[Fis]: Re: Distribution of Energy is (not) the same as disorder?

To: "fis-listas.unizar.es" <fis@listas.unizar.es>
Subj: [Fis]: Re: "Distribution of Energy is (not) the same as "disorder"?

Dear Jerry, dear FISers,

Thanks, Jerry, for this very interesting question.
In fact there are several questions here:
(a) Is "Distribution of Energy" the same as "disorder" ?
(b) Is entropy the same as "Distribution of Energy" ?
(c) Is entropy the same as "disorder" ?

Let us look first to "disorder". There was a thread initiated on the
FIS forum the 28 April 2004: <<[Fis] definition(s) of order/disorder ?>>.
It seems from the messages posted about this topic, that the "disorder"
concept is still undefined, and thus it is an intuitive concept, despite
it is useful for those who teach thermodynamics. As noted by Jerry in this
forum the 24 May 2004, the situation is different for "order", since the
mathematicians have a definition for this term: see partial ordering,
total ordering,... But in thermodynamics, this definition is not
suitable.
It follows that we cannot answer "yes" to questions (a) and (c),
or, rather, (a) and (c) cannot be answered until somebody exhibits
a rigorous definition of "disorder".

Let us look now to (b): "Distribution of Energy" is defined from
two known terms: "Energy", in the sense of Newtonian mechanics
(we could take a more advanced definition, but I prefer restrict
here to simple thermodynamic systems), and "distribution", in the
sense of probability theory, or at least in the Newtonian mechanics
sense (e.g., for a mass distribution, the total mass has to be unity
to be modelized by a probability distribution).
It follows that answering "yes" to (b) assumes that the thermodynamic
system is modelized such that the energy has indeed a <<distrbution>>,
varying along the time (then come problems related to equilibrium,...)
I observed that many people (scientists or not) used probabilistic
terms in a non adequate manner: e.g. probability that it rains today,
etc.. (I do it myself sometimes). Alas, it happens sometimes also
in a more scientific context. Thus, many care should be carried
to ensure that the "distribution of Energy" makes indeed sense.
Anyway, if the probabilistic tools are adequately used in the
model, relating entropy to distribution of energy may be
successful.

Jerry asks also:
> How would this change of semantics influence the philosophy of science a=
> ssociated with the concept of entropy?

Here it is much more difficult to reply. I just would remark that
even mathematicians use non adequate vocabulary since a long:
e.g., the Dirac delta function is not a function, the random variables
are not variables, etc... So I thank the thermodynamicians for
their efforts done to clarify the teaching of their science, which
I found to be the more difficult that I have learned when I was
student.

Michel Petitjean Email: petitjean@itodys.jussieu.fr
Editor-in-Chief of Entropy entropy@mdpi.org
ITODYS (CNRS, UMR 7086) ptitjean@ccr.jussieu.fr
1 rue Guy de la Brosse Phone: +33 (0)1 44 27 48 57
75005 Paris, France. FAX : +33 (0)1 44 27 68 14
http://www.mdpi.net/entropy http://www.mdpi.org/entropy
http://petitjeanmichel.free.fr/itoweb.petitjean.html
....................................................................
> From fis-bounces@listas.unizar.es Thu Sep 9 20:36:40 2004
> Date: Thu, 09 Sep 2004 11:35:18 -0700
> From: Jerry_Lr_ Chandler <jerry_lr_chandler@mac.com>
> To: fis@listas.unizar.es
> Subject: [Fis] "Distribution of Energy is (not) the same as "disorder"?
>
> Dear Colleagues:
>
> I would like to open an academic aspect of the entropy issues.
>
> I recently rec'd the email copied below. It is being circulated among l=
> eaders of the chemical community.
>
> The objective of the dialogue is to substitute the words "distribution o=
> f energy" in the place of "disorder" in developing a semantic terminolog=
> y for entropy. The arguments for this substitution are given in publicat=
> ions that are referenced. Many of these are available on line.
>
> I ask the following questions:
>
> What are the views of experts on entropy on this semantic substitution?
>
> (No syntactical change is proposed. The general problem of relating synta=
> x to semantics extends across the sciences and includes mathematics and m=
> odels.)
>
> How would this change of semantics influence the philosophy of science a=
> ssociated with the concept of entropy?
>
> Cheers
>
> Jerry LR Chandler
>
>
>
>
> -----Original Message-----=20
> From: CHEMICAL INFORMATION SOURCES DISCUSSION LIST=20
> [mailto:CHMINF-L@LISTSERV.INDIANA.EDU]On Behalf Of=20
> dzrlib@LIBRARY.CALTECH.EDU=20
> Sent: Tuesday, August 17, 2004 1:10 PM=20
> To: CHMINF-L@LISTSERV.INDIANA.EDU=20
> Subject: Entropy is NOT disorder ...=20
> . . . snipped . . .
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Received on Fri Sep 10 11:12:22 2004