Command and Control

Although the question of how to control an atomic bomb had inspired a good deal of thought, a different issue now seemed more urgent: Would the thing work? Before leaving Los Alamos, two hundred miles to the north, some of the Manhattan Project’s physicists had placed bets on the outcome of the upcoming test, code-named Trinity. Norman F. Ramsey bet the device would be a dud. J. Robert Oppenheimer, the project’s scientific director, predicted a yield equal to 300 tons of TNT; Edward Teller thought the yield would be closer to 45,000 tons. In the early days of the project, Teller was concerned that the intense heat of a nuclear explosion would set fire to the atmosphere and kill every living thing on earth. A year’s worth of calculations suggested that was unlikely, and the physicist Hans Bethe dismissed the idea, arguing that heat from the explosion would rapidly dissipate in the air, not ignite it. But nobody could be sure. During the drive down from Los Alamos on Friday the thirteenth, Enrico Fermi, who’d already won a Nobel for his discoveries in physics, suggested that the odds of the atmosphere’s catching fire were about one in ten. Victor Weisskopf couldn’t tell if Fermi was joking. Weisskopf had done some of the calculations with Teller and still worried about the risk.

As Louis Slotin prepared to assemble the plutonium core, the safety precautions were as rudimentary as the work space. Jeeps waited outside the house, with their engines running, in case everyone had to get out of there fast. Slotin was a Canadian physicist in his early thirties. For the past two years at Los Alamos he’d performed some of the most dangerous work, criticality experiments in which radioactive materials were brought to the verge of a chain reaction. The experiments were nicknamed “tickling the dragon’s tail,” and a small mistake could produce a lethal dose of radioactivity. At the ranch house, Slotin placed a neutron initiator, which was about the size of a golf ball, into one of the plutonium hemispheres, attached it with Scotch tape, put the other hemisphere on top, and sealed a hole with a plutonium plug. The assembled core was about the size of a tennis ball but weighed as much as a bowling ball. Before handing it to Brigadier General Thomas F. Farrell, Slotin asked for a receipt. The Manhattan Project was an unusual mix of civilian and military personnel, and this was the nation’s first official transfer of nuclear custody. The general decided that if he had to sign for it, he should get a chance to hold it. “So I took this heavy ball in my hand and I felt it growing warm,” Farrell recalled. “I got a sense of its hidden power.”

The idea of an “atomic bomb,” like so many other technological innovations, had first been proposed by the science fiction writer H. G. Wells. In his 1914 novel The World Set Free, Wells describes the “ultimate explosive,” fueled by radioactivity. It enables a single person to “carry about in a handbag an amount of latent energy sufficient to wreck half a city.” These atomic bombs threaten the survival of mankind, as every nation seeks to obtain them — and use them before being attacked. Millions die, the world’s great capitals are destroyed, and civilization nears collapse. But the novel ends on an optimistic note, as fear of a nuclear apocalypse leads to the establishment of world government. “The catastrophe of the atomic bombs which shook men out of cities… shook them also out of their old established habits of thought,” Wells wrote, full of hope, on the eve of the First World War.

The atomic bombs in The World Set Free detonated slowly, spewing radioactivity for years. During the 1930s, the Hungarian physicist Leó Szilárd — who’d met with H. G. Wells in 1929 and tried, without success, to obtain the central European literary rights to his novels — conceived of a nuclear weapon that would explode instantly. A Jewish refugee from Nazi Germany, Szilárd feared that Hitler might launch an atomic bomb program and get the weapon first. Szilárd discussed his concerns with Albert Einstein in the summer of 1939 and helped draft a letter to President Franklin D. Roosevelt. The letter warned that “it may become possible to set up a nuclear chain reaction in a large mass of uranium,” leading to the creation of “extremely powerful bombs of a new type.” Einstein signed the letter, which was hand delivered to the president by a mutual friend. After British researchers concluded that such weapons could indeed be made and intelligence reports suggested that German physicists were trying to make them, the Manhattan Project was formed in 1942. Led by Leslie R. Groves, a brigadier general in the U.S. Army, it secretly gathered eminent scientists from Canada, Great Britain, and the United States, with the aim of creating atomic bombs.