Trans-Planckian censorship of multistage inflation and dark energy
  We explore the bound of the trans-Planckian censorship conjecture on an
inflation model with multiple stages. We show that if the first inflationary
stage is responsible for the primordial perturbations in the cosmic microwave
background window, the $e$-folding number of each subsequent stage will be
bounded by the energy scale of the first stage. This seems to imply that the
lifetime of the current era of accelerated expansion (regarded as one of the
multiple inflationary stages) might be a probe for distinguishing inflation
from its alternatives. We also present a multistage inflation model in a
landscape consisting of anti-de Sitter vacua separated by potential barriers.
