Relativity Science Calculator - Thumbnail History of the Time Clock

1924 - 27: Quantum Mechanics: developed by Niels Bohr, Danish physicist, Werner Heisenberg, German theoretical physicist, et al. According to quantum theory a quantum particle can be present in two different states
(  wave – particle duality ) at the same time, but not observed simultaneously. The Copenhagen interpretation ( one of the earliest and most commonly taught interpretations of quantum mechanics ) states that the wave - particle duality does not mean that a photon or any other subatomic particle is both a wave and particle simultaneously, but that it could manifest either a wave or a particle aspect depending on circumstances.

1927: Quartz clock ( crystal frequency oscillator ): the first electronic oscillating quartz clock was built by Warren Marrison ( 1896 - 1980, Canada ), Canadian telecommunications engineer and J. W. Horton at Bell Telephone Laboratories in Canada.

1927: Arrow of Time ( Time's Arrow ): a concept developed by British astronomer Arthur Eddington to describe the seemingly asymmetric, "one - way direction" of time.

1955: Atomic clock: Louis Essen ( 1908 - 1997, English physicist ) in collaboration with Jack Parry, most notably built the first practically accurate atomic clock for the most precise measurement of time as well as involving himself in yet another determination of the speed of light, all based upon a certain transition of the caesium - 133 atom, at the National Physical Laboratory UK. As a greater sceptic of time dilation ( time slows ) as part of special relativity, Essen published "The Special Theory of Relativity: A Critical Analysis"", 1971.

1994: GPS ( Global Positioning System ): a space - based satellite navigational system, consisting of a constellation of five geosychronous satellites, was developed by the U.S. Department of Defense ( DOD ) under the DARPA program for locating space and time information here on earth by employing both Special and General Relativity triangulation calculations. GPS is used to synchronize timekeeping systems all across the earth's surface.

2011: World's 2nd most accurate clock: UK's atomic clock is world's 2nd most accurate at the UK's National Physical Laboratory (NPL).

2015: World's most accurate clock: a joint project of the University of Warsaw, Jagiellonian University and Nicolaus Copernicus University, now "ticking away" at the National Laboratory of Atomic, Molecular and Optical Physics in Torún, Poland 'is world's most accurate', where "... it would take tens of billions of years for an error of a single second to accumulate - which is several times longer than the time that has passed since the Big Bang."