  In recent work we analyzed the evolution of primordial perturbations
satisfying Planck-scale-modified dispersion relations and showed that there is
no cosmological "squeezing" in the critical model that produces perturbations
with a scale invariant spectrum. Nevertheless, the perturbations reenter the
horizon as standing waves with the correct temporal phase because of the
late-time decay of the momentum mode. Here we shed light on the absence of
primordial squeezing by re-examining the problem in the dual rainbow frame,
where $c$ is set to 1, shifting the varying $c$ effects elsewhere. In this
frame gravity switches off at sub-Planckian wavelengths, so that the
fluctuations behave as if they were in Minkowski spacetime. This is ultimately
why they are not squeezed. However, away from the critical model squeezing does
occur if the fluctuations spectrum is red, as is the case for scalar
perturbations. Should the primordial gravity waves have a blue spectrum, we
predict that they might not reenter the horizon as standing waves, because the
momentum mode would be enhanced in the primordial phase.
