In his book Nuclear Rites, anthropologist Hugh Gusterson described the enormous sense of anticipation that preceded nuclear blasts. "The most exciting tests were the ones where we had enormous difficulties," a weapons designer from the Lawrence Livermore National Laboratory tells him, "and through some enormous heroic development of solutions to problems we were able to save the test ... And the sense of reward then is just enormous, just fantastic." There's a fair bit of bravado, too. In John McPhee's 1973 book, The Curve of Binding Energy, he described weapons designer Theodore Taylor lighting a Pall Mall off a nuclear detonation of a device called Scorpion in the Nevada desert.

The light came first, and then the waves and waves of heat. Many seconds later came the sound, which varied from a dull thud to a sharp crack. Scorpion, on its day, spread out into the sky in a way that indicated at once a yield in the range its designer wanted--a fantastic hint of how light and compact a nuclear-explosive device could ultimately be. Fifteen seconds after Scorpion flashed, Ted reached down to the parabolic mirror beside him and took from behind it a smoldering Pall Mall. He drew in a long, pleasing draught of smoke. He had lit a cigarette with an atomic bomb.

Perhaps the most staggering remains of large-scale testing are at the Sedan Crater, the result of a 1962 detonation. The test, just months before the Cuban Missile Crisis, was part of a plan called the Plowshare Program, in which U.S. officials wanted to see if there were ways to use nuclear bombs for peaceful purposes like excavating massive areas to build canals or harbors.

According to an official history of the test, the 104-kiloton blast "lifted a huge dome of earth 290 feet in the air, moved 6.5 million cubic yards of earth and rock," and "sent a cloud of radioactivity off in the direction of Salt Lake City," 400 miles away. What remains today is a crater that's 1,200 feet across and 320 feet deep, and a small metal platform installed for tourists like us to see the astonishing damage.

There's so much interest in this site that National Security Technologies LLC, the company that manages it on behalf of the Department of Energy, gives public tours for which tickets must be reserved far in advance. But the guide on our trip, arranged by special invitation, was Stephen Younger, president of the company. A nuclear weapons designer, he studied physics at Catholic University and then the University of Maryland, and now, in addition to his day job, does scholarly anthropological work studying the roots of human violence.

Younger says that when Gene Burke, the fellow who designed the device that detonated for the Sedan test, talked about it, he had a tear in his eye because he was so proud of the technical accomplishment. In one of Younger's books, Endangered Species: How We Can Avoid Mass Destructionand Build A Lasting Peace , he described a crater of particular interest to himself: it "was only about 500 feet across and 50 feet deep; there were certainly bigger ones at the Nevada Test Site. What was special about this one was that it was my crater, made with the first nuclear explosive that I had designed on my own. What had started as a pencil sketch eighteen months before ended in a fireball hotter than the surface of the sun, an energy pulse that vaporized thousands of tons of rock to create a huge bubble over a thousand feet below the desert floor." As he walked up to the edge, he wrote, "there was a sense of accomplishment, of having done something that was important and having done it well." It was also the moment, he wrote, that he understood in his heart as well as his mind, "the magnitude of destruction that could be caused by nuclear explosions."