Many will know the name of Hans Geiger as the inventor of the electronic counter used to detect radiation. The Geiger counter revolutionized atomic, nuclear, particle, and cosmic-ray physics in the 1930s. Geiger’s contributions to other aspects of physics in the first half of the 20th century are less well known. This talk will summarize Geiger’s life and career, which included professorships at 3 leading German universities and significant discoveries in nuclear structure and radioactive decay. Geiger also performed a critical Compton-scattering experiment in the 1920s that clearly settled the wave-particle duality issue for X rays and disproved a theory promoted by Niels Bohr that tried to preserve the wave model. Working with Einstein, he made another attempt at resolving wave-particle duality for visible light that was inconclusive owing to a theory error by Einstein. Geiger mentored at least 39 doctoral students as well as many pre-doctorals and post-docs, many of whom have themselves been significant contributors to physics and technology. If he had not died prematurely at age 62 in 1945, he almost certainly would have been awarded a share of the 1954 physics Nobel Prize.

Refreshments will be offered half an hour before the colloquium in Weniger 379