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Good pieceGood piecePosted Nov 29, 2012 20:45 UTC (Thu) by man_ls (subscriber, #15091)In reply to: Good piece by Cyberax Parent article: LCE: Don't play dice with random numbers You are aware that Laplace's demon (as Maxwell's) is nothing short of God-like in nature. And that its very nature was refuted (as seen in Wikipedia) by the second law of Thermodynamics: According to chemical engineer Robert Ulanowicz, in his 1986 book Growth and Development, Laplace's demon met its end with early 19th century developments of the concepts of irreversibility, entropy, and the second law of thermodynamics. In other words, Laplace's demon was based on the premise of reversibility and classical mechanics; however, under current theory, thermodynamics (i.e. real processes) are thought to be irreversible in practical terms (compared to the age of the universe, for instance).Apparently this last part has not been stated convincingly enough since I brought it up several comments up, and it is indeed hard to grasp. The consequence is that no entity can predict what will happen in a system with absolute precision, not even a theoretical demon, not even in theory. In theory the amount of information that can be stored is always limited, so that (to state it in modern terms) below the noise level the signal is unpredictable. And the noise level cannot be made arbitrarily small.
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Good piece Posted Dec 4, 2012 22:31 UTC (Tue) by chithanh (guest, #52801) [Link]
> You are aware that Laplace's demon (as Maxwell's) is nothing short of God-like in nature. And that its very nature was refuted (as seen in Wikipedia) by the second law of Thermodynamics:
And the second law of thermodynamics has been refuted by Poincaré recurrence.
Good piece Posted Dec 5, 2012 8:35 UTC (Wed) by man_ls (subscriber, #15091) [Link] Hardly a rebuttal since this theorem and the second law operate on different time scales. Boltzmann had a similar argument for the whole universe; it only made the second law stronger.Whenever something contradicts the second law, that something loses. But if you feel better with a recurrence every 10^10^100... seconds or so, then so be it.
Good piece Posted Dec 5, 2012 21:25 UTC (Wed) by mathstuf (subscriber, #69389) [Link]
> recurrence every 10^10^100
And don't fret, those 10's are rounded up from e, so it's not as long as it might seem (though I think you're missing few stacks and should be 10^10^10^10^10^1.1).
Good piece Posted Dec 5, 2012 21:38 UTC (Wed) by man_ls (subscriber, #15091) [Link] You are right, I added the ellipsis on a Googolplex because I could not find any good estimate at the moment. Now I have: in the Wikipedia no less, and it is as you say. Saying it is bigger than the age of the universe is a bit of an understatement. So don't hold your breath for a recurrence.Besides, it would only happen if our universe is an energy-conserving system; probably just changing size would break the recurrence. Finally, even if a recurrence was possible in an expanding universe, it would just leave us at the starting point; not just diminish the entropy.
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