An atomic clock measured how general relativity warps time across a millimeter

The record-breaking result reveals the incredible precision achievable by atomic clocks

illustration of a clocks floating across the sky at different heights showing different times

Clocks at different heights tick at different rates. An atomic clock has now revealed this key feature of the general theory of relativity on a scale of a millimeter.

Hiroshi Watanabe/Getty Images Plus

A millimeter might not seem like much.