The topology of Branching Universes

The purpose of this paper is to survey the possible topologies of branch-ing space-times, and, in particular, to refute the popular notion in the literature that a branching space-time requires a non-Hausdorff topology. 1 Branching MWI space-times Two basic types of branching universe have been suggested in modern mathe-matical physics: universes which branch in a style befitting the ‘many-worlds’ interpretation (MWI) of quantum theory; and universes which bifurcate to im-plement a topology-change cobordism. This section, concerned with the former type of branching universe, is not intended as a defence or analysis of the many-worlds interpretation. It is not even the intention to argue that the many-worlds interpretation genuinely en-tails such a branching model of space-time. Rather, the intention is to analyse the topological implications of such a branching model of space-time, and to question some of the assumptions normally found in the literature