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Re: [Phys-l] Gibbs paradox

Who am I to confound an honest debater of physics concepts?

I expect that to a physicist, an ideal gas composed of distinguishable
molecules is a possibility to be dealt with.
And so, if a dealer in such possibilities runs into a contradiction - and begins to write his way out of it, I am not shocked..

But I could not qualify as a physicist in any reasonable way, and so I feel quite comfortable in saying that an ideal gas of distinguishable particles does not fit my prejudiced perception of a possible entity, so that I do not feel any obligation to attempt to understand the development of a related thesis.

Hope this was a help? :-)

Brian W


On 3/29/2011 3:48 PM, Carl Mungan wrote:
No one replied to my message. Maybe because everyone is too busy to
look up and read the two articles. Okay, let's make it easier on
everyone. I have now written up a summary of the crux of the argument:

http://usna.edu/Users/physics/mungan/Scholarship/DistinguishableEntropy.pdf

Now let's see if anyone has comments. -Carl

---- original message follows:

This month's issue of AJP has a provocative article about entropy:
April 2011 p. 342.

A key point in it that catches my attention:

TRUE or FALSE - The entropy of a classical ideal gas of
DISTINGUISHABLE particles (say monatomic for simplicity) is not
extensive and is different from the entropy of a clasical ideal gas
of indistinguishable particles?

The author makes the bold claim that the answer to this question is
FALSE. The Sackur-Tetrode equation is EXACTLY the same for a gas of
distinguishable particles as it is for indistinguishable particles.
The factor of N! belongs in both cases.

To fully understand Swendsen's argument, you probably have to look up
his Ref. 2 (in the Journal of Statistical Physics) which is in a bit
harder of a journal to track down than AJP.

Anyways, I'd love to hear some comments from the list. It sure
contradicts how I've understood the Gibbs paradox about mixing gases
which are or are not composed of different species of particles
(distinct by kind, isotope, spin, etc).