Transition dating into relationship
Large ensembles of ultracold alkaline earth atoms have provided impressive clock stability for short averaging times, surpassing that of single-ion-based systems.So far, interrogation of neutral-atom-based optical standards has been carried out primarily in free space, unavoidably including atomic motional effects that typically limit the overall system accuracy.
The second thus defined is consistent with the ephemeris second, which was based on astronomical measurements.Within a few years, most British precision clockmakers were producing longcase clocks and other clockmakers soon followed. In 1832, Gauss proposed using the second as the base unit of time in his millimeter-milligram-second system of units.The British Association for the Advancement of Science (BAAS) in 1862 stated that "All men of science are agreed to use the second of mean solar time as the unit of time." BAAS formally proposed the CGS system in 1874, although this system was gradually replaced over the next 70 years by MKS units.Both the CGS and MKS systems used the same second as their base unit of time.MKS was adopted internationally during the 1940s, defining the second as In 1956, the second was redefined in terms of a year (the period of the Earth's revolution around the Sun) for a particular epoch because, by then, it had become recognized that the Earth's rotation on its own axis was not sufficiently uniform as a standard of time.