After the atomic bombings of Hiroshima and Nagasaki, in 1945, the scientists behind the bomb decided to mark the dawn of the nuclear age with the creation of the Doomsday Clock.1 For the past seventy-five years, it has been set to alert humanity to how close we are to “midnight,” or total destruction, as a result of human-made technology. The clock has been moved twenty-four times over its history (backward eight times and forward sixteen), but with the war in Ukraine and the climate crisis, the annual assessment, released in January, now feels more relevant than ever. We asked Rachel Bronson, president and CEO of the Bulletin of the Atomic Scientists—a Chicago-based nonprofit that assesses global security issues—to unravel the science behind the clock.
When the clock debuted in 1947, it read seven minutes to midnight. In 2020, the time decreased to 100 seconds, where it remains today. How is the number calculated?
