Topology of the Universe

Abstract

The Hilbert-Einstein equations are insufficient t describe the geometry of the Universe, as they onl constrain a local geometrical property: curvatur A global knowledge of the geometry of space, if pos sible, would require measurement of the topolog of the Universe. Since the subject was discussed i 1900 by Schwarzschild, observational attempts t measure global topology have been rare for most o this century, but have accelerated in the 1990’s du to the rapidly increasing amount of observations o non-negligible fractions of the observational spher A brief review of basic concepts of cosmic topolog and of the rapidly growing gamut of diverse an complementary observational strategies for measu ing the topology of the Universe is provided here.