ИСТИНА

We consider properties of the trajectory with the zero momentum inside a spherically symmetric black hole. We work mostly in the Painlevé -Gullstrand frame and use the consept of the "river model of black hole". This consept allows us to decompose (in a "cosmological manner") the geodesic motion of a test particle into a "flow" of the frame and a peculiar motion with respect to this frame. After this decomposition the application of standard formulae of special relativity for kinematic processes becomes possible. Using this approach we present a novel description of particle collisions occuring near black hole horizons inside the event horizon. In particular, we show that the trajectory under discussion is relevant for ultra-high energy collisions.