Atomic | Clock

Scientists use these clocks to detect tiny changes in gravity (General Relativity) and to search for dark matter. Precision Limits

You likely interact with atomic clocks every day without realizing it: Atomic Clock

The best modern atomic clocks are so stable that they wouldn't lose or gain a single second in —a span of time longer than the age of the universe. Scientists use these clocks to detect tiny changes

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 Why It Matters If the microwave frequency is

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

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