Richard Feynman

by John Gribbin

  He sometimes had less time for more senior members of Caltech. Helen Tuck’s office was between the offices of Murray Gell-Mann and Richard Feynman, and she looked after both of them. The door to her office was on the right-hand side of the wall, facing her desk, and it just happened that there was a structural pillar to the left of the door, inside her room, so that the chair used by visitors, its back against the wall, was not in sight from the doorway. Often, Feynman would sit in that chair, chatting to her about life in general, when he wasn’t in the mood to work. Sometimes, a visitor would come to the door, asking, ‘Is Professor Feynman in his office?’ She would glance at Dick, and if he shook his head she would reply, truthfully, ‘No, he isn’t in his office just now’, and the visitor would go away. It was a harmless way to avoid being imposed on when he wasn’t in the mood, calculated to avoid giving offence (much worse to be told, ‘Yes, he is in but he doesn’t want to see you’), and Tuck and her colleagues were deeply hurt when one biographer described how Feynman ‘hid behind her door’ to avoid being seen; the comment, she felt, displayed a fundamental lack of understanding of Feynman’s character.9

  Even with the best intentions, though, Feynman found it very difficult to be responsible for research students. He said, ‘I’ve put a lot of energy into my students, but I think I wreck them somehow. I have never had a student that I felt I did something for, and I have never had a student who hasn’t disappointed me in some way. I don’t think I did very well.’10 As this comment shows, Feynman blamed himself, not the students, for what he perceived as their failure to make a mark in science. Part of the problem, as we have mentioned, was that Feynman couldn’t resist solving problems. If he found a good problem for a student to work on, he’d end up solving it himself; if students came to him with a problem, he couldn’t help but solve it for them, rather than just giving them enough of a hint to get them going in the right direction to solve it themselves. He didn’t mean to, but he couldn’t help it; present Feynman with a problem, from a Mayan codex to a locked safe to the mysteries of quantum electrodynamics, and he would just have to solve it – the exception that proves the rule, of course, being his promise to his sister Joan to leave the aurora to her. Hans Bethe, Feynman’s old mentor, had the same problem. So while some great physicists, such as Oppenheimer, produced a stream of doctoral candidates who had learned to do physics the Oppenheimer (or whatever) way, and carried the style of their teacher forward into the next generation, there was never a ‘school’ of Feynman students in the same sense.

  Another problem was that Feynman made no concessions to students. He treated everybody the same way. When he was a youngster at Los Alamos, he did not hesitate to tell Bethe he was a fool if the older man made a mistake; now that he was a senior scientist, he did not hesitate to tell his students (or anyone else) they were fools if they made a mistake. It was no more, and no less, than he expected himself – indeed, he would often describe his own errors as foolish, or stupid, mistakes. But it is hard for graduate students to cope with that kind of criticism from their supervisor. One Caltech student who went on to achieve eminence in the field of relativity theory, Kip Thorne, says that as a young researcher he was terrified of giving a seminar when Feynman was in the audience.11 But although it could be distressing to have Feynman bluntly pointing out the flaws in your argument, as another former Caltech student pointed out to us12 it was, ultimately, always acceptable, for one important reason. Feynman was always right. He could see the faults in an argument quicker than other people could. If he said there was a flaw in the argument, there was; and it was surely better, when it came down to it, to find out from him, before you made a complete fool of yourself by publishing the mistake in a journal for all the world to see. It was also a good idea to be careful what you wore to give a seminar at Caltech, especially if there were flaws in your argument. Feynman’s dislike of uniforms and authority could encourage him to even stronger attacks on anyone who seemed to be trying to pull rank; ‘if somebody came to give a lecture in a suit, he would be merciless’.13

  The students who did do well (in spite of Feynman’s disclaimer, there were some) were the ones who quickly learned that the abrupt dismissal of bad ideas was not meant personally, and who worked through the curtness without taking offence. You needed initiative in order to convince Feynman that you were worth spending time on. There’s another important point. According to some of those who worked alongside him, it wasn’t so much that Feynman was a failure with graduate students as that he had relatively few of them. This was because he didn’t work at the head of a large group, but mainly on his own, so that when an interesting problem occurred to him it was natural to get on with it himself, rather than pass it on to other members of a team.14

  One of the best examples of how to succeed as a research student with Feynman comes from Michael Cohen, who explained his approach in Most of the Good Stuff. Cohen graduated from Cornell in 1951, but had scarcely known Feynman there. He moved to Caltech to work for his PhD, hoping to work with Feynman, who was away in Brazil during Cohen’s first year on the West Coast. They got to know each other when Feynman returned to Pasadena, and Cohen made a deliberate effort to make himself useful by studying Feynman’s own papers on liquid helium, and looking for areas in which the work could be extended, rather than simply going to Feynman and asking for a problem to work on. This led to a genuine collaboration, and Cohen also learned much about intellectual honesty from Feynman.

  As Cohen’s thesis adviser, Feynman worked through all Cohen’s calculations in the first draft of the thesis, and found a numerical error. With the error in place, the calculation gave almost perfect agreement with a number determined by Lev Landau; with the correction, Cohen’s result was 20 per cent higher than Landau’s. Just because the first calculation had seemed to give the ‘right’ answer didn’t mean that it shouldn’t be checked, and the honest result was the one that appeared in the final version of the thesis. Cohen stayed on with Feynman for eighteen months after completing his PhD work, until 1957. Then, at Feynman’s recommendation, Oppenheimer took him on at the Institute for Advanced Study.

  Feynman cannot have been too disappointed with this particular student if he recommended him to Oppie! So no matter how gloomy Feynman may have felt about his track record with research students on the day in 1988 that he discussed them with Mehra (only shortly before his death), there were some successes, and his comments on that occasion should be taken with a pinch of salt, as rather extreme self-criticism.

  The problem with most research students was that they fell into a gap between two kinds of scientist who could benefit from Feynman’s unique ability. Undergraduates could benefit from contact with him precisely because he was a kind of oracle who could fill their heads with ideas and images about the wonderful world of physics. Graduate students had trouble because he couldn’t give them space to develop their own ideas. But his peers in research, who had already found their own space, could benefit from precisely the trait that caused trouble with many research students, his compulsion to solve puzzles. If anybody was stuck with how to develop an idea in physics, they only had to call Dick Feynman and he would point the way through the immediate logjam so that they could get on with their work.

  As Willy Fowler told Mehra, ‘you just had to tell him a few lines, and he would jump up with ideas and diagrams. He was very helpful and encouraging. Feynman was interested in everything … He was just tremendous.’

  Another physicist, Richard Sherman, saw just how tremendous Feynman could be in this problem solving role, when Sherman was halfway through his first year as a graduate student at Caltech, doing research on superconductivity. He was in Feynman’s office, writing up equations on the blackboard, and Feynman was analysing the work almost as quickly as Sherman could write. Then, the telephone rang. The caller had a question about a problem in high-energy physics. Feynman immediately switched into a discussion of the complicated problem involved, talked for about ten minutes and resolv
ed the caller’s difficulty. He hung up the phone, switched back to superconductivity and carried on exactly where he had left off, until the phone rang again. Somebody else had a problem, involving solid state physics. Feynman solved it, and went back to superconductivity again. ‘This sort of thing went on for about three hours – different sorts of technical telephone calls, each time in a completely different field, and involving different types of calculation. [It] made a tremendous impression on me. It was staggering. I have never seen that kind of thing again.’15

  Another Caltech graduate student, who was supervised by Murray Gell-Mann in the 1960s, unconsciously echoed Marc Kac’s comments about the nature of genius (which he was unaware of at the time) when he told us that ‘Murray was clever, but you always had the feeling that if you weren’t so lazy and worked really hard, you could be just as clever as him. Nobody ever felt that way about Dick.’16 Feynman may not have built up a large school of graduate students under his direct supervision, but he was a father figure and inspiration to all the graduate students in physics at Caltech during his time there, even the ones supervised by Gell-Mann!

  Hagen Kleinert, who now works at the Institute for Theoretical Physics in Berlin, visited Caltech as a young professor in 1972. ‘I had actually been hired by Gell-Mann,’ he told us, ‘but he was very hard to learn from since he always pretended to know everything from pure intuition without any ditch work.’17 The person Kleinert learned most from during his visit was Feynman, who gave a weekly seminar on the path integral approach to the young postdoctoral researchers. During the course of these seminars, Feynman explained that he had stopped teaching path integrals at a less advanced level, because he had never derived a complete path integral description of the hydrogen atom, and was embarrassed by this failure. The path integral idea provided a superb mental picture to give a physical feel for what is going on, but the calculations had proved intractable. Actually, this was no real disgrace. The standard approach to quantum mechanics, using Schrödinger’s wave equation, was not much better, since even the Schrödinger equation could only be solved to give an exact description of hydrogen, the simplest atom of them all.

  The idea stuck in Kleinert’s head, and several years later he not only solved the problem (much to Feynman’s delight), but wrote a major textbook on the path integral approach, re-establishing path integrals as a research tool, not only conceptually useful but now capable of solving problems as easily as using the Schrödinger equation.

  In 1982, Kleinert was back in California (this time based at Santa Barbara), and visited Caltech several times. ‘Feynman knew of my work on the path integral of the hydrogen atom by then, and was very friendly to me and open to discussion.’ The friendship extended to some joint work, updating some of Feynman’s earlier ideas with the aid of a Sinclair home computer, one of the first computers available to the public, that Kleinert had just bought at Woolworth’s for $15.00. At first, the work seemed of only minor importance. But in the 1990s Kleinert and his colleagues developed the technique, known as the variational principle, into a powerful tool which made it possible to use path integrals to solve increasingly difficult problems in the quantum world. And it all stemmed from Feynman’s continuing active involvement in fundamental science, as a father figure pointing the way for younger researchers, well into the 1980s.

  Feynman was also a father figure to the undergraduates. In the 1974 commencement address, which we mentioned in Chapter 10, he provided them with words of wisdom about science which were also words of wisdom about life in general, just the sort of thing a father ought to pass on to his children before they go out into the world. Shooting down the widespread public acceptance of what he regarded as pseudosciences like astrology and spoonbending18 (and, one of his eternal bugbears, psychology), he explained what it was that real science had that these pseudosciences did not:

  It’s a kind of scientific integrity, a principle of scientific thought that corresponds to a kind of utter honesty – a kind of leaning over backwards. For example, if you’re doing an experiment, you should report everything that you think might make it invalid – not only what you think is right about it: other causes that could possibly explain your results; and things you thought of that you’ve eliminated by some other experiment, and how they worked – to make sure the other fellow can tell they have been eliminated.

  Details that could throw doubt on your interpretation must be given, if you know them. You must do the best you can – if you know anything at all wrong, or possibly wrong – to explain it. If you make a theory, for example, and advertise it, or put it out, then you must also put down all the facts that disagree with it, as well as those that agree with it.19

  Few scientists have such complete integrity. Even the most honest subconsciously cut the odd corner, or neglect to mention all of the evidence in conflict with their pet theory. But Feynman never succumbed to his own wishful thinking. He never fooled himself. In Fowler’s words, ‘Feynman was a very wise man, who set very high standards for everyone. He motivated you to achieve them. Just the fact that he was around, all of us at Caltech thought that we had to live up to his standards. In this indirect way he influenced us all.’20

  The fatherly, ‘wise man’ influence extended outside the campus, to Feynman’s wider circle of friends and acquaintances. By the end of the 1970s, he had yet another outside interest to add to his list, one that was to be a recurring preoccupation in the last decade of his life. In the summer of 1977, he had just about finished his work on quark jets, Carl was soon to be beginning his junior year at the local high school, and Michelle had completed first grade.21 Ralph Leighton had a job teaching mathematics at the same Pasadena high school where Carl was a student, but confessed to Feynman over dinner one day that what he would really like would be to teach geography. Feynman responded by asking Leighton if he had ever heard of a place called Tannu Tuva, which Feynman knew from his childhood hobby of stamp collecting. No philatelist himself, and convinced that Feynman was pulling his leg, Leighton insisted that they look for it in the atlas at the back of the Encyclopaedia Britannica. What they found, nestling to the northwest of Mongolia, was a tiny region labelled ‘Tuvinskaya ASSR’, part of the Union of Soviet Socialist Republics. Ralph conceded that the region could once have been called Tannu Tuva, after noting the Tannu Ola Mountains to the south. When they discovered that the capital of the country was called Kyzyl, a name completely without a vowel in it, there was only one reaction:

  ‘We must go there,’ said Gweneth.

  ‘Yeah!’ exclaimed Richard. ‘A place that’s spelled K-Y-Z-Y-L has just got to be interesting!’

  Richard and I grinned at each other and shook hands.22

  At the time, the problems of visiting such a remote region of the USSR seemed insurmountable, which made the project all the more appealing. Of course, Feynman would have been able to arrange an official lecture tour of the Soviet Union, with a guaranteed trip to Kyzyl as part of his payment. But that would have been too easy. Just as he wanted to be treated on merit as a drummer, not regarded as some kind of freak spectacle, a ‘physicist who drums’ (like a dog walking on its hind legs), so he wanted to visit Tuva as an explorer, if only he could find the way through the red tape and bureaucracy that would inevitably confront an American citizen (who happened to have worked on the atomic bomb) trying to visit a communist country (and one far off the tourist trails) during what was still then the Cold War.

  They made slow progress with the project, mostly because for a long time it wasn’t a serious endeavour, and partly because it was around this time that Feynman first became seriously ill with cancer.

  Richard and Gweneth were on holiday in the Swiss Alps – one of their regular haunts – in the summer of 1977 when Richard first showed signs that something was wrong. There may have been symptoms before, which he had ignored, having other things on his mind; but on this occasion he frightened Gweneth by suddenly running into the bathroom and vomiting.23 Although clearly ill
, Richard pushed his own health worries to one side, not least because of his concern about Gweneth, who had cancer and had to undergo an operation. So it was only at the end of the summer of 1978, when he went to the doctor complaining of abdominal pains, that his own cancer was diagnosed. By then, it was ‘a fourteen-pound mass of cancer the size of a football’,24 and showed as a visible lump at Feynman’s waist. Growing in his abdomen to this enormous size, the tumour had crushed Feynman’s left kidney and adrenal gland, and had wrecked his spleen.

  One day, Helen Tuck phoned round to Feynman’s colleagues at Caltech, including David Goodstein, to inform them that Dick had cancer, and would be undergoing major surgery the following Friday. On the Monday before the operation, Goodstein recalls,25 he mentioned to Feynman that there seemed to be an error in a piece of work they had done together. It was nothing of great importance, but the work had been published, and they ought to set the record straight. Feynman agreed to look into it, and was soon absorbed. ‘He didn’t know whether he was going to live through the week, but here he was absorbed by a really not important problem in elastic theory.’

  At the end of the afternoon, they decided that the problem couldn’t be solved, and went home. Two hours later, Goodstein had a phone call from Feynman. He was on a complete high, absolutely exhilarated, because he had found the solution to the problem, which he dictated to Goodstein there and then. It was four days before the operation, and the problem was still unimportant, but solving it had made Feynman’s day. ‘I think’, says Goodstein, ‘that tells you a little bit about what drove the man to do what he did.’