The expansion of the universe directly redshifts photons by increasing their wavelength proportionally to the increasing distances between galaxies. This phenomenon occurs independently of the relative motion of distant objects, which may appear to be moving away due to the expansion. The key takeaway is that the redshift observed in light from distant galaxies is a result of the universe's expansion rather than the velocity of the galaxies themselves.
PREREQUISITESAstronomers, physicists, and students of cosmology seeking to understand the relationship between the universe's expansion and the redshift of light from distant galaxies.
Yes, the expansion itself redshifts photons. Basically, the wavelength of photons is increased by the same factor as the distances between galaxies is increased with expansion.edoarad said:does the expansion itself redshifts photons (if so, does the expansion affect the photon in his frame of referance?) or is it because the distant object that emits them is seemingly moving away from us (in cases where the expansion is much more dominant of course)? The latter doesn't makes much sense to me because the object isn't really moving as fast as he seems.