Georges Sagnac
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Georges Sagnac (1869-1926) was a French physicist who lent his name to the Sagnac effect, a phenomenon which is at the basis of interferometers and laser gyroscopes developed since the 1970s.
Little is known about the life of Georges Sagnac, other than that he was one of the first people in France to study X-rays, following Wilhelm Conrad Röntgen while he was still a lab assistant at the Sorbonne.
Marie Curie says that the Curie couple had traded ideas with Sagnac around the time of the discovery of radioactivity.
He belonged to a group of friends and scientists that notably included Pierre and Marie Curie, Paul Langevin, Jean Perrin, and the mathematician Émile Borel.
In 1913, Georges Sagnac showed that if light is sent in two opposite circular directions on a revolving platform, the speed of the light beam turning in the same direction as the platform will be greater than the speed of the light beam that is turning opposite the direction of the table.
The results of this experiment seemed to contradict the then-new theory of relativity. Georges Sagnac was an ardent opponent of the theory of relativity, but it was soon proven that the results could very well be explained by general relativity and later on special relativity.
