Auto set movements have changed the way we adjust clocks for Daylight Saving Time (DST). For the past decade or so radio controlled movements were the best way to do this. The clock movement would receive a radio signal, and either stop or fast forward an hour when needed. In theory this was a great idea because the time broadcast is based on the Caesium -131 Atomic Clocks in Fort Collins, Colorado.
The accuracy is the result of the process of radioactive decay. The term decay in this case means “change.” A radioactive substance naturally changes by emitting particles (protons, neutrons, or electrons) which results in the production of a different element.