Re: maximum entropy and the seeking of lowest PE

["Rauber, Joel Phys" <RAUBERJ@mg.sdstate.edu>]

> > I am aware of no such principle.  What is usually meant is that the system
> > is seeking a state of maximum entropy; and the 2nd Law of Thermodynamics 
is
> > really the basis that should be used to explain phenomena where
> > "minimization of Potential energy" is often  quoted.

> The principle is minimization of mechanical energy in mechanical systems.
> The minimization must be accomplished in accord with the laws of angular
> and linear momentum conservation, for example. Without those laws the
> Earth would plummet into the Sun because that is a state of much lower
> potential energy than the present state. Such a process could not simul-
> taneously conserve angular momentum and finish in a lower rotational
> kinetic energy state, however.

> Why not a principle of minimization of mechanical energy, Joel? Could it
> not be just another form of the second law of thermodynamics operating
> according to the mechanism David described which maximizes the entropy
> of the system? There are certainly other statements of the second law
> which don't mention entropy at all.

I'm not quite sure how to respond, because I either agree or disagree. 
 Depending on what is meant by Mechanical Energy.  If by "mechanical energy" 
one means the sum total of all the kinetic and potential energies of all 
particles in the mechanical system in question; then I disagree, as I would 
maintain that this is a conserved quantity.

On the other hand (auf die andere Seite), if by "mechanical energy" you mean 
only that part of the energy described above that David referred to as 
"macroscopic degrees of freedom" then I think I agree and at 8:00am in the 
morning on the great plains think that it is a more or less equivalent 
statement for the 2nd law.  My personal taste is too find this to be a 
rather restrictive statement applicable only to mechanical systems and only 
if you divvy up the total energy in the specified fashion.    E.g. does the 
statement help with understanding why excited atoms tend to decay to their 
ground state emitting a photon.  I guess I'm stating a preference for 
statements of the 2nd law that refer to entropy, as being the basic or 
fundamental principal.  Other specialized statements coming from the 
entropic version.

Leigh, thanks for responding, I made the post hoping that some of you more 
experienced folks would give us (me) the benefit of your experience.

David, I hope I haven't misrepresented your opinions or statements you've. 
 Do you have any comments or opinions on what I've said?

Joel