Towards a physical interpretation for the Stephani Universes

A physically reasonable interpretation is provided for the perfect fluid, s pherically symmetric, conformally Rat "Stephani Universes". The free parame ters of this class of exact solutions are determined so that the ideal gas relation p = nk(B)T is identically fulfilled, while the Full equation of st ate of a classical monatomic ideal gas and a matter-radiation mixture holds up to a good approximation in a near dust, matter dominated regime. Only t he models having spacelike slices with positive curvature admit a regular e volution domain that avoids an unphysical singularity. In the matter domina ted regime these models are dynamically and observationally indistinguishab le from "standard" FLRW cosmology with a dust source.