Overheard: How atomic clocks work

Without atomic clocks, GPS navigation would be impossible, the Internet would not synchronize, and the position of the planets would not be known with enough accuracy for space probes and landers to be launched and monitored. Douglas Dwyer, How Atomic Clocks Work

The big difference between a standard clock in your home and an atomic clock is that the oscillation in an atomic clock is between the nucleus of an atom and the surrounding electrons.

Photo: National Bureau of Standards Director Dr. Edward Condon and Dr. Harold Lyons with the first atomic clock.