

The Quantum Thermodynamic Revolution - dnetesn
http://fqxi.org/community/articles/display/202

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SilasX
I don't follow: the article just goes through several known physical laws from
thermodynamics. Where is the quantum revolution therein?

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PeterWhittaker
Essentially, the Laws of Thermodynamics, as normally stated, don't really work
at the QM level and Oppenheim is working on restating them to be more
applicable.

For example, changing the second law from "the entropy of a closed system
never decreases" to "the free energy of a closed system never increases". It's
a subtle change, but macroscopically all energies can be treated the same
while at the QM level they have to be accounted for more carefully.

It occurs to me as I write this that entropy is harder to explain physically
than energy, and that while we have math to manage entropy calculations, it
isn't really anything "real", while energy is always conveyed by real things
(photons, electrons, etc.).

So the second law has always been stated in a sort of negative (some thing
"not a real thing" never decreases) while Oppenheim's work will reformulate in
a positive way ("some real thing, quite a complex set of things, actually,
never increases").

Intriguing. Simple changes of perspective sometimes have tremendous impacts on
physics.

~~~
SilasX
But I don't see the quantum difference: those very same problems exist at the
macro scale eg Loschmidt's paradox [1] about time-asymmetric entropy while the
laws of physics are time-symmetric (even classically). And the free energy
reformulation has been just as relevant to classical macro systems.

[1] I prefer the Barbour/Drescher resolution, that the second law is an
artifact of observer's abilities to contain memories, not the physical laws
themselves.

