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arXiv · gr-qc/9511043

Almost-homogeneity of the universe in higher-order gravity

David R Taylor·Roy Maartens
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Abstract

In the $R+αR^2$ gravity theory, we show that if freely propagating massless particles have an almost isotropic distribution, then the spacetime is almost Friedmann-Robertson-Walker (FRW). This extends the result proved recently in general relativity ($α=0$), which is applicable to the microwave background after photon decoupling. The higher-order result is in principle applicable to a massless species that decouples in the early universe, such as a relic graviton background. Any future observations that show small anisotropies in such a background would imply that the geometry of the early universe were almost FRW.

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David R Taylor, Roy Maartens. 1995-11-15. Almost-homogeneity of the universe in higher-order gravity. https://doi.org/10.1007/bf02153319

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