Thursday, 5 March 2015

quantum mechanics - Can Schrödinger Equation be derived from Huygens' Principle?


Notes of Enrico Fermi start from an analogy between mechanics and optics and with 4 pages he derives the Schrödinger equation. In all my courses, I have seen as an axiom - this is how wave-particles behave. Here it is being derived from Fermat's least action principle.




  • Maupertuis Principle -- $$S = \int mv\,\mathrm ds = \int p \,\mathrm dq$$



    • This is integral over phase space so this is not the same as Hamilton principle $$S = \int L \, \mathrm dt$$

    • Maupertuis felt space and time should be put on equal footing





  • Fermat principle -- $$S = \int n \, \mathrm ds$$ principle of least time, Snell's law of refraction, etc



    • this is principle of least time rather than principle of least action

    • Similar to Huygens principle.






Can Quantum Mechanics be understood in terms of wave-fronts and their singularities? I would wonder what how the free particle or scattering might look in this setting.


The only other source I could find is Sir Michael Berry, who has written quite a lot.





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