Trinity Detonated: The Atomic Age Dawns in New Mexico

A flash brighter than any sun that had ever risen over New Mexico turned the desert sand to glass at 5:29 a.m. on July 16, 1945, and the atomic age began in a millisecond. The Trinity test detonated a plutonium implosion device atop a 100-foot steel tower in the Jornada del Muerto desert, yielding an explosion equivalent to roughly 21,000 tons of TNT. J. Robert Oppenheimer, director of the Los Alamos laboratory that built the bomb, later recalled that the Hindu scripture came to mind: "Now I am become Death, the destroyer of worlds." The Manhattan Project had consumed $2 billion (roughly $30 billion in modern value), employed 125,000 people across thirty sites, and operated under such extreme secrecy that Vice President Harry Truman did not learn of its existence until twelve days after Roosevelt's death. Two bomb designs emerged from Los Alamos: a uranium gun-type weapon considered reliable enough to use without testing, and a plutonium implosion device whose complex geometry of shaped explosive charges required validation. Trinity tested the implosion design. Scientists were genuinely uncertain about the outcome. Enrico Fermi offered side bets on whether the bomb would ignite the atmosphere. Edward Teller suggested it might trigger a chain reaction in the nitrogen of the air and sterilize the planet. The betting pool at Los Alamos ranged from zero yield to 45,000 tons. General Leslie Groves, the project's military director, had prepared a cover story about an ammunition depot explosion in case the test failed or killed nearby civilians. None of these fears materialized, but the blast shattered windows 120 miles away and was felt in three states. The mushroom cloud rose 40,000 feet, and the steel tower was completely vaporized. At ground zero, the sand fused into a glassy, mildly radioactive mineral later named trinitite. Kenneth Bainbridge, the test director, turned to Oppenheimer and said: "Now we are all sons of bitches." Three weeks later, the gun-type weapon destroyed Hiroshima and the implosion design destroyed Nagasaki, killing roughly 200,000 people and ending the Second World War. The Trinity site, still faintly radioactive, is open to the public two days a year.