# RMA

## Seminar

### The cosmic microwave background and the shape of the Universe

Seminar Room 1, Newton Institute

#### Abstract

The anisotropy of the cosmic microwave background (CMB) is analysed in nearly flat hyperbolic universes possessing a non-trivial topology with a fundamental cell which is stretched out into an infinitely long horn. It is shown that the horned topology does not lead to a flat spot in the CMB sky maps in the direction of the horn as predicted by Levin, Barrow, Bunn, and Silk.Two particular topologies are discussed in detail: the Sokolov-Starobinsky model having an infinite spatial volume, and the Picard orbifold which has a finite volume. It is demonstrated that the recent observations of the "Wilkinson Microwave Anisotropy Probe" (WMAP) hint that our Universe may be shaped like the Picard space.

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