Baby Universes born from the Void

TL;DR

This paper introduces a new third quantized framework for baby universes in quantum gravity, fixing microscopic parameters and linking wormholes to boundary dual quantum field theories through gauge group representations.

Contribution

It presents a novel construction of the baby universe Hilbert space that fixes microscopic parameters and relates wormholes to boundary observables involving gauge group representations.

Findings

Replaces $eta$-parameters with fixed microscopic parameters.

Connects wormholes to boundary dual QFT observables.

Defines superselection sectors via gauge group representations.

Abstract

We propose a novel construction of a third quantised baby universe Hilbert space $\mathcal{H}_{BU}$ for the quantum gravity path integral. In contrast to the original description of $\alpha$-parameters, both the bulk and boundary microscopic parameters are fixed in our proposal. Wormholes and baby universes appear due to refined observables, of the boundary dual quantum field theories, that crucially involve the space of representations of the gauge group. Irreducible representations, on which the path integral factorises, give rise to field theoretic superselection sectors and replace the $\alpha$ states.