Properties of particles in Kerr metric are compared with properties of
particles in rotating coordinates in Minkowski space-time. It is shown that
particles with negative and zero energies existing in the ergosphere of the
rotating black hole also exist in the region out of the static limit in
rotating coordinates in Minkowski space-time. Some similarities like the
Penrose process and differences in both cases are analyzed.Comment: 20 pages, 3 figure
