Matter-driven change of spacetime topology

TL;DR

This paper investigates how matter fields influence the topology of quantum universes in the CDT model, revealing a phase transition that can alter the universe's topology from non-trivial to trivial.

Contribution

It introduces a new parameter for scalar fields in CDT and demonstrates a matter-induced phase transition affecting universe topology.

Findings

Scalar fields induce a phase transition in the quantum universe.

The phase transition can change the universe's topology to simply connected.

The study highlights matter's role in quantum topology changes.

Abstract

Using Monte-Carlo computer simulations, we study the impact of matter fields on the geometry of a typical quantum universe in the CDT model of lattice quantum gravity. The quantum universe has the size of a few Planck lengths and the spatial topology of a three-torus. The matter fields are multi-component scalar fields taking values in a torus with circumference $\delta$ in each spatial direction, which acts as a new parameter in the CDT model. Changing $\delta$, we observe a phase transition caused by the scalar field. This discovery may have important consequences for quantum universes with non-trivial topology, since the phase transition can change the topology to a simply connected one.