History 181B - Class 24

History 181B: Modern Physics

Class 24 (3/17/03)
Making quantum mechanics (1)

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Outline

The first route to a quantum mechanics
    The (old) quantum theory of atomic structure
        Who, where, and what
        Troubles of the theory
    Frustration with orbits opens the door to positivism
    Heisenberg's new foundation (1925)
        Sticking to observables
        Exploring the relation between classical and quantum
        Strange quantities, noncommutative multiplication
    Matrix mechanics and its implications

And a second route (start)
The (old) quantum theory of radiation
And the dualism of waves and particles

Names and terms

Primary

Secondary

Copenhagen, Munich, Göttingen
Arnold Sommerfeld (1861-1951)
Max Born (1882-1970), NP 1954
perturbation theory, celestial mechanics
Wolfgang Pauli (1900-1958), NP 1945
Werner Heisenberg (1901-1976), NP 1932
simple harmonic oscillator
"The Quantum-Theoretical Reinterpretation of Kinematic and Mechanical Relations" (1925)
commutation relation: pq - qp = -i h-bar
noncommuting variables, noncommutative multiplication, etc.
Paul Dirac (1902-1984), NP 1933
Louis de Broglie (1892-1987), NP 1929
electron diffraction

Zeeman effect, Stark effect, dispersion theory
Compton scattering
standing wave

Assignment

Werner Heisenberg, "Quantum Theory and its Interpretation," in Niels Bohr: His Life and Work as Seen by His Friends, ed. S. Rozental (Amsterdam: North-Holland, 1967), 94-108.

    How did Heisenberg compare Sommerfeld's, Bohr's, and his own styles of doing physics?
    How did he describe the essence of quantum mechanics?
    What was at stake in the Copenhagen discussions of Schrödinger's theory?

Extra credit: First Nobel option due.