Scientists use these clocks to detect tiny changes in gravity (General Relativity) and to search for dark matter. Precision Limits
High-speed data transfers and cellular networks require perfectly synchronized "stamps" to ensure packets of data arrive in the correct order.
An atomic clock is the world’s most accurate timekeeping device. While a grandfather clock relies on a swinging pendulum and a digital watch relies on a vibrating quartz crystal, an atomic clock uses the ultra-stable vibrations of atoms—usually cesium or strontium—to measure the passage of time. How It Works
You likely interact with atomic clocks every day without realizing it:
Cesium atoms are sprayed into a vacuum chamber and hit with microwaves.
Stock exchanges use atomic time to log trades down to the microsecond, preventing fraud and ensuring a fair "first-come, first-served" system.