Page "Michelson–Gale–Pearson experiment" Paragraph 7

As it was already pointed out by Michelson in 1904, a positive result in such experiments contradicts the hypothesis of complete aether drag.

On the other hand, the stationary ether concept is in agreement with this result, yet it contradicts ( with the exception of Lorentz's ether ) the Michelson-Morley experiment.

Thus special relativity is the only theory which explains both experiments.

The experiment is consistent with relativity for the same reason as all other Sagnac type experiments ( see Sagnac effect ).

That is, rotation is absolute in special relativity, because there is no inertial frame of reference in which the whole device is at rest during the complete process of rotation, thus the light paths of the two rays are different in all of those frames, consequently a positive result must occur.

It's also possible to define rotating frames in special relativity ( Born coordinates ), yet in those frames the speed of light is not constant in extended areas any more, thus also in this view a positive result must occur.

Today, Sagnac type effects due to Earth's rotation are routinely incorporated into GPS.