Is there proof that backreaction of inhomogeneities is irrelevant in cosmology

@article{Buchert2015IsTP,
  title={Is there proof that backreaction of inhomogeneities is irrelevant in cosmology},
  author={Thomas Buchert and Mauro Carfora and George F R Ellis and Edward W. Kolb and Malcolm A. H. MacCallum and Jan J. Ostrowski and Syksy Rasanen and Boudewijn F. Roukema and Lars-Erik Andersson and Alan Coley and David L. Wiltshire},
  journal={arXiv: General Relativity and Quantum Cosmology},
  year={2015}
}
No. In a number of papers Green and Wald argue that the standard FLRW model approximates our Universe extremely well on all scales, except close to strong field astrophysical objects. In particular, they argue that the effect of inhomogeneities on average properties of the Universe (backreaction) is irrelevant. We show that this latter claim is not valid. Specifically, we demonstrate, referring to their recent review paper, that (i) their two-dimensional example used to illustrate the fitting… Expand
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