Perturbations and the Future Conformal Boundary
  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.
