A higher-dimensional view on quantum cosmology

TL;DR

This paper explores how boundary conditions in quantum cosmology are influenced by the underlying UV completion, using a braneworld model to connect bubble nucleation physics with boundary condition choices.

Contribution

It demonstrates how boundary conditions in quantum cosmology can be derived from UV-complete theories, specifically through a braneworld scenario involving bubble nucleation.

Findings

Boundary conditions depend on the UV completion of gravity.

The model fixes boundary conditions via bubble nucleation physics.

Vilenkin weighting is selected for the wave function amplitude.

Abstract

We argue that the choice of boundary condition for the wave function in quantum cosmology depends on the UV completion of general relativity. We provide an explicit example using a braneworld scenario in which a de Sitter cosmology is induced on the surface of a Coleman-de Luccia bubble in a 5-dimensional AdS space. The corresponding boundary conditions are unambigously fixed by demanding consistency with the known physics of bubble nucleation and this selects the Vilenkin weighting for the amplitude from a 4D viewpoint.