Perceived contradiction in non-locality principle

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Discussion Overview

The discussion revolves around the perceived contradictions in the non-locality principle as it pertains to polarization-entangled photons measured by two observers, Alice and Bob. Participants explore the implications of measurement on the properties of entangled particles, the nature of wave function collapse, and the role of polarization filters in this context.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants question how the polarizations of photons A and B relate to each other after measurements, suggesting a contradiction in the interpretation of their states.
  • Others argue that it is speculative to infer unmeasured properties of the photons and emphasize that the measurements are probabilistic rather than definitive.
  • There is a discussion about whether the measurement by one observer causes the wave function collapse of the other, with differing views on the role of the polarization filter in this process.
  • Some participants propose that the wave function collapse occurs when the quantum system interacts with a macroscopic object, such as a detector, rather than the filter itself.
  • Others suggest that the filter and particle may enter an entangled superposition, complicating the interpretation of measurement outcomes.

Areas of Agreement / Disagreement

Participants express differing views on the nature of wave function collapse and the implications of measurement on entangled particles. There is no consensus on whether the polarization filter causes wave function collapse or if it is the subsequent detection that plays a critical role.

Contextual Notes

Participants highlight the challenges in distinguishing cause and effect in measurements involving entangled particles, noting that the ordering of events may not be meaningful. The discussion also touches on the implications of relativity in understanding these measurements, with some arguing that relative motion does not affect the predictions of quantum mechanics.

  • #61
.Scott said:
That lack of time-based cause and effect is the core reason for taking the entire measurement process as one fully-integrated event.
Lets say you measure one particle from entangled pair and then depending from the measurement result you decide to perform or not perform entanglement swapping of second particle with a particle from another entangled pair.
Can you take it as one fully-integrated event?
 
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  • #62
zonde said:
Lets say you measure one particle from entangled pair and then depending from the measurement result you decide to perform or not perform entanglement swapping of second particle with a particle from another entangled pair.
Can you take it as one fully-integrated event?
Well, you can. But that makes things too easy. Normally you want to keep one measurement from having an obvious influence on the other so that there is no "hidden value" solution.
Perhaps more importantly, the measurement of just one particle is "random", he equivalent of a coin flip. It is only when you have a population of A measurements to compare to a corresponding population of B measurements that you see a pattern.
 

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