Perturbations and the future conformal boundary
Published in Phys. Rev. D, 105(8):083514, 2022
Recommended citation: A.N. Lasenby, W.J. Handley, D.J. Bartlett, and C.S. Negreanu (2022). "Perturbations and the future conformal boundary." Phys. Rev. D, 105(8):083514.
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.
Radiation, matter and potential perturbations for the first three solutions which remain finite on both sides of the future conformal boundary in a $\Lambda$CDM universe containing only perfect fluids with cosmological parameters set to the Planck 2018 best-fit values.