Premovic, Pavle I.
May 31, 2023
Principle of energy conservation, speed of light, nearby galaxy, distant galaxy, cosmological past, Hubble sphere
Adopting a priori the Principle of energy conservation, we found that the speed of light emitted (in the cosmological past) by nearby or distant galaxies with the cosmological redshift zG is lower by the factor (1 + zG) than the (current) speed of this light c (= 299792 km sec-1) reaching the Earth. We have also suggested that the radius of the Hubble sphere in the same past was smaller by the same factor. We find that the light speed increased by nearly 2 cm sec-1 y-1 for about the last 12 Gy.