A photon from the big bang has lost most of its momentum and energy. What does it push against? Does it break the 'laws' of conservation of energy and momentum? Is there any possibility that momentum is conserved or that in any other way these ancient photons are not precisely identical modern photons of the same wavelength?
If the photon's momentum and energy is given up to expand the universe, but the flux of photons at a point of empty space is not perfectly even over a long time scale, what does this imply?
