  The familiar Newtonian version of the Rayleigh criterion demands that for
dynamical stability the specific angular momentum should increase with the
increasing circumferential radius of circular trajectories of matter. However,
sufficiently close to a black hole the Rayleigh criterion reverses: in stable
fluids, the angular momentum must decrease with the increasing circumferential
radius. The geometrical reason for this reversal is that the space is so very
strongly warped that it turns inside-out.
