3-DIMENSIONAL TOPOLOGY-INDEPENDENT METHODS TO LOOK FOR GLOBAL TOPOLOGY

The spacelike hypersurface of the Universe at the present cosmological time is a three-dimensional manifold. A non-trivial global topology o f this spacelike hypersurface would imply that the apparently observab le universe (the sphere of particle horizon radius) could contain seve ral images of the single, physical Universe. Recent three-dimensional techniques for constraining and/or detecting this topology are reviewe d. Initial applications of these techniques using x-ray bright cluster s of galaxies and quasars imply tweak) candidates for a non-trivial to pology.