Sagnac Experiment

The Sagnac Experiment is essentially the same experiment as the Michelson-Morley Experiment, except that it is on a rotating turn-table. The results of the Sagnac Experiment shows that when the table is rotated on a horizontal axis, the velocity of light indeed changes, contradicting the Michelson-Morley Experiment that was designed to use the supposed movement of the earth to change position, and which showed no change in light velocity.

From a paper on the Sagnac Effect we read:

{{cite|Since its discovery at the beginning of the XX century the Sagnac effect [1] has play an important role in the understanding and development of fundamental physics (for a review see [2]). The Sagnac effect is the dependence of the interference pattern of the rotating interferometer on the direction and speed of rotation. This phenomenon is universal and manifested for any kind of waves, including the matter waves and has found a variety of applications for the practical purposes and in the fundamental physics [2].

...In the context of the Sagnac effects the null result of the Michelson-Morley experiment is also not clear. Applying the same logic to Sun centered rotating frame in which Earth is fixed, one would expect different light speeds as seen from Earth. ”