2005/06/30 by Edward W. Kolb, E. W. Kolb, S. Matarrese +2 · 18 citations
Physics and Astronomy · #Acceleration #Astrophysics #Classical mechanics #Cosmological perturbation theory #Cosmology #Cosmology and Gravitation Theories #Dark energy #De Sitter universe #Galaxies: Formation, Evolution, Phenomena #General relativity #Hubble volume #Hubble's law #Metric expansion of space #Physics #Solar and Space Plasma Dynamics #Universe #astro-ph #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1088/1367-2630/8/12/322
published as New J.Phys.8:322,2006 · 33 pages, LaTeX file. Revised to match the final version accepted for publication in NJP
arxiv created 2006/06/22 · openalex publication_date 2006/12/19 · arxiv updated 2014/10/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We elaborate on the proposal that the observed acceleration of the Universe is the result of the backreaction of cosmological perturbations, rather than the effect of a negative-pressure dark-energy fluid or a modification of general relativity. Through the effective Friedmann equations describing an inhomogeneous Universe after smoothing, we demonstrate that acceleration in our local Hubble patch is possible even if fluid elements do not individually undergo accelerated expansion. This invalidates the no-go theorem that there can be no acceleration in our local Hubble patch if the Universe only contains irrotational dust. We then study perturbatively the time behaviour of general-relativistic cosmological perturbations, applying, where possible, the renormalization group to regularize the dynamics. We show that an instability occurs in the perturbative expansion involving sub-Hubble modes. Whether this is an indication that acceleration in our Hubble patch originates from the backreaction of cosmological perturbations on observable scales requires a fully non-perturbative approach.