Completeness for a single particle

Click For Summary

Discussion Overview

The discussion revolves around the completeness of quantum mechanics, particularly in the context of a single particle, such as an electron, passing through a hole and being detected by a spherical detector. Participants explore the implications of wavefunction collapse and the constraints imposed by conservation laws.

Discussion Character

  • Debate/contested, Conceptual clarification, Technical explanation

Main Points Raised

  • One participant argues that quantum mechanics does not explain why a wavefunction should collapse to a single point rather than multiple points, suggesting a need for an instantaneous interaction.
  • Another participant counters that detecting an electron at two points is forbidden by conservation of electric charge, implying that the nature of the particle affects the detection process.
  • A question is raised about whether the situation is resolved differently for photons, indicating a complexity in their detection compared to electrons.
  • A later reply suggests that quantum field theory (QFT) provides a more comprehensive framework for understanding photon interactions, although it may complicate the analysis by including self-interactions.
  • It is noted that traditional quantum mechanics thought experiments often overlook these self-interactions and assume simple interactions with detectors.

Areas of Agreement / Disagreement

Participants express differing views on the completeness of quantum mechanics and the implications of wavefunction collapse, with no consensus reached on the underlying processes or the adequacy of existing theories.

Contextual Notes

The discussion highlights limitations in the current understanding of wavefunction collapse and the assumptions made in traditional quantum mechanics, particularly regarding particle interactions and conservation laws.

jk22
Messages
732
Reaction score
25
Another argument than EPR that quantum mechanics were not complete by Einstein is the following : suppose a single electron passing through a hole and going further to a spherical detector. Quantum mechanics describes this as a wavefunction fulling the whole space inside the sphere and then collapsing to a single point on the screen.

The question was in this description which process forbids that the wavefunction collapses in two points ? There should be an instantaneous interaction ?
 
Physics news on Phys.org
Detecting the electron at two points is forbidden by conservation of electric charge. If it were a photon, then it's more complicated, but the detected photons would have to have energies that added up to that of the original photon.
 
  • Like
Likes   Reactions: atyy and jk22
For photons It is simply solved by quantum field theory ?
 
jk22 said:
For photons It is simply solved by quantum field theory ?

Yes, the typical QM thought experiments ignore self-interactions and assume the particle will only interact with a screens, filters, or the detectors. If you use QFT you can consistently treat all of the other possible interactions at the risk of making things very complicated. But the amplitudes by construction satisfy the ordinary QM rules.
 
  • Like
Likes   Reactions: bhobba and atyy

Similar threads

  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 16 ·
Replies
16
Views
3K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 36 ·
2
Replies
36
Views
9K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 17 ·
Replies
17
Views
4K
  • · Replies 17 ·
Replies
17
Views
3K