Most accurate clock ever can tick for 40 billion years without error

The most accurate clock in the world will lose less than 1 second every 40 billion years, or around three times the current age of the universe. While we have no direct need for such extreme timekeeping, the clock could help investigations in multiple areas of physics, including detecting dark matter.

At the core of the clock, built by Alexander Aeppli at the University of Colorado Boulder and his colleagues, are about…