The Physical Principles of the Quantum Theory

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Dover Publications, 1949 - Science - 183 pages

The contributions of few contemporary scientists have been as far reaching in their effects as those of Nobel Laureate Werner Heisenberg. His matrix theory is one of the bases of modern quantum mechanics, while his "uncertainty principle" has altered our whole philosophy of science.
In this classic, based on lectures delivered at the University of Chicago, Heisenberg presents a complete physical picture of quantum theory. He covers not only his own contributions, but also those of Bohr, Dirac, Bose, de Broglie, Fermi, Einstein, Pauli, Schrodinger, Somerfield, Rupp, ·Wilson, Germer, and others in a text written for the physical scientist who is not a specialist in quantum theory or in modern mathematics.
Partial contents: introduction (theory and experiment, fundamental concepts); critique of physical concepts of the corpuscular theory (uncertainty relations and their illustration); critique of the physical concepts of the wave theory (uncertainty relations for waves, discussion of an actual measurement of the electromagnetic field); statistical interpretation of quantum theory (mathematical considerations, interference of probabilities, Bohr's complementarity); discussion of important experiments (C. T. R. Wilson, diffraction , Einstein-Rupp, emission, absorption and dispersion of radiation, interference and conservation laws, Compton effect, radiation fluctuation phenomena, relativistic formulation of the quantum theory).
An 80-page appendix on the mathematical apparatus of the quantum theory is provided for the specialist.

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Contents

INTRODUCTORY
1
d The ComptonSimon Experiment
7
CRITIQUE OF THE PHYSICAL CONCEPTS OF THE COR
13
Copyright

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About the author (1949)

Werner Heisenberg, a German physicist, is regarded as the founder of quantum mechanics, which describes atomic structure in mathematical terms. During the 1920s quantum theory became a controversial topic, following Niels Bohr's model proposal for the hydrogen atom. Heisenberg, dissatisfied with the prevalent mechanical models of the atom, conceived an abstract approach using matrix algebra. In 1925, Heisenberg, Max Born, and Pascual Jordan developed this approach into a theory they termed matrix mechanics. Unfortunately, the theory was difficult to understand, since it provided no means of visualizing the phenomena it explained. Erwin Schrodinger's wave formulation, proposed the following year, proved more successful. In 1944 Heisenberg's and Schrodinger's formulations were shown to be mathematically equivalent by John Von Neumann. In 1927 Heisenberg stated the uncertainty principle, for which he is best known. According to this principle, it is impossible to specify simultaneously both the position and the momentum of a particle, such as an electron. This is caused by interference with those quantities by the radiation that is used to make the observation. The uncertainty principle was demonstrated by means of a thought experiment rather than by a physical observation. Heisenberg also explained ferromagnetism, tracing it to an atomic structure. In 1932 he was awarded the Nobel Prize. Heisenberg was one of the few outstanding German physicists to remain in Germany during World War II. During the war he supervised atomic research in Germany, with the goal of constructing an atomic bomb, although he claimed not to be a supporter of the Nazi regime. Whether by intent or by circumstance, this effort proved to be unsuccessful, and contradictory statements by Heisenberg have not satisfactorily explained the outcome of the project. After the war, Heisenberg publicly declared that he would no longer take part in the production or testing of atomic weapons.

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