Over the Desert, A Nuclear Dawn
Fifty years ago, as war in the Pacific raged, scientists in New Mexico opened the door to the Atomic Age
`MINUS 30 seconds,'' intoned physicist Samuel Allison over the network. ''Twenty-five ... 20 ... 15 ....'' At 10 he began calling off each second: ''Nine ... eight ... seven ... six ... five....''Skip to next paragraph
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At five seconds, the shortwave radio in the Carrizozo, N.M., tourist court failed momentarily. Los Alamos scientist Diz Graves continued her own countdown: ''Four ... three ... two ... one ... zero. It didn't go,'' she said to her scientist husband, Alvin. But she had counted too fast. At exactly 5:29:45 a.m., the sky ignited with a light brighter than the noonday sun.
In Albuquerque, Capt. Thomas Jones's hotel room lighted up as if a photo-flood lamp had been turned on. ''Wonder if anyone is still alive at Trinity, Tom?'' Phil Belcher said to his roommate. Then, realizing the significance of his remark, Belcher tried to contact Trinity base camp. After a suspenseful minute, a voice on the phone answered calmly, ''All is well.''
Inside the control shack, his back to the tower, Robert Oppenheimer had been looking south through the open door toward Mockingbird Gap when the flash illuminated the sky with a brilliance that for an instant bleached the desert to a ghastly white. Across Oppenheimer's mind flashed a passage from the sacred Hindu text, the Bhagavad-Gita: ''I am become death, the destroyer of worlds.'' For a second there was stunned silence in the shelter. Then the men rushed outside.
A great reddish-yellow ball of fire a quarter-mile wide was boiling and churning over ground zero. The suddenly unleashed nuclear force expanded, its fireball reaching back to the ground as if the sun had suddenly come down to sear the earth. Then the fireball shot upward, sucking up the desert floor beneath it into a column that within 20 seconds reached a mile into the sky.
Thirty seconds after the flash of light, the explosion's thunderous boom reached South-10,000, accompanied by a shock wave that buffeted the men standing in the open and sent desert debris flying before it.
At base camp, physicist Enrico Fermi counted off the seconds after the flash of light. Just before he estimated the blast wave would arrive, he held his right hand high in the air and released some scraps of paper he had been clutching. As the scraps fluttered toward the ground the blast wave hit and blew them several feet away. Fermi measured the distance, made some hasty calculations, and predicted to his colleagues that the bomb's yield would prove to be on the order of 20,000 tons of TNT.
All over the desert amphitheater, the observers shook hands or clapped each other on the back in elation. At South-10,000, Oppenheimer climbed to the roof of the control shelter and joined George Kistiakowsky. The day before, with Oppenheimer's spirits at their lowest, Kistiakowsky had bet his next month's salary against Oppenheimer's $10 that the detonators would fire. Now, as they watched the massive, mile-wide cloud mushrooming and climbing to 40,000 feet, Kistiakowsky exuberantly demanded payment. Oppenheimer dug out his wallet and looked inside. There was nothing in it except the four-leaf clover his wife, Kitty, had given him. Oppenheimer grinned and showed his friend the empty wallet. ''Guess you'll have to wait for your money,'' he said.
As the initial elation subsided and the mushroom cloud dispersed, the scientists began collecting the data needed to measure the bomb's explosive yield. By 10 a.m., enough evidence had accumulated to determine that the gadget was indeed a potential superweapon.
Physicist Herbert Anderson had made a brief expedition to ground zero in a sealed, lead-lined Army tank. Through the tank's periscope he had seen a huge, shallow crater 1,200 feet in diameter. The ground was covered with a green, glassy substance, pieces of which Anderson gathered with a clawlike device attached to the tank. The heat from the explosion had been so intense that the sand and gravel from the desert near the tower had fused into this ceramiclike material, which the scientists named ''Trinitite.'' In some of the samples of Trinitite there were streaks of brown, the only remains of the steel tower, vaporized by the fireball.
From the force of the shock wave, the size of the fireball, and the level of radiation in the samples taken from the bomb crater, it was determined that the yield was, as Fermi's simple experiment had predicted, equivalent to 20,000 tons of TNT. It had exceeded by 2,000 tons the highest guess in the betting pool. Nobel Prize-winner I. I. Rabi's guess of 18,000 tons won the $102 pot.