Saturday, January 7, 2012

Re: Entropy again

Some blog followers might be interested in a recent discussion-list post “Re: Entropy again”[Hake (2012)]. The abstract reads:

ABSTRACT: Antti Savinainen in his Phys-L post “Entropy again” wrote that:
(a) he was about to teach entropy at the high school level but realized that the syllabus statement “entropy is a system property that expresses the degree of disorder in the system” was not a satisfactory characterization of entropy; and
(b) “it would be interesting to hear ideas on how to define or characterize entropy at an introductory level.”

Antti pointed to 4 references on entropy by Denker, Lambert, and Leff that he regarded as “useful, or at least interesting.” I add 6 more references to Antti’s list and then quote portions of Denker’s response to Antti, in which Denker advocates the “probabilistic approach” to entropy and severely criticizes the “spreading metaphor” of Lambert and Leff.

Henri Poncare wrote: “When we say force is the cause of motion we talk metaphysics, and this definition, if we were content with it, would be absolutely sterile. FOR A DEFINITION TO BE OF ANY USE, IT MUST TEACH US TO MEASURE FORCE; moreover, that suffices; it is not at all necessary that it teach us what force is in itself, nor whether it is the cause or the effect of motion.”

Likewise, in discussions of entropy it would seem worthwhile to specify HOW ENTROPY CAN BE MEASURED. Leff (2012) does so in the context of the “spreading metaphor.” I wonder if Denker could explain how his favored “probabilistic approach” specifies how to physically MEASURE entropy in real substances?

To access the complete 16 kB post please click on

Richard Hake, Emeritus Professor of Physics, Indiana University
Honorary Member, Curmudgeon Lodge of Deventer, The Netherlands
President, PEdants for Definitive Academic References which Recognize the
Invention of the Internet (PEDARRII)

“Conflict is the gadfly of thought. It stirs us to observation and memory. It instigates to invention. It shocks us out of sheep-like passivity, and sets us at noting and contriving. Not that it always effects this result; but that conflict is a sine qua non of reflection and ingenuity.”
John Dewey “Morals Are Human,” Dewey: Middle Works, Vol.14, p. 207

REFERENCES [All URL’s shortened by and accessed on 07 Jan 2012.]
Hake, R.R. 2012. “Re: Entropy again,” online on the OPEN! AERA-L archives at Post of 7 Jan 2012 14:51:15-0800 to AERA-L and Net-Gold. The abstract and link to the complete post are being transmitted to several discussion lists..

Leff, H. 2012. “Removing the Mystery of Entropy and Thermodynamics - Part I,” Phys. Teach. 50(1): 28-31; online to subscribers at Parts II-V will be published in Phys. Teach 50 (2012).

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