Werner Karl Heisenberg (December 5, 1901 February 1, 1976) was a celebrated German physicist and Nobel laureate, one of the founders of quantum mechanics. He was born in Würzburg, Germany and died in Munich. Heisenberg was the head of Germany's nuclear energy program, though the nature of this project, and his work in this capacity, has been heavily debated. He is most well-known for discovering the Heisenberg uncertainty principle, one of the central principles of modern physics. In his book The 100, Michael H. Hart ranks Heisenberg as the 46th most influential person in history.
Heisenberg was born in Würzburg, Germany, the son of Dr. August Heisenberg and Annie Wecklein. He attended school in Munich and studied Physics at the University of Munich under, amongst others, Arnold Sommerfeld and Wilhelm Wien. As a young man, Heisenberg was an enthusiastic hiker and walker and greatly loved the outdoor life. In 1922 he studied physics at Göttingen where he was taught by Max Born and David Hilbert. His Ph.D. was from the University of Munich following which, he joined Max Born at the University of Göttingen. In 1924 he began work on quantum mechanics with Niels Bohr, at the University of Copenhagen, where in 1926 he was given a Lecturership in Theoretical Physics. In 1927 he took the chair in theoretical physics at Leipzig. He won the Nobel Prize in 1932 for his work on quantum mechanics. In 1937 he married Elizabeth Schumacher.
He elected to remain in Germany for the Second World War, despite problems with the government. His war work is discussed in a separate section below. In 1941 he was appointed Professor of Physics at the University of Berlin. At the end of the Second World War he, and other German physicists, were captured by allied troops as part of Operation Alsos which targeted the capture of Axis nuclear scientists.
After the end of the war, Heisenberg toured various countries giving lectures including England, the United States and Scotland before moving to work in Munich at the Max Planck Institute for Physics. In 1955-56 he gave the Gifford Lectures at St. Andrews University, which resulted in the book Physics and Philosophy.
In 1957 Heisenberg together with Otto Hahn, Max von Laue, Carl Friedrich von Weizsäcker and Max Born formulated and signed a protest against nuclear arming of the German Armed Forces and world-wide nuclear armaments, the so-called "Göttingen Declaration of the German Nuclear Physicists".
He died on February 1, 1976.
As a student, he met Niels Bohr in Göttingen in 1922. A fruitful collaboration developed between the two.
He invented matrix mechanics, the first formalization of quantum mechanics in 1925. His uncertainty principle, discovered in 1927, states that the simultaneous determination of both the position and momentum of a particle each has an inherent uncertainty, the product of these being not less than a known constant. Together with Bohr, he would go on to formulate the Copenhagen interpretation of quantum mechanics.
He received the Nobel Prize in physics in 1932 "for the creation of quantum mechanics, the application of which has, inter alia, led to the discovery of the allotropic forms of hydrogen".
During the early days of the Nazi regime in Germany, Heisenberg was harassed as a "White Jew" for teaching the theories of Albert Einstein in contrast with the Nazi-sanctioned Deutsche Physik movement. After a character investigation that Heisenberg himself instigated and passed, SS chief Heinrich Himmler banned any further political attacks on the physicist.
Work during the War
Nuclear fission was discovered in Germany in 1939. Heisenberg remained in Germany during World War II, working under the Nazi regime. He belonged to a team led by Professor Walther Bothe to develop one of Germany's many nuclear weapon/nuclear power programs, but the extent of his cooperation in the development of weapons has been a subject of historical controversy. Heisenberg's work comprised various efforts to create sustained fission reactions and possibly the creation of a Plutonium breeder reactor at the cave in Hechingen. A rival atomic bomb project was led by Prof. Kurt Diebner for Heerswaffenamt. In contrast, Prof. Kurt Diebner and Dr Paul Harteck worked on uranium enrichment and a uranium based atomic bomb.
It is indicated (from the Farm Hall transcripts) that Heisenberg, even in 1945, was mistaken in his calculations of the critical mass of uranium required for an atomic bombhe did not take into account the "drunkard's walk" trajectory of the slow neutrons emitted, grossly overestimating the critical mass, and concluding that it was too great to allow a bomb to be madeand therefore Germany was not even close to producing a nuclear weapon during the war. Covert eavesdropping on the interned scientists revealed that, on hearing the news of the Allied bombing of Hiroshima, he was convinced that it was an untrue propaganda trick, so sure was he that the critical mass was impracticably large. Some historians have questioned the reliability of the transcripts, as Heisenberg probably knew that he was being monitored; others believe that his shock could not have been feigned.
It has been pointed out that Japanese physicist Dr. Yoshio Nishina did manage to correctly calculate the critical mass of uranium required to sustain a chain reaction. There was co-operation between Nazi scientists and the Japanese bomb project; Nazi Germany shipped uranium oxide to Japan for enrichment during 1944.
Heisenberg revealed the atomic bomb program's existence to Bohr at a conference in Copenhagen in September 1941. After the meeting, the lifelong friendship between Bohr and Heisenberg ended abruptly. Bohr later joined the Manhattan Project. It is known that Reich's munitions minister Albert Speer was Heisenberg's strongest ally in the Nazi leadership and that Speer attempted to divert research funds away from nuclear weaponry. Speer came into conflict with other Nazi leaders for this stance. For this reason the SS ensured that funding was also given to rival nuclear projects without Speer's knowledge.
It has been speculated that Heisenberg had moral qualms and tried to slow down the project. Heisenberg himself attempted to paint this picture after the war, and Thomas Power's book Heisenberg's War and Michael Frayn's play Copenhagen adopted this interpretation. Part of this interpretation is based on the fact that Heisenberg did not champion the project to Albert Speer in a way which got it any attention or very much funding (which Samuel Goudsmit of the ALSOS project interpreted as being partially because Heisenberg himself was not fully aware of the feasibility of an atomic bomb). At best (for Heisenberg), he may have tried to hinder the German project; at worst, he may have just been ignorant of how to create an atomic bomb (it has been wryly commented that one can know either Heisenberg's morality in this respect, or his competence, but not both).
A passage from a 1943 letter from Heisenberg to Dutch scientist Hendrik B. G. Casimir indicates that at the very least Heisenberg was a strong German nationalist:
History legitimizes Germany to rule Europe and later the world. Only a nation that rules ruthlessly can maintain itself. Democracy cannot develop sufficient energy to rule Europe. There are, therefore, only two possibilities: Germany and Russia, and perhaps a Europe under German leadership is the lesser evil. (Blood and Water, Dan Kurzman, 1997, p. 35, ISBN 0-8050-3206-1)
In February 2002, following the attention generated by Copenhagen a letter written by Bohr to Heisenberg in 1957 (but never sent) was released by the Niels Bohr Archive. In it, an angry Bohr relates that Heisenberg, in their 1941 conversation, did not express any moral problems with the bomb making project, that Heisenberg had spent the past two years working almost exclusively on it, and that he was convinced that the atomic bomb would eventually decide the war. Bohr was responding to the recent publication of journalist Robert Jungk's Brighter Than a Thousand Suns, which painted Heisenberg as having single-handedly and purposely derailed the German project for moral reasons. To justify the claim, Jungk had printed an excerpt from a personal letter from Heisenberg which gestured towards such a moral role. The excerpt, however, was taken heavily out of context, and in the full letter Heisenberg was far more demure about whether he had taken a strong moral stance. After reading the out-of-context excerpt, Bohr was understandably flustered that Heisenberg was (apparently) claiming to have purposely derailed the Nazi bomb project, as it did not match his own perception of Heisenberg's war work at all.
Some historians of science have taken this letter as evidence that the previous interpretation of Heisenberg's resistance was wrong, but others have argued that Bohr profoundly misunderstood Heisenberg's intentions at the 1941 meeting, or that his reaction to Jungk's work was overly passionate. As a piece of evidence, the letter has had little effect on overall historical conclusions. The Bohr letters had been sought after by historians for many years, but remained off limits on the wishes of the family; part of the reason they were released was to satisfy curiosity about whether they contained any drastically new historical information (they did not).
It is also thought that Italian scientist Gian Carlo Wick approached Heisenberg in January 1944 as an emissary for the OSS as part of Operation Sunrise, to negotiate the capitulation of Nazi scientists to the ALSOS mission. Allied intelligence through Stockholm continued to sound alarm about Nazi uranium research right up to war's end, but this was part of Diebner's project and not Heisenberg's.
"He lies somewhere here" has been his epitaph.
According to an apocryphal story, Heisenberg was asked what he would ask God, given the opportunity. His reply was: "When I meet God, I am going to ask him two questions: Why relativity? And why turbulence? I really believe he will have an answer for the first."
This story is probably untrue, as it bears an uncanny likeness to the following reported incident: The difficulty of explaining and studying turbulence in fluids was wittily expressed in 1932 by the British physicist Horace Lamb, who, in an address to the British Association for the Advancement of Science, reportedly said, "I am an old man now, and when I die and go to heaven there are two matters on which I hope for enlightenment. One is quantum electrodynamics, and the other is the turbulent motion of fluids. And about the former I am rather optimistic." 
One author wrote that Heisenberg was an unexpectedly good essayist.
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