Regarding Bill's comment:
>The science of thermo was studied to improve the efficiency of steam
>engines and in that field it is totally quantified and there is nothing
>mysterious about it.
This was not even true of 19th century classical thermodynamics. In that
self-contained theory its fundamental concepts (e.g. heat, temperature,
etc.) were left effectively undefined, and in that sense were mysterious
as to their true meaning. Such concepts were understood only in a
superficial intrumentalist fashion (e.g. temperature is what a
thermometer measures, heat is what raises or lowers the temperature of a
water bath, etc.). Even its derived concepts (e.g. entropy) were
quite mysterious in that they seemed to involve weird relationships
among the fundamental concepts. For example the entropy change for a
process a system undergoes from one equilibrium state to another was
defined as the integral of the sequence of the infinitesimal heats
absorbed by the system divided by the system's temperature when it
absorbed those heats as the system progressed from its initial state
before the process to its final state after the process via a path that
was everywhere locally reversible *even though* the actual process didn't
follow that path was never reversible! The actual *meaning* of this
quantity was mysterious indeed. Although classical thermodynamics was/is
*very* adept at relating one mysterious functional relationship to
another (e.g. the various Maxwell relations between the various
thermodynamic functions, or the fact that the ratio of the isobaric
specific heat to the isochoric specific heat was *always identical* to
the ratio of the isothermal compressibility to the adiabatic
compressiblity) it never let anyone know just what these functions really
*meant*, nor did it give any prescription as to how one might try to
calculate an irreducible subset of these quantities from theory in a
given particular instance (so that the rest of the quantities could be
found from their mutual functional relationships). In all cases the
important quantities always had to be found from experiment by
measurement. Classical thermo, is at heart, a nearly (conceptually, if
not practically) sterile excercise in multivariable calculus relating one
set of functions of a few variables to other such sets.
Beginning with the work of Boltzmann things began to change. The
statistical interpretation of thermodynamic processes open up an avenue
for conceiving of macroscopic thermodynamic processes in terms of a
reduction to the statisics of the dynamics of the microscopics of the
system. Modern statistical thermodynamics (which is a marriage of
classical thermo and modern classical & quantum statistical mechanics)
allows us to unambiguously understand the meaning of the various
thermodynamics quantities in terms of the microscopic degrees of
freedom describing the system. And it gives us an algorithm for
theoretically calculating all the macroscopic thermodynamic quantities
in terms of a few quantities governing just the microscopics of the
situation (i.e. the masses of the constituent particles & their mutual
pairwise potential energy function). We now know what heat, temperature,
entropy, etc. *mean*. In addition to this expansion of meaning has come
a much greater purview for thermo. Now thermo is considered to be
applicable for *any* physical system whose number of microscopic parts
(i.e. molecules, atoms, subatomic particles, etc.) is much larger than 1.
This includes a *lot* more systems than just steam engines.
(BTW, now it is entropy and energy that are considered as the fundamental
quantities, and temperature is a quantity derived in terms of them.)
>Thermo has been hijacked by metaphysicians and theologians who speak in
>general terms but are totally unable to quantify the objects of their
>speculations.
No comment.
>Thermo is only scientifically useful in terms of BTUs and heat transfer
>and bound systems.
This is a gross limitation on its usefulness. It applies to *any*
system of lots of microscopic parts, and that excludes very few systems.
David Bowman
David_Bowman@georgetowncollege.edu
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