  The interpretation of the expanding universe as an expansion of space has
recently been challenged. From the geodesic equation in Friedmann universe
models and the empty Milne model, we argue that a Newtonian or special
relativistic analysis is not applicable on large scales, and the general
relativistic interpretation in terms of expanding space has the advantage of
being globally consistent. We also show that the cosmic redshift, interpreted
as an expansion effect, containts both the Doppler effect and the gravitational
frequency shift.
