Big Bangs and Bounces on the Brane
  In view of our accelerating universe, one of the outstanding theoretical issues is the absence of a quantum-gravitational description of de Sitter space. Although speculative, an intriguing circumvention may be found in the realm of brane-world scenarios; where the physical universe can be interpreted as a non-critical 3-brane moving in a higher-dimensional, static bulk. In this paper, we focus on the cosmological implications of a positively curved brane world evolving in the background of a ``topological'' anti-de Sitter black hole (i.e, Schwarzschild-like but with an arbitrary horizon topology). We show that the bulk black hole will typically induce either an asymptotically de Sitter ``bounce'' universe or a big bang/big crunch FRW universe, depending on a critical value of mass. Interestingly, the critical mass is only non-vanishing in the case of a spherical horizon geometry. We go on to provide a holographic interpretation of this curiosity. 
A.J.M. Medved (University of Alberta)