Re: Entropy question


Hi Andy,


> I don't think that's what I'm saying. Although, to be truthful, I'm not
> sure what you mean by "normal" mechanics. Newtonian? Continuum? Quantum?


Well, at the current time quantum is the gold standard, but you use the
others, which can be derived as approximations to QFT, when you've got
to solve a problem in the time available.


> All have their advantages and disadvantages, and (partially
> overlapping) spheres of applicability.


But they have a hierarchy of validity.


> > IMHO "emergence" is the second-last refuge of the scoundrel.
>
> Yeah, I'm no fan of buzzwords either.


Glad to hear it.


> > Yes, structures emerge, usually when they have been designed in
> > (including evolution as the blind watchmaker). They can be explained
> > adequately by statistical mechanics, but the systems actually obey the
> > standard laws of mechanics, which cannot be discarded if you want to
> > understand the kinetics of the process.
>
> I don't think that's true at all- contact line motion cannot currently
> be explained by mechanics.


What have you got against the Blake theory? I think that the fit to it
is quite reasonable, all things considered. I think that it might be
possible to get a better theory by taking account of the
2-dimensionality of surfaces: Blake's theory is essentially
one-dimensional. However enlightenment has not yet arrived in this
particular brain.


> Chemi-osmotic processes (Peter Mitchell's
> Nobel winning theory on cellular respiration) cannot be explained by
> mechanics,


Of course they can. They involve pumping protons and other ions across
insulating membranes against a voltage gradient. Totally mechanical.


> nor can any chemical-mechanical system like muscles. "Heat"
> can't be explained in terms of mechanics.


Of course it can. What do you think statistical thermodynamics is all
about? In the first ten pages of their textbook, Landau and Lifshitz
derive from fairly general concepts of equilibrium that the probability
of a state of a system with energy E is proportional to exp(-E/kT). You
can then write down the internal energy U = (1/Z) Sum E.exp(-E/kT)
where Z = Sum exp(-E/kT). If you move from one condition to another,
the change of U is not all accounted for by mechanical work: energy
must have been put in in another form: the difference dQ is heat. It is
easy to show that the quantity dQ/T is integrable: entropy S. Next, the
simplest expression for a thermodynamic quantity is F = U-TS = kTln(Z),
from which you can derive all the others. Thence all of classical
thermodynamics. A doddle.


> I'm leery of using the buzzword "designed" especially in the current
> political environment :)


Which is why I added the rider about evolution.

Cheers,

Zigoteau.

.