2011/02/10 by David L. Wiltshire, Wiltshire, David L. · 2 citations
Earth and Planetary Sciences · Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Geophysics and Gravity Measurements #Relativity and Gravitational Theory #Solar and Space Plasma Dynamics
paper · pdf · doi:10.48550/arxiv.1102.2045
openalex publication_date 2011/02/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Below scales of about 100/h Mpc our universe displays a complex inhomogeneous\nstructure dominated by voids, with clusters of galaxies in sheets and\nfilaments. The coincidence that cosmic expansion appears to start accelerating\nat the epoch when such structures form has prompted a number of researchers to\nquestion whether dark energy is a signature of a failure of the standard\ncosmology to properly account, on average, for the distribution of matter we\nobserve. Here I discuss the timescape scenario, in which cosmic acceleration is\nunderstood as an apparent effect, due to gravitational energy gradients that\ngrow when spatial curvature gradients become significant with the nonlinear\ngrowth of cosmic structure. I discuss conceptual issues related to the\naveraging problem, and their impact on the calibration of local geometry to the\nsolutions of the volume-average evolution equations corrected by backreaction,\nand the question of nonbaryonic dark matter in the timescape framework. I\nfurther discuss recent work on defining observational tests for average\ngeometric quantities which can distinguish the timescape model from a\ncosmological constant or other models of dark energy.\n