Monopoles as Big as a Universe

TL;DR

The paper shows that monopoles produced during inflation can themselves undergo exponential expansion, and that this internal inflation can continue even after external inflation ends, allowing monopoles to seed eternal self-reproduction of the inflationary universe. This leads to a fractal hierarchy of inflating defects and wormhole-like structures, with each inflating monopole containing its own inflating interior. The result holds broadly for models where the effective potential curvature at $\phi=0$ is smaller than the Hubble rate, including SU(5) Coleman-Weinberg theories. This challenges the traditional monopole problem narrative and suggests a novel global spacetime structure in inflationary cosmology.

Abstract

We show that, contrary to the standard belief, primordial monopoles expand exponentially during inflation in the new inflationary universe scenario. Moreover, inflation of monopoles continues without an end even when inflation ends in the surrounding space. Therefore primordial monopoles (as well as other topological defects produced during inflation) can serve as seeds for the process of eternal self-reproduction of inflationary universe.