Global monopoles can change Universe's topology

TL;DR

Global monopoles formed during a universe phase transition can alter the topology of spatial sections, transforming them from infinite and open to finite and closed, without changing the overall space-time manifold.

Contribution

This paper demonstrates that global monopoles can change the topology of spatial sections in a flat universe using Myers' theorem, a novel insight into topological effects of topological defects.

Findings

Spatial sections become finite and closed after monopole formation

Global monopoles do not alter the space-time manifold topology

Topology change depends on monopole creation or destruction

Abstract

If the Universe undergoes a phase transition, at which global monopoles are created or destroyed, topology of its spatial sections can change. More specifically, by making use of Myers' theorem, we show that, after a transition in which global monopoles form, spatial sections of a spatially flat Universe become finite and closed. This implies that global monopoles can change topology of Universe's spatial sections (from infinite and open to finite and closed). We emphasize that global monopoles cannot alter topology of the space-time manifold.