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Semiclassical physics

From Wikipedia, the free encyclopedia

In physics, semiclassical refers to a theory in which one part of a system is described quantum mechanically, whereas the other is treated classically. For example, external fields will be constant, or when changing will be classically described. In general, it incorporates a development in powers of the Planck constant, resulting in the classical physics of power 0, and the first nontrivial approximation to the power of (−1). In this case, there is a clear link between the quantum-mechanical system and the associated semi-classical and classical approximations, as it is similar in appearance to the transition from physical optics to geometric optics.

History

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Max Planck was the first to introduce the idea of quanta of energy in 1900 while studying black-body radiation. In 1906, he was also the first to write that quantum theory should replicate classical mechanics at some limit, particularly if the Planck constant h were infinitesimal.[1][2] With this idea he showed that Planck's law for thermal radiation leads to the Rayleigh–Jeans law, the classical prediction (valid for large wavelength).[1][2]

Instances

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Some examples of a semiclassical approximation include:

See also

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References

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  1. ^ a b Liboff, Richard L. (1984-02-01). "The correspondence principle revisited". Physics Today. 37 (2): 50–55. doi:10.1063/1.2916084. ISSN 0031-9228.
  2. ^ a b Planck, Max (1906). Vorlesungen über die Theorie der Warmestrahlung. Leipzig: Verlag von Johann Ambrosius Barth.