Re: Entropy, Objectivity, and Timescales

[Leigh Palmer <palmer@sfu.ca>]

Dan says (and I omit much I do not choose to argue further)...:

> The time-dependent Schrodinger equation is fully
> deterministic and allows one to predict a future state with precision,
> provided that the initial state is also known with precision.
> 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.

....and, in conclusion, he upbraids me for what I acknowledge as a
lack of tact. I am far from perfect:

> My point is not that we should rely on authority, only
> that intelligent people who have thought very carefully about entropy
> are *not* in agreement over whether it is objective or subjective.
> So let's be a little more polite to each other, ok?

I'm sorry if I seem impolite, but you seem obtuse. How can you
possibly challenge the authoritative view of entropy when it is
a definition!?* The postmodernists may believe that entropy is
a mutable thing, but I really don't want to participate in the
committee that redefines it.

Did these other intelligent people reflect at liesure or did
you badger them like you seem to enjoy badgering me? Or do I
not qualify as an intelligent person? I give up; you win. The
entropy is a subjective quantity. (Eppur si muove.)

Will someone else please chime in here? A voice of sanity?

I just looked up a course description:

> Physics 318. Thermal Physics (4)
>
> Course Description: Thermodynamics deals with systems containing
> very large numbers of particles, bridging the gap between the
> microscopic and macroscopic description of such systems. We will
> see how heat, temperature, and pressure are related to the motions
> and energies of individual atoms. We will also learn why many
> processes are irreversible and study the implications of this fact.
>
> Prerequisites: Phsx 163 and Math 113
>
> References: K. Stowe, Introduction to Statistical Mechanics and
> Thermodynamics; F. Mandl, Statistical Physics; C. Kittel and
> H. Kroemer, Thermal Physics.
>
> Suggested Syllabus: Heat, work, and the first law; ideal gases;
> statistics of model systems; entropy and the second law; heat
> engines and refrigerators; the Boltzmann distribution; chemical
> equilibrium; phase transitions; quantum statistics; blackbody
> radiation; heat capacities of solids.

Looks familiar, doesn't it? Would you insert comments about the
subjective nature of entropy into such a course? I'll wager that
the texts cited here would not support your view.

Leigh

*The dictum "Question Authority" was never meant to be applied
to the work of Peano*. (He's the guy who defined two to be the
sum of one and one.)