Sizing up the Universe

The Wilkinson Microwave Anisotropy Probe (WMAP) has delivered our sharpest view yet of the early Universe. The WMAP data has ushered in a new era of precision cosmology, yielding tight constraints on the age, composition and curvature of the Universe. But the WMAP data was not without it surprises: it appears that the first stars formed much earlier than expected, and there are a number of puzzling features to be found in the large scale anisotropies. It has been suggested that these strange features are a sign that the Universe is spatially finite. We are able to test this hypothesis by looking for a tell-tale signature in the WMAP data. Turning the search around, the absence of such a signature can be used to place a lower bound on the size of the Universe. I will describe recent progress in our search for topological signatures in the WMAP data, and announce some new results.