WHO SETS THE DOOMSDAY CLOCK?

In the shadow of my family's atomic legacy, I set out to understand the increasingly urgent debate about humanity's capacity to end itself and what it can teach us about living.

- EMILY STRASSER

Set annually by scientists and policy experts, the Doomsday Clock is a graphic and metaphoric symbol of how close humanity is to self-destruction.

On a warm day in mid-July, a roomful of Nobel laureates and nuclear security experts, some 80 pairs of eyes, gaze out of the expansive windows of a 10th floor University of Chicago conference room, imagining their deaths by nuclear explosion.

A presenter directs the group's attention past the trees and gothic buildings of campus, over the apartment buildings in Hyde Park, and out to the Chicago skyline, hazy with wildfire smoke from Canada. He points out which neighborhoods would vanish in blasts of varying size, estimating casualties, injuries, and radiation effects.

What I know, what everyone there knows, is that if a nuclear bomb were to explode right then, right over us, it would be better to be inside that room, in the zone of vaporization, than in an outer ring of slow, painful death.

It's the opening session of the three-day 2025 Nobel Laureate Assembly for the Prevention of Nuclear War. The gathering is convened by scientists and nuclear security experts alarmed that a new arms race, eroding global cooperation, and the rise of artificial intelligence in warfare—among other factors—are pushing civilization closer to catastrophe. Timed to the 80th anniversary of the Trinity Test, the world's first nuclear explosion, the assembly aims to produce a declaration urging world leaders to reduce the nuclear threat.

The same urgency drives the Bulletin of Atomic Scientists and its iconic Doomsday Clock, the stark graphic that represents how close we are to self-annihilation. The clock is set yearly by the Bulletin's Science and Security Board chaired by Daniel Holz, PhD, a theoretical astrophysicist at the University of Chicago.