Watch Modern Marvels Season 12 Episode 18 Online

Developed in 1947 as an image to symbolize urgency in the Cold War and the threat of nuclear disaster, the mission of the Doomsday Clock has expanded to include non-nuclear global security issues. Maintained by the Board of Directors of the Bulletin of the Atomic Scientists, it’s based at the University of Chicago. In response to world events, they move the clock’s minute hand closer to or away from midnight–doomsday. In this hour, we cover the clock’s history, its effectiveness, and its critics.