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Degrees of Freedom

  1. May 28, 2008 #1
    Dear PF,
    I have a question about degrees of fridom.

    Electron is 1/2 spin particle so it needs 2 component wave function. But instead haveing 1 equation of second order we linearize and have two equations of order 1 for two spinors and these two equations can be re-written in one equation for 4 component spinor.

    But this four component wave function has complex components ...and so there are eight independent elements in wave function.

    What I am confused is that electron has degrees of freedom 2 (spin up/down) and wave function 8 ? correcct or what I dont understand? or complexity of wave function does not account in degrees of freedom?

  2. jcsd
  3. May 29, 2008 #2
    Stupid question ? :(
  4. May 29, 2008 #3


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  5. May 31, 2008 #4
    There is also the positron, with its two degrees of freedom. Thus, we have four of them.

    And for a single "degree of freedom" of a wave we need one second order or two first order equations.

    I also recommend you not to name the Dirac field psi "wave function", and to ignore all texts which use such a naming convention. Think of the Dirac equation as a classical wave equation, as the analogon of the Maxwell equation for particles with spin 1/2.
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