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Schrödinger's equation to Dirac's

  1. Dec 4, 2011 #1


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    Gold Member

    The Shrödinger's equation is [itex]i \hbar \frac{\partial \Psi (\vec r, t) }{\partial t}=-\frac{\hbar ^2}{2m} \nabla ^2 \Psi (\vec r ,t ) + V(\vec r ) \Psi (\vec r ,t)[/itex].
    Where m is the mass of the considered particle at rest. I would like to know why the pass to the relativistic equation isn't as simple as changing m for [itex]\gamma m_0[/itex].
    Say, if instead of using "m" in the Schrödinger's equation, I use [itex]\gamma m_0[/itex] where [itex]m_0[/itex] is the mass of the particle at rest and gamma is Lorentz factor, what would I obtain? Wouldn't this be a more accurate equation than Schrödinger's?
  2. jcsd
  3. Dec 4, 2011 #2


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    Staff: Mentor

    It's related to why you can't substitute [itex]\gamma m_0[/itex] for m in the non-relativistic kinetic energy equation, and thereby get the relativistic kinetic energy.

    The terms of the SE, as you've written it, correspond to the statement

    total energy = kinetic energy + potential energy

    using the classical relationship between kinetic energy and momentum, [itex]K = p^2 / 2m[/itex].
  4. Dec 4, 2011 #3


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    Science Advisor

    In relativistic quantum mechanics the terms in an equation for a wave function must transform according to some representation of the Lorentz group (just like in relativistic mechanics). You can't achieve that simply by introducing some gamma-factors
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