“Surely You’re Joking, Mr. Feynman”: Adventures of a Curious Character

They thought I was joking. But the thing that I had trouble with at the Rochester meeting—the neutron and proton disintegration: everything fit but that, and if it was V and A instead of S and T, that would fit too. Therefore I had the whole theory!

That night I calculated all kinds of things with this theory. The first thing I calculated was the rate of disintegration of the muon and the neutron. They should be connected together, if this theory was right, by a certain relationship, and it was right to 9 percent. That’s pretty close, 9 percent. It should have been more perfect than that, but it was close enough.

I went on and checked some other things, which fit, and new things fit, new things fit, and I was very excited. It was the first time, and the only time, in my career that I knew a law of nature that nobody else knew. (Of course it wasn’t true, but finding out later that at least Murray Gell-Mann—and also Sudarshan and Marshak— had worked out the same theory didn’t spoil my fun.)

The other things I had done before were to take somebody else’s theory and improve the method of calculating, or take an equation, such as the Schrodinger Equation, to explain a phenomenon, such as helium. We know the equation, and we know the phenomenon, but how does it work?

I thought about Dirac, who had his equation for a while—a new equation which told how an electron behaved—and I had this new equation for beta decay, which wasn’t as vital as the Dirac Equation, but it was good. It’s the only time I ever discovered a new law.

I called up my sister in New York to thank her for getting me to sit down and work through that paper by Lee and Yang at the Rochester Conference. After feeling uncomfortable and behind, now I was in; I had made a discovery, just from what she suggested. I was able to enter physics again, so to speak, and I wanted to thank her for that. I told her that everything fit, except for the 9 percent.

I was very excited, and kept on calculating, and things that fit kept on tumbling out: they fit automatically, without a strain. I had begun to forget about the 9 percent by now, because everything else was coming out right.

I worked very hard into the night, sitting at a small table in the kitchen next to a window. It was getting later and later—about 2:00 or 3:00 AM. I’m working hard, getting all these calculations packed solid with things that fit, and I’m thinking, and concentrating, and it’s dark, and it’s quiet … when suddenly there’s a TAC-TAC- TAC-TAC—loud, on the window. I look, and there’s this white face, right at the window, only inches away, and I scream with shock and surprise!

It was a lady I knew who was angry at me because I had come back from vacation and didn’t immediately call her up to tell her I was back. I let her in, and tried to explain that I was just now very busy, that I had just discovered something, and it was very important. I said, “Please go out and let me finish it.”

She said, “No, I don’t want to bother you. I’ll just sit here in the living room.”

I said, “Well, all right, but it’s very difficult.”

She didn’t exactly sit in the living room. The best way to say it is she sort of squatted in a corner, holding her hands together, not wanting to “bother” me. Of course her purpose was to bother the hell out of me! And she succeeded—I couldn’t ignore her. I got very angry and upset, and I couldn’t stand it. I had to do this calculating; I was making a big discovery and was terribly excited, and somehow, it was more important to me than this lady—at least at that moment. I don’t remember how I finally got her out of there, but it was very difficult.

After working some more, it got to be very late at night, and I was hungry. I walked up the maims street to a little restaurant five or ten blocks away, as I had often done before, late at night.

On early occasions I was often stopped by the police, because I would be walking along, thinking, and then I’d stop—sometimes an idea comes that’s difficult enough that you can’t keep walking; you have to make sure of something. So I’d stop, and sometimes I’d hold my hands out in the air, saying to myself, “The distance between these is that way, and then this would turn over this way …”

I’d be moving my hands, standing in the street, when the police would come: “What is your name? Where do you live? What are you doing?”

“Oh! I was thinking. I’m sorry; I live here, and go often to the restaurant …” After a bit they knew who it was, and they didn’t stop me any more.

So I went to the restaurant, and while I’m eating I’m so excited that I tell a lady that I just made a discovery. She starts in: She’s the wife of a fireman, or forester, or something. She’s very lonely—all this stuff that I’m not interested in. So that happens.

The next morning when I got to work I went to Wapstra, Boehm, and Jensen, and told them, “I’ve got it all worked out. Everything fits.”

Christy, who was there, too, said, “What beta-decay constant did you use?”

“The one from So-and-So’s book.”

“But that’s been found out to be wrong. Recent measurements have shown it’s off by 7 percent.”

Then I remember the 9 percent. It was like a prediction for me: I went home and got this theory that says the neutron decay should be off by 9 percent, and they tell me the next morning that, as a matter of fact, it’s 7 percent changed. But is it changed from 9 to 16, which is bad, or from 9 to 2, which is good?

Just then my sister calls from New York: “How about the 9 percent—what’s happened?”

“I’ve just discovered that there’s new data: 7 percent …”

“Which way?”

“I’m trying to find out. I’ll call you back.”

I was so excited that I couldn’t think. It’s like when you’re rushing for an airplane, and you don’t know whether you’re late or not, and you just can’t make it, when somebody says, “It’s daylight saving time!” Yes, but which way? You can’t think in the excitement.

So Christy went into one room, and I went into another room, each of us to be quiet, so we could think it through: This moves this way, and that moves that way—it wasn’t very difficult, really; it’s just exciting.

Christy came out, and I came out, and we both agreed: It’s 2 percent, which is well within experimental error. After all, if they just changed the constant by 7 percent, the 2 percent could have been an error. I called my sister back: “Two percent.” The theory was right.

(Actually, it was wrong: it was off, really, by 1 percent, for a reason we hadn’t appreciated, which was only understood later by Nicola Cabibbo. So that 2 percent was not all experimental.)

Murray Gell-Mann compared and combined our ideas and wrote a paper on the theory. The theory was rather neat; it was relatively simple, and it fit a lot of stuff. But as I told you, there was an awful lot of chaotic data. And in some cases, we even went so far as to state that the experiments were in error.

A good example of this was an experiment by Valentine Telegdi, in which he measured the number of electrons that go out in each direction when a neutron disintegrates. Our theory had predicted that the number should be the same in all directions, whereas Telegdi found that 11 percent more came out in one direction than the others. Telegdi was an excellent experimenter, and very careful. And once, when he was giving a talk somewhere, he referred to our theory and said, “The trouble with theorists is, they never pay attention to the experiments!”

Telegdi also sent us a letter, which wasn’t exactly scathing, but nevertheless showed he was convinced that our theory was wrong. At the end he wrote, “The F-C (Feynman—Gell-Mann) theory of beta decay is no F-C.”

Murray says, “What should we do about this? You know, Telegdi’s pretty good.”

I say, “We just wait.”

Two days later there’s another letter from Telegdi. He’s a complete convert. He found out from our theory that he had disregarded the possibility that the proton recoiling from the neutron is not the same in all directions. He had assumed it was the same. By putting in corrections that our theory predicted instead of the ones he had been using, the results straightened out and were in complete agreement.

I knew that Telegdi was excellent, and it would be hard to go upstream against him. But I was convinced by that time that something must be wrong with his experiment, and that he would find it—he’s much better at finding it than we would be. That’s why I said we shouldn’t try to figure it out but just wait.