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If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving [[relative]] to the first will generally assign different times to the two [[events]]. This is illustrated in the ladder [[paradox]], a [[thought]] [[experiment]] which uses the example of a ladder moving at high speed through a garage.

If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving [[relative]] to the first will generally assign different times to the two [[events]]. This is illustrated in the ladder [[paradox]], a [[thought]] [[experiment]] which uses the example of a ladder moving at high speed through a garage.

A mathematical form of the relativity of simultaneity ("local time") was introduced by [http://en.wikipedia.org/wiki/Hendrik_Lorentz Hendrik Lorentz] in 1892, and physically interpreted (to first order in v/c) as the result of a synchronization using light signals by [http://en.wikipedia.org/wiki/Henri_Poincar%C3%A9 Henri Poincaré] in 1900. However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable [[frame of reference]], and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers. It was [[Albert Einstein]] in 1905 who abandoned the ([[classical]]) aether and emphasized the significance of [[relativity]] of simultaneity to our understanding of [[space and time]]. He deduced the failure of [[absolute]] simultaneity from two stated assumptions:

A mathematical form of the relativity of simultaneity ("local time") was introduced by [https://en.wikipedia.org/wiki/Hendrik_Lorentz Hendrik Lorentz] in 1892, and physically interpreted (to first order in v/c) as the result of a synchronization using light signals by [https://en.wikipedia.org/wiki/Henri_Poincar%C3%A9 Henri Poincaré] in 1900. However, both Lorentz and Poincaré based their conceptions on the aether as a preferred but undetectable [[frame of reference]], and continued to distinguish between "true time" (in the aether) and "apparent" times for moving observers. It was [[Albert Einstein]] in 1905 who abandoned the ([[classical]]) aether and emphasized the significance of [[relativity]] of simultaneity to our understanding of [[space and time]]. He deduced the failure of [[absolute]] simultaneity from two stated assumptions:

* the principle of [[relativity]]—the equivalence of inertial frames, such that the [[laws]] of [[physics]] apply equally in all inertial coordinate [[systems]];

* the principle of [[relativity]]—the equivalence of inertial frames, such that the [[laws]] of [[physics]] apply equally in all inertial coordinate [[systems]];

* the constancy of the [[velocity|speed]] of [[light]] detected in empty [[space]], independent of the relative [[motion]] of its source.[http://en.wikipedia.org/wiki/Relativity_of_simultaneity]

* the constancy of the [[velocity|speed]] of [[light]] detected in empty [[space]], independent of the relative [[motion]] of its source.[https://en.wikipedia.org/wiki/Relativity_of_simultaneity]

[[Category: Physics]]

[[Category: Physics]]