Is Eternal Inflation Eternal?

TL;DR

This paper investigates the conditions under which eternal inflation can occur, showing that certain initial conditions and symmetry breakings prevent its eternal continuation, challenging the traditional view of eternal inflation.

Contribution

It demonstrates that eternal inflation is not necessarily eternal due to symmetry breakings and initial condition effects, providing a new perspective on inflation's longevity.

Findings

Past-incomplete inflation cannot be future eternal.

Bubble collisions are highly probable near initial conditions.

Eternal inflation may be impossible due to symmetry breaking.

Abstract

In this paper we explore the relationship between the existence of eternal inflation and the initial conditions leading to inflation. We demonstrate that past and future completion of inflation is related, in that past-incomplete inflation can not be future eternal. Bubble universes nucleating close to the initial conditions hypersurface have the largest Lorentz boosts and experience the highest anisotropy. Consequently, their probability to collide upon formation is one. Thus instead of continuing eternally inflation ends soon after it starts. The difficulty in actualizing eternal inflation originates from the breaking of two underlying symmetries: Lorentz invariance and the general covariance of the theory which lead to an inconsistency of Einstein equations. Eternal inflation may not be eternal.