Werner Karl Heisenberg
1901-1976
German Physicist
Werner Heisenberg was a pioneer of quantum mechanics, a theory that deals with atomic particles in terms of probability functions. He was awarded the Nobel Prize in physics in 1932 for his formulation of quantum mechanics using matrices, or arrays of mathematical expressions. He is best known for his uncertainty principle, which states that it is impossible to simultaneously and precisely measure the position and velocity of a particle.
Heisenberg was born on December 5, 1901, in Würzburg into a well-to-do academic family. He was a bright and ambitious student, always at the top of his class at the gymnasium (secondary school), and also enjoyed playing classical piano. World War I disrupted this comfortable life, bringing shortages of food and fuel. With most men serving in the military, students were expected to be tough and independent and were indoctrinated with nationalistic views. Heisenberg belonged to a military training unit at his school, and was elected leader of a group associated with the New Boy Scouts, a right-wing youth movement.
At the University of Munich, Heisenberg studied under Arnold Sommerfeld (1868-1951); Wolfgang Pauli (1900-1958) was among his classmates. He obtained his doctorate in 1923 with the first mediocre grade of his life, derived from averaging an outstanding performance in theoretical physics with a hopeless showing in laboratory work. After a postdoctoral year in Göttingen with Max Born (1882-1970), he went to the Institute for Theoretical Physics in Copenhagen, Denmark, to work on quantum theory with Niels Bohr (1885-1962).
Werner Heisenberg. (Library of Congress. Reproduced with permission.)The quantum theory described light in terms of particle-like photons, with energy related to their wavelength. Heisenberg realized that this model implied a limit to the accuracy of certain measurements. An object is typically observed by bouncing electromagnetic radiation off it. Ordinary visible light is not useful for looking at something the size of an electron, because such light's wavelength is too long. For sufficient resolution, the wavelength must be comparable to or smaller than the size of the object being observed. Photons with very short wavelengths, such as gamma rays, have very high energy. When they strike an electron, they change its velocity. The attempt to observe the situation thus affects it.
Heisenberg published his uncertainty principle in 1927. The same year, he was appointed professor at the University of Leipzig. As the Nazi regime rose to power, many other physicists urged him to leave Germany. He refused, despite increasingly shrill attacks by the Nazis upon those working in theoretical physics, which they viewed as a Jewish enterprise. In 1937, deemed guilty by association with his colleagues, he was labeled a "White Jew" and threatened with imprisonment in a concentration camp. Shaken, he pleaded his case to Nazi chief Heinrich Himmler and was "cleared."
With the outbreak of World War II, Heisenberg received orders to report to the Army Weapons Bureau, where he headed the German effort to build a nuclear weapon. Together with Otto Hahn (1879-1968), who had discovered nuclear fission, he worked on a reactor, but failed to develop a bomb, to the great relief of the rest of the world. Controversy remains to this day on whether Heisenberg's project was unsuccessful because he was provided with insufficient resources, was as a theorist a poor choice to head up what was essentially an engineering project, or because he was reluctant to arm Adolf Hitler with nuclear weapons. The latter, although an appealing theory, is dismissed by most historians. Heisenberg wasn't a Nazi, but he was steeped in German nationalism.
After the war Heisenberg was briefly interned in England with other German nuclear scientists but was released in 1946. He was appointed director of the Max Planck Institute for Physics, first at Göttingen and, after 1958, in Munich. His goals were to rebuild not only his institute but also German science as a whole, working with international authorities and the West German government. He died in Munich on February 1, 1976.
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