Otto Stern. Historical portrait of the German-US physicist Otto Stern (1888-1969). Stern was born and educated in Germany, but emigrated to the USA in 1933 in opposition to Hitler's policies. His main research was on molecular beams. In 1920 he worked with Walter Gerlach, using a molecular beam of silver atoms to test a prediction of quantum theory. The prediction was that the atoms had magnetic moments that were quantized into two orientations. The beam split into two as predicted and earned Stern the 1943 Nobel Prize for Physics. He also measured the magnetic moment of the proton and successfully observed diffraction of atoms and molecules, demonstrating wave-particle duality.