The universe could be dark, ma non troppo

Abstract

We will present new insights into the dark phenomena, i.e., the recent acceleration of the universe linked to a sort of dark energy, and to the unknown dark matter. The study is based only on Einsteins equations without cosmological constant, and on ordinary matter described as point masses. We will be limited, thereby, to the post -recombination epoch. We shall revise the outspread statement that a universe made of colission-less particles is well represented by dust, i.e; by an Einstein-de Sitter universe. Using well known results on the N-body problem expressed as a infinite series, and starting at zero order with the empty Milne universe, we shall get the aforementioned EdS universe at the first order, but at the next one we shall obtain a cosmological model whose energy density could explain the dark phenomena. No exotic dark components are necessary in principle, but we need to know the redshift of formation of the dominant particles in the present epoch, that we identify with the galaxies. Thus, assuming that redshift to be of the order of eleven, we shall get that the time evolution of the acceleration, and the supernovae luminous distance-redshift relation, are indistinguishable from the ones predicted by the ACDM model. However, if there was no realistic evolution model that could justify such an early galaxy formation epoch, then some quantity of dark energy would be necessary, ma non troppo.