Probability of particle to exceed C?

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Discussion Overview

The discussion revolves around the probability of particles, including photons, exceeding the speed of light. It touches on concepts from quantum field theory (QFT) and non-relativistic quantum mechanics (QM), exploring theoretical implications and interpretations.

Discussion Character

  • Debate/contested, Technical explanation, Conceptual clarification

Main Points Raised

  • Some participants question whether there is a small probability for a particle or photon to exceed the speed of light.
  • Others argue that most physicists believe this does not occur in reality, particularly within the framework of relativistic QFT.
  • It is noted that non-relativistic QM allows for a non-zero probability of faster-than-light motion, but this is viewed as a failing of the theory.
  • One participant emphasizes that non-relativistic theories inherently permit faster-than-light travel, which aligns with their definitions.
  • A later reply references virtual particles in QFT, suggesting that faster-than-light behavior is only applicable to them and likens it to violations of energy conservation.

Areas of Agreement / Disagreement

Participants express differing views on the existence and implications of faster-than-light probabilities, indicating that multiple competing perspectives remain without a consensus.

Contextual Notes

The discussion highlights limitations in the interpretations of non-relativistic QM and the conditions under which faster-than-light travel is considered, particularly in relation to virtual particles.

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Is there a small probability for a particle or a photon to appear slightly exceed the speed of light?
 
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Most physicists probably think this does not happen in reality. In [relativistic] QFT it is not possible. In non-relativistic QM there is such a non-zero probability of getting a particle to move faster than light but it is considered a failing of the theory.
 
Last edited:
MisterX said:
but it is considered a failing of the theory.

Of course there is nothing surprising about a non-relativistic theory allowing faster-than-light travel - that's part of what being non-relativistic means.
 
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