Genius_ The Life and Science of Richard Feynman - James Gleick [96]
The impatient Princeton group signed up en masse. Wilson rushed out to see the site and rushed back to report on the mud and confusion, a theater being built instead of a laboratory, water lines being mislaid. The state of secrecy was such that Feynman already knew that Groves and Oppenheimer were arguing over the state of secrecy. Cyclotron parts and neutron-counting gear started heading out by rail in wooden crates from the Princeton station. Princeton’s carloads provided the new laboratory’s core equipment, followed eventually by a painstakingly dismantled cyclotron from Harvard and other generators and accelerators. Soon Los Alamos was the best-equipped physics center in the world. The Princeton team began leaving soon after the crates of gear. Richard and Arline went with the first wave, on Sunday, March 28. Instructions were to buy tickets for any destination but New Mexico. Feynman’s contrariety warred for a moment with his common sense, and contrariety won out. He decided that, if no one else was buying a New Mexico ticket, he would. The ticket seller said, Aha—all these crates are for you?
The railroad provided a wheelchair and a private room for Arline. She had begged Richard tearfully to pay the extra price for the room and hinted that at last she might have a chance to be all that a wife should be to the husband she loves. For both of them the move out West portended an open-skied, open-ended future. It cut them off finally from their protective institutions and their childhoods. Arline cried night after night from worry and filled Richard with her dreams: curtains in their home, teas with his students, chess before the fireplace, the Sunday comics in bed, camping out in a tent, raising a son named Donald.
Chain Reactions
Fermi’s pile of uranium and graphite, sawed and assembled by professional cabinetmakers in a University of Chicago racquets court, became the world’s first critical mass of radioactive material on December 2, 1942. Amid the black graphite bricks, the world’s first artificial chain reaction sustained itself for half an hour. It was a slow reaction, where a bomb would have to be a fast reaction—less than a millionth of a second. From the two-story-high ellipsoid of Chicago pile number one to the baseball-size sphere of plutonium that exploded at Trinity, there could be no smooth evolutionary path. To go from the big, slow pile to a small, fast bomb would require a leap. There were few plausible intermediate stages.
Yet one possibility was playing itself out in Feynman’s mind the next April, as he sat in a car just outside the makeshift security gate on the Los Alamos mesa. Hydrogen atoms slowed neutrons, as Fermi had discovered ages ago. Water was cheaply bound hydrogen. Uranium dissolved in water could make a powerful compact reactor. Feynman waited while the military guards tried to straighten out a mistake about his pass. Left and right from the security gate stretched the beginnings of a barbed-wire fence. Behind it lay no laboratory, but a few ranch buildings and a handful of partially complete structures rose from the late-winter mud in what the army called modified mobilization style, namely fast-setting concrete foundations, wood frame, plain siding, asphalt roofs. The thirty-five-mile ride from Santa Fe had ended in a harrowing dirt road cut bluntly into the mesa walls. Feynman was not the only physicist who had never been farther west than Chicago. The recruiters had warned scientists that the army wanted isolation, but no one quite realized what isolation would mean. At first the only telephone link was a single line laid down by the Forest Service. To make a call one had to turn a crank on the side of the box.
As he sat waiting for the military police to approve his pass, Feynman was running through some calculations for the hypothetical in-between reactor that would be called a water boiler. Instead of blocks of uranium interspersed with graphite, this unit would use a uranium solution in water, uranium enriched with a high concentration