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{{Short description|Electromagnetic radiation from a charged particle in a medium}} [[File:Advanced Test Reactor.jpg|thumb|right|Cherenkov radiation glowing in the core of the [[Advanced Test Reactor]] at [[Idaho National Laboratory]]] ...

...2962 }} The [[Planck (spacecraft)#2015 data release|Planck Collaboration]] in 2015 published the estimate of 13.799 ± 0.021 billion years ago (68% confid ...law#Laws of physics|laws of physics]] may not have applied; the emergence in stages of the four known [[fundamental interaction]]s or [[force]]s—first [ ...

...al prototypes. Rather than the various complex systems of subdivision then in use, they also preferred a decimal system to ease their calculations. ...scovered that this length varied from place to place with local gravity. A new unit of length, the ''metre'' was introduced – defined as one ten-millionth ...