Is the QM phase of a particle a coincidence in relativistic quantum mechanics?

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Discussion Overview

The discussion centers on the nature of the quantum mechanical phase of a particle in the context of relativistic quantum mechanics, specifically questioning whether the relationship expressed by the phase term (r•p – Et) is merely a coincidence or has deeper implications. The scope includes theoretical considerations and connections to classical electromagnetism.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant states that the quantum mechanical phase of a single particle can be expressed as (r•p – Et), linking it to the dot product of space-time and energy-momentum four-vectors.
  • Another participant asserts that this relationship is not a coincidence and applies to any relativistic wave, including classical electromagnetism.
  • A subsequent post questions which classical electromagnetism equations contain this phase term, indicating a search for connections in Maxwell's Equations.
  • Another participant provides the form of a classical electromagnetic wave, suggesting a potential link to the phase expression discussed.
  • One participant explains that the phase's properties arise from the relativistic wave equation and its connection to the Schrödinger equation in the non-relativistic limit, emphasizing Lorentz invariance and covariance of the four-vector.

Areas of Agreement / Disagreement

Participants express differing views on whether the relationship is a coincidence, with some asserting it is not, while others seek clarification on its implications in classical electromagnetism. The discussion remains unresolved regarding the connection to classical equations.

Contextual Notes

There are limitations in the discussion regarding the specific classical equations that relate to the quantum phase term, as well as the assumptions underlying the claims about Lorentz invariance and the applicability of the relativistic wave equation.

LarryS
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The QM phase of a single particle traveling freely in 3 dimensions is (rp – Et), where r and p are the 3-D position and momentum vectors. This is also the dot product of the space-time four-vector (r,-t) with the Energy-Momentum four-vector (p,E)

Is this "coincidence" related to relativistic QM?

Thanks in advance.
 
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No. It is not a coincidence. It is the case in any relativistic wave, including classical EM.
 
clem said:
No. It is not a coincidence. It is the case in any relativistic wave, including classical EM.
What classical EM equation(s) contain this term? I looked at the original version of Maxwell's Equations and could not see any connection. Thanks.
 
A classical EM wave is [tex]{\bf E}\exp[i({\bf k\cdot r}-\omega t)][/tex].
 
It is a consequence of the fact that relativistic fields satisfies the relativistic wave equation which in the non-relativistic limit gives the Schrödinger eq, and of the de Broglie relation: E = \hbar \omega, p = \hbar k. As a consequence the phase of a field is Lorentz invariant and the four-vector (\omega, k) is covariant.
 

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