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PHYS 342
ll 2011
Fall 2011
Lecture 22: Intro. to Statistical Physics
Ron Reifenberger
Birck Nanotechnology Center
Purdue University
The language and math of statistical physics
are very different. No more
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View Full Document The BIG Picture
The working of one atom may be mysterious but it is
by and large
organized, tidy and predictable.
In contrast, there is an evident imbalance in the way nature works when
any
toms are grouped together.
many
atoms are grouped together.
The microscopic world of many atoms shows a natural tendency to
disperse (equally distribute, spread out) energy.
Dispersal is accompanied by
loss of quality
in the way energy is stored .
ALL spontaneous processes exhibit a seemingly purposeless spreading
of energy governed by chance and a complete lack of regulation.
In 1865, the concept of ENTROPY was invented to measure
and track
e dispersal of energy
the dispersal of energy.
Surprisingly, Chaos
and
Randomness
become powerful drivers in the
microscopic world of many atoms .
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FEW KEY IDEAS
A FEW KEY IDEAS
Probabilities
describe incomplete knowledge.
Distribution functions
(discrete and continuous) describe collections of
probabilities.
Multiplicity
: The multiplicity of events is the total number of ways in
which different outcomes can possibly occur. If the number of outcomes
f A is n
nd the total number of outcomes of B is n
the total possible
of A
s n
A
and the total number of outcomes of B
s n
B
, the total poss ble
number of possible combination of outcomes is the multiplicity W=g=n
A
n
B
.
The
probability
of a particular outcome depends on the number of
possible ways it can occur.
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View Full Document A Few Simple Intuitive Definitions
utually exclusive
On the single roll of a die 2 and 5
Mutually exclusive
: On the single roll of a die, 2 and 5
are mutually exclusive because only one number can
appear “up” after a given roll.
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This note was uploaded on 12/08/2011 for the course PHYS 342 taught by Professor Staff during the Fall '08 term at Purdue UniversityWest Lafayette.
 Fall '08
 Staff
 Physics

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