Dark energy and inhomogeneity

Abstract

The standard understanding that distant supernova data implies existence of either dark energy or a cosmological constant Λ relies on the assumption of spatial homogeneity of the universe. A large-scale smoothed-out model of the universe ignores small-scale inhomogeneities, but the averaged effects of those inhomogeneities may alter both observational and dynamical relations at the larger scale, mimicking the effect of a cosmological constant. Alternatively large scale spatial inhomogeneity with zero Λ might mimic the effect of a positive cosmological constant. Whether this is the case or not is open to direct observational testing.