Local Observation in Eternal inflation

TL;DR

This paper uses the no-boundary wave function to predict local cosmological observations in landscape models with eternal inflation, indicating a tensor-to-scalar ratio of about 10% from the lowest potential exit point.

Contribution

It introduces a method to calculate small inhomogeneities within our light cone using the no-boundary wave function in eternal inflation models.

Findings

Predicts a tensor-to-scalar ratio of about 10%.

Shows the dominant contribution from the lowest potential exit.

Provides a measure for local cosmological predictions.

Abstract

We consider landscape models that admit several regions where the conditions for eternal inflation hold. It is shown that one can use the no-boundary wave function to calculate small departures from homogeneity within our past light cone despite the possibility of much larger fluctuations on super horizon scales. The dominant contribution comes from the history exiting eternal inflation at the lowest value of the potential. In a class of landscape models this predicts a tensor to scalar ratio of about 10%. In this way the no-boundary wave function defines a measure for the prediction of local cosmological observations.