Feynman's Safecracking Hobby at an Atomic Bomb Lab

When someone asked Richard Feynman to open a safe, he would say that he needed to fetch his tools. Back in his own office, he consulted the combination information he had already collected. On his return, he made sure to put a screwdriver in his back pocket.

He closed the office door, opened the safe and then settled down with a magazine. On average, he spent about twenty minutes waiting. He wanted the job to look difficult enough to justify his reputation. Only after allowing enough time did he emerge to announce that the safe was open. This was the routine he later described in his recollections.

The setting was Los Alamos, where scientists were developing the atomic bomb during the Second World War. Alongside his physics work, Feynman studied locks. Important research documents were kept in locked filing cabinets, and he found the challenge of opening them hard to resist.

People's habits interested him as much as the mechanisms. Colleagues left cabinets open while they worked. Visiting their offices to talk, he learned information about the combinations and remembered it. That helped explain his confidence when someone needed a document from a cabinet whose owner was away.

There were locks he could not open. Returning to Los Alamos after the war to finish some papers, he needed material from the library. It was Saturday, and no one was available to retrieve it. The library's large vault was beyond his abilities. Then he remembered that his colleague Freddy DeHoffman kept copies of the documents in his own office. Tired of going back and forth to the library, DeHoffman had gathered the material in nine filing cabinets across two rooms.

Feynman tried mathematical constants that he thought DeHoffman might have chosen for a combination. His first guess failed; the next one worked. Once he had opened one cabinet, he found that the same combination opened the other eight. He had gained access to a collection of atomic-bomb theories and calculations. The feat added to his reputation, though he described the success as a matter of luck.

At Oak Ridge, another facility in the atomic-bomb project, he demonstrated his skills on a colonel's safe. The colonel kept Feynman's report inside it. While the officer read the report, Feynman inspected the open safe. After the doors were closed, he opened it again and explained the problem: leaving the mechanism accessible made it possible to learn combination information. Staff should keep their filing cabinets locked while working.

On his next visit, employees told him to stay away. The colonel had asked whose offices Feynman had visited or passed near, then ordered those people to change their combinations. Changing and memorizing a new combination was a nuisance. The employees avoided Feynman because another visit might mean having to do it again.

They had learned to be wary of the physicist. According to his account, they still left their filing cabinets open while they worked.