The cosmological redshift is primarily caused by the metric expansion of space, which stretches photons as they travel through the universe. This phenomenon results in a shift of light towards longer wavelengths, typically observed as redshift in distant galaxies. Compton scattering with free electrons in stellar atmospheres does not contribute to cosmological redshift, as it cannot shift emission lines to different wavelengths. Instead, the redshift is accurately measured through specific emission lines unique to each atom, which remain consistent despite the expansion of space.
PREREQUISITESAstronomers, astrophysicists, and students of cosmology seeking to deepen their understanding of redshift phenomena and the underlying principles of light behavior in an expanding universe.