The pendulum of this mid-century beauty is made ... With access to a 10-MHz timebase from a cesium fountain atomic clock — no less a clock than the one that’s used to define the SI second, ...

The most precise clocks in the world will lose only one second every 300 billion years—and someday they might fit in your pocket.

Think of it like the pendulum of a grandfather clock swinging back and forth—only these clocks tick more than a trillion ...