19/11/2015 - Thibault Damour - The Structure of Cosmological Singularities

Through a Glass Darkly: the Structure of Cosmological Singularities
Abstract. Belinskii, Khalatnikov and Lifshitz (BKL) introduced the idea that the geometry of spacetime near a generic, inhomogeneous cosmological (i.e. spacelike) singularity has (for the four-dimensional vacuum Einstein equations) a chaotic structure. After reviewing the status of BKL ideas as well as their extension to the higher-dimensional vacuum Einstein equations, and to the Einstein-matter systems of most relevance in the context of current theoretical physics, we shall present a precise formulation of the BKL conjecture (in the chaotic case) in terms of an Iwasawa-type parametrization of the spatial metric. We shall also present recent developments suggesting that the chaotic BKL behavior is the shadow of a hidden symmetry (possibly related to M-theory dualities) involving infinite-dimensional hyperbolic Kac-Moody algebras.
philippelefloc...