Genius_ The Life and Science of Richard Feynman - James Gleick [114]
because I like puzzles so much. Each lock is just like a puzzle you have to open without forcing it. But combination locks have me buffaloed.
You do too, sometimes, but eventually I figure out you.
Locks mixed human logic and mechanical logic. The designer’s strategy was constrained by the manufacturer’s convenience or the limits of the metal, as it was in so many of the bomb project’s puzzles. The official logic of a Los Alamos safe, as displayed in the dial’s numbers and hatch marks, indicated a million different combinations—three numbers from 0 to 99. Some experimentation, though, showed Feynman that the markings disguised a considerable margin of error, plus or minus two, attributable to plain mechanical slackness; if the correct number was 23, anything from 21 to 25 would work as well. When he was searching combinations systematically, therefore, he needed only to try one number in every five—0, 5, 10, 15 … —to be sure of hitting the target. By thinking in terms of error ranges, instead of accepting the authority of the numerals on the dial, he brought a pragmatic physicist’s intuition to bear. That one insight effectively reduced the total combinations from one million to a mere eight thousand, almost few enough to try, given a few hours.
An American folklore had developed about safes and the yeggs who cracked them. Through the cowboy era and the gangster era safes grew thicker and more elaborate—double walls of cast iron and manganese, triple side bolts and bottom bolts, curb tumblers and pressure handles—and the legend, too, grew thicker and more elaborate. The consummate safeman was thought to need sandpapered fingers and hypersensitive ears. His essential skill: a feeling for the vibrations of tumblers lining up or falling into place. This was pure myth. It was true that once in a long while someone would open a safe by feel, but, the lore notwithstanding, the chief tools of successful safecrackers were crowbars and drills. Safes were cracked; holes were torn in their sides; handles and dials were torn off. When all else failed, safes were burned. The safeman used “soup”—nitroglycerin. The Los Alamos physicists had been conditioned by the myth, and when word started spreading that the laboratory had a skilled safecracker on its staff, most of them believed—and never stopped believing—that Feynman had mastered the art of listening to the tiny clicks.
To learn how to crack safes he had to find his way past the same myth. He read pulp memoirs of safemen to look for their secrets. They inspired him to dreams of glory: these authors boasted about opening bullion-filled safes underwater; he would write the book that would top them all. In its preface he would intone, I opened the safes which contained behind them the entire secret of the atomic bomb: the schedules for the production of plutonium, the purification procedures, how much was going to be needed, how the atomic bomb worked, how the neutrons are generated … the whole schmeer. Only gradually, as he looked for the nuggets of useful information, did he realize how mundane the business was. Because his repertoire would have to omit drills and nitroglycerin, it would have to make the most of such practical rules as he could find. Some he read; others he learned as he went along. Most were variations on a theme: People are predictable.
They tend to leave safes unlocked.
They tend to leave their