A New Guest in the Third Quantized Multiverse

TL;DR

This paper addresses a conceptual issue in third quantization of quantum gravity by introducing a new quantum field that mediates interactions between universes, affecting entanglement and thermodynamic properties.

Contribution

It proposes adding a new quantum field to the third quantization formalism to account for universe interactions and heat baths, resolving previous conceptual limitations.

Findings

The entanglement entropy varies with the scale factor, indicating interactions.

A new quantum field mediates interactions between universes.

The model can include a heat bath, influencing universe dynamics.

Abstract

In the present article we point out a conceptual issue of the Third Quantization formalism for Canonical Quantum Gravity. Based on earlier results on interuniversal entanglement, the picture of noninteracting universe-antiuniverse pairs is incomplete. In particular, the variation of the entanglement entropy with the scale factor, understood as a measure of time, implies either an interaction between pairs of universes or universes with a heat bath, i.e. an external field. We propose a simple solution to the problem by adding a new quantum field to the formalism. Correspondingly, particles of this field mediate interactions between universes -- depending on the model at tree level or one loop -- and may further provide a heat bath in the background.