Abstract

The time of mechanics is the eternal and unchangeable time of Parmenides, it is Plato’s idea of time, whereas the time of thermodynamics is Heraclitus’ flowing time, Thomas Aquinas’ time measured by various phenomena. I once wrote [2] that people who are not used to a physicist’s way of thinking are (at best) confused by the idea of a symmetrical time of mechanics. Physicists on the other hand often believe that the time of thermodynamics (irreversibility) does not really exist, and is merely an illusion. It seems therefore that both of these aspects of time, the time of mechanics and the time of thermodynamics, should be treated as complementary, in anticipation of a future “theory of everything” which will somehow reconcile them.