In the small hours of 16 July 1945, in a scrap of New Mexico desert bleakly named the Jornada del Muerto — the Dead Man's Journey — a plutonium device its makers called simply "the gadget" sat atop a hundred-foot steel tower, waiting out a thunderstorm. In bunkers and at a base camp miles away, some of the greatest physicists alive rubbed sunburn lotion onto their faces in the dark, passed around slabs of welder's glass, and tried to sleep. Enrico Fermi, to the irritation of the soldiers around him, was offering side bets on whether the bomb would ignite the atmosphere — and, if so, whether it would merely incinerate New Mexico or destroy the world.
The test was the climax of the Manhattan Project, the vast secret enterprise racing to build an atomic weapon before the end of the Second World War. Its uranium bomb, Little Boy, used a gun-type design so straightforward that nobody thought it needed testing. The plutonium bomb was another matter: it worked by implosion, crushing a plutonium core with a perfectly synchronised shell of high explosives, and there was every chance the fiendish arrangement would fizzle. The gadget had been hoisted up its tower over a bed of borrowed Army mattresses, piled there in case the winch cable snapped. Robert Oppenheimer, the project's scientific director, chose the code name Trinity; asked about it years later, he could not quite say why, pointing uncertainly to the devotional sonnets of John Donne. The test had originally been set for 4 a.m., and as the storm rumbled on, General Leslie Groves fretted about a deadline of a different kind: President Truman was at Potsdam, negotiating with Stalin, waiting to learn what kind of card he held.
The gallows humour had a formal side. The physicists ran a betting pool, at a dollar a ticket, on the explosive yield. Oppenheimer pessimistically took a modest 300 tons of TNT; Edward Teller, characteristically, went high at 45,000. Isidor Rabi, arriving late, took the 18,000-ton ticket nobody else wanted — and won, with the blast generally reckoned at roughly 20 kilotons. As for Fermi's wager about setting fire to the sky, the question had been taken seriously enough that Hans Bethe's theorists ran the numbers and concluded that igniting the atmosphere was, to all intents, impossible. The bets were physicists whistling in the dark.
Brighter than daylight
At 5:29 a.m., after a night of rain and lightning, the gadget fired. The flash was seen about 180 miles away; windows rattled across the state; a mushroom cloud climbed several miles into the dawn sky. The Army's prepared cover story went out on cue: an ammunition magazine had exploded at the Alamogordo air base, with no loss of life. At the control bunker the test director, Kenneth Bainbridge, turned to Oppenheimer with a line as well documented as it is unrepeatable in polite company: "Now we are all sons of bitches." Oppenheimer later said the moment brought to mind a line from the Hindu scripture the Bhagavad Gita — "Now I am become Death, the destroyer of worlds" — though that recollection came in a television interview twenty years on; his brother Frank, standing beside him in the desert, remembered him saying simply, "It worked."
The desert kept a stranger record of the morning. The fireball vaporised the steel tower and fused the sand beneath it into a sheet of light-green glass — an anthropogenic glass found nowhere else, christened trinitite. Souvenir hunters carted it off by the boxful in the years after the war before removal from the site was banned; specimens still circulate among collectors, mildly radioactive pebbles from the first seconds of the atomic age.
From the desert to Japan
The interval between rehearsal and performance was three weeks. A coded cable — reporting, in effect, that the baby had been safely delivered — reached the American delegation at Potsdam within hours. On 6 August 1945 the untested uranium bomb destroyed Hiroshima; on 9 August Fat Man, a near-copy of the Trinity gadget, fell on Nagasaki, and within days Japan surrendered. Only then did news of the New Mexico test emerge, and the ranchers who had watched a second sunrise that July morning learned what it was they had seen. The Trinity site, deep inside the White Sands Missile Range, was later declared a National Historic Landmark, its ground zero marked by a plain obelisk of dark lava rock.
Every nuclear detonation since — well over two thousand tests in the decades that followed — descends from that single tower in the Jornada del Muerto. The most consequential experiment in modern science lasted a few millionths of a second, and the desert still holds its glass receipt.
Quiz nuggets
- The Trinity test took place at 5:29 a.m. on 16 July 1945 in New Mexico's Jornada del Muerto desert.
- Physicists ran a dollar-a-ticket betting pool on the yield; Isidor Rabi won with 18,000 tons of TNT against an actual roughly 20 kilotons.
- Enrico Fermi jokingly took bets on whether the bomb would ignite the atmosphere; Hans Bethe's group had calculated it could not.
- The blast fused the desert sand into a light-green glass called trinitite, found nowhere else in nature.
- Nagasaki's Fat Man was a near-copy of the Trinity gadget, while Hiroshima's Little Boy design was never tested beforehand.