  The energy dissipation in a gas of structured objects, e.g. molecules, is
considered in density matrix formalism. It is shown that the macroscopic
irreversibility of the kinetic processes can be considered as a consequence of
the microscopic operator ordering. Our approach is free of any special
assumptions on the space-time geometry, except for the general causality
assumptions, so it can be applied to a wide variety of processes, from the
cosmological processes at Big Bang stage till the energy dissipation in
molecular gases.
