I'm right now reading Hans Reichenbach's The Direction of Time, the section on the "The sectional nature of Time Direction" is breath-taking in its imaginative scope. If postive time direction is defined as the direction in which entropy increases, and thermodynamic processes are random, then the positive direction of time will change at different "times". However, a time sequence can still be determined (that is, thermodynamics will give us a unique ordering of events, but not a consistent postive direction).
Reichenbach goes further, since human life could not survive in the peaks and troughs of entropy values, there is no possibility of experiencing time as flowing in the other direction and no possibility for contradicting experience.
This is not as detailed as Reichenbach's preceding arguments, and the conclusion itself is such an excessive speculation that, had it been presented along, I would have put the book and not come back. I prefer my science fiction with characters and plot. However, the arguments preceding this are so carefully constructed and the methods of analysis so interesting in the book, that I can afford to really enjoy Reichenbach's moments of imaginative freedom.
Of course, Reichenbach doesn't leave the apparent paradox in play. Reference to non-deterministic laws might be useful in figuring out which way the future lies, but more importantly, the various branching processes that we encounter in everday life are always increasing in entropy, so that must be the positive time direction, those temporal regions in which time might flow in the opposite direction are so distant as to not exist.
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so- i figure. no experiment can be repeated infinately = no 100% certainty can be reached? is only a problem in linear time. but huh. making entropy non-attached to time, or uh, rather making it the deciding factor. thats cute. whats entropy, delta s? anyhow, it sounds like speculative flip-floping of the denomonator & numerator. right?
Well, its not so much about the degree of confirmation concerning our theories, so much as it is a consequence of one theory about future cosmological evolution.
The universe is expanding, we know that. And the measurements of branchings of thermodynamic (entropy increasing) interactions depned on that. For Reichenbach, these interactions define our time direction. Hence, if the universe were contracting, then the entropy relations would seem to all be leading in the opposite direction (towards a minimal entropy).
In the far distant future, broken things will reassemble themselves and water will flow up hill. Of course, any conscious creating living in such time will be working with a brain that's also moving in the reverse time direction, so things may well seem to be moving in what we would consider the proper direction.
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