This article explains how time is measured and maintained globally through a complex network of atomic clocks and international cooperation. Timekeeping relies on highly accurate atomic clocks, such as hydrogen masers and cesium beam clocks, which are used to maintain the official time in the United States. These clocks are constantly monitored and compared to ensure accuracy. Even more precise cesium fountain clocks, like NIST-F3 and NIST-F4, are used to define the official second and calibrate other clocks. These clocks are so accurate that if they had been running since the time of the dinosaurs, they would have lost or gained less than one second.
The global time standard, called Coordinated Universal Time (UTC), is maintained by the International Bureau of Weights and Measures (BIPM), which collects data from over 450 clocks in 90 national labs around the world. Each month, BIPM publishes updates to help countries adjust their time scales to stay in sync with UTC. In the U.S., both NIST and the U.S. Naval Observatory are responsible for maintaining accurate time, and they ensure their time scales are synchronized to within 20 nanoseconds. Time is then distributed to the public through radio signals, the internet, and GPS satellites, ensuring that devices like smartphones and smartwatches can provide accurate time to users worldwide. This global effort ensures that time remains consistent and reliable for everything from daily life to critical systems like the power grid and financial markets.
Source: https://www.nist.gov/atomic-clocks/how-do-we-know-what-time-it
Keywords: atomic clocks, timekeeping, metrology
