# Differentiating the gravitational redshift and the cosmological redshift?

If general relativity accounts for a redshift, independent of inflation, how can we still know that inflation is viable? Moreover, how do we differentiate the the gravitational redshift and the cosmological redshift observationally?

• I once happened to ask this same question in APOD. The answers given by astronomers/physicists there may add something worthwhile to the discussion here. – Jyrki Lahtonen Oct 31 '14 at 14:14