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- | ====== Classical Theories ====== | ||
- | Classical theories are useful approximations of [[theories:quantum_theory|quantum theories]]. | ||
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- | [{{ :theories:classicaltheories.png?nolink&800 |Source: http://www.pmaweb.caltech.edu/Courses/ph136/yr2012/1201.1.K.pdf}}] | ||
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- | ===== FAQ ===== | ||
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- | --> How can we understand the transition from quantum to classical physics?# | ||
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- | For a nice discussion, see chapter 2 in Sleeping Beauties in Theoretical Physics by Thanu Padmanabhan: | ||
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- | "Particles do not follow trajectories. They are described by | ||
- | wavefunctions but under appropriate circumstances the constructive interference | ||
- | of the phases of the wavefunction will single out a path which | ||
- | we call a classical trajectory. The [[equations:hamilton-Jacobi_equation]] is just the | ||
- | lowest-order Schrodinger equation if we use the ansatz in Eq. (2.1). The ¨ | ||
- | mysterious procedure in Hamilton-Jacobi theory — of differentiating the | ||
- | solution to Hamilton-Jacobi equation and equating it to a constant — is | ||
- | just the condition for constructive interference of the phases of waves | ||
- | differing slightly in the parameter E. The procedure based on Hamilton-Jacobi | ||
- | theory works in [[theories:classical_theories:classical_mechanics|classical mechanics]] because it is supported by the | ||
- | [[equations:schroedinger_equation|Schrodinger equation]]" | ||
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- | See also: | ||
- | [[http://vvkuz.ru/books/zurek.pdf|Decoherence and the Transition from Quantum to Classical—Revisited]] by Zurek and [[https://arxiv.org/abs/1404.2635|The quantum-to-classical transition and decoherence]] by Maximilian Schlosshauer | ||
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