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The Cosmic Microwave Background and Scalar-Tensor Theories of Gravity

C. A. Clarkson·A. A. Coley·E. S. D. O'Neill
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Abstract

We show that if all observers see an isotropic cosmic microwave background in an expanding geodesic perfect fluid spacetime within a scalar-tensor theory of gravity, then that spacetime must be isotropic and spatially homogeneous. This result generalizes the Ehlers-Geren-Sachs Theorem of General Relativity, and serves to underpin the important result that any evolving cosmological model in a scalar-tensor theory that is compatible with observations must be almost Friedmann-Lemaitre-Robertson-Walker.

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C. A. Clarkson, A. A. Coley, E. S. D. O'Neill. 2001-05-07. The Cosmic Microwave Background and Scalar-Tensor Theories of Gravity. https://doi.org/10.1103/physrevd.64.063510

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