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

mean, the bolt is still down? It means the bolt is in the slot made by the three discs, which are still properly lined up. Ahhhh!

Now, if I turn the wheel away from ten a little bit, the bolt comes up; if I immediately go back to ten, the bolt goes back down again, because I haven’t yet disturbed the slot. If I keep going away from ten in steps of five, at some point the bolt won’t go back down when I go back to ten: the slot has just been disturbed. The number just before, which still let the bolt go down, is the last number of the combination!

I realized that I could do the same thing to find the second number: As soon as I know the last number, I can turn the wheel around the other way and again, in lumps of five, push the second disc bit by bit until the bolt doesn’t go down. The number just before would be the second number.

If I were very patient I would be able to pick up all three numbers that way, but the amount of work involved in picking up the first number of the combination by this elaborate scheme would be much more than just trying the twenty possible first numbers with the other two numbers that you already know, when the filing cabinet is closed.

I practiced and I practiced until I could get the last two numbers off an open filing cabinet, hardly looking at the dial. Then, when I’d be in some guy’s office discussing some physics problem, I’d lean against his opened filing cabinet, and just like a guy who’s jiggling keys absent-mindedly while he’s talking, I’d just wobble the dial back and forth, back and forth. Sometimes I’d put my finger on the bolt so I wouldn’t have to look to see if it’s coming up. In this way I picked off the last two numbers of various filing cabinets. When I got back to my office I would write the two numbers down on a piece of paper that I kept inside the lock of my filing cabinet. I took the lock apart each time to get the paper—I thought that was a very safe place for them.

After a while my reputation began to sail, because things like this would happen: Somebody would say, “Hey, Feynman! Christy’s out of town and we need a document from his safe—can you open it?”

If it was a safe I knew I didn’t have the last two numbers of, I would simply say, “I’m sorry, but I can’t do it now; I’ve got this work that I have to do.” Otherwise, I would say, “Yeah, but I gotta get my tools.” I didn’t need any tools, but I’d go back to my office, open my filing cabinet, and look at my little piece of paper: “Christy—35, 60.” Then I’d get a screwdriver and go over to Christy’s office and close the door behind me. Obviously not everybody is supposed to be allowed to know how to do this!

I’d be in there alone and I’d open the safe in a few minutes. All I had to do was try the first number at most twenty times, then sit around, reading a magazine or something, for fifteen or twenty minutes. There was no use trying to make it look too easy; somebody would figure out there was a trick to it! After a while I’d open the door and say, “It’s open.”

People thought I was opening the safes from scratch. Now I could maintain the idea, which began with that accident with Staley, that I could open safes cold. Nobody figured out that I was picking the last two numbers off their safes, even though—perhaps because—I was doing it all the time, like a card sharp walking around all the time with a deck of cards.

I often went to Oak Ridge to check up on the safety of the uranium plant. Everything was always in a hurry because it was wartime, and one time I had to go there on a weekend. It was Sunday, and we were in this fella’s office—a general, a head or a vice president of some company, a couple of other big muck-a-mucks, and me. We were gathered together to discuss a report that was in the fella’s safe—a secret safe—when suddenly he realized that he didn’t know the combination. His secretary was the only one who knew it, so he called her home and it turned out she had gone on a picnic up in the hills.

While all this was going on, I asked, “Do you mind if I fiddle with the safe?”

“Ha, ha, ha—not at all!” So I went over to the safe and started to fool around.

They began to discuss how they could get a car to try to find the secretary, and the guy was getting more and more embarrassed because he had all these people waiting and he was such a jackass he didn’t know how to open his own safe. Everybody was all tense and getting mad at him, when CLICK!—the safe opened.

In 10 minutes I had opened the safe that contained all the secret documents about the plant. They were astonished. The safes were apparently not very safe. It was a terrible shock: All this “eyes only” stuff, top secret, locked in this wonderful secret safe, and this guy opens it in ten minutes!

Of course I was able to open the safe because of my perpetual habit of taking the last two numbers off. While in Oak Ridge the month before, I was in the same office when the safe was open and I took the numbers off in an absentminded way—I was always practicing my obsession. Although I hadn’t written them down, I was able to vaguely remember what they were. First I tried 40-15, then 15-40, but neither of those worked. Then I tried 10 -45 with all the first numbers, and it opened.

A similar thing happened on another weekend when I was visiting Oak Ridge. I had written a report that had to be OKed by a colonel, and it was in his safe. Everybody else keeps documents in filing cabinets like the ones at Los Alamos, but he was a colonel, so he had a much fancier, two-door safe with big handles that pull four l- inch-thick steel bolts from the frame. The great brass doors swung open and he took out my report to read.

Not having had an opportunity to see any really good safes, I said to him, “Would you mind, while you’re reading my report, if I looked at your safe?”

“Go right ahead,” he said, convinced that there was nothing I could do. I looked at the back of one of the solid brass doors, and I discovered that the combination wheel was connected to a little lock that looked exactly the same as the little unit that was on my filing cabinet at Los Alamos. Same company, same little bolt, except that when the bolt came down, the big handles on the safe could then move some rods sideways, and with a hunch of levers you could pull back all those l-inch steel rods. The whole lever system, it appeared, depends on the same little bolt that locks filing cabinets.

Just for the sake of professional perfection, to make sure it was the same, I took the two numbers off the same way I did with the filing cabinet safes.

Meanwhile, he was reading the report. When he’d finished he said, “All right, it’s fine.” He put the report in the safe, grabbed the big handles, and swung the great brass doors together. It sounds so good when they close, but I know it’s all psychological, because it’s nothing but the same damn lock.

I couldn’t help but needle him a little bit (I always had a thing about military guys, in such wonderful uniforms) so I said, “The way you close that safe, I get the idea that you think things are safe in there.”

“Of course.”

“The only reason you think they’re safe in there is because civilians call it a ‘safe.’ ” (I put the word “civilians” in there to make it sound as if he’d been had by civilians.)

He got very angry. “What do you mean—it’s not safe?”

“A good safecracker could open it in thirty minutes.”

“Can you open it in thirty minutes?”

“I said a good safecracker. It would take me about forty-five.”

“Well!” he said. “My wife is waiting at home for me with supper, but I’m gonna stay here and watch you, and you’re gonna sit down there and work on that damn thing for forty-five minutes and not open it!” He sat down in his big leather chair, put his feet up on his desk, and read.

With complete confidence I picked up a chair, carried it over to the safe and sat down in front of it. I began to turn the wheel at random, just to make some action.

After about five minutes, which is quite a long time when you’re just sitting and waiting, he lost some patience: “Well, are you making any progress?”

“With a thing like this, you either open it or you don’t.”

I figured one or two more minutes would be about time, so I began to work in earnest and two minutes later, CLINK—it opened.

The colonel’s jaw dropped and his eyes bugged out.

“Colonel,” I said, in a serious tone, “let me tell you something about these locks: When the door to the safe or the top drawer of the filing cabinet is left open, it’s very easy for someone to get the combination. That’s what I did while you were reading my report, just to demonstrate the danger. You should insist that everybody keep their filing cabinet drawers locked while they’re working, because when they’re open, they’re very, very vulnerable.”

“Yeah! I see what you mean! That’s very interesting!” We were on the same side after that.

The next time I went to Oak Ridge, all the secretaries and people who knew who I was were telling me,