Particles with negative energies are considered for three different cases: inside of horizon of Schwarzschild black hole, Milne's coordinates in flat Minkowski space-time (Milne's universe using nonsynchronous coordinates) and in cosmological G\"{ o}del model of the rotating universe. It is shown that differently from the G\"{ o}del model with nondiagonal term where it occurs that negative energies are impossible they are present in all other cases considered in the paper. Particles with zero energy are also possible in first two cases.
Categories: gr-qc