Abstract

A detailed attempt to ground the topological properties of time in the laws of micro- and macro-physical processes. The reversible processes of mechanics are used to define an order among temporally separated events, which is invariant under reversals of time direction. So long as consideration is limited to a single isolated system, a time ensemble, the transfer of the reversibility of the constituent processes of such a system to the system as a whole makes it impossible to define time direction by means of the entropy curve. The directionality of time, accordingly, can only be defined as the direction of the entropy increase of multiple systems, of a space ensemble. A macrostatistical definition of time direction is then based upon the causal relation. The author's view of causation is non-deterministic: the conjunction of two events is caused if they occur together more frequently than can be expected from their chance coincidence. Reichenbach's analyses and arguments are careful and thorough; the book as a whole is a solid achievement. -- M. F.