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I came into physics myself, rather more than a decade after this glorious episode in 1925. And oddly enough, the people that I've known in my working life have not quite been the people that one might have expected, the sort of chap you would expect to meet if you came from Cambridge. If you're at Cambridge in the early thirties, might have been the great Rutherford. In fact, if I saw Rutherford twice in the distance, that was about all. He died in the year in which I became a grad student. And I can quite assure you if you were an undergraduate at Cambridge, you didn't send postcards to Rutherford.

[LAUGHTER]

So I never encountered him, nor did I ever Meet Einstein, which I have always regretted that I never did. But where I was lucky was that four of the great five, of the five great pioneers in quantum mechanics, I did know, some of them quite well as it turned out. Bohr, I only saw once. And that was when I was a young-- so shortly after getting my, what you would call your doctorate.

I was a junior assistant at Cambridge at the time. There was a conference there, and Bohr was down to speak. And he was as naturally befitted, such an august figure. He was the first speaker. And I was shattered to find, in my enthusiasm for physics and so on, I just didn't understand a word he said. And this reminded me very much of a remarkable boss when somebody said to him, Bohr, why don't you speak more clearly? He thought for a moment, and he said, because I don't like to speak more clearly than I think.

[LAUGHTER]

Well, Schrodinger, I got to know in a very queer sort of way. This is when he became a professor in Ireland, during the last World War. And in the years after that, I had a great friend who was the president of the university. And that way, I saw Schrodinger. And I saw a very unusual aspect to him because this was in his poetry writing era.

And I think perhaps not many physicists know that Schrodinger wrote a great deal of poetry, not of the style that many physicists do, rather slick, funny poetry, Limerick type stuff. He tried to write serious lyrical poetry, which was-- I wouldn't say it was great stuff. I mean, it reflects a great man. They're mostly poems addressed to his latest girlfriend, I might add. But these are things that maybe physicists might one day take a look at

[LAUGHTER]

It may be useful. Heisenberg, again, somewhat unusually, I got to know him quite well. Because after the war, he was invited to Cambridge for six months. And he, as it were, was in my college. He lived in my college at a time when I was living there. And I was in almost daily contact with him for about six months. And in the course of that time, he taught me an enormous amount about the early days of quantum mechanics.

And I dearly wish I could remember quite a bit of it. But I dearly wish I'd written it all down, just as I expect Vicky wishes he'd taken 10 times as many pictures. I wish I had. But Heisenberg wasn't quite a man of whom you could have a lot of funny stories. He was kind of tended to be mostly on duty all the time. But Pauli was very much otherwise. It's very easy to think of stories about Pauli.

And right from the beginning, following this lecture of Bohr's that I spoke about, apparently was the next speaker. And he started off in the most amazing way. He went up to the podium, and he said, concerning Professor Bohr's long lecture. Then he began to laugh.

[LAUGHTER]

He went on laughing. Well, it seemed like five minutes. But it was probably about 30 seconds. And during this laughter, he quivered all over. I mean, he quivered. Even at that time, he was getting a tolerable approximation to a sphere.

[LAUGHTER]

And then without telling us a word what criticisms he had of Bohr's lecture, he went on with his own when he finished laughing.

[LAUGHTER]

Anyway, I was told the next day that Pauli wanted to see me. And that frightened me. Because I was aware of all these Pauli stories. And perhaps if Vicky will excuse me, I'll tell one about Pauli and Ehrenfest. I don't know whether it's apocryphal or not. And perhaps he can tell us. But I already had heard this story from a chap called Kemmer, the physicist, Nick Kemmer.

The story is that Ehrenfest and Pauli had had some disagreement. And they'd been sparring quite a bit. And they'd come together at a conference, at a meeting. And these rows have been going on. And I think Ehrenfest hadn't got quite the better of the exchange. And he went up to Pauli afterwards and said, look, Pauli, when I didn't know you, when I read your papers, I had a very high respect for you. But now that I've kind of met you personally, I find you rather an unpleasant sort of fellow.

[LAUGHTER]

Pauli, in a flash, said, ha ha, he said, with me, it's just the other way about.

[LAUGHTER]

The absolute sharpness in a flash of a second. Anyway, I went along to this meeting with Pauli. And it shows a lot for the extreme kindliness of the man. I was very junior at this time. And I had been put by my research director, I was just about in my first year, on what became known later as wave equations of higher spin, on which Pauli had worked with Marcus Fierz, I think it was.

And what Pauli wanted to make sure, he'd heard somebody else was on it. And he wanted to make sure that if I had really got as far as they got, they weren't going to cut me out. It was a very nice thing for him to do. But I just hadn't got as far as they got. And I think when Pauli saw I hadn't got very far, he didn't, from then on, respect me very much as a scientist, not until I began to write science fiction. And from the moment I started to write science fiction, I couldn't get Pauli off my back. He took this very, very seriously.

The other individual belonging to this great era, of course, is Paul Dirac. And I met Dirac at an even earlier time than the episode that I'm telling you now. Because this is just before the war started. And I was just a grad student at the time. Now, Dirac took no students. But the faculty went to Dirac. They had no people-- their research directors like Ralph Fowler were very full of research students. And they said to Dirac, will you take this chap? He's a queer fellow. He won't trouble you at all. And they pressured Dirac, and Dirac finally agreed.

And so I have the distinction, as it were, of being one of the very two or three people who can claim to have been a student of Dirac. Well, I honored this agreement. But Dirac felt he was duty bound to invite me to tea, once every semester. And I used to go along. And I honored it to such a degree that we didn't used to talk about physics at all. We used to talk about mowing the lawn, about the birds, and so forth. And we became quite good friends. In fact, after a little while, I found it difficult to get away.

After our marriage, my wife got on extremely well with Dirac. And the notion that he will never talk, this is to some extent true. He's a very shy man. But once he really starts to talk, he sure does. But he never had very much feeling for my way of tackling problems. He'd always say, oh, much too brutal that method. You should really go for the beauty of it. And I tried to find out from him what was beauty. That, he says, well, you have to think about it, you know, and worry.

But he was trained as an engineer. And the whole of the mystique that Dirac is a very impractical man is a deliberate ploy on his part so that he doesn't get involved in things. When during the war, the nuclear program was being started, Dirac didn't want to get involved. But the British government badly wanted to get him as one of their names on the program, in order that the US government would take the program very seriously.

And the minister for this got on the telephone and rang Dirac. And Dirac hummed and hawed about whether he'd come to see him. And finally, the minister retreated and said, well, are you ever in London? Dirac says, yes, about once a year. I mean, there's just no way, even from the highest level of government, where he could be pressed into doing what he didn't want to do. But if he really wanted to do something, he's absolutely on the ball.