| Werner Heisenberg
1901 - 1976
Werner Heisenberg's high school years were interrupted by World War I, when he had to leave school to help harvest crops in Bavaria. Back in Munich after the war, he volunteered as a messenger for democratic socialist forces that fought and ousted the communist government that had taken control of the Bavarian state. He was involved in youth groups trying to rebuild German society out of the ashes of World War I, including the "New Boy Scouts" which hoped to renew German life through direct experience of nature, Romantic poetry, music, and thought.
An unusual start for a great contributor to twentieth-century physics. In 1920 he entered the University of Munich to pursue a degree in math. But the math professor wouldn't allow him into an advanced seminar, so he quit. He transferred to physics. He immediately took an interest in theoretical physicists, and soon met many scientists whose work would dominate the coming decades, including Niels Bohr, Wolfgang Pauli, Max Born, and Enrico Fermi. One of his chief interests was working out problems involved in the Bohr-Rutherford model of the atom. He just barely received his PhD in 1923 -- nearly failing because he had neglected his laboratory work. His advisor argued on his behalf and he was granted the degree. He became a professor at the University of Gottingen at age 22. Because he suffered from severe seasonal allergies, during pollen season he left Bavaria for the island of Heligoland. While there he had time to think and work out problems with the atomic model. He realized the limitations of visual models and suggested working strictly with experimental data and mathematical results. To do this he applied a mathematical system to atomic physics, called matrix mechanics. It was a turning point for physics. Many in the field disliked it because it didn't provide a physical model to relate to. Erwin Schrödinger came up with the theory of wave mechanics about a year later. Those uncomfortable with Heisenberg's system jumped on the wave mechanics side. The conflict between the theories was resolved when Schrödinger proved that they were, in fact, identical.
In 1926 Heisenberg joined Bohr at the Institute for Theoretical Physics in Copenhagen. This turned out to be one of the most productive periods in Heisenberg's life. In 1927 he was puzzling over the basic quantum properties of electrons. He realized that the act of measuring an electron's properties by hitting it with gamma rays would alter the electron's behavior. Indeed, you could measure the position of an electron (or other particle) OR you could measure its momentum. But the more precisely you measure one property, the more you throw the other off. He tied this up in an equation using Planck's constant, and called it the uncertainty principle. While many resisted this idea, it eventually became accepted as a fundamental law of nature.
Later in 1927 Heisenberg returned to Germany and became the youngest full professor in the country. Professorship entailed a full plate of teaching and administrative duties, and his scientific output naturally dwindled. With the political turmoil in Germany and World War II, Heisenberg's life became complicated. There was a mass exodus of German scientists in the 1930s, but Heisenberg was one of the few top-notch scientists who decided to remain. Along with Max Planck, he expressed hope of being able to preserve Germany's scientific traditions and institutions. At first he and others tried to resist Hitler's efforts to "purify" science and academics, but soon the Nazis controlled the universities. His own position was shaky since the Nazis viewed theoretical physics as "Jewish" and suspect. Efforts to promote him met with violent opposition from political leaders and even some colleagues. There were times his personal safety was uncertain.
But as the war began the government recognized, suspect or not, the importance of Heisenberg's knowledge. He was made director of the German atom bomb project. He spent five years working on it.
At war's end, Heisenberg was captured by the Allies and was imprisoned in England for six months. He was released and returned to Germany where he reestablished the Kaiser Wilhelm Institute for Physics, but renamed it the Max Planck Institute, in honor of his friend and colleague. He held many administrative posts in West Germany and represented his country at international meetings. He retired in 1970, and died in 1976 survived by his wife of 39 years and seven children.
"Natural science does not simply describe and explain nature; it is part of the interplay between nature and ourselves; it describes nature as exposed to our method of questioning."