.
History 181B: Modern Physics

Class 10 (2/12/03)
Kinetic theory and statistical mechanics

 

Navigation
Home Schedule < Previous Class Next Class >
Outline Reconciling macro and micro, mechanics and thermo

Kinetic theory: Molecular motion and statistical reasoning
    What is a kinetic theory (for instance, of gases)?
    A first model: Elastic spheres
    Clausius's first stab (1857)
    Maxwell's statistical treatment (1860)

Excursus 1: How did statistics get into physics?
Excursus 2: What does this presume about atoms?

Toward a statistical understanding of the second law of thermo
    Maxwell's demon (1867)
        Thought experiment: A "small but lively being"
        Does the second law hold at the micro level?
    Macro irreversibility but micro reversibility?
    Conclusion: The second law is only statistically valid
    Boltzmann's new understanding of entropy

Why is this important?
    Statistical vs. deterministic laws, and the point of science
    Stat mech vs. thermo

Names and terms
Primary Secondary
Rudolf Clausius (1822-1888)
"On the Kind of Motion We Call Heat" (1857)
James Clerk Maxwell (1831-1879)
Maxwell distribution
Ludwig Boltzmann (1844-1906)
social statistics
atomism, atomic debates
"arrow of time"
delta S >= 0
S = k log W
mean free path
f(v) ~ v2 exp (-mv 2/2kT)
Maxwell-Boltzmann factor: exp (-E/kT)
John Dalton (1766-1844)
Josiah Willard Gibbs (1839-1903)
Assignment Martin J. Klein, "Mechanical Explanation at the End of the Nineteenth Century," Centaurus 17 (1972): 58-82.

    This is a difficult piece. Don't get bogged down by the math or the monocycles; skip section 3 if you like. Read the essay for two things: a birds-eye review of much that we have covered so far, and a first introduction to statistical mechanics.
    Who carried the torch of the mechanical world picture at the end of the nineteenth century?
    What challenges did they face? Lay these out in a list or simple scheme.
    Would you agree with Whitehead that this was "an age of successful scientific orthodoxy"?

Copyright © Cathryn Carson 2003