ATOMIC CLOCK

The atomic clock is the instrument for measuring Time most precise ever designed to this Day. It no longer uses as oscillator a Balance or a Quartz, but the Frequency extremely high and remarkably stable of electromagnetic radiation emitted or absorbed during energy transitions of atoms, with cesium 133 serving as the reference. Since 1967, the second of the International System has in fact been defined based on this transition, at a rate of 9,192,631,770 periods. The best atomic clocks drift by only one second over several million, or even billion, years. They constitute the standard of International Atomic Time and of Coordinated Universal Time (UTC), and are essential to satellite navigation systems, telecommunications, and fundamental research. In watchmaking, the atomic clock represents the ultimate reference against which all timepieces are compared, including mechanical chronometers and quartz watches. It embodies the culmination of the long human quest for an ever more precise measurement of time.