Abstract

There is little doubt that light and other electromagnetic (EM) waves propagate through free space with a speed that is a constant with respect to something, but the nature of that something is still a subject of much debate. Beckmann has proposed that "the velocity of light is constant with respect to the local gravitational field through which it propagates," and as noted by Hayden, this model "makes a specific prediction that the velocity of light with respect to an observer moving at velocity u through the field is c * u, i.e., the light velocity combines vectorially with field velocity. II This proposal will be called the gravitational velocity theory.

It can also be hypothesized that the local gravitational field acts as an absolute reference for the scaler speed of EM waves. In this case, the wave speed = c + n * v_g, where n is the unit vector normal to the wave front and v_g is the velocity (in the chosen coordinates) of the local gravitational field. This model will be called the graVitational speed theory. These two theories are equivalent when v_g is parallel to n, but their predictions are quite different when v_g is orthogonal to n.