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

A library at Los Alamos held all of the documents we had ever worked on: It was a solid, concrete room with a big, beautiful door which had a metal wheel that turns—like a safe-deposit vault. During the war I had tried to look at it closely. I knew the girl who was the librarian, and I begged her to let me play with it a little bit. I was fascinated by it: it was the biggest lock I ever saw! I discovered that I could never use my method of picking off the last two numbers to get in. In fact, while turning the knob while the door was open, I made the lock close, so it was sticking out, and they couldn’t close the door again until the girl came and opened the lock again. That was the end of my fiddling around with that lock. I didn’t have time to figure out how it worked; it was much beyond my capacity.

During the summer after the war I had some documents to write and work to finish up, so I went back to Los Alamos from Cornell, where I had taught during the year. In the middle of my work I had to refer to a document that I had written before but couldn’t remember, and it was down in the library.

I went down to get the document, and there was a soldier walking back and forth, with a gun. It was a Saturday, and after the war the library was closed on Saturdays.

Then I remembered what a good friend of mine, Frederic de Hoffman, had done. He was in the Declassification Section. After the war the army was thinking of declassifying some documents, and he had to go back and forth to the library so much—look at this document, look at that document, check this, check that—that he was going nuts! So he had a copy of every document—all the secrets to the atomic bomb—in nine filing cabinets in his office.

I went down to his office, and the lights were on. It looked as if whoever was there-perhaps his secretary—had just stepped out for a few minutes, so I waited. While 1 was waiting I started to fiddle around with the combination wheel on one of the filing cabinets. (By the way, I didn’t have the last two numbers for de Hoffman’s safes; they were put in after the war, after I had left.)

I started to play with one of the combination wheels and began to think about the safecracker books. I thought to myself, “I’ve never been much impressed by the tricks described in those books, so I’ve never tried them, but let’s see if we can open de Hoffman’s safe by following the book.”

First trick, the secretary: she’s afraid she’s going to forget the combination, so she writes it down somewhere. I started to look in some of the places mentioned in the book. The desk drawer was locked, but it was an ordinary lock like Leo Lavatelli taught me how to open—ping! I look along the edge: nothing.

Then I looked through the secretary’s papers. I found a sheet of paper that all the secretaries had, with the Greek letters carefully made—so they could recognize them in mathematical formulas—and named. And there, carelessly written along the top of the paper, was pi = 3. 14159. Now, that’s six digits, and why does a secretary have to know the numerical value of pi? It was obvious; there was no other reason!

I went over to the filing cabinets and tried the first one: 31-41-59. It didn’t open. Then I tried 59-41-31. That didn’t work either. Then 95-14-13. Backwards, forwards, upside down, turn it this way, turn it that—nothing!

I closed the desk drawer and started to walk out the door, when I thought of the safecracker books again: Next, try the psychology method. I said to myself, “Freddy de Hoffman is just the kind of guy to use a mathematical constant for a safe combination.”

I went back to the first filing cabinet and tried 27-18-28—CLICK! It opened! (The mathematical constant second in importance to pi is the base of natural logarithms, e:2.71828 …) There were nine filing cabinets, and I had opened the first one, but the document I wanted was in another one-they were in alphabetical order by author. I tried the second filing cabinet: 27-18-28–CLICK! It opened with the same combination. I thought, “This is wonderful! I’ve opened the secrets to the atomic bomb, but if I’m ever going to tell this story, I’ve got to make sure that all the combinations are really the same!” Some of the filing cabinets were in the next room, so I tried 27-18-28 on one of them, and it opened. Now I’d opened three safes—all the same.