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

the hole and came in, went out again, and so on, until the sergeant at the gate began to wonder what was happening. How come this guy is always going out and never coming in? And, of course, his natural reaction was to call the lieutenant and try to put me in jail for doing this. I explained that there was a hole.

You see, I was always trying to straighten people out. And so I made a bet with somebody that I could tell about the hole in the fence in a letter, and mail it out. And sure enough, I did. And the way I did it was I said, You should see the way they administer this place (that’s what we were allowed to say). There’s a hole in the fence seventy-one feet away from such-and-such a place, that’s this size and that size, that you can walk through.

Now, what can they do? They can’t say to me that there is no such hole. I mean, what are they going to do? It’s their own hard luck that there’s such a hole. They should fix the hole. So I got that one through.

I also got through a letter that told about how one of the boys who worked in one of my groups, John Kemeny had been wakened up in the middle of the night and grilled with lights in front of him by some idiots in the army there because they found out something about his father, who was supposed to be a communist or something. Kemeny is a famous man now.

There were other things. Like the hole in the fence, I was always trying to point these things out in a non- direct manner. And one of the things I wanted to point out was this—that at the very beginning we had terribly important secrets; we’d worked out lots of stuff about bombs and uranium and how it worked, and so on; and all this stuff was in documents that were in wooden filing cabinets that had little, ordinary common padlocks on them. Of course, there were various things made by the shop, like a rod that would go down and then a padlock to hold it, but it was always just a padlock. Furthermore, you could get the stuff out without even opening the padlock. You just tilt the cabinet over backwards. The bottom drawer has a little rod that’s supposed to hold the papers together, and there’s a long wide hole in the wood underneath. You can pull the papers out from below.

So I used to pick the locks all the time and point out that it was very easy to do. And every time we had a meeting of everybody together, I would get up and say that we have important secrets and we shouldn’t keep them in such things; we need better locks. One day Teller got up at the meeting, and he said to me, “I don’t keep my most important secrets in my filing cabinet; I keep them in my desk drawer. Isn’t that better?”

I said, “I don’t know. I haven’t seen your desk drawer.” He was sitting near the front of the meeting, and I’m sitting further back. So the meeting continues, and I sneak out and go down to see his desk drawer.

I don’t even have to pick the lock on the desk drawer. It turns out that if you put your hand in the back, underneath, you can pull out the paper like those toilet paper dispensers. You pull out one, it pulls another, it pulls another … I emptied the whole damn drawer, put everything away to one side, and went back upstairs.

The meeting was just ending, and everybody was coming out, and I joined the crew and ran to catch up with Teller, and I said, “Oh, by the way let me see your desk drawer.”

“Certainly,” he said, and he showed me the desk.

I looked at it and said, “That looks pretty good to me. Let’s see what you have in there.”

“I’ll be very glad to show it to you,” he said, putting in the key and opening the drawer. “If,” he said, “you hadn’t already seen it yourself.”

The trouble with playing a trick on a highly intelligent man like Mr. Teller is that the time it takes him to figure out from the moment that he sees there is something wrong till he understands exactly what happened is too damn small to give you any pleasure!

Some of the special problems I had at Los Alamos were rather interesting. One thing had to do with the safety of the plant at Oak Ridge, Tennessee. Los Alamos was going to make the bomb, but at Oak Ridge they were trying to separate the isotopes of uranium—uranium 238 and uranium 235, the explosive one. They were just beginning to get infinitesimal amounts from an experimental thing of 235, and at the same time they were practicing the chemistry. There was going to be a big plant, they were going to have vats of the stuff, and then they were going to take the purified stuff and repurify and get it ready for the next stage. (You have to purify it in several stages.) So they were practicing on the one hand, and they were just getting a little bit of U235 from one of the pieces of apparatus experimentally on the other hand. And they were trying to learn how to assay it, to determine how much uranium 235 there is in it. Though we would send them instructions, they never got it right.

So finally Emil Segre said that the only possible way to get it right was for him to go down there and see what they were doing. The army people said, “No, it is our policy to keep all the information of Los Alamos at one place.”

The people in Oak Ridge didn’t know anything about what it was to be used for; they just knew what they were trying to do. I mean the higher people knew they were separating uranium, but they didn’t know how powerful the bomb was, or exactly how it worked or anything. The people underneath didn’t know at all what they were doing. And the army wanted to keep it that way. There was no information going back and forth. But Segre insisted they’d never get the assays right, and the whole thing would go up in smoke. So he finally went down to see what they were doing, and as he was walking through he saw them wheeling a tank carboy of water, green water—which is uranium nitrate solution.

He said, “Uh, you’re going to handle it like that when it’s purified too? Is that what you’re going to do?”

They said, “Sure—why not?”

“Won’t it explode?” he said.

Huh! Explode?

Then the army said, “You see! We shouldn’t have let any information get to them! Now they are all upset.”

It turned out that the army had realized how much stuff we needed to make a bomb—twenty kilograms or whatever it was—and they realized that this much material, purified, would never be in the plant, so there was no danger. But they did not know that the neutrons were enormously more effective when they are slowed down in water. In water it takes less than a tenth—no, a hundredth—as much material to make a reaction that makes radioactivity. It kills people around and so on. It was very dangerous, and they had not paid any attention to the safety at all.

So a telegram goes from Oppenheimer to Segre: “Go through the entire plant. Notice where all the concentrations are supposed to be, with the process as they designed it. We will calculate in the meantime how much material can come together before there’s an explosion.”

Two groups started working on it. Christy’s group worked on water solutions and my group worked on dry powder in boxes. We calculated about how much material they could accumulate safely. And Christy was going to go down and tell them all at Oak Ridge what the situation was, because this whole thing is broken down and we have to go down and tell them now. So I happily gave all my numbers to Christy and said, you have all the stuff, so go. Christy got pneumonia; I had to go.

I had never traveled on an airplane before. They strapped the secrets in a little thing on my back! The airplane in those days was like a bus, except the stations were further apart. You stopped off every once in a while to wait.

There was a guy standing there next to me swinging a chain, saying something like, “It must be terribly difficult to fly without a priority on airplanes these days.”

I couldn’t resist. I said, “Well, I don’t know. I have a priority.

A little bit later he tried again. “There are some generals coming. They are going to put off some of us number threes.”

“It’s all right,” I said. “I’m a number two.”

He probably wrote to his congressman—if he wasn’t a congressman himself—saying, “What are they doing sending these little kids around with number two priorities in the middle of the war?”

At any rate, I arrived at Oak Ridge. The first thing I did was have them take me to the plant, and I said nothing. I just looked at everything. I found out that the situation was even worse than Segre reported, because he noticed certain boxes in big lots in a room, but he didn’t notice a lot of boxes in another room on the other side of the same wall—and things like that. Now, if you have too much stuff together, it goes up, you see.

So I went through the entire plant. I have a very bad memory but when I work intensively I have a good