Rayleigh and Solberg criteria reversal near black holes: the optical geometry explanation

Abstract

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.