Trans-Planckian Censorship and Inflationary Cosmology
  We study the implications of the recently proposed Trans-Planckian Censorship
Conjecture (TCC) for early universe cosmology and in particular inflationary
cosmology. The TCC leads to the conclusion that if we want inflationary
cosmology to provide a successful scenario for cosmological structure
formation, the energy scale of inflation has to be lower than $10^9$ GeV.
Demanding the correct amplitude of the cosmological perturbations then forces
the generalized slow-roll parameter $\epsilon$ of the model to be very small
($<10^{-31}$). This leads to the prediction of a negligible amplitude of
primordial gravitational waves. For slow-roll inflation models, it also leads
to severe fine tuning of initial conditions.
