German physicist (1864–1928)
The son of a farmer from Gaffken in Eastern Europe, Wien studied mathematics and physics for a brief period in 1882 at the University of Göttingen. Having recommenced his studies in 1884 at the University of Berlin, he received a doctorate in 1886 for a thesis on the diffraction of light. At various times he considered becoming a farmer but after his parents were forced to sell their land he decided on an academic career in physics. In 1890 he joined the new Imperial (now Federal) Institute for Science and Technology in Charlottenburg, Berlin, as assistant to Hermann von Helmholtz, under whom he had studied. From 1896 to 1899 he worked at the technical college in Aachen and in 1900 was appointed professor of physics at the University of Würzburg. In 1920 he became professor at the University of Munich.
Wien was highly competent in both theoretical and experimental physics. His major research was into thermal or black-body radiation. In 1893 he showed that the wavelength at which the maximum energy is radiated from a source is inversely proportional to the absolute temperature of the source. Thus in heating an object it first glows red hot, emitting most of its energy at the wavelengths of red light; as the temperature is increased, the wavelength at which maximum energy is emitted becomes shorter, and the body becomes white hot. This behavior is known as Wien's displacement law. In 1896 Wien derived a formula, now known as Wien's formula, for the distribution of energy in black-body radiation for a whole range of wavelengths. Its importance for future research lay in the fact that although successful at short wavelengths it disagreed with experiments at longer wavelengths. The discrepancy, which is sometimes known as the ‘ultraviolet catastrophe’, highlighted the inadequacies of classical mechanics and inspired Max Planck to develop the quantum theory. Wien was awarded the Nobel Prize for physics in 1911 for his discoveries regarding the laws governing the radiation of heat.
Wien also studied the conduction of electricity in gases and, while teaching in Aachen, confirmed that cathode rays consisted of high-velocity particles (1897) and were negatively charged (1898). In addition he showed that canal rays were positively charged particles. He later conducted research into x-rays.
