• 6 •
“Princeton is a quaint and ceremonious village, peopled by demigods on stilts.”
—EINSTEIN, in a letter to the queen of Belgium after he arrived in Princeton in 1933
THE LETTERS in this chapter were written from the Institute for Advanced Study in Princeton, except for one from Boston.
In 1948 Hideki Yukawa was the most famous Japanese physicist. In 1935 he had published the first field theory of nuclear forces, based on the conjectured existence of a new massive particle, the meson. During the war he remained at Kyoto as professor, not engaged in war work, teaching and taking care of students. In 1946 he started a new English-language journal, Progress in Theoretical Physics and succeeded in publishing it in the chaotic conditions of postwar Japan. The early issues of the journal contained amazing work done by Japanese physicists during the war when they were totally isolated from the rest of the world. Yukawa mailed copies of the early issues to Oppenheimer and other leading physicists, to let them know that Japanese science was still alive. Oppenheimer invited Yukawa to the Princeton institute in 1948, and mesons were produced experimentally in Berkeley in the same year. Yukawa won the Nobel Prize in Physics in 1949 for his prediction of the meson.
Yukawa has turned up and is most friendly and approachable. We are hoping to get him to talk to a seminar before long. Besides him, there are few eminent people but a lot of good young ones. They are all struggling to understand the Schwinger radiation theory. I have not told them that I have been struggling to supersede it; that would be bad manners. I am planning to publish my bombshell as soon as possible, preferably before Oppenheimer comes to pull it to pieces, and meanwhile say as little as possible.
SEPTEMBER 30, 1948
After a brief visit to Cornell to collect my belongings, I settled down to work at writing up the physical theories I mentioned in the last letter. I was for five days stuck in my rooms, writing and thinking with a concentration which nearly killed me. On the seventh day the paper was complete, and with immense satisfaction I wrote the number 52 at the bottom of the last page. While I was struggling to get these ideas into shape, I thought they were so difficult I should never make them intelligible; however, reading the paper through after it was done, it seemed so simple and clear as hardly to be worth the effort expended on it. It is impossible for me to judge at present whether the work is as great as I think it may be. All I know is, it is certainly the best thing I have done yet.
My big paper is now finished, and I have recovered from the ordeal of writing it. Meanwhile I had a letter from Bethe inviting me to spend a day at Columbia and tell the people there about the work. I am going up tomorrow morning and will probably have an all-day session discussing these problems, just as we used to in the old days at Cornell. One thing I have discovered since I wrote the paper. I was trying to keep it as short as possible, so there are questions and developments which I avoided mentioning so as to keep the argument simple. I shall now be able to write a whole string of papers going into these various points, so I shall have no lack of subject matter for my work for the next few months. To arrive at the frontiers of physics is like breaking through a crust, after which one finds plenty of room to move in a lot of directions.
Next piece of news; I have been offered the job of chief assistant at Greenwich Observatory, with excellent prospects of being Astronomer Royal by about 1965, and have decided to turn it down. I had a long letter about this from a man called Atkinson, the present senior chief assistant and heir presumptive. He gave me all possible information about the position, painting in glowing terms the scenery and architecture of Herstmonceux. It is a strange irony that this should happen; I wonder what I should have said at the age of eight if I had been told I should one day refuse such a job. You can imagine the reasons I shall give for not applying for the position. Fundamentally, I have fallen in love with the most modern part of physics and cannot now leave go of it. During the next five years, there is a gambler’s chance of my doing something substantial in this field, but only if I give it a lot of my time and attention. The important thing is to use this chance while it is here. By the time I am forty, the game will be played out. I have quite a high opinion of my ability to do most things, but one thing I know I can’t do, and that is to work like Einstein in isolation and produce epoch-making work. And that is what I should have to do if I were at Herstmonceux.
One thing which I must always keep in mind to prevent me from getting too conceited is that I was extraordinarily lucky over the piece of work I have just finished. The work consisted of a unification of radiation theory, combining the advantageous features of the two theories put forward by Schwinger and Feynman. It happened that I was the only young person in the world who had worked with the Schwinger theory from the beginning and had also had long personal contact with Feynman at Cornell, so I had a unique opportunity to put the two together. I should have had to be rather stupid not to have put the two together. It is for the sake of opportunities like this that I want to spend five more years poor and free rather than as a well-paid civil servant.
OCTOBER 4, 1948
On Friday I went to New York and was welcomed by Bethe, who was as friendly and informal as ever. He talked a good deal about what he had seen in Europe and all my acquaintances he had met. He said the places where most physics was being done were Zürich, Bristol, and Birmingham. At Cambridge, he said, there was still the same lot of people displaying the same masterly inactivity. One message he brought was from [Nevill] Mott at Bristol offering me a good job as lecturer there, with expectations of a professorship soon. This is certainly much more in my line than being an astronomer. However, my feeling about that too is that I shall have enough of my life being a professor and I need not be in any hurry to start.
Nevill Mott was the professor of theoretical physics at Bristol. Together with the experimentalist Cecil Powell, he made Bristol the most active center of physical research in England at that time.
Two interesting pieces of news I heard recently which show that England still can do pretty well in physics, even if it can’t build such big machines as they have here. First, the blotting paper technique for analysing organic chemicals, which I wrote about recently and which is called paper chromatography, was invented and first used at the Wool Industries Research Laboratories at Leeds, in the year 1944. These people used dyes to identify the various substances on their papers; hence the name. The use of tracers for this part of the work was suggested quite early, but Berkeley having one of the best radiochemical labs in the world has been the first to exploit it thoroughly. Second, attached to the institute here is an electronic computer project, which is aiming to be able to handle any conceivable problem. The technical side of it is under the Radio Corporation of America, and the general design is being looked after by von Neumann. The most important single technical problem in building such a machine is to make a “memory” for it, a device for storing numbers during a calculation so that they can be used later. The RCA has invented an instrument for this purpose called a selectron tube, which will hold a thousand digits and enable any particular one to be read and used in one-twenty-five-thousandth part of a second. The complete machine was to have had a memory unit with forty of these tubes. However, the project has been held up now for some time because after two years of intensive work, the RCA still could not get their tubes to work reliably. At this point there came a report from a man called Frederic Williams at Birmingham, describing a different and much simpler kind of tube which will do the same job. And within six weeks the RCA had built a tube from Williams’s specification and found that it worked satisfactorily. There is no doubt that the great fault of American science is overconcentration on fashionable fields. So long as there are in England a lot of odd groups of people working on odd things, they have nothing to fear from American competition.
I must tell you about my meeting with Gödel. There is not a great deal to be said about it, since we talked mainly about mathematics and physics; he is an amusing talker, and not so pathologically shy in his home as he is at the institute. He is a little man of about forty, with a fat little Austrian wife, and they live together seeing very little of anybody and will no doubt continue to do so for many years to come since he is a permanent member of the institute. The interesting thing to me was to learn what Gödel is doing and proposes to do in the way of research. He produced during his youth two epoch-making discoveries in pure mathematics, one in 1932 and one in 1939, and since then nothing has been heard from him. With the whole of mathematics to choose from and his unrivalled talents, I was curious to know what such a man would choose to do. The answer, when it came, was completely baffling. It turns out that he has spent the last few years working in physics, in collaboration with Einstein, on problems of general relativity.
Gödel had discovered some new solutions of Einstein’s equations of general relativity, describing rotating universes. The solutions known before Gödel’s discovery did not rotate. Gödel invited me to his home because he wanted to know whether there was any chance that one of his rotating solutions might be true. Were the observations of the real universe accurate enough to decide whether it was rotating or not? I knew enough about observational astronomy to answer his question. The answer was negative. The observations at that time were far from being accurate enough to detect visible effects of rotation. If Gödel had asked the question today, the answer would have been different. Since the microwave background radiation has been discovered and accurately measured, we have a far more precise understanding of the dynamics of the universe, and the Gödel solutions are now definitely excluded.
I will try to explain why this is baffling. In the first place, there is no question of Gödel suffering from deterioration of intellect; he understands general relativity and its position in physics as well as anybody and knows quite well what he is about. He has found some results which will certainly be of interest to specialists in relativity. On the other hand, it is clear to most people that general relativity is one of the least promising fields that one can think of for research at the present time. The theory is from a physical point of view completely definite and completely in agreement with all experiments. Most of the work that has been done on it recently has been done by mathematicians who were interested in the mathematics of it rather than the physics, and this work was not of much value to mathematics and still less to physics. The best papers on the subject in recent years have been those of Einstein, who has done some good things, but it was generally agreed that he was continuing work on it more as a hobby for his old age than in the hope of important new discoveries. It is the general view of physicists that the theory will remain much as it is until there are either some new experiments to upset it or a development from the direction of quantum theory to include it. In spite of all this, there is Gödel. Von Neumann, when he found himself in a similar situation, looking around for something to do worthy of his powers, went in for calculating machines in a big way. That one can understand; indeed it was a wise move.
OCTOBER 10, 1948
There is one consideration involved in this question of physics versus astronomy which I did not mention when I wrote before. It might have been supposed until recently that, as nuclear physics was a subject in which secrecy was having a seriously hampering effect on research, at least astronomy would have the advantage of being free from this. However, it turns out that the kind of fundamental nuclear physics which I am doing at present is completely free and likely to remain so, since it is quite impracticable to use it for predicting the behaviour of matter in bulk. On the other hand, it is just in the borderline between physics and astronomy that the most delicate problems involved in constructing superpowerful atomic bombs arise, and in this field I imagine are the most jealously guarded secrets. A superbomb is probably more like a nova (new star) than anything else we can see, so the time may come when telescopes become more important military weapons than piles.
The fear that I felt, of astronomy becoming secret because of the connection between exploding stars and exploding hydrogen bombs, turned out to be unwarranted. Fortunately, the tricks that we use to make hydrogen bombs explode are quite different from the tricks that Nature uses to make stars explode. Secrecy is a problem for astronomers only if they are observing man-made objects close to the earth.
On Wednesday Oppenheimer returns. The atmosphere at the institute during these last days has been rather like the first scene in Murder in the Cathedral, with the women of Canterbury awaiting the return of their archbishop. In passing, I may add that Eliot [the author of Murder in the Cathedral] is now at the institute, having been invited by Oppenheimer to come for a three-month visit and do what he likes; I have not seen him yet. During these days the secretaries have been busily cleaning and tidying up the room of the great man, where we have been making ourselves at home during his absence. Next week we are to move into a new wing of the building which is now in process of completion. (Even the institute has not escaped the disease of postwar expansion.)
I had enormous admiration for T. S. Eliot as a poet and playwright, but I was too shy to start a conversation with him when I saw him drinking tea in the institute common room. I never found out whether he saw as I did the uncanny resemblance of the opening scene of Murder in the Cathedral, with the women of Canterbury awaiting the return of their archbishop, and the opening scene of the institute at Princeton, with the young physicists awaiting the return of their director.
This morning the celebrated theologian Dr. Reinhold Niebuhr was preaching in the University Chapel, and I went along to hear him and see the service. I enjoyed it very much, the last time I went to church must have been on Christmas Day in New York. The singing was enthusiastic if not polished, and the building is a pleasant one, in the style of many a Cambridge college chapel. The main attraction, the sermon, did not disappoint. Niebuhr spoke on the text “Except a grain of corn fall to the ground, and die, it abideth alone; but if it die, it bringeth forth much fruit.” He spoke fast, and it took all my wits to follow him. But what he had to say was worth the effort, and I found his words both stimulating and consoling; he did not hesitate to apply his remarks to political and international problems. The gist of them was, just as the individual man can save his soul only be ceasing to worry about himself and immersing his actions in some larger ends, so also we shall stand a better chance of saving our civilisation if we do not worry too much over the imminent destruction of the little bit of it to which we happen to belong. Niebuhr has the reputation of being gloomy, but I think to anyone who has faced facts squarely, his remarks were exceptionally cheerful.
Reinhold Niebuhr came in 1957 to spend a year as a visiting member of the institute. Unlike Eliot, he sat and ate lunch every day with the younger members, and we got to know him well. His table conversation was as illuminating as his sermons.
OCTOBER 16, 1948
Oppenheimer is unreceptive to the new ideas in general and in particular to Feynman. Oppenheimer shocked me when he arrived by taking a semidefeatist attitude to the whole business and showing complete lack of enthusiasm for a lot of the things I consider most hopeful of fruitful advances. It is this general attitude of hesitation which I now see I shall have to fight in the next few weeks; I am sure I shall have no difficulty in the long run, and the great thing at present is to avoid antagonising people by being impatient at their conservatism.
In the afternoons I have managed to explore the country around here. It is excellent walking country, and I have met numbers of strange new birds, insects, and plants. The weather could not be better, and I hope to continue this form of exercise indefinitely. My young colleagues are unwilling to join me, as they are obsessed with the American idea that you have to work from nine to five even when the work is theoretical physics. To avoid appearing superior, I have to say that it is because of bad eyes that I do not work in the afternoons.
An interesting member of our group has recently arrived, a young man called Abraham Pais from Holland. He spent several years during the war in hiding to escape being deported and probably killed by the Germans as a Jew. He is a man of wide interests and culture and a favourite of Oppenheimer for that reason. I hope to establish a friendship with him as time goes on.
I will write a letter now to counteract the last one, which was written at a moment when I felt like Elijah in the wilderness. Since then three things have happened which have transformed the situation completely. First, on Sunday I felt so irritable that I wrote the enclosed letter to Oppenheimer. So my remarks about teaching Oppenheimer some physics came true. On Sunday night I went for a walk into a field outside the town, where the sky was unobscured by lights, and sat down on the grass to make up my mind whether I should send the letter off. After some time I had decided to do it, and then suddenly the sky was filled with the most brilliant northern lights I have ever seen. They lasted only about five minutes, but were a rich bloodred and filled half the sky. Whether the show really was staged for my benefit I doubt, but certainly it produced the same psychological effect as if it had been. I sent the letter off. On Monday I heard from the editor of the Physical Review that my paper has been accepted in entirety for publication in the issue of January 15. This is remarkably quick, considering that somebody had to read through the paper and referee it in that time. Since this is one of the longest papers the Physical Review has ever published, they might well have asked me to shorten it, which would have been a horrible task. I have much to be thankful for. Later on Monday Oppenheimer ran into me, said he was delighted with my letter and will give me opportunity to expound my views publicly next week. Finally, the same night I went uninvited to call on some of the young people at the Institute Housing Project and found they were having a party. I was very glad to join them and sat around and talked for some time, about eight of us in all. After a time they asked me what I would have to drink, and I said whiskey since that was offered. Since this episode my relations with these people have been on a much more friendly basis, so the whiskey did me a good service.
The following letter to Oppenheimer contains some technical language which nonexpert readers should skip. Translated into plain language, the letter tells Oppenheimer to listen to what Feynman has to say and stop raising silly objections. I disguised this rude message by wrapping it up in polite and diplomatic phrases.
OCTOBER 17, 1948
Dear Dr. Oppenheimer:
As I disagree rather strongly with the point of view expressed in your Solvay Report (not so much with what you say as with what you do not say), and as my own opinions are not firmly enough based for me to put them up against yours in public discussion, I decided to send you a short written memorandum. This is a statement of aims and hopes, and I would be glad if you would read it before starting on the arid details of my long paper on radiation theory.
MEMORANDUM.
I. As a result of using both old-fashioned quantum electrodynamics (Heisenberg-Pauli) and Feynman electrodynamics, on problems in which no divergence difficulties arise, I am convinced that the Feynman theory is considerably easier to use, understand, and teach.
II. Therefore I believe that a correct theory, even if radically different from our present ideas, will contain more of Feynman than of Heisenberg-Pauli.
III. I believe it to be probable that the Feynman theory will provide a complete fulfilment of Heisenberg’s S-matrix program. The Feynman theory is essentially nothing more than a method of calculating the S-matrix for any physical system from the usual equations of electrodynamics. It appears as an experimental fact (not yet known for certain) that the S-matrix so calculated is always finite; the divergences only appear in the part of the theory which Heisenberg would in any case reject as meaningless. This seems to me a strong indication that Heisenberg is really right, that the localisation of physical processes is the only cause of inconsistency in present physics, and that so long as all experiments are interpreted by means of the S-matrix the theory is correct.
IV. The Feynman theory exceeds the original Heisenberg program in that it does not involve any new arbitrary hypothesis such as a fundamental length.
V. I do not see any reason for supposing the Feynman method to be less applicable to meson theory than to electrodynamics. In particular I find the argument about “open” and “closed” systems of fields irrelevant.
VI. Whatever the truth of the foregoing assertions may be, we have now a theory of nuclear fields which can be developed to the point where it can be compared with experiment, and this is a challenge to be accepted with enthusiasm.
NOVEMBER 1, 1948, HOTEL AVERY, BOSTON
My physics goes on splendidly. What annoyed me in Oppenheimer’s initial lethargy was not that my finished work was unappreciated, but that he was making it difficult for me or anybody else to go ahead with it. What I want to do now is to get some large-scale calculations done to apply the theory to nuclear problems, and this is too big a job for me to tackle alone. So I had to begin by selling the theory to him. As soon as he understands and believes in it, he will certainly have a great deal of useful advice and experience to offer us in applying it. Also he may be able to help me to decide what I should do next, though I am fairly determined already on a thoroughgoing attempt to prove the whole theory consistent.
After my last letter to you I decided that I needed a long weekend away from Princeton. I persuaded Cécile Morette to come with me to see Feynman at Ithaca. This was a bold step on my part, but it could not have been more successful, and the weekend was just deliriously happy. Feynman himself came to meet us at the station, after our ten-hour train journey, and was in tremendous form, bubbling over with ideas and stories and entertaining us with performances on Indian drums from New Mexico until one a.m.
Cécile Morette was the brightest of the young physicists who arrived at the institute at the same time as I did. She was the only one who quickly grasped the new ideas of Feynman. We immediately became friends. The fact that she happened to be female was irrelevant to our friendship. She was a natural leader, she understood modern mathematics better than I did, and she had a great sense of humor.
The next day, Saturday, we spent in conclave discussing physics. Feynman gave a masterly account of his theory, which kept Cécile in fits of laughter and made my talk at Princeton a pale shadow by comparison. He said he had given his copy of my paper to a graduate student to read, then asked the student if he himself ought to read it. The student said no, and Feynman accordingly wasted no time on it and continued chasing his own ideas. Feynman and I really understand each other; I know that he is the one person in the world who has nothing to learn from what I have written, and he doesn’t mind telling me so. That afternoon Feynman produced more brilliant ideas per square minute than I have ever seen anywhere before or since. In the evening I mentioned that there were just two problems for which the finiteness of the theory remained to be established; both problems are well-known and feared by physicists, since many long and difficult papers running to fifty pages and more have been written about them, trying unsuccessfully to make the older theories give sensible answers to them. When I mentioned this fact, Feynman said, “We’ll see about this,” and proceeded to sit down and in two hours, before our eyes, obtain finite and sensible answers to both problems. It was the most amazing piece of lightning calculation I have ever witnessed, and the results prove, apart from some unforeseen complication, the consistency of the whole theory. The two problems were the scattering of light by an electric field, and the scattering of light by light.
After supper Feynman was working until three a.m. He has had a complete summer of vacation and has returned with unbelievable stores of suppressed energy. On the Sunday Feynman was up at his usual hour (nine a.m.), and we went down to the physics building, where he gave me another two-hour lecture of miscellaneous discoveries of his. One of these was a deduction of Maxwell’s equations of the electromagnetic field from the basic principles of quantum theory, a thing which baffles everybody including Feynman, because it ought not to be possible. Meanwhile Cécile was at mass, being a strict Catholic. At twelve on the Sunday we started our journey home, arriving finally at two a.m. and thoroughly refreshed. Cécile assured me she had enjoyed it as much as I had. I found a surprising intensity of feeling for Ithaca, its breezy open spaces and hills and its informal society. It seemed like a place which I belonged to, full of nostalgic memories. I suppose it really is my spiritual home.
Perhaps I should tell you something about Cécile, but I hardly know where to start. No doubt I will have occasion to mention her again, so this time I will confine myself to a bare chronology. 1922, Cécile born in France, of a wealthy industrial family. 1932, father died, leaving mother and six children. Mother soon remarries. 1940, family living in Caen when German occupation starts, Cécile studying at Caen university. 1942, Cécile starts studying at Paris university, travelling to and fro weekly. 1944, Cécile caught in Paris on D-day. House in Caen destroyed, mother and one sister killed. After Germans leave, Cécile seizes one of their flats reserved for American army and installs self. Later she collects stepfather and sister and installs them too. They are still there. 1945, Cécile goes to Dublin, Institute for Advanced Study, to learn theoretical physics. 1947, Cécile moves to Copenhagen to work in Bohr’s institute. 1948, Cécile comes to Princeton with institute fellowship. Future, Cécile intends to marry and have lots of children.
The town of Caen is on the Normandy coast, at the center of the region where Allied troops landed in 1944. The town was largely destroyed in two weeks of fierce fighting before the Germans were driven out.
NOVEMBER 4, 1948
First, there is this election. Everyone is immensely pleased by the result; it is clear that it will make no great difference to the way the country is governed for the next four years, but it is of great importance politically that the Democratic Party has managed to win an election without the support of the South; the worst southern states have written themselves out of the party, and the influence of the others will be much weakened. I sat up and listened to the returns coming in for about two hours; it was clear right from the start that Truman was doing much better than expected, but even so I was as surprised as everybody else by the result next morning. One has to take off one’s hat to the American voters for not being bamboozled by the newspapers and the political experts.
The 1948 election had four parties contending for the presidency, the Republicans led by Robert Dewey, the Democrats led by Harry Truman, the Progressives led by Henry Wallace, and the Dixiecrats led by Strom Thurmond. Since the Democratic voters were split into three parties, it was obvious to everybody that Truman would lose and Dewey would win.
Next piece of news. I have received a letter from Professor [Isidor Isaac] Rabi, Nobel Prizeman, brains of the Columbia Radiation Laboratory which has done all the crucial experiments of the last three years, and head of the physics department at Columbia University. Content, offer of a job on his faculty. I wrote a letter back refusing the offer and explaining my circumstances, but I must confess with bitterness in my heart. Objectively, I can think of no place in the world that would be better for me than Columbia. They have the finest experimental department in the world, and it is just in the contact with experimentalists that I have most to learn; they are weak in theorists, and so I should have a free field to cultivate in building up the theoretical side, while still being close to Bethe and Oppy for consultation; finally, Columbia is a magnificent centre where everyone visiting New York stops, and is itself in easy reach of Europe. To throw away such a chance seems madness, but it seems there is no help for it. It would not matter so much were I older, but I have not yet learnt half of what America has to teach me, and it is a grim prospect to be cut off without more than rumours and months-old reports of what Feynman or Schwinger or Columbia or Berkeley is doing. Also perhaps might be added that Cécile is intending to stay here another year.
The Harkness Foundation was generously supporting me as a student in America. When I accepted their Commonwealth Fellowship, I solemnly promised to return to England for at least two years after the fellowship. The promise was intended to ensure that the fellowship should not be used as a stepping-stone for permanent emigration of English students to America. If I accepted the Columbia job, I would clearly be breaking my promise and violating the trust of the foundation.
I believe I have never written you anything about the appearance and character of Rabi. He is a tiny, impish little man, with a broad grin on his face, and is always making good-humoured jokes at somebody’s expense. Where he comes from I do not know; his eyes and colour are more Mongolian than anything else. There is a celebrated song which is often sung at physical gatherings, which describes Rabi receiving the Nobel Prize. The refrain goes, “It ain’t the money; it ain’t the money; it’s the principle of the thing.” The department at Columbia may fairly be said to worship the ground he treads on, and there is a general agreement among all experimental departments outside Columbia that it is useless to try to do molecular beam experiments, because it would take anybody else about five years to arrive at where Rabi is now.
Yesterday I went to New York and spent two hours profitably with Bethe, discussing physics. He is enthusiastic about the new theory and has been using it extensively. He told me the great thing with Oppy is not to be driven frantic by him (as many people are) but to exercise calm and patience. I had come to the same conclusion myself, and I think I have been putting it into effect successfully. On Tuesday I gave the second of my seminar talks, and Oppy interrupted constantly with criticisms, some relevant and some nonsensical, so that the audience was quite bewildered; as far as I could, I went steadily on and avoided argument. The next morning, the same audience without Oppenheimer asked me to give them another seminar on the same stuff, this time without interruptions, and so I did. To me, the interruptions provided many valuable new ideas.
NOVEMBER 14, 1948
After I wrote to you from Boston, I had an unequalled opportunity of seeing the real Boston, when I went out onto Boston Common (a very small park about one-tenth the size of Hyde Park) on a night which happened by good luck to be a coincidence of Sunday, Halloween, and Election Week. The common was seething with people, talking every possible language but mostly Irish, and there were innumerable speakers standing on soapboxes in the best Hyde Park tradition, denouncing the wickedness of the world, Mr. Dewey, Mr. Truman, Mr. Stalin, and the Roman Catholic Church. I had never before seen an American crowd taking religion and politics seriously. Boston is the most European of American cities, superficially reminiscent of London. Even the slums are old and built of brick, in contrast to the typical American slums which are built of wood and corrugated iron. After two hours pleasantly spent listening to the various orators, ending with the best of them all, a little Italian who stood high up on a bandstand and periodically pointed an accusing finger at some defenceless member of his audience, exclaiming ferociously “There stands Satan”; after two hours of this I knew less than nothing about Boston politics but a lot about Boston character. The drive back from Boston was as lovely as the drive there; trees everywhere, and of a brilliance of scarlet and gold colouring such as I had never seen even in this country. Boston may be like London, but the New England countryside is nothing like England.
Oppenheimer is in California this weekend, talking to people there. He returns on Tuesday. It is no wonder he is such a nervous wreck, with all this gadding around. The wonder is rather that he manages to keep as clear-headed as he does. I have been observing rather carefully his behaviour during seminars. If one is saying, for the benefit of the rest of the audience, things that he knows already, he cannot resist hurrying one on to something else; then when one says things that he doesn’t know or immediately agree with, he breaks in before the point is fully explained with acute and sometimes devastating criticisms, to which it is impossible to reply adequately even when he is wrong. If one watches him, one can see that he is moving around nervously all the time, never stops smoking, and I believe that his impatience is largely beyond his control. On Tuesday we had our fiercest public battle so far, when I criticised some unwarrantably pessimistic remarks he had made about the Schwinger theory. He came down on me like a ton of bricks and conclusively won the argument so far as the public was concerned. However, afterwards he was very friendly and even apologised to me. When life is like this, the great thing is to keep a sense of proportion and avoid becoming a nervous wreck like Oppy. So far I think I am succeeding, but you should not be surprised when I write melancholic letters occasionally.
Fortunately there are occasional diversions. On Friday a carload of us young people drove to a local cinema where we saw Rope, a new film. It is a masterpiece, directed by Alfred Hitchcock in his best style. After the film, we got back into the car and hardly had we driven a block when we saw a genuine corpse, with an ugly wound on its head, stretched out across the pavement. Pais, who owns the car, drove off to fetch a doctor while the rest of us joined the gathering crowd around the corpse. The wife of the corpse turned up, not at all perturbed. She shook the corpse vigorously, and it opened its eyes and snorted something incomprehensible at her. “I told him he shouldn’t go out,” she said to the crowd. “He was dead drunk when he left the house. Mind you, this is not the first time this has happened.” At this point a police car arrived and carried the corpse away to hospital, and the crowd dispersed. Several minutes later Pais returned, fortunately having failed to find a doctor. After this episode we assembled to drink wine in Pais’s rooms.
Norman Kroll is the most mature and quiet of the young people and is married to an equally quiet biologist wife; I met them at Ann Arbor in the summer, and I like them very much though I do not see much of them now. Norman has done during the last two months some work which I consider first rate, on the Schwinger theory. I am hoping that as soon as I can get through with my series of talks to the seminar, he will take over and talk about what he has done. However, I go ahead so slowly under Oppenheimer’s fire that an end is hardly yet in sight. Kroll is wisely not pressing his claims. Kroll was a pupil of Lamb at Columbia, but this is the first important thing he has done. I shall be surprised if Rabi does not now invite him back to Columbia to fill the place he offered me. Kroll deserves it as much as I do, and I shall not grudge it to him. It is pleasant to find that Kroll has been quietly going ahead with the theory and making progress, undeterred by the floods of scepticism which Oppenheimer pours on the whole business. This has a good effect on the morale of the young people, who were getting thoroughly confused and discouraged, in spite of all I could say.
Rabi did offer the job at Columbia to Kroll, and Kroll accepted it. Kroll stayed for many years as a mainstay of the Columbia physics department after Rabi retired. Kroll was particularly well suited to be in the Columbia department, since he had been a leader in the development of high-frequency radar equipment during the war. He could talk as an expert with experimenters as well as with theorists. In that way, he was better qualified for the Columbia job than I was.
Cécile amused us all yesterday by bringing down a French millionaire to see the institute (an industrial magnate of some kind). She said she hinted to him strongly that France could do with an institute of a similar sort; she said if she were made director of the French institute, she would invite all of us to come and lecture there. It will be interesting to see if anything comes of it.
The millionaire that Cécile brought to the institute was Léon Motchane, a man of many talents. He had achieved fame in three separate careers, as a mathematician, as an entrepreneur, and as an active leader of the French resistance. Cécile’s plan, that Motchane could be cajoled into building a comparable institution in France, succeeded brilliantly. Within a few years, Motchane had helped to found two institutions in France, the Institut des Hautes Études Scientifiques in Bures-sur-Yvette with himself as director, and the Les Houches summer school with Cécile as director. The IHÉS is a smaller version of the Princeton institute, housed in a beautiful château in the village of Bures on the southern edge of Paris. The Les Houches summer school is a high-level school of theoretical physics, meeting for six weeks every summer in the French Alps, attracting first-rate teachers and students from all over the world. Both institutions are still flourishing sixty years later. Cécile kept her promise and invited me to teach at Les Houches in 1954. I taught the brightest class of students that I ever encountered. The brightest of the bright was Georges Charpak, who won a Nobel Prize for Physics in 1992.
During the past week I at last began to make some progress in explaining my ideas. Up till this week I had given only two talks in two months, and those two were mainly occupied with fighting Oppenheimer; several times I had been scheduled to talk and then put off at the last moment because something else had to be discussed; you can imagine how frustrating it was to go on for two months like this. However, at last on Wednesday of this week, Bethe came to my rescue. He came down to talk to the seminar about some calculations he has been doing with the Feynman theory. He was received in the style to which I am accustomed, with incessant interruptions and confused babbling of voices, and had great difficulty in making even his main points clear; while this was going on he stood very calmly and said nothing, only grinned at me as if to say, “Now I see what you are up against.” After that he began to make openings for me, saying in answer to a question, “Well, I have no doubt Dyson will have told you all about that,” at which point I was not slow to say in as deliberate a tone as possible, “I am afraid I have not got to that yet.” Finally Bethe made a peroration in which he said explicitly that the Feynman theory is much the best theory and that people must learn it if they want to avoid talking nonsense; things which I have been saying for a long time but in vain.
After the seminar Bethe had supper with the Oppenheimers; I did not see him except during the seminar. But the next morning I found that my triumph was complete; three extra seminars had been arranged for me in one week. And in the first of these on Thursday Oppenheimer actually listened to me and did not interrupt. The next two are on Monday and Tuesday, and that will be enough for me to get the main essentials done with. Bethe is a great and good man, and I wrote to him and told him so. The tact and strategy which he used, to pull the opinion of the institute onto my side, could not have been more effective. My own researches meanwhile go on with renewed momentum. I have already enough material for a new paper to the Physical Review. I am in no hurry to write it, and I am taking things as easy as possible. As I expected at the time, the result of writing the first paper so quickly is that there is very little of it that I should not like to change now. It was right to publish it fast for the benefit of people in Europe and Japan.
It is strange how easily and unintentionally I have slid into the position of a pundit. Now when I give a seminar, I usually find that [Eugene] Wigner has come over from the university to listen to it, and he has once come up to me afterwards to talk. Wigner is the chief professor of theoretical physics at the university, a man with a tremendous reputation and perhaps the greatest living expert on the theory of piles. He is a Hungarian by birth and a very polished and pleasant personality. It is strange that my modest contribution to physics should bring me such a reward as this. It seems somehow out of proportion that to clear up a minor muddle in one branch of physics should be such a serious matter. What is even more strange is that I find myself giving these seminars, without notes or preparation, with Wigner and such people in the audience, and without feeling nervous. A year ago this would have been completely unthinkable.
The word pile was then used for the objects which we now call nuclear reactors. Enrico Fermi built the first nuclear reactor in Chicago in 1942, with Wigner working out the theory of its operation. Wigner then used the theory to design the first high-power reactor that was used to produce plutonium for the Nagasaki bomb. Reactor engineers all over the world have used Wigner’s theory as the basis of their designs. For Wigner, the theory of reactors was only a sideline. He had broad interests in physics and in public affairs. He was one of the group of brilliant Hungarian physicists who came to America in the 1930s. He came as an immigrant, not as a refugee. His main contribution to science was to understand the laws of nature as consequences of mathematical symmetry. He showed how general ideas of symmetry could lead to detailed understanding of the behavior of atoms and nuclei.