Since 1967, the International System of Units (SI) has defined one second as exactly 9,192,631,770 oscillations of the radiation produced by this transition in a cesium-133 atom. Why It Matters
Scientists use these clocks to detect tiny changes in gravity (General Relativity) and to search for dark matter. Precision Limits Atomic Clock
If the microwave frequency is exactly right, the atoms change states. Since 1967, the International System of Units (SI)
You likely interact with atomic clocks every day without realizing it: You likely interact with atomic clocks every day
Stock exchanges use atomic time to log trades down to the microsecond, preventing fraud and ensuring a fair "first-come, first-served" system.
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