Re: Entropy, Objectivity, and Timescales

[David Bowman <dbowman@tiger.gtc.georgetown.ky.us>]

Leigh wrote:

> David Bowman has weighed in. He didn't pick up on the fact that
> the thermodynamics course description  was for a course given by
> Dan, not by me. SFU has two courses, one at second year level in
> classical thermodynamics and one at third year level in
> statistical physics.

Oops.  It looks like I must have gotten lost in a discussion that has
accreted so many layers of quotes and re-quotes that I mis-attributed a
quote from Leigh's post.  I guess I got thrown off by Leigh's statement
that he "looked up a course description"

> I just looked up a course description:
>
> > Physics 318. Thermal Physics (4)
> >
> > Course Description: Thermodynamics deals with systems containing ....

I thought the extra > layer in the description was because Leigh had copied
the description from a catalog or other written document that he had at
hand.

Leigh continues:
> I find it astonishing that so much talk of quantum mechanics is
> introduced here. The classical entropy is very easy to
> understand. Sure, it's difficult for students to understand it
> at first, but they eventually get it.
>
> This is tiresome, but...

I find it astonishing (or maybe amusing is a better term) that Leigh seems
to have changed his mind about the relevance of quantum mechanics for
understanding entropy in mid-discussion without skipping a beat.

Leigh earlier wrote:

> Dan says (and I omit much I do not choose to argue further)...
>
> >  <SNIP, D.B.>
> > In any case, the issue of quantum indeterminacy surely is not
> > relevant to understanding entropy.  (If you think it is relevant,
> > then please elaborate.)
>
> It is certainly relevant. It is a cognitive error to believe that
> any fully deterministic equation describes Nature in a valid
> fashion when applied to predicting the future over the timescales
> I mentioned. That view has not been responsibly held by anyone
> since early in this century. Perhaps Creationists still hold to a
> Cartesian world view, but no serious physicists do. What we are
> discussing here is the description of the real world; physics is
> the topic at hand, not epistemology. Clearly quantum indeterminacy
> is central to microscopic interpretation of thermodynamics.

Notice Leigh's first and last statements in his quote above and compare
them with his more recent contribution (farther) above.

However, Leigh quotes Dan and then comments:
> ...
> > Look, I don't want to argue quantum mechanics here.  But I've never
> > before heard anyone claim that you need to understand quantum
> > indeterminacy to understand entropy.
>
> You don't have to know anything about quantum mechanics to understand
> entropy. It can be understood entirely as a macroscopic classical
> phenomenon.

I'm glad to see that both Dan and Leigh (and me) can now agree on (at
least) this.

In the context of Leigh's comments about creationism, postmodernism, his
(and many other physicists') atheism, objective realism, reductionism, and
holism he sums it up with:

> I wish to point out that point of view plays a very important role
> in physics. Understanding the philosophical orientation of a
> colleague is central to understanding what he means when he says
> things about physics.

I think what is central is the mathematics that encodes the physics.  When
physicists can agree on the mathematics, their philosophical differences
become a matter of personal taste which may influence how they interpret
or attach meaning to the physical phenomena described by the mathematics.
When the physicists agree on the math then they agree on what physical
theory predicts concerning the outcomes of experiments.  That agreement is
at the level of physics.  Differences in philosophy and religion may
be present concerning what the ultimate meaning of it all is, but these
differences tend to remain philosophical and religious, and seldom
penetrate to the level of the physics of the situation.  For example,
physicists may differ on their interpretations of quantum mechanics at a
philosophical level, but they agree on the predictions that QM makes
concerning the outcomes of experiments because they agree on the
mathematical formulation of QM.

In light of my belief about the place of philosophy and religion in doing
physics I want to state that I would rather not see Leigh using this
physics forum as a platform to spout his religious beliefs.  Such
statements seem to be gratuitous flame-bait (even if they are not so-
intentioned.)  There are plenty of flaming newsgroups out there that
specialize in such religious wars.  I would hope that our discussions here
continue to remain on a high plane of discourse.

I'm sorry to seem to have dumped so heavily on Leigh here, especially since
he has been so nice to me in his posts.  (I suppose that after this post I
may feel the point of his sharp pen in the future.)  I usually appreciate
Leigh's curmudgeonly style, and his unflinching willingness to call them as
he sees them in spite of the possible fallout for being on the wrong side
of political correctness.  I also very much appreciate his considerable 
physics insights (and often agree with them).  Its just that it seems to
me that his parading of his religous values goes beyond the purview of
this list.  (But my thoughts are easily ignorable on this matter since I am
not the list moderator.  If I was I would probably have to censure myself
for repeatedly posting excessively long posts.)

On another point I have to credit Ludwik for his ability to innocently 
instigate extended (and sometimes heated) discussions by others.

David Bowman
dbowman@gtc.georgetown.ky.us