Non-homogeneity-driven universe acceleration (Q2752478)

Observational evidence supports the hypothesis that the expansion of the universe is accelerating. The acceleration hypothesis is based on supernovae (SnIa) observations. The authors of the paper under review relax the assumption of the homogeneity of space by replacing the usual cosmological principle by the Copernican cosmological principle stating that our galaxy is at the centre of the universe. From the epistemological point of view, this assumption seems to be artificial. However, the intention of the authors is to demonstrate that even an exotic cosmological model is not in contradiction with the SnIa observations. The calculations are performed with the spherically symmetric Stephani cosmological model in which the energy density is uniform and the pressure depends upon the distance of the center of symmetry. For this model, the deceleration parameters and the redshift are discussed. It is shown that the deceleration decreases with the distance and is negative for sufficiently distant galaxies. In addition, the age of the universe in the model is found to be remarkably larger than in isotropic and homogeneous cosmological models.