Atomic Clock [iPhone SIMPLE]

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

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

High-speed data transfers and cellular networks require perfectly synchronized "stamps" to ensure packets of data arrive in the correct order. Atomic Clock

If the microwave frequency is exactly right, the atoms change states.

You likely interact with atomic clocks every day without realizing it: Since 1967, the International System of Units (SI)

Stock exchanges use atomic time to log trades down to the microsecond, preventing fraud and ensuring a fair "first-come, first-served" system.

Scientists use these clocks to detect tiny changes in gravity (General Relativity) and to search for dark matter. Precision Limits How It Works High-speed data transfers and cellular

At the heart of the clock is a physical constant: the "resonant frequency" of an atom. When atoms are exposed to specific frequencies of microwave or light energy, their electrons jump between energy levels. In a standard cesium atomic clock: