The spectrum of perturbations inside the Schwarzschild black hole
  We study the spectrum of the bound state perturbations in the interior of the
Schwarzschild black hole for the scalar, electromagnetic and gravitational
perturbations. Demanding that the perturbations to be regular at the center of
the black hole determines the spectrum of the bound state solutions. We show
that our analytic expression for the spectrum is in very good agreement with
the imaginary parts of the high overtone quasi normal mode excitations obtained
for the exterior region. We also present a simple scheme to calculate the
spectrum numerically to good accuracies.
