The Arrow of Time in Quantum Mechanics

The application of quantum mechanics as presented in most textbooks appears superficially to demand an "arrow of time",in that one usually specifies initial rather than final conditions.However,as appreciated long ago by Aharonov and co-workers,it is perfectly possible to reformulate the formalism per se in an explicitly time-reversal-invariant manner;any asymmetry must then enter through the concepts of "preparation" and "measurement".In the light of this observation this talk will discuss the question:Is the "arrow of time" as it appears in quantum mechanics just a special case of the thermodynamic arrow,or does it have a more fundamental significance?