Seventy-five years ago today, on Aug. 6, 1945, the world erupted into a new era. A single B-29 Superfortress airplane, nicknamed Enola Gay, dropped a new kind of weapon—an atomic bomb—on the Japanese city of Hiroshima. Releasing the blast power of 12,500 tons of TNT, the heat of the sun, and a mushroom cloud of radiation, it obliterated 5 square miles of the city and killed 150,000 people, half of them instantaneously. Along with a second A-bomb dropped on Nagasaki three days later, it forced the Japanese to surrender, ending the Second World War. But it also triggered a nuclear arms race that continues to this day; and while the possession of whole arsenals of these weapons, in the hands of nine nations, may have deterred political leaders from starting a few wars, it is also true that, if these bombs—most of them tens or hundreds of times more powerful than the one dropped on Hiroshima—are ever used in anger again, the consequences could be catastrophic, possibly resulting in a “nuclear winter” that ends most life on Earth.
And so, on the anniversaries of Hiroshima, like some doomsday variant of Passover, we ask the four questions that ethicists and historians have been posing for decades: