# Eternal inflation and the quantum birth of cosmic structure

## TL;DR

This paper explores how incorporating an objective wave function collapse mechanism into eternal inflation models can address the quantum measurement problem and produce primordial inhomogeneities consistent with observations.

## Contribution

It introduces a collapse-based approach to eternal inflation, providing a potential solution to the quantum measurement problem and explaining primordial anisotropies from symmetric initial states.

## Key findings

- Collapse mechanism generates primordial inhomogeneities.
- Eternal inflation condition can be bypassed with collapse.
- Primordial spectrum matches observational data.

## Abstract

We consider the eternal inflation scenario of the slow-roll/chaotic type with the additional element of an objective collapse of the wave function. The incorporation of this new agent to the traditional inflationary setting might represent a possible solution to the quantum measurement problem during inflation, a subject that has not reached a consensus among the community. Specifically, it could provide an explanation for the generation of the primordial anisotropies and inhomogeneities, starting from a perfectly symmetric background and invoking symmetric dynamics. We adopt the continuous spontaneous localization model, in the context of inflation, as the dynamical reduction mechanism that generates the primordial inhomogeneities. Furthermore, when enforcing the objective reduction mechanism, the condition for eternal inflation can be bypassed. In particular, the collapse mechanism incites the wave function, corresponding to the inflaton, to localize itself around the zero mode of the field. Then the zero mode will evolve essentially unperturbed, driving inflation to an end in any region of the Universe where inflation occurred. Also, our approach achieves a primordial spectrum with an amplitude and shape consistent with the one that best fits the observational data.