From: jlg@cochiti.lanl.gov (Jim Giles)
Subject: Re: sci.skeptic FAQ version 0.2.
Organization: Los Alamos National Laboratory
Distribution: na
Date: Mon, 31 Aug 1992 17:32:41 GMT

In article <25867@dog.ee.lbl.gov>, sichase@csa1.lbl.gov (SCOTT I CHASE) writes:
|> In article <1992Aug28.215515.29547@newshost.lanl.gov>, jlg@cochiti.lanl.gov (Jim Giles) writes...
|> [...]
|> >In the meantime, even if all the gas in your box runs to the corner, how
|> >do you use that event to get heat to flow against a temperature gradient
|> >or to get work directly from heat?  Those are the things that Clausius,
|> >Kelvin, and Plank excluded from possibility.  Nope, all things considered,
|> >the second law will still be observed.
|> 
|> I guess it depends on what you mean by "observed."  To me it means that you
|> intend to do an experiment, where you set up some initial conditions and
|> watch the time evolution of the system.  In this situation, there will
|> undoubtedly be some experiments in which all the particles run into one
|> corner of the box.  The final state is more ordered than the initial state.

In what way is the final state `more ordered'?  They're all in the 
same corner, but conservation laws require that the energy density 
be higher.  The pressure is locally higher there as well.  The `order' 
of the system is not clearly changed: up *or* down.  Further, in what
way is this a `final state'?  Unless you *confine* the particles there,
it is an intermediate, non-equilibrium state (this is actually irrelevant,
but you maintain below that it is not so).  Finally, as the main
point of my original response in this thread clearly stated, the word 
`order' is irrelevant to the issue.  If you disagree, please find a
*single* thermodynamics text which gives a technical meaning to the
term `order' or which uses that term in its *definition* (as opposed
to informal discussion) of the second law.

The term `order' is not part of the *thermodynamic* definition of
the second law nor of entropy.  In statistical mechanics (a related
but different field), the *definition* of entropy is in terms of the
number and relative probabilities of *available* energy `micro-states'.
One such state of a box full of gas is when they're all in the corner,
but, since the gas still has *all* the energy states *available* to
it, the entropy remains unchanged.  In other words, the entropy is 
defined in terms of availability, not in terms of *which* micro-state 
the system *actually* occupies at a given time.  The diversity of such 
states was, at some time in the past, mistakenly described as the `disorder'
of the system - that's the origin of the spurious argument we're having.

|> [...]
|> Finally, let me point out that the second law only applies to equilibrium
|> thermodynamics.  There is no reason to expect that abiogenesis took place
|> under conditions even remotely resembling near-equilibrium, in which case
|> the second law is completely irrelevant.

Well, actually the original statements of the second law applied to 
the interactions between states which began isolated and came to
equilibrium through interacting.  In fact, entropy is *defined*
in terms of differential quantities which are only non-zero as
the system changes state.

No, the reason that the second law doesn't prohibit evolution is that
the word `order' (which is used to evoke the apparent conflict) is 
irrelevant to the thermodynamic concept.  In statistical mechanics, 
a *much* better term would be `diversity', as in "systems approach 
maximum diversity of available energy states."  Interestingly, this 
is also part of what evolution predicts: "mutation increases the 
genetic diversity of a species."

-- 
J. Giles



-- 
J. Giles
Xref: sparky sci.skeptic:15389 talk.origins:10369