Abstract

The idea of mirage cosmology – the cosmological evolution induced on the worldvolume of a probe D-brane geodesically falling in some ambient spacetime – is quite an appealing one, at least from the point of view of string-cosmological model building. In this talk, I review the mirage cosmology of a closed D3-brane wrapping the 3-sphere in the AdS part of AdS_{5} \times S^{5} and show that when this D3-brane is a giant graviton, the resulting cosmology on the giant worldvolume is static. Unlike the Einstein static universe of GR though, this solution is not unstable to homogeneous perturbations. On the other hand, AdS giants are known to exhibit an instability due to the emission of closed strings. Using some recently developed technology for computing correlators of giant gravitons in the dual N=4 SYM , I show how this instability may be understood as gravitational radiation from the D-brane and interpreted in the cosmological context.