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  • Journal Club, April 11, 2008

    Joseph Henry Room, 12:00pm
    Ben Craps, Vrije Universiteit Brussel and The International Solvay Institutes, Belgium
    "Quantum resolution of cosmological singularities using AdS/CFT"

    ABSTRACT:
    Despite impressive phenomenological successes, cosmological models are incomplete without an understanding of what happened at the big bang singularity. Depending on the model, one would like to understand how appropriate “initial conditions” were selected at the big bang singularity, or how a pre-existing contracting universe underwent a big crunch/big bang transition, if such transitions are possible at all. In this talk, based on work with T. Hertog and N. Turok, I discuss a five-dimensional model cosmology with a big crunch singularity and ask whether time evolution can be consistently defined beyond this singularity, which would then be the big bang of an expanding universe. We use the AdS/CFT correspondence to map the problem to the study of a dual quantum field theory with a potential unbounded below, where the singularity corresponds to a field reaching infinity in finite time. The main idea is to use “self-adjoint extensions”, which amounts to putting boundary conditions at infinity in field space. Our results suggest that, at least in a certain parameter regime, a big crunch/big bang transition is the most likely outcome of cosmological evolution. We end with some speculations on the generation of nearly scale invariant cosmological perturbations.

    Order a hoagie


  • Research supported by: The National Science Foundation and The National Aeronautics and Space Administration