How Atomic Clocks Work

In October 2026, physicists in Vienna and Braunschweig reported a clock that keeps time with the nucleus of a thorium atom and keeps itself on track for more than a day. To see why anyone wants such a clock, this film tells how timekeeping works: the pendulum clocks of Huygens and Harrison, the vibrating quartz in a watch, the first caesium clock of 1955, how a feedback loop locks a radio wave to atoms and defines the second, why GPS depends on billionths of a second, the optical clocks that are about to redefine the second, how they sense gravity, and the new nuclear clocks.

Counting the ticks of atoms

How a clock became precise enough to tell you where you are.

Things that swing

Something that repeats, and something that counts.

Crystals and atoms

From a ringing stone to a pendulum nature makes identical.

The caesium second

When the atom became the world’s timekeeper.

Time tells you where you are

Why your phone’s map runs on atomic time.

Clocks made of light

More ticks per second, finer slices of time.

Into the nucleus

A pendulum more than ten thousand times smaller.

Read the full story as text · อ่านภาษาไทย

This interactive 3D film needs JavaScript. PlanetPast home