Re: [Phys-l] thermodynamics without entropy ?!??

[John Denker <jsd@av8n.com>]

On 10/04/2007 04:10 PM, chuck britton wrote:

> Energy and Entropy are (IMHO) the two most important cross-discipline  
> topics that there are.

Agreed.

> Introductory Thermo gets short shrift in most Intro Physics courses  

Agreed.

I was surprised that Arons tried to go so far with it, even 
attempting a discussion of friction.  

> and I suspect that the evil head of entropy is a major reason to  
> 'skip' it.

Evil?  I assume that's facetious.

Arons's effort definitely needs to be skipped, even though 
it doesn't mention entropy.

> I'd gladly give up 'entropy' as soon as I see how to do the same  
> stuff differently.

I assume that's mostly facetious.

In my experience, entropy doesn't create problems; it solves 
problems.  I'd give up almost everything else before I gave
up entropy.

I've seen a number of cases where somebody tried to do thermo
without entropy ... and in each case the results were disastrous.

I'd like to send these guys a memo, or maybe an embroidered
sampler to hang on the wall:

                You can't do 
               thermodynamics
               without entropy.


Entropy is one of the /easiest/ concepts to teach, if you lay
the proper groundwork.  The fanciest part of the groundwork is 
probability, which is worth covering in any case.


As a specific example, consider the interminable holy wars 
about "the" definition of heat.  I've come to the realization 
that although I've worked with heat all my life, and know what 
it means in particular situations, I don't have any unique,
prescriptive definition.  None of the "definitions" on offer
are satisfactory.  

The important part is the good part:  I don't need to define
heat.  Not at all.  That's because any "heat" problem worth 
doing can be reformulated in terms of energy and entropy, and 
the reformulated version is in all ways better, AFAICT.