Shebang: There's a book that Einstein writes and then he says to Wolfgang Pauli, 'Make sure that Pais gets this'
Pais: Ja, Ja. That was the last edition of the book called 'The Meaning of Relativity'. And I have the galley proofs of Einstein's contribution in that book, and on the cover it said, 'Pauli nach Brustnahme bitte Pais geben' - 'Pauli, after perusal please give to Pais'
My attitude about Einstein was like this. That he was a great man was beyond dispute. That was obvious. That he had written superb papers was beyond dispute. Those I had never read, because those I had been taught as a student so you don't read them. He also wrote bad papers, those I
didn't read because why should you read anybody's bad papers. So I had not read Einstein. I did not know the oeuvre, really. And I do regret it because now that I have really read Einstein's work from beginning to end, there are questions that I could have asked him, but I never knew the questions, because I didn't know what he had said.
Shebang: Well, that's the great thing about your writing. On the one hand there's your perspective as a physicist, and on the other hand we go with you, we're with you -
Pais: I try to do that. That is my effort. You see, I like to write for physicists perhaps first and foremost. But I also like to stretch the knowledge about physics to a wider audience. I try. That's very difficult. It is a noble task. I find it a difficult task and I do my best.
Shebang: You do it brilliantly. The feeling of the man, the person, this guy Einstein. Obviously, you know he's a very famous person, but I suppose those of us who have been lucky enough to know very famous people in our lives
Pais: Yes.
Shebang: We find that at a certain point they become just, on some level, just people. You went on lots of walks with him. You talked.
Pais:  We talked about the war, we talked about politics, we talked about Jewish issues, we talked about Jewish jokes. One day I told Einstein a Jewish joke. And while I was telling it to him I saw his face change. He became younger and younger, in his face. And when I told the punch-line he burst out laughing and his laugh was like the barking of a seal. And so I said to myself, 'I had so much fun, if I know another joke, I'll tell him again'. So once in a while I told him a joke. I love to tell jokes, and both he and I loved Jewish jokes. I think the Jews have made a great contribution to human culture, and one of them is their particular humour. I think Jewish humour is special - not better or worse that other humour, but special.
Shebang:   Gentle humour.
Pais:  Yes.
Shebang:You have described Einstein and Bohr, too as having very gentle, soft voices.
Pais: Very gentle voices.
Shebang: So the argument between them was always done very cordially -
Pais: Cordially, courteously.
Shebang: But the stakes -
Pais: Oh yes! Very high
Shebang: It's really some distinction that you knew them both so well
Pais: Yes, it is. That came about as follows. When the War was over, I was in Holland and went to my professor and he said 'Now you have to do your post-doc. And there are two possibilities. One is that you go to the Institute in Princeton' - because Pauli was there. 'The other one is that you go to Bohr. Why don't I write a recommendation for both places'. And I got accepted by both places. So what the professor said then to me is, first you go to Bohr for a year, explain the situation, then go to Princeton, then come back. And that's what I did. I came to Copenhagen, spent an utterly marvelous year here with Bohr - and his family. Then I went to Princeton. And then something very strange happened, people started to offer me jobs. And I being a total innocent said, 'I thank you very much for the kind offer but I have other plans'. What I did know is that's the way to up the ante in American style. So I got better offers and better offers. And I said, maybe I should stay. And I have never taken up a second year. I have been here during Bohr's time, for months, but never did that year.
Shebang: You write about causality, and the fact that Einstein seemed to cling to it.
Pais: Ja, Ja
Shebang: It doesn't seem to worry you. The challenge to causality is something you have accepted.
Pais: As we say in New York, you can't fight Tammany Hall! [i.e. You can't fight the Mayor and the City officials] [LAUGHTER] I mean, you know, that's the way Nature tells us things are. I am accepting of that.
Shebang: It's not a generational matter, it's not that you came along later? It's just that it made sense to you.
Pais: It made sense to me, it was explained to me carefully. The transition was explained to me carefully. And then I came to Bohr. And then Bohr began to talk about causality to me. I said, 'What the hell's he talking about?' And I remember my reaction. I began to understand it was like sportsmen, before they start playing the ball game, they warm up. And Bohr always warmed up by talking about causality.
Shebang: He was just -
Pais: Just getting into the spirit and the mood of things. And that was in '46. And then, only after I had talked many hours with Bohr did I understand the tremendous shock it must have been to people in '25, '26. It must have been a real shock. As my professor George Uhlenbeck said to me, 'After quantum mechanics it was as if our life had changed,' And that I can understand and respect. You see I became a student in 1935, ten years later. By that time the basics were understood: complementarity, causality, the formalism in its outline was understood. So I got it served up, you know, like a ready-made meal. And that ten years made a tremendous difference. So, no, I had no problems accepting uncertainty, lack of causality, not at all.
Shebang: There is a wonderful anecdote you tell. It arises again, forgive us for staying with this theme of Einstein and Bohr arguing -
Pais: In fact Bohr would argue with Einstein after Einstein was dead.
Shebang: We're sure
Pais: He would talk to me as if Einstein were still sitting there. [LAUGHTER]
Shebang: And the story takes place with you working on a paper with Bohr, you worked on Bohr's papers a lot of the time -?
Pais: Not a lot of the time, but some of the time.
Shebang: And, what, he would call you in?
Pais: Ja
Shebang: What did he call you?
Pais: 'Pais'. 'Bram'. No, no, 'Pais'.
Shebang: 'Pais'. Really? Always surnames?
Pais: Almost always surnames yes. That was the style of the time
Shebang: So he'd call you in and say sit there and
Pais: He didn't say 'Sit there'. 'Would you be so kind as to sit there [LAUGHTER] I need a recording assistant.' That's how he put it.
Shebang: And you describe Bohr arguing fervently with an Einstein who he thought wasn't there, but Einstein crept in and gave Bohr a shock
Pais: He crept in because he came for tobacco. The doctor had forbidden Einstein to buy tobacco. But as Einstein explained, the doctor had not forbidden him to steal tobacco. [LAUGHTER] Einstein had a sense of humour that was out of this world.
Shebang: So, it had been so intense, but now, laughter -
Pais: Of course! We were having a wonderful time! [LAUGHTER]