OCTOBER 25, 1952
Now for our main news. Two weeks ago I made up my mind that this life of being a professor with a lot of students to look after, combined with a growing family, is taking up too much of my energies, so that it is not possible for me to do much in the way of serious thinking. I decided that I ought to do serious thinking during the next few years, when I have a chance of making important contributions to science. So I decided to write to Oppenheimer and ask him if he would give me a permanent job at the institute at Princeton. Several times in the past he has said casually he would like to have me with him. So I wrote a carefully worded letter asking what he could offer me, laying all my cards on the table and explaining my difficulties. Two days later there came a long-distance call from Princeton, Oppy on the line. He said, “Certainly I will get you a permanent position at Princeton if you want one. Only it will take a little time before I can get a formal offer approved by my committee and sent out to you.” So it seems definite that we shall move to Princeton, either in fall 1953 or fall 1954. The exact terms of the offer I do not yet know. But I presume they will be satisfactory.
We are both happy about this change. First, it means I will have some mental peace and the best conditions for working. Second, the Princeton climate is much more agreeable. We already had snow which stayed on the ground two days, it is freezing hard tonight, and we now have a solid six months of winter to look forward to. In Princeton the winters are not so exhausting. Third, the friends Verena has in Princeton are closer and more desirable to her than any she has here. This means a lot in the long run. I also find the same thing true of myself. Hans Bethe is the one man here with whom I really feel at home, and he is here so little of the time and he is so busy that I do not see much of him.
By an unhappy coincidence of which I was unaware, I arrived as a professor at Cornell in September 1951, just at the time when Edward Teller and Stanislav Ulam discovered the trick that makes hydrogen bombs feasible. The secret program to develop hydrogen bombs at Los Alamos changed suddenly from a leisurely stroll to a furious sprint. Hans Bethe was called in to help with the design of the Ivy Mike thermonuclear device, which was built in a hurry, tested on November 1, 1952, and exploded with a yield of ten megatons. So it happened that Bethe was away from Cornell for much of the first year after my arrival, and I did not know where he was. He was missing just when I needed him most.
Since I wrote to Oppy, I find there is one more complication. Unknown to me, Bethe himself had recently also been offered a permanent position at Princeton, and he is seriously considering accepting it, for much the same reasons as I. This actually does not make much difference to me. If he goes, it will only be better for me in Princeton and worse here. All the same, I somehow doubt if he will go, he is so much a part of the landscape here, and he feels strongly rooted too. I have no doubt that if I had to stick it out here, I would manage to make life easier for myself and should end up being happy and able to do good work. But since I have this opportunity of escaping, I may as well make the most of it.
Two days after the phone call from Oppy, I had a conversation with Bethe, and out of it I got a new idea for a major piece of research in physics. This has absorbed me completely during the last ten days. It goes ahead well and already has led to good results in understanding some recent experiments in the properties of certain particles called mesons. I have been able to find jobs for some of my students to do in connection with this idea, and this makes them happy too. I have hopes this will lead in a few weeks or months to a big step forward in the clarification of the whole meson theory. These last ten days have been great fun, but they make it even more clear how necessary it is to go to Princeton. I simply cannot go on at this pace. All my routine jobs are left undone and are piling up ahead of me. Still it is good to have such work to do, and in time I shall get it done in spite of exhaustion. Bethe is wonderful, if only I could see more of him and less of the students. We definitely go to California for the summer. That is June to September. I am teaching a summer school in Berkeley. This will be a fine change of air for Verena. We shall go all together and rent a house for the summer.
NOVEMBER 1, 1952 [THE DAY OF THE IVY MIKE TEST]
The decision is now definitely made that we leave here and go to Princeton. Only it is a question whether they can find a successor in time for us to leave next year. The successor is likely to be Ed Salpeter, who is already here as a research associate and does Hans Bethe’s lectures for him on the frequent occasions when Hans is away. Ed is a very good man, and I think they could not do better. I am happy that he is here. It makes me feel less compunction about leaving Cornell that they have such a good man to put in my place. This is still completely unofficial. Ed Salpeter is an Australian originally from Vienna who took his degree with Peierls in Birmingham and came here three years ago. He is not a deep thinker, but he is a productive worker and a good teacher and above all physically and mentally tough, so he should be suitable for this job. He and Hans Bethe are good friends too. He has married a Lithuanian-Canadian girl who was a student here and is now taking a degree in animal psychology. The question whether Hans Bethe will leave is not to be decided for several months. I believe he will not go.
I have been busy this week. It goes well with my new ideas and the calculations connected with them. Now I have about six people here working on this job, including Salpeter. I am rapidly reaching the point where I only talk and the others do the work. I hope it will not stay like that—I need to get back to real work myself if we are to keep on making progress. The most remarkable thing is the way people outside are already beginning to get excited about this work. On Wednesday I had a phone call from Princeton from a young Chinese physicist called Lee. He announced he would arrive on Thursday by air in order to learn what we were doing. He duly arrived, and I spent a day telling him all about it. He is a charming young man and understood everything readily.
Tsung Dao Lee was a brilliant young theorist who had been a student of Fermi in Chicago with his countryman Chen Ning Yang. Lee and Yang together won the Nobel Prize in Physics in 1957 for their revolutionary theory of weak interactions. Lee spent most of his life as a professor at Columbia University in New York. In later years he was given a royal welcome in China and organized a program for bringing Chinese students to study physics in America. After one of his visits to China, he told me with pride that he had survived thirty-one consecutive banquets.
Esther is the healthiest baby I ever saw, now that the cold weather is back and her cheeks are red again like ripe apples. But she still doesn’t talk. Katrin is growing up fast and beginning to get more helpful around the house.
My activities in the department are growing by leaps and bounds. I now am directing an empire of eight people who are working hard on the meson calculations which I started six weeks ago. It is amazing how things are humming. Everyone is happy, and they are getting interesting results. It is easy to run such a group once you have a suitable job for them to do. I am happy about it all. When I leave here, they will say “Look how he built the department up in two years” instead of “He didn’t like it so he quit after two years.” This makes a great difference.
The big program of calculations of meson scattering that I had organized at Cornell was intended to explain the big program of experimental measurements of meson scattering organized by Enrico Fermi at Chicago. I took our theoretical results to Chicago and showed them to Fermi. They agreed quite well with his experiments. But Fermi was not impressed. He said, “How many input numbers did you use to fit the experiments?” I said, “Four.” He said, “As my friend John von Neumann likes to say, with four input numbers I can fit an elephant.” For Fermi, the numerical agreement meant nothing. He said politely that our calculations were worthless because they were not based on a well-defined theory. His intuition told him that our description of nuclear processes by a set of equations borrowed from quantum electrodynamics had missed something essential. Fermi died two years late
r, long before the missing ingredient in our description was discovered. The missing ingredient was quarks. I returned from Chicago to Ithaca to tell the students the sad news that our whole program of meson scattering calculations was a grand illusion.
DECEMBER 17, 1952
In the evening there was a big party of the whole physics department, students and staff, about two hundred people. It was not a birthday party for me but the regular annual Christmas party. However, it turned out to be something special. They gave an entertainment which consisted of a representation of a qualifying examination, an oral exam which each Ph.D. student has to take individually before three professors. The professors are always one theoretician, one experimenter, and one mathematician. Each professor has to do these exams rather frequently since there are a lot of students. I do it about once a month. The play was in two parts, first the exam as seen by the professors (with an offensively stupid student and very patient professors) and then as seen by the student (with a clever student falling into traps laid for him by the malicious professors). It was all very funny. But the funniest thing for me was that the theoretical professor spoke with a pure English accent and said “Bad luck” when the student made mistakes, and started to eat a sandwich halfway through the exam. He was unmistakably intended to be Professor Dyson. This was for me completely unexpected, and it is good to find that I have already become enough of a public institution to have such jokes made about me.
DECEMBER 30, 1952
I came back from the Rochester conference with two Japanese physicists, Yoichiro Nambu and Toichiro Kinoshita, who stayed with us overnight, and the next day went out with me and Katrin and helped cut down and carry home the Christmas tree. They were interested in the quaint customs of the Westerners. They have been over here only four months and are at the Princeton institute. I had long talks with them about physics and learned a lot.
I was lucky to get to know these two Japanese geniuses when they were still young and not yet famous. Both of them stayed in America and became central figures of the theoretical physics community, Nambu in Chicago and Kinoshita at Cornell. Nambu won a belated Nobel Prize in 2008 for his theory of broken symmetry. Kinoshita spent his life pushing the calculations of quantum electrodynamics to higher and higher accuracy, barely keeping pace with the increasing accuracy of experimental measurements. In 1952 the theory and experiment agreed to an accuracy of two places of decimals. We all then expected that discrepancies would arise when theory and experiment would go to higher accuracy. In 2013 Kinoshita came to my ninetieth birthday celebration in Singapore to report on the latest comparison, which showed theoretical and experimental results still in agreement to an accuracy of eleven places of decimals. It still seems miraculous to me that our makeshift theory, which we expected to be quickly superseded, is still alive. After sixty years of rigorous testing, Nature still dances to our tune.
In the letters, there is no mention of any discussions with our Japanese visitors about the bombing of Hiroshima and Nagasaki. In those days there was a general agreement on both sides that the bombing had saved lives by bringing the war to a quick end. We all had vivid memories of the war and felt that we were lucky to have survived it. Serious questioning of the ethics of the bombing arose later, after the joy of surviving the war had faded.
FEBRUARY 3, 1953
I had a letter from [Maurice] Bowra, vice chancellor of Oxford, offering me the chair from which Sydney Chapman is retiring. You may remember Chapman was my boss at Imperial College in 1946. It is a fine offer, and in many ways both Verena and I would be glad to go. I think if I had not this new job in Princeton, I would have had a hard time making up my mind about it. Oxford would offer just the things we lack here, a more international society, contacts with Europe, longer vacations, and more leisure. However, now that Princeton offers us all the same things and double the salary, we decided without much difficulty to say no to Oxford. Also we both feel appalled at the thought of once more packing up all our stuff to cross the Atlantic. I think I may one day come back and take such a position at Oxford, but it will not be before the children are grown up and able to take care of themselves. Say in twenty years from now. If they still want me.
On March 26, 1953, our son George was born at the Ithaca hospital. Another healthy baby, this time without legal problems. It came as a great relief to have him born in a country that gave him citizenship as a birthright, even if he was an illegitimate child of two aliens.
APRIL 1, 1953
Since Katrin has no school this week, she is allowed to stay up later. The three of us sat over our drinks and discussed the world and its problems. Katrin is coming now for the first time into contact with these questions. It is beautiful to see how she grasps and reacts to them. This evening she started the conversation with a little speech. I do not know where this came from. I did not talk to her about such questions because I was full of the new baby and our family problems. She started off saying, “But it’s true, isn’t it, Freeman, that the world is in bad shape? The whole world, I mean, not just America and Switzerland and stuff like that. There are so many people everywhere who are bullies, and there are so many wars all the time, and there are all kinds of things that hurt people. I don’t see why there should be so many things that hurt people, do you, Freeman? I think I should like not to kill anything, never to kill anything, not even flies and stuff like that, and chickens and rabbits. And then maybe the bees in the garden wouldn’t want to sting us anymore. And the people in different countries could all be friends with us, think how fine it would be, we could all belong to one tremendous big family, and think how many babies we should have to look after, what a big family it would be. And maybe even the lions would get friends with us and we wouldn’t be afraid of them anymore.” All this came out suddenly, out of the blue, and I made an effort to remember it and write it down just as she said it. I love Katrin more and more as time goes on. She has so much tenderness and imagination, and her life is not easy being the eldest in the family.
MAY 23, 1953
I am giving my final lectures, ending one week from now, and setting exams, settling the affairs of my students. I enjoy all of it, because this is the last time I do these things. I had yesterday two surprise invitations. One was to serve as assistant editor of the Physical Review, of which there are about twelve; it is a tedious job, but I accepted as a public service. The other was to give two weeks of lectures about physics next year at Harvard. Both these are things I am well fitted for. It is a great advantage of my going to Princeton that I can take on such incidental jobs without difficulty. If I were at Cornell, I could hardly go to Boston for two weeks in term time, and the Physical Review job would be only a burden. But in Princeton I can do such things and have enough time over for myself as well. I feel the move to Princeton will not only be good for my natural laziness but will also be the right thing for increasing my usefulness to society. Anyway let us hope so.
• 11 •
MYCENEAN TABLETS AND SPIN WAVES
IN BERKELEY, CALIFORNIA, there was a lively group of solid-state physicists with experimenters and theorists working together. Arthur Kip was the leading experimenter, Charles Kittel the leading theorist. I wanted to move out of particle physics and try my hand at something new, so I arranged to spend the summer of 1953 working with Kip and Kittel. I taught quantum mechanics to a class of summer school students and meanwhile taught myself solid-state physics by working on problems suggested by Kittel. The whole family came to Berkeley, and we rented a beautiful old house on the steep hillside above the campus.
AUGUST 14, 1953
I am getting a lot of good physics done since my lectures stopped. I sent off one paper to the Physical Review, and I am now deep in another one. This latest piece of work is in connection with the solid-state project which is paying part of my salary while I am here. Fortunately they had some problems which I was able to solve, so I am earning my keep. It is good that they get value for their money, so I will find
it easy to get invited here again.
The main problem that I solved was to explain Arthur Kip’s experiment on electron spin resonance in metals. Kip put a piece of metal into a cavity filled with microwaves at a fixed frequency with a variable magnetic field and measured the absorption of microwaves by the metal. He found an unexpectedly sharp resonance, which I was able to explain as a consequence of the dynamics of electron spins in the metal. The microwaves only penetrate into a thin skin on the surface of the metal, and the electrons in the metal see the microwaves only for brief snatches of time, but the electrons remember the phase of the microwaves from one snatch to the next. The accurate phase memory of the electrons makes the resonance sharp.
In September 1953 I started my career as professor at the Institute for Advanced Study. We lived for three years in a house rented from the institute, then in 1956 bought the house that became our permanent home. The main change at the institute since my previous visit in 1950 was the Computer Project, bringing together engineers and scientists to build the machine and use it. In 1953 the project was in vigorous operation. My closest friends were the two people who were leading the project, Julian Bigelow, the chief engineer, and Jule Charney, the chief meteorologist. John von Neumann was nominally in charge, but his work designing the machine was finished, and he was spending most of his time in Washington as a member of the U.S. Atomic Energy Commission. I looked forward to a future with the institute leading the world in two new sciences, computer science led by Bigelow and climate science led by Charney. My hopes were quickly crushed. Within two years, von Neumann was dying of cancer, and the institute had decided to close the project down. I was the only member of the institute faculty who considered the closing to be a disastrous mistake. Oppenheimer was not interested in keeping the project alive, and I could do nothing to save it.
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