Full set of scenarios of high energy collision in the Schwarzschild background and kinematic censorship

Abstract

We consider collisions between particles moving freely in the Schwarzschild background. We suggest classification of scenarios that lead to unbounded energy output in the center of mass frame. Although this is forbidden in the exterior of a black hole, the phenomenon becomes possible with account of white hole region and mirror universe in the complete space-time diagram. Also, we scrutinize collisions in the vicinity of the bifurcation point and reveal the role of resting observers in the inner region beyond the horizon. In some scenarios $E_{c.m.}$ not only diverges but becomes seemingly infinite that is, as a matter of fact, impossible according to the principle of so-called kinematic censorship. We resolve a corresponding paradox and argue, why this principle remains valid.