Relativity, gravitation, and the redshift of galaxies.

The question of whether the redshifts of galaxies can be explained by gravitation requires a study of the interaction between photons and gravitons. For this kind of interaction between two particles/waves, both moving with the velocity of light, Einstein's special and general theories of relativity have to be improved. In this case the problem of special relativity can be solved only by giving up Einstein's assumption that the velocity of light is constant not only relative to any inertial system, but also in absolute terms. The problem of general relativity, however, here cannot be solved with the aid of a Riemannian space, but only with the aid of a Euclidean space, choosing the frame of reference in which the momentum of the total system of the interacting particles/waves is zero. The combination of both improvements leads to the consequence that the redshift of galaxies is at least in part an effect of the gravitational fields the light has crossed on its way from a galaxy to the Earth.