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...eld emerged in the [[Hellenistic period|Hellenistic world]] during the 3rd century BC from applications of [[geometry]] to [[Astronomy|astronomical studies]]. [[Sumer]]ian astronomers studied angle measure, using a division of circles into 360 degrees.<ref>{{ ...

At the start of the 18th century the [[Reforms of Peter I of Russia|reforms of Peter the Great]] (founder of ...ding universe model in 1922 which greatly influenced cosmology in the 20th century. [[Georgiy Gamov]] proposed the theory of the [[alpha decay]] of a nucleus ...

...actions. The system became the standard of France and Europe within half a century. Other measures with unity ratios<ref group="Note">ratios of 1 between mag ...ts for length, mass and time. Advances in [[electromagnetism]] in the 19th century necessitated additional units to be defined, and multiple incompatible syst ...

...the [[seconds pendulum]] (a pendulum with a half-period of one second) one century earlier, but this was rejected as it had been discovered that this length v ...des Archives]]}}, a platinum bar held in Paris. During the mid nineteenth century, following the [[American Revolution]] and [[Decolonization of the Americas ...