How generic is eternal inflation?

TL;DR

This paper investigates the generic conditions under which eternal inflation occurs, using numerical simulations of various inflation models to understand the likelihood of a multiverse without fine-tuning.

Contribution

It introduces a systematic numerical approach to assess the prevalence of eternal inflation across different inflationary models and measures.

Findings

Eternal inflation can be generic under certain conditions.

The likelihood of a multiverse depends on the chosen measure.

Numerical simulations reveal parameter regimes favoring eternal inflation.

Abstract

Everlasting inflation has far-reaching implications for cosmology and the standing of self-localizing inferences made by observers, which have been subjects of renewed interest in light of the growing acceptance of theory landscapes and the attendant anthropic arguments. Under what assumptions and to what extent does inflation generically produce an eternal "multiverse," without fine-tuning with respect to measures over the space of inflationary cosmologies driven by a single minimally coupled scalar field? We address this and related questions with numerical simulations of inflationary dynamics across populations of randomly generated inflation models, instantiating a few particular simply-defined measures.