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Summary
DescriptionObserver in special relativity.svg
English: In special relativity, the term "observer" has a meaning that differs significantly from the ordinary English meaning of the term. Each location in spacetime is marked by four numbers defined by a frame of reference: the position in space, and the time (which can be visualized as the reading of a clock located at each position in space). The "observer" synchronizes the clocks according to their own reference frame.
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