Kusch, Polykarp (1911-1993), a German-born American physicist, made the first precise measurement of the magnetic properties of the electron, the negatively charged particle that forms the outer parts of all atoms. Kusch found that the electron's magnetism differed from theoretical predictions of the time, and his work stimulated improvements in the theories of how matter and radiation interact. For this work, Kusch was awarded half of the 1955 Nobel Prize for physics. The other half was awarded to American physicist Willis Lamb (see Lamb, Willis Eugene).