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7:30 pm, Wednesday, January 10, 2007
Fairmont Social Lounge, St. John's College
At the End of the Rainbow: Optical Dispersion as the Bridge between
the Old Quantum Theory and Matrix Mechanics
Michel Janssen
University of Minnesota
Optical dispersion, observed in rainbows and prisms, was already
studied seriously by Descartes and Newton. A satisfactory theory is hard:
it involves the difficult problem of the interaction between light and
matter, and Lorentz's elaboration of Maxwell's electrodynamics in the
1890s, two centuries after Newton, was the first to give a reasonable
account of dispersion. It was however called into question by Bohr's
quantum model of the atom. In the early 1920s the problem of dispersion
took center stage. The famous Umdeutung (reinterpretation) paper
with which Heisenberg ushered in the era of modern quantum mechanics
grew directly out of a quantum theory of dispersion proposed by
Kramers, Bohr's right-hand man at the time. Drawing on work by
Einstein and Ladenburg, Kramers was able to reconcile Lorentz's
theory of dispersion with Bohr's theory of the atom. With hindsight, it
was only a small step from Kramers' theory to Heisenberg's matrix
mechanics.
Find out more by visiting his
website.
Additional resources for this talk: video, slides.
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