Atomic watches are the most accurate watches on the market. They say that the atomic clock, which sends the signal, only has an error of one second over the course of 100,000,000 years. As long as the atomic watch is in range to receive its daily signal, it will always keep the most accurate time.

Atomic clocks measure the actual length of a second, which is what calculates time. A second is defined by the time a defined atom of caesium takes to oscillate 9,192,631,770 times. These atomic clocks are used to keep Coordinated Universal Time throughout the world.