Tick-Tock, Tick-Tock: Studying Time with Ever More Precise Clocks

The International Space Station (ISS) is equipped with special clocks. These atomic clocks measure how time in outer space flows differently than time on Earth, or to say it with Einstein, how our planet’s gravity slows down time. The experiment sprang from an idea developed by Christophe Salomon, laureate of the 2025 Balzan Prize.

In today’s world, precise timekeeping is essential. One application that we use every day and that simply cannot function without extremely accurate clocks is GPS. We rarely think about it while navigating, but if the clocks in GPS satellites were off by even a fraction of a second, we would be hopelessly lost.