Eternal inflation and the present universe

TL;DR

This paper discusses how eternal inflation leads to diverse regions with varying cosmological parameters, affecting density fluctuation spectra, and introduces a method to calculate probability distributions of these parameters.

Contribution

It presents a general method for computing probability distributions of variable cosmological parameters in eternally inflating universes, with application to density fluctuation spectra.

Findings

Density fluctuation spectra vary across different thermalized regions.

A new method for calculating probability distributions of cosmological parameters.

Implications for understanding the diversity of universe regions.

Abstract

Eternally inflating universes can contain thermalized regions with different values of the cosmological parameters. In particular, the spectra of density fluctuations should be different, because of the different realizations of quantum fluctuations of the inflaton field. I discuss a general method for calculating probability distributions for such variable parameters and analyse the density fluctuation spectrum as a specific application.