Perturbations and the Future Conformal Boundary

TL;DR

This paper explores how certain cosmological models with a future conformal boundary allow for analytical continuation of perturbations beyond this boundary, potentially affecting observable cosmic microwave background features.

Contribution

It introduces a method to extend perturbations beyond the future conformal boundary and links these theoretical models to observable CMB features, contrasting with conformal cyclic cosmologies.

Findings

Perturbations can be analytically continued beyond the conformal boundary.

The models predict a quantized power spectrum consistent with CMB observations.

Theoretical models can be interpreted as a mirrored or double-cover universe.

Abstract

The concordance model of cosmology predicts a universe which finishes in a finite amount of conformal time at a future conformal boundary. We show that for particular cases we study, the background variables and perturbations may be analytically continued beyond this boundary and that the "end of the universe" is not necessarily the end of their physical development. Remarkably, these theoretical considerations of the end of the universe might have observable consequences today: perturbation modes consistent with these boundary conditions have a quantised power spectrum which may be relevant to features seen in the large scale cosmic microwave background. Mathematically these cosmological models may either be interpreted as a palindromic universe mirrored in time, a reflecting boundary condition, or a double cover, but are identical with respect to their observational predictions and stand in contrast to the predictions of conformal cyclic cosmologies.