Abstract

Recent claims that ether drag is compatible with stellar aberration are falsified using independent ex-perimental data regarding clock behavior. There is substantial evidence that clock velocity and clock position in a gravitational potential affect the clock readings by causing biases in clocks that are separated in a moving frame. These clock biases cause the apparent speed of light in the frame to be isotropic and equal to c even though the true speed of light is not affected by the motion and is anisotropic relative to the moving frame. These clock biases are verified by comparison with millisecond pulsars. Thus alternative explanations for the isotropy of the speed of light, such as Special Relativity Theory (SRT) or ether drag, are thereby falsified.