Re: entropy - motivation for definition

[Mark Sylvester <msylvest@XNET.IT>]

Thanks for the helpful replies. The course I'm teaching touches entropy
only qualitatively, and I'm always a little bit unsure about what I can say.

> I often hear that Q/T "explains" the spontaneous direction.  I would say
> it doesn't explain it.  It was rigged to come out positive for
> spontaneous change by defining it as Q/T and by knowing that
> thermal-energy flows from hot to cold.

This is precisely the sort of thing that motivates my question.

Arising from John's reply, since the (modern) definition of entropy is
probabilistic,  how did the early thermodynamicists envisage it? My
recollection is that Boltzmann was so clever precisely because he came up
with the statistical interpretation of the pre-existing concept. Was it a
question of "rigging" something to "explain" the Clausius and Kelvin
versions of the Second Law?

Mark



Mark Sylvester
UWCAd
Duino Trieste Italy