Exact solution to the averaging problem in cosmology.

@article{Wiltshire2007ExactST,
  title={Exact solution to the averaging problem in cosmology.},
  author={David L. Wiltshire},
  journal={Physical review letters},
  year={2007},
  volume={99 25},
  pages={
          251101
        }
}
  • D. Wiltshire
  • Published 6 September 2007
  • Physics
  • Physical review letters
The exact solution of a two-scale Buchert average of the Einstein equations is derived for an inhomogeneous universe that represents a close approximation to the observed universe. The two scales represent voids, and the bubble walls surrounding them within which clusters of galaxies are located. As described elsewhere [New J. Phys. 9, 377 (2007)10.1088/1367-2630/9/10/377], apparent cosmic acceleration can be recognized as a consequence of quasilocal gravitational energy gradients between… 

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References

SHOWING 1-10 OF 38 REFERENCES

Cosmic clocks, cosmic variance and cosmic averages

Cosmic acceleration is explained quantitatively, purely in general relativity with matter obeying the strong energy condition, as an apparent effect due to quasilocal gravitational energy differences

Averaging in spherically symmetric cosmology

The averaging problem in cosmology is of fundamental importance. When applied to study cosmological evolution, the theory of macroscopic gravity (MG) can be regarded as a long-distance modification

On Average Properties of Inhomogeneous Fluids in General Relativity: Dust Cosmologies

For general relativistic spacetimes filled with irrotational ‘dust’ a generalized form of Friedmann's equations for an ‘effective’ expansion factor aD of inhomogeneous cosmologies is derived.

Regional averaging and scaling in relativistic cosmology

Averaged inhomogeneous cosmologies lie at the forefront of interest, since cosmological parameters such as the rate of expansion or the mass density are to be considered as volume-averaged quantities

Spatial averaging limit of covariant macroscopic gravity: Scalar corrections to the cosmological equations

It is known that any explicit averaging scheme of the type essential for describing the large scale behavior of the Universe must necessarily yield corrections to the Einstein equations applied in

Cosmological solutions in macroscopic gravity.

This work presents exact cosmological solutions to the equations of macroscopic gravity for a spatially homogeneous and isotropic Macroscopic space-time and finds that the correlation tensor is of the form of a spatial curvature term.

Averaging spherically symmetric spacetimes in general relativity

We discuss the averaging problem in general relativity, using the form of the macroscopic gravity equations in the case of spherical symmetry in volume preserving coordinates. In particular, we

Cosmological parameters are dressed.

In the context of the averaging problem in relativistic cosmology, we provide a key to the interpretation of cosmological parameters by taking into account the actual inhomogeneous geometry of the

Towards a theory of macroscopic gravity

By averaging out Cartan's structure equations for a four-dimensional Riemannian space over space regions, the structure equations for the averaged space have been derived with the procedure being

Averaging out the Einstein equations

A general scheme to average out an arbitrary 4-dimensional Riemannian space and to construct the geometry of the averaged space is proposed. It is shown that the averaged manifold has a metric and