Trans-Planckian censorship, inflation and excited initial states for
  perturbations
  The recently proposed trans-Planckian censorship conjecture (TCC) seems to
require that the energy scale of inflation is significantly lower than the
Planck scale $(H_\text{inf}<10^{-20} \Mpl)$. This, in turn, implies that the
tensor-to-scalar ratio for inflation is negligibly small, \textit{independent}
of assumptions of slow-roll or even of having a single scalar field, thus
ruling out inflation if primordial tensor modes are ever observed. After
demonstrating the robustness and generality of these bounds, we show that
having an excited initial state for cosmological perturbations seems to be a
way out of this problem for models of inflation.
