 There is a peculiar and intimate relation between the Second Law of ordinary thermodynamics and time. That physical systems always seem to change in such a way that entropy never decreases picks out a privileged direction in time, as it were. At the present moment, there are two “directions” in time one may consider: that pointing to the future, and that to the past. The Second Law says, roughly speaking, that order never spontaneously increases toward the future. Looking back towards the past, however, that is exactly how it may appear to us: if one thinks of the ordinary change of physical systems as running backwards in time, then it will exactly appear as though order is spontaneously increasing. 