The Nobel Prize in Physics 1943
Born: 17 February 1888, Sorau (now Zory), Germany (now Poland)
Died: 17 August 1969, Berkeley, CA, USA
Affiliation at the time of the award: Carnegie Institute of Technology, Pittsburgh, PA, USA
Prize motivation: "for his contribution to the development of the molecular ray method and his discovery of the magnetic moment of the proton"
Field: nuclear physics
Otto Stern received his Nobel Prize one year later, in 1944.
Electrons and atoms can be regarded as rotating charges giving rise to a magnetic field. In a 1922 experiment, Otto Stern and Walter Gerlach sent a beam of silver atoms through an inhomogeneous magnetic field. According to classical physics, the beam should have spread out to a distribution but instead, two distinct beams were observed. The result was in accordance with quantum physics: electrons and atoms occupy only certain states of energy and movement. Angular momentum was shown to be quantised.