In 1952 the US American National Bureau of Standards successfully and accurately measured the resonance of the Cesium atom. Three years later The National Physical Laboratory in England succeeded in constructing the first ever Cesium - beam clock intended to be used as a scientific calibration standard source rather than a conventional clock.

After a further three years, (1958) Cesium Atomic Clocks had become available commercially at a cost of $20,000 each, a considerable sum at that time.
In 1967 the 13th General Conference on Weights and Measures defined the second on the basis of vibrations of the Cesium 133 atom; for the first time the world’s timekeeping standard was not based on astronomical observations but on Quantum Physics.
By the mid 1970's the Atomic Clock was able to achieve accuracies better than one second in 300,000 years.
As the New Millennium  swept across the world, Cesium Atomic clocks in both the US and Europe were able to measure its progress to an accuracy better than 0.05 seconds per million years.

How Does the Atomic Clock Work?
All atoms emit or absorb electromagnetic energy when changing their energy state following the laws of quantum physics. As resonant emission frequencies are identical for every atom of a given element, when an atom such as Cesium 133 decays it radiates energy at a fixed frequency, in the case of Cesium 133, 9,192,631,770 cps. An Atomic clock Using the known fixed magnetic resonance of an atom as its reference is incredibly accurate compared to mechanical and astronomical methods. It is important to remember that the Atomic clock is primary a reference source and does not give the time of day as such but only the rate of time passing, in other words it is the equivalent of a clock or watch escapement. The time of day still follows its astronomical origins hence terms like "GMT" and "time zones" are still relative to knowing the correct local time of day.

Why do we need Atomic Clocks?
Science and Navigation are the two main areas in which extreme accuracy are required, for example the Global Positioning System used so much to day can only be as accurate as the passage of time can be measured by a clock.
Atomic Clocks are used to regulate radio time signals which are in turn used to calibrate and correct Clocks and even some wrist watches. It is also possible to download free software from the internet for windows based computers to allow them to check and correct the time on your own computer, we have included a link to such a site at the bottom of this page which may interest you, the software will periodically or at your command check the clock on your PC against the National Institute of Standards and Technology Atomic Clock internet Servers in the US, if your PC clock is in error you will have the option to automatically sync it to the US National Institute of Standards and Technology Atomic Clock.