  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, after an
introduction to these questions, an attempt is described to study cosmological
singularities using the AdS/CFT correspondence. A specific model in which
asymptotically AdS initial data evolve into a big crunch singularity is
discussed and a dual field theory description is provided.
