0n the Hartman paradox, electromagnetic wave tunneling and superluminal velocities (comment on “Tunneling of electromagnetic waves: paradoxes and prospects” by A. B. Shvartsburg)

Some paradoxes are discussed concerning the propagation of particles through potential barriers and of nonstationary electromagnetic waves (pulses) through nonuniform media. In particular, frequency dispersive — and hence dissipative — media are considered. It is emphasized that, based on rigorous nonstationary analysis, velocities for the transportation of physical substance cannot be superluminal, whereas some kinematically defined velocities — for example the group velocity — can.