The (old) quantum theory of atomic structure
          Who, where
          And what
          Troubles of the theory

     Heisenberg's new foundation (1925)
          Eliminating talk of orbits, sticking to observables
          Exploring the relation between classical and quantum
          Strange quantities, noncommutative multiplication

     Matrix mechanics and its implications

And a second route

     The (old) quantum theory of radiation
          Review:  Planck and Einstein, 1900-1905
          The dualism of waves and particles
          Einstein on the light quantum (1910s)
          de Broglie on waves associated with matter (1923)

     Schrödinger's wave mechanics (1926) (next time)