One Bubble to Rule Them All

TL;DR

This paper uses quantum mechanics principles to predict local observations in a universe with bubble nucleation during eternal inflation, focusing on coarse-grained histories within a single bubble to derive observable probabilities.

Contribution

It introduces a quantum cosmology framework that predicts local universe properties from coarse-grained histories, bypassing the need for detailed large-scale information.

Findings

Predicted our universe emerged from the dominant decay channel of the lowest false vacuum.

Provided a quantum cosmology approach to the measure problem in eternal inflation.

Showed coarse-grained histories suffice for local observational predictions.

Abstract

We apply the principles of quantum mechanics and quantum cosmology to predict probabilities for our local observations of a universe undergoing false vacuum eternal inflation. At a sufficiently fine-grained level, histories of the universe describe a mosaic of bubble universes separated by inflationary regions. We show that predictions for local observations can be obtained directly from sets of much coarser grained histories which only follow a single bubble. These coarse-grained histories contain neither information about our unobservable location nor about the unobservable large-scale structure outside our own bubble. Applied to a landscape of false vacua in the no-boundary state we predict our local universe emerged from the dominant decay channel of the lowest energy false vacuum. We compare and contrast this framework for prediction based on quantum cosmology with traditional approaches to the measure problem in cosmology.