, Hoenl and Burgers and Dorgelo. These impressed me deeply and I felt that evidently the matter was much simpler than these complicated orbits with all sorts of irrationalities. “This is not it—it is much simpler.” And I had the conception of spheres and also that it does not radiate; I said, “It’s evidently something that is a permanent thing and nothing changes.”

Kuhn:

A sort of diffused charge?

Wigner:

Yes. But somehow the picture I had was that it was a transparent film which surrounds it as a shell.

Kuhn:

If you knew and were deeply impressed by the sum rules you clearly must have known a lot of the spectroscopic literature.

Wigner:

I read Hund’s book eventually, but I don’t know when that was.

Kuhn:

You read Sonmerfeld surely.

Wigner:

No, I did not, but in that colloquium the sum rules and intensity rules, Dorgelo’s intensity rules, were discussed; and it impressed me that evidently the orbits are not real and the reality is some thing much simpler.

Kuhn:

Had you tried to do problems with orbits?

Wigner:

Yes I did, and I discovered one rule: that quantum jumps never need to involve a jump in position, but only a jump in velocity. But then I thought that this was not relevant. The idea of the shells I had in Hungary; this sort of overpowered me and I discussed it a good deal with a physician friend, Deutsch, who unfortunately is not living.

Kuhn:

This is in Hungary and probably before the Born-Heisenberg-Jordan paper?

Wigner:

Oh, yes, because when I read that paper I felt that my ideas were not the right thing. However, it was very shortly before that, so that the Born-Heisenberg-Jordan papers so to speak, upset that. I must have been in Hungary—Deutsch lived in Hungary.

Kuhn:

When we were talking with Dirac I don’t know whether you mentioned who had been in on these discussions, but I had the impression that these were conversations perhaps at the cafe. Apparently one of the problems was the problem of the Einstein—Ehrenfest paradox: you can’t have space—quantization because if you have a gyroscope it will precess where it is; where is the force that puts it into the quantized orbit?

Wigner:

I remember that. Von Laue reported on that in the colloquium and it was very interesting.

Kuhn:

I may say that this probably had to do with the fact that Einstein was in Berlin; in Goettingen and at Munich I don’t think people worried about that.

Wigner:

You are absolutely right. Einstein had a very clear vision of all these difficulties and influenced all of us deeply.

Kuhn:

What other problems were there? You’ve said that at this point in Berlin people were clear that things were badly the matter, that it had to change; your shells are an attempt to find another way.

Wigner:

It was after my first Berlin life; it was in Budapest. And it was a good thing that I got away from the daily bustle.

Kuhn:

But what other things deeply bothered people?

Wigner:

Light interference and the photo-electric effect—that the electrons come out right away when the light arrives. This kind of thing was most bothersome.

Kuhn:

Were people bothered by problems like the helium atom, the wrong ionization energy for ionized hydrogen, that sort of problem? The failure of three body—

Wigner:

No; I felt, though, that this quantization prescription was not a valid one because I felt that it could not be applied except to periodic motion and I was convinced that helium was not periodic. I felt that the quantization prescription was not yet the right thing, but that was all.

Kuhn:

The photon problem was a very live problem, though? It wasn’t in very many places. Were you in Berlin when the Compton effect was discovered?

Wigner:

Yes. I was working for Mark at that time, or rather, doing my thesis with Mark. There was a lot of discussion and then a paper by Duane came and Mark decided, “There is no such Compton effect.” But I think that my fluctuation calculation was more stimulated by the Compton effect than by anything else. I am not sure of that, but that certainly strikes a chord.

Kuhn:

That may well he. I had not related those two things but it is very likely right. How did other people feel? Was Mark the only one who felt that the Compton effect was wrong?

Wigner:

I don’t know. I think soon enough people got back to the Compton effect’s being right after all.

Kuhn:

What about the Bohr-Kramers-Slater paper?

Wigner:

I felt that that was the right thing and I was very sorry when it appeared that it was not. Einstein said, “Oh, no, things are not so simple,” and it puzzled me a little bit because that seemed a straight expression of the observations, the Fuehrungsfeld. However, Einstein was against it to begin with and, when the experiment turned out to be negative, people abandoned it. It sort of shrouded things into mystery. You realize that all these solutions were partial solutions because the Fuehrungsfeld doesn’t explain the quantized orbit; my shells do not explain the Compton effect; there was no real coherent structure. But it dawned upon me perhaps ten years later that Bohr, Kramers and Slater were entirely right except that the Fuehrungsfeld is in configuration space; I still hope to see that sometime in print, but no one says it.

Kuhn:

Slater doesn’t put it quite this way, but he says something not unlike this. I think he is clearly not the man to put it in print now, but it’s an interesting idea.

Wigner:

Slater afterwards published a paper dissociating himself from the Bohr-Kramers-Slater paper.

Kuhn:

I’m interested to have you say that, I know he did but also in his version he dissociates himself from their version, but he gives his own version; it’s in his own version that it’s really proper to speak of a Fuehrungsfeld. In the Bohr-Kramers-Slater paper this radiation is really not guiding a quantum through the fields; it's really exactly getting rid of that element that is Bohr and Kramers’ influence on Slater’s original thought.

Wigner:

I think that Slater probably had many good ideas with which I am not familiar, many important contributions.

Kuhn:

The interview was broken off at this point in order to allow Professor Wigner to make a train.

Session I | Session II | Session III