is reversed, so that entropy is progressively lowered, the system becomes unpredictable, because, as Prigogine showed, when the entropy of a system is lowered, an increasing number of possible states appears, states that are macroscopically quite distinct but have similar entropy levels. But only one of these can actually exist, and in general we have no certain way of knowing which one that will be. The same phenomenon appears in reversed computation. In other words the reversed time future is characterized by a bifurcation tree of possibilities. Its future is open; it is no longer deterministic or fully predictable, but rather path dependent. This discussion of reversed time futures applies to isolated systems, the ones for which thermodynamic theory was developed. However, we do not live in an isolated system. Our planet is bathed in solar energy, which keeps it far from equilibrium, and we supplement this with increasing amounts of energy from other sources. Thus our open-system world is equivalent to a reversed time, isolated-system world. It is a world of path dependency and open futures of a self-organizing system.

The open futures of these systems is a source of unpredictability or uncertainty, just as is the uncertainty arising 