physicist who demonstrated that difficulties with
Niels Bohr's model of
the atom, in which electrons move around a central nucleus in circular orbits,
could be overcome by supposing that electrons adopt elliptical orbits.
This led him in 1916 to predict a series of spectral lines based on the relativistic effects that would occur with elliptical orbits. Friedrich Paschen (1865-1945) undertook the spectroscopic work required and confirmed Sommerfeld's predictions.
Sommerfeld was born and educated in Königsberg, Prussia (now Kaliningrad, Russia). He was professor at the Mining Academy in Clausthal 1897-1900, at the Technical Institute in Aachen 1900-06, and then moved to Munich University as director of the Institute of Theoretical Physics, specially established for him. Sommerfeld built his institute into a leading centre of physics.
Sommerfeld was active as a theoretician both in physics and engineering, and he produced a four-volume work on the theory of gyroscopes 1897-1910 with mathematician Felix Klein. Sommerfeld's other works include Atombau und Spektrallinien/Atomic Structure and Spectral Lines 1919 and Wellenmechanischer Ergänzungsband/Wave Mechanics 1929.