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Re: [Phys-l] entropy +- disorder +- complexity



Specifically: It's more-or-less true that processes that tend
to increase the disorder also tend to increase the entropy.
The process of /stirring/ is an example. Shuffling a deck of
cards is another example. This is, alas, treacherous, as we
can see by considering processes that go in the other direction.
There are plenty of processes that decrease the entropy but do
*not* decrease the disorder. A classic example is peeking at the
deck of cards after it has been shuffled; the disorder remains
large but the entropy goes instantly to zero.

My problem with this (the card example) is that it still avoids the question of quantifying disorder (no need to respond to this point - see below). At the same time, I completely acknowledge that a shuffled deck strongly appeals to our anthropologic sense of "what disorder must mean." Even I want to use the term.

Perhaps different subject, but what is your suggestion as to a effective analog to this (card) example in "real" thermodynamics, when speaking to someone better at physics than card-sharking? (I'm getting at the "peeking" more than the entropy going to zero).


One problem with any discussion of disorder is the lack of any
agreed-upon way to quantify the disorder.

Exactly. And when I ask someone to give me any measure of it, even a weak one, there is much faltering. It usually amounts to that same anthropologic appeal to "well I can't measure it but you can plainly see it."

I usually make at least some headway if I can get across the fact that a deck of cards in a *specific* (already-shuffled) microstate has the same probability as a perfectly "ordered" deck right out of the box (ignoring the fact that it was *prepared* that way specifically). To say then that there are many many more microstates (countable in fact) that are not "perfectly ordered," compared to the few perfectly ordered possibilities, is at least some measure of people's sense of "disorder." Good enough for casual card players, but not sure it has broader utility.


It turns out that most of the things we consider to be highly
disordered also have high algorithmic complexity. So we have
nothing to lose and much to gain by talking about complexity
instead of disorder.

OK thank you for the reference to Chaitin. I'll need to figure out at least something about algorithmic complexity myself first before hoping to explain it as an alternative to disorder. If you want to jump start me, add a relevant algorithmic complexity section to your entropy page [sections 2.3/2.4] :-)


Stefan Jeglinski