dS=0

[Jim Green <JMGreen@SISNA.COM>]

Bob, in great insight says the following:

> I'm not sure what you're after here, but the term dW = PdV, in the First
> law applied to a gas, would be replaced by the generalized term YdX for a
> more general system (eg.: charged particles in E fields, magnetic dipoles
> in B fields, masses in gravitational fields).  In these systems, are not
> adiabatic variations of the applied field pertinent to your
> considerations?

Bob, I understand what you say and I think that in principle I ought to be
able to do this sort of  calculation.  Maybe it is just that I don't know
enough physics or maybe that I am just stymied, but I have not been able to
do so -- I have tried!

Hence an appeal to the list: Read my derivation of dS on the web page in
question and do such a derivation for some other system which ends with
dS=0.  You will have to correct the stats error on the page in the process.
<g>  Bob, do you remember that you and I have already discussed an aspect
of this briefly?  All should feel free to point out the error on the web
page derivation -- at least until I get a chance to correct it -- however
the error happily doesn't change the result.  (But first I need to find a
decent d-bar.gif <g> and learn to do a better job wiht the equatins.)

My current opinion is that the form of the First Law that we now have is
based simply on Carnot's desire to understand steam engines (with it's
piston-in-an-adiabatic-cylinder simplification) -- if he had been concerned
with some other war making equipment, our current thermo would be quite
different I suspect -- and so would our nuclear arsenal. <g>

Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen