Eric Schlosser - Command and Control

The shape and composition of the explosive lenses were irrelevant, however, if the lenses failed to detonate at exactly the same time. The shock wave would travel through the device at a speed of one millimeter per millionth of a second. If a single lens detonated a few ten millionths of a second before the others, it could shatter the plutonium without starting a chain reaction. Blasting caps and Primacord were the detonators usually employed with conventional explosives. But both proved incapable of setting off thirty-two charges simultaneously. The physicist Luis Alvarez and his assistant, Lawrence Johnston, invented a new type of detonator for the job — the exploding-bridgewire detonator. It sent a high-voltage current through a thin silver wire inserted into an explosive. The current vaporized the wire, created a small shock wave, and detonated the explosive. Donald F. Hornig, who was one of the youngest scientists at Los Alamos, devised a contraption, the X-unit, that could store 5,600 volts in a bank of capacitors and then send that electricity instantaneously to all the detonators.

In theory, the X-unit and the exploding bridgewires would set off thirty-two explosive lenses at once, creating the perfect shock wave and imploding the plutonium core. In reality, these new inventions were unpredictable. Cracked insulation frequently caused the detonators to short-circuit. When that happened, they didn’t work. And a week before the Trinity test, an X-unit fired prematurely during a lightning storm. It had been triggered by static electricity in the air. The misfire suggested that a nuclear weapon could be set off by a lightning bolt.

At eighteen past three in the afternoon on July 13, 1945, the plutonium core was delivered to a steel tower a couple of miles from the McDonald Ranch House. The tower rose about a hundred feet above the desert and resembled an oil rig with a small shed on top. The rest of the nuclear device sat inside a tent at the base of the tower, awaiting completion. At first, the core wouldn’t fit inside it. For a few minutes, nobody could understand why, and then the reason became clear. The plutonium was warm, but the housing that it was supposed to enter had been cooled by the shade of the tent. Once the housing warmed, the core easily slid in. At about four o’clock, a thunderstorm threatened, and the tent started to flap violently in the wind. The small group of scientists left the base of the tower and waited for half an hour at the ranch house until the storm passed. When they returned, Kistiakowsky supervised the placement of the last explosive lenses, and at dusk the device was bolted shut. The next morning, as it was slowly hoisted to the top of the tower, surplus Army mattresses were stacked to a height of fifteen feet directly beneath it, in case the cable broke.

The nuclear device was an assortment of spheres within spheres: first, an outer aluminum casing, then two layers of explosives, then a thin layer of boron and plastic to capture neutrons that might enter from outside the core, then more aluminum, then a tamper of uranium-238 to reflect neutrons that might escape from inside the core, then the ball of plutonium, and finally, at the very center, the golf ball-size neutron initiator — a mixture of beryllium and polonium that would flood the device with neutrons, like a nuclear fuse, when the shock wave from the lenses struck. Inside the metal shed atop the tower, the detonators were installed by hand, two for every explosive lens, linked to a pair of X-units. The device now looked like something concocted in a mad scientist’s laboratory — a six-foot-tall aluminum globe with a pair of large boxes, the X-units, attached to it and thirty-two thick electrical cables leaving each box, winding around the sphere, and entering evenly spaced holes on its surface.

The Trinity test was scheduled for four in the morning on July 16, but forecasters predicted bad weather. Going ahead with the test could prove disastrous. In addition to the threat of lightning, high winds and rain could carry radioactive fallout as far as Amarillo, Texas, three hundred miles away. Postponing the test had other drawbacks: the device could be damaged by the rain, and President Harry S. Truman was in Potsdam, Germany, preparing to meet with Winston Churchill, the British prime minister, and Joseph Stalin, the general secretary of the Soviet Union’s Communist Party. Nazi Germany had recently been defeated, and Truman was about to demand an unconditional surrender from the Japanese. Having an atomic bomb would make it easier to issue that demand. General Groves argued that the test should go forward, as planned, and Oppenheimer agreed. Both men became increasingly nervous, on the evening of the fifteenth, not only about the weather but also about the risk of sabotage. And so Donald Hornig was instructed to “babysit the bomb.”

At 9:00 P.M., Hornig climbed to the top of the hundred-foot tower as rain began to fall. He brought a collection of humorous essays, Desert Island Decameron . His reading was interrupted by the arrival of a violent electrical storm. Atop the tower in a flimsy metal shed, Hornig sat alone with the book, the fully armed device, a telephone, and a single lightbulb dangling from a wire. He was twenty-five years old and had recently earned a Ph.D. in chemistry at Harvard. Having designed the X-unit, he knew better than anyone how easily it could be triggered by static electricity. Whenever he saw a lightning bolt, he’d count the seconds — one — one thousand, two — one thousand, three — one thousand — until he heard the thunder. Some of the lightning felt awfully close. At midnight, the phone rang, and Hornig was told to come down. Hornig did so, gladly, in the pouring rain. He was the last person to see the device.

The test was pushed back to 5:30 in the morning, right before dawn. The rain ended, and the weather cleared. The radio frequency used to announce the final countdown was similar to that of a local station. Thanks to interference, at the moment of detonation, Tchaikovsky’s Serenade for Strings cheerfully played in the control bunker. Kistiakowsky stepped out of the bunker to see the fireball and was knocked to the ground by the blast wave. He was about six miles from where the tower had just stood. This is what the end of the world will look like, he thought — this is the last thing the last man will see. Victor Weisskopf saw the flash and felt heat on his face from a distance of ten miles. His heart sank. For a moment, he thought that his calculations were wrong and the atmosphere was on fire. “The hills were bathed in brilliant light,” Otto Frisch, a British physicist, observed, “as if somebody had turned the sun on with a switch.” General Farrell expressed the mixture of fear, awe, pride, and an underlying attraction that this new power inspired:

The whole country was lighted by a searing light with the intensity many times that of the midday sun. It was golden, purple, violet, gray, and blue. It lighted every peak, crevasse and ridge of the nearby mountain range with a clarity and beauty that cannot be described…. It was that beauty the great poets dream about but describe most poorly and inadequately. Thirty seconds after, the explosion came first, the air blast pressing hard against the people and things, to be followed almost immediately by the strong, sustained, awesome roar which warned of doomsday and made us feel that we puny things were blasphemous to dare tamper with the forces heretofore reserved to The Almighty.

Kenneth Bainbridge, the supervisor of the test, turned to Oppenheimer and said, “Now we are all sons of bitches.” Within minutes the mushroom cloud reached eight miles into the sky.

THE ATOMIC BOMB was no longer the stuff of science fiction, and the question now was what to do with it. On September 1, 1939, President Franklin D. Roosevelt had issued a statement condemning the “inhuman barbarism” of aerial attacks on civilian populations. Nazi Germany had invaded Poland that day, and the Second World War had begun. Aerial bombardment promised to make the trench warfare of the previous world war — long a symbol of cruel, pointless slaughter — seem almost civilized and quaint. In April 1937 the German air force, the Luftwaffe, had attacked the Spanish city of Guernica, killing a few hundred civilians. Eight months later, the Japanese had bombed and invaded the Chinese city of Nanking, killing many thousands. An era of “total war” had dawned, and traditional rules of warfare seemed irrelevant. President Roosevelt appealed to the European powers for restraint. “The ruthless bombing from the air of civilians in unfortified centers of population,” he said, “has profoundly shocked the conscience of humanity.”