Abstract
The near isotropy of the cosmic microwave background (CMB) is considered to be the strongest indication for the homogeneity and isotropy of the Universe, a cornerstone of most cosmological analysis. We derive new theorems which extend the Ehlers-Geren-Sachs result that an isotropic CMB implies that the Universe is either stationary or homogeneous and isotropic, and its generalization to the almost isotropic case. We discuss why the theorems do not apply to the real Universe, and why the CMB observations do not imply that the Universe would be nearly homogeneous and isotropic.
- Received 24 March 2009
DOI:https://doi.org/10.1103/PhysRevD.79.123522
©2009 American Physical Society