  The discovery of the string theory landscape has recently brought attention
to the eternal nature of inflation. In contrast to the common belief that
eternal inflation may be a generic feature of most inflationary models, in this
note we argue that the suppressed amplitude of perturbations due to adiabatic
regularization, together with a fine-tuning constraint on the equation of state
of the rare inflating pockets with large fluctuations, render eternal inflation
expensive in energy and may make it unlikely to occur. The energy scales of the
eternally inflating pockets have to be very close to the transplanckian regime
in order to compensate for the suppression of regularized perturbations.
