The fissioning universe: Topological inflation and Kaluza-Klein cosmologies

Abstract

We propose a Kaluza-Klein cosmology by reversing the usual scenario: instead of starting with a flat 4 + N dimensional universe in which N of the dimensions curl up into a compact manifold, we start with a compact 3 + N dimensional manifold in which 3 of the dimensions are allowed to peel off and expand into the known universe. We reverse the usual “spontaneous compactification” scenario and begin with a closed manifold M 3+ N which undergoes “spontaneous fissioning” into a product manifold M 3 × M N . Remarkably, the 3-dimensional universe M 3 can undergo a rapid de Sitter expansion large enough to solve the horizon and flatness problem. We call this “topological inflation”, which we propose as an alternative to the usual GUT inflation. The inflationary phase automatically terminates into a big bang phase.