Article

# Reinterpreting dark energy through backreaction: the minimally coupled morphon field

12/2006; DOI: 10.1142/9789812834300_0268

Source: arXiv

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**ABSTRACT:**We evaluate the average expansion rate of a universe which contains a realistic evolving ensemble of non-linear structures. We use the peak model of structure formation to obtain the number density of structures, and take the individual structures to be spherical. The expansion rate increases relative to the FRW value on a timescale of 10-100 billion years, because the universe becomes dominated by fast-expanding voids. However, the increase is not rapid enough to correspond to acceleration. We discuss how to improve our treatment. We also consider various qualitative issues related to backreaction. Comment: 49 pages, 6 figures. v2: Added clarifications and references. v3: Published version. Corrected typosJournal of Cosmology and Astroparticle Physics 01/2008; · 6.04 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**New statistical ensembles of classical extreme black holes are introduced. Each ensemble is proven to represent a non extreme, finite temperature black hole. This mean or average black hole is surrounded by a mean electromagnetic field and a so-called apparent matter, which is the large scale trace of the averaged upon small scale fluctuations of the gravitational and electromagnetic fields. However, the total mass and the total charge of space–time is not modified by the averaging.Physica A: Statistical Mechanics and its Applications 01/2009; · 1.68 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We derive the redshift and the angular diameter distance in rotationless dust universes which are statistically homogeneous and isotropic, but have otherwise arbitrary geometry. The calculation from first principles shows that the Dyer-Roeder approximation does not correctly describe the effect of clumping. Instead, the redshift and the distance are determined by the average expansion rate, the matter density today and the null geodesic shear. In particular, the position of the CMB peaks is consistent with significant spatial curvature provided the expansion history is sufficiently close to the spatially flat LambdaCDM model. Comment: 33 pages. v2: Published version. Corrected typosJournal of Cosmology and Astroparticle Physics 12/2008; · 6.04 Impact Factor

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