Statistical
mechanics treats the detailed state
of a system
(its quantum
state or, in classical models, its position in phase space) as unknown and subject to statistical
uncertainties; entropy
is a measure of this uncertainty. Statistical mechanics describes the
distribution of states
in an equilibrium system
at a given temperature
(describing either the distribution of probabilities of quantum states
or the probability density
function in phase
space), and can be used to derive thermodynamic properties from properties at
the molecular
level. These equilibrium results are useful in nanomechanical design.
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