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theories:classical_theories [2017/11/10 16:37] jakobadmin [FAQ] |
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- | ====== Classical Theories ====== | ||
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- | <tabbox Why is it interesting?> | ||
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- | Classical theories are useful approximations of quantum theories. | ||
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- | <tabbox Layman> | ||
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- | <note tip> | ||
- | Explanations in this section should contain no formulas, but instead colloquial things like you would hear them during a coffee break or at a cocktail party. | ||
- | </note> | ||
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- | <tabbox Student> | ||
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- | <note tip> | ||
- | In this section things should be explained by analogy and with pictures and, if necessary, some formulas. | ||
- | </note> | ||
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- | <tabbox Researcher> | ||
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- | <note tip> | ||
- | The motto in this section is: //the higher the level of abstraction, the better//. | ||
- | </note> | ||
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- | <tabbox Examples> | ||
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- | --> Example1# | ||
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- | <-- | ||
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- | --> Example2:# | ||
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- | <-- | ||
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- | <tabbox 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: The quantum-to-classical transition and decoherence by Maximilian Schlosshauer | ||
- | <-- | ||
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- | <tabbox History> | ||
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- | </tabbox> | ||
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