A Covariant Road to Spatial Averaging in Cosmology : Scalar Corrections to the Cosmological Equations

Abstract

A consistent approach to Cosmology requires an explicit averaging of the Einstein equations, to describe a homogeneous and isotropic geometry. Such an averaging will in general modify the Einstein equations. The averaging procedure due to Buchert has attracted considerable attention recently since it offers the tantalizing hope of explaining the phenomenon of dark energy through such corrections. This approach has been criticized, however, on the grounds that its effects may be gauge artifacts. We apply the fully covariant formalism of Zalaletdinov's Macroscopic Gravity and show that, after making some essential gauge choices, the Cosmological equations receive \emph{spacetime scalar} corrections which are therefore observable in principle, and further, that the broad structure of these corrections is \emph{identical} to those derived by Buchert.

arXiv comment8 pages; This essay received an Honourable Mention in the Gravity Research Foundation's Essay Competition, 2007

References in corpus (4)

• On average properties of inhomogeneous fluids in general relativity I: dust cosmologies
• On average properties of inhomogeneous fluids in general relativity II: perfect fluid cosmologies
• The Spatial Averaging Limit of Covariant Macroscopic Gravity - Scalar Corrections to the Cosmological Equations
• Space-time Averages in Macroscopic Gravity and Volume-preserving Coordinates

Cited by in corpus (8)

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• Light propagation in statistically homogeneous and isotropic dust universes
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• Is backreaction really small within concordance cosmology?
• Back-reaction and effective acceleration in generic LTB dust models
• A Complete Cosmological Solution to the Averaged Einstein Field Equations as found in Macroscopic Gravity
• Weighed scalar averaging in LTB dust models, part I: statistical fluctuations and gravitational entropy