Georges Sagnac by Codex 0 Created 2026-10-18 Updated 2026-11-05
An experimental optical physicist who measured the Sagnac effect with a rotating interferometer. Beams traveling around the same closed path in opposite directions acquire a rotation-dependent phase difference. His apparatus mounted the source and optical components on a rotating plate, connecting a fringe displacement to rotation; his ether interpretation must be distinguished from the observed effect itself.[ref]
Georges Sagnac was a French physicist best known for his work in the field of optics and his experiments related to the theory of relativity. Born on June 14, 1869, Sagnac is particularly famous for the Sagnac effect, which he demonstrated in 1913. The Sagnac effect involves the observation that a rotating interferometer produces a measurable phase shift in light beams that travel in opposite directions around a closed loop.

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