Nonideal self-gravity and cosmology: the importance of correlations in
  the dynamics of the large-scale structures of the Universe
  Inspired by the role of correlations in the statistical mechanics of nonideal
self-interacting fluids, we suggest that unresolved sub-structures (i.e.
correlations) have to be taken into account in the Virial theorem of
self-gravitating astrophysical systems. We demonstrate that their omission
leads to a missing mass problem by using the semi-analytic polytropic solutions
of the Lane-Emden equation. This problem suggests to extend the Friedmann
equations to the nonideal regime by taking into account correlations in the
dynamics of the expansion. The increase of correlations induced by the
formation of the large-scale structures could explain naturally the accelerated
expansion of the Universe in such a paradigm.
