Werner Karl Heisenberg, (December 5th 1901 - 1976) is a Physicien, founder of the quantum Mécanique, Nobel Prize (1932). It was born with Würzburg, Germany and died in Munich.
Quantum mechanics
It developed the first formalization of the quantum Mécanique, in 1925, at the same time as Erwin Schrödinger. However the mathematical formalism was different, Heisenberg used a matric formalization, whereas Schrödinger used an approach by the differential equations. This made it possible to think, first of all, that the theories were distinct, but the following year, Schrödinger showed the mathematical equivalence of the two formulations. Heisenberg has redécouvert on the occasion the algebra of the matrices for the needs for the calculation applied to the experimentation; the matrices were taught to him then by the German physicist Pascual Jordan.Its Principle of uncertainty, discovered in 1925, affirms that the determination of certain couples of values, for example the position and the momentum, cannot be done with an infinite precision. One can formalize it in the shape of a product: Δ px Δ X ≈ H where Δ px represents the indetermination on the momentum and Δ X the indetermination on the position. This product cannot be lower than the constant h/4 , and thus any precision in the measurement of one of the two quantities is done with the detriment of the other. This uncertainty is not related to measurement, but is a real property of the values in question: to improve the precision of the instruments will not improve the precision of this simultaneous measurement.
Starting from 1929, it worked with Wolfgang Pauli with the development of the Quantum theory of the fields.
It accepted the Nobel Prize of physics in 1932 for “the creation of quantum mechanics and of its applications which allowed the discovery of the allotropic shapes of hydrogen (orthohydrogen and parahydrogen)”.
After the discovery of the Neutron by James Chadwick in 1932, Heisenberg proposed the model proton-neutron of the Atomic nucleus, and made use of it to explain the nuclear Spin Isotopes.
Its work during the Second world war
The Nuclear fission was discovered in Germany in 1938. Heisenberg remained in Germany during the Second world war and worked under the mode Nazi. He directed the German program of nuclear armament to the Kaiser Wilhelm Institut of Berlin, but the reality of its collaboration is prone to controversy.
It revealed the existence of the program with Niels Bohr at the time of a conference with Copenhagen in September 1941. This meeting put an end to the very long friendship between Heisenberg and Bohr, which joined the Projet Manhattan. However, the Germans did not succeed in producing nuclear weapon.
There were many controversies to know if Heisenberg had really tried to slow down the project. Heisenberg, itself, affirmed after the war that it would have slowed down this program if it had been likely to succeed. The book Heisenberg' S War of Thomas Power, and the play Copenhagen of Michael Frayn expose this vision of the things.
In February 2002, one finds a written letter by Bohr, but ever sent, dated 1957 and intended for Heisenberg. In this one, Bohr tells that Heisenberg, at the time of their meeting in 1941, did not express any moral scruple concerning the German project of atomic bomb, and that it had spent the two last years before this meeting to be worked exclusively on this project. It was convinced that it would decide exit of the war.
Many historians of sciences take this letter like a proof of the implication of Heisenberg in the German program, but several people have advanced the assumption that Bohr had not included/understood the intentions of Heisenberg at this meeting.
Heisenberg wrote several books of Vulgarisation, as well as a work entitled Der Teil und das Ganze ( the Part and the Whole ) in connection with his life, of his friendship with Bohr and the evolution of the quantum physics.
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