Dear James A. Putnam,
Speed of light plays the important role in understanding of the nature of time. Three possible reasons exist for an explanation of the observable constancy of speed of light:
1. Feature of propagation of light in the vacuum;
2. Feature of propagation of light in the luminiferous ether;
3. Feature of propagation of light in the gravitational field.
The first reason is considered in the special theory of relativity, where speed of light in vacuum is the constant for any inertial observer. The second item is presented in different variants of the ether theory. The third reason is researched in the essay The Theory of Time, Space and Gravitation, where the constancy of speed of light is consequence of action of gravitation. In this theory it is proved, that the time dilation and increase in inertial mass are gravitational effects. The inconsistent effect of longitudinal length contraction in the new theory is absent. Any contradictions typical for the special theory relativity, for example, the clock paradox are absent also. As is well known, in the general theory of relativity a problem of gravitational energy still remains not solved. In the new theory gravitational energy is precisely localized.
Regards,
Robert Sadykov