Quasiregular singularities taken seriously

TL;DR

This paper explores the possibility that quasiregular singularities, generalizations of conical singularities, might exist in the universe without contradicting general relativity, potentially observable as cosmic strings or in early universe scenarios.

Contribution

It challenges the common assumption that quasiregular singularities must be excluded, proposing they could exist and have observable consequences in cosmology.

Findings

Quasiregular singularities may appear where causality is threatened.

Such singularities could resemble cosmic strings.

It is possible that we already observe quasiregular singularities.

Abstract

I discuss a special class of singularities obtained as a natural 4-dimensional generalization of the conical singularity. Such singularities (called quasiregular) are ruinous for the predictive force of general relativity, so one often assumes (implicitly as a rule) that they can be somehow excluded from the theory. In fact, however, attempts to do so (without forbidding the singularities by fiat) have failed so far. It is advisable therefore to explore the possibility that their existence is not prohibited after all. I argue that quasiregular singularities, if allowed, may appear either in situations where causality is endangered or in the early Universe. In the latter case objects might appear strongly (though not quite) resembling cosmic strings. Those objects would be observable and, moreover, it is not impossible that we already do observe one.