Who establishes the correct time in the United States?
The United States National Institute of Standards and Technology (NIST) uses an atomic cesium beam clock to determine the correct time in the United States. The atomic second was adopted as the basic unit of atomic time in 1967, by the thirteenth General Conference of Weights and Measures. An atomic second is defined as 9,192,631,770 oscillations (vibrations) of the radioactive cesium atom. This cesium-beam clock of the NIST is referred to as a “primary clock” because, independently of any other reference, it keeps highly precise time. Sources: Considine, Glenn D., ed. Van Nostrand’s Scientific Encyclopedia, 8th ed., p. 3101; Passport to World Band Radio, p. 70.
