Semiclassical physics

Summary

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.
  • R. Resnick; R. Eisberg (1985). Quantum Physics of Atoms, Molecules, Solids, Nuclei and Particles (2nd ed.). John Wiley & Sons. ISBN 978-0-471-87373-0.
  • P.A.M. Dirac (1981). Principles of Quantum Mechanics (4th ed.). Clarendon Press. ISBN 978-0-19-852011-5.
  • W. Pauli (1980). General Principles of Quantum Mechanics. Springer. ISBN 3-540-09842-9.
  • R.P. Feynman; R.B. Leighton; M. Sands (1965). Feynman Lectures on Physics. Vol. 3. Addison-Wesley. ISBN 0-201-02118-8.
  • C.B. Parker (1994). McGraw-Hill Encyclopaedia of Physics (2nd ed.). McGraw-Hill. ISBN 0-07-051400-3.