Quantum Entanglement: No Comm Thm & Counterfactual Def

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Discussion Overview

The discussion revolves around quantum entanglement, specifically addressing the no communication theorem and its implications for non-locality. Participants explore the relationship between entangled particles, communication, and the concept of counterfactual definiteness within the framework of quantum mechanics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions how the no communication theorem does not negate the possibility of non-locality, suggesting that entangled particles cannot communicate with each other.
  • Another participant seeks clarification on whether non-locality refers to particles communicating and how the no-communication theorem relates to observations from an external reference frame.
  • Some participants assert that while entangled particles cannot communicate, an outside source may be able to communicate with both particles.
  • One participant provides an example involving entangled photons, arguing that the intrinsic connection between them could explain non-locality, while also noting that correlation does not imply causation.
  • Another participant reiterates the no communication theorem, emphasizing that actions on one particle do not allow for message transmission to an observer of the other particle.

Areas of Agreement / Disagreement

Participants express varying interpretations of the no communication theorem and its implications for non-locality. There is no consensus on the relationship between entangled particles and communication, nor on the implications of counterfactual definiteness.

Contextual Notes

Some participants mention a lack of understanding regarding the mathematical proofs related to the no communication theorem, indicating potential limitations in their arguments. Additionally, the discussion reflects differing perspectives on the nature of correlation and causation in quantum mechanics.

Physicsunderstand1
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I've recently been reading up on quantum entanglement, and I was wondering how the no communication theorem does not rule out non locality. From my understanding the theorem proves that two entangled particles could not communicate to one another, and this is what occurs within the framework of quantum non locality. My second question also pertains to entanglement. I was wondering how assuming that counterfactual definitness is false rids the need of non locality.
 
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Stupid question, but I'm going to ask it anyway...isn't non-locality referring to "particles" or "photons" communicating with each other? Also isn't the no-communication theorem referring to the actual observation by an outside reference frame?
 
It is my understanding that the no communication theorem proves that the two particles cannot communicate to one another, however an outside source may communicate to both. I'm not sure of the mathmatical proof reguarding the theory, however this is what I've been told by a physicist.
 
I don't know how relevant it is, but ill use photons as an example. If you upconvert into two complimentary entangled photons, it is (as far as we know) impossible to delay one of the photons without affecting the other photon in some way. This intrinsic "connection" could be one reason on how non-locality can occur in this scenario.
 
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yeezyseason3 said:
I don't know how relevant it is, but ill use photons as an example. If you upconvert into two complimentary entangled photons, it is (as far as we know) impossible to delay one of the photons without affecting the other photon in some way. This intrinsic "connection" could be one reason on how non-locality can occur in this scenario.
My understanding is that no connection has been shown, only correlation.

In the human realm, we often say, "Correlation doesn't prove causation." But our human experience is otherwise; usually a correlation means someone did something. Yet the quantum world is not the world of human experience, so perhaps the adage is true?
 
Physicsunderstand1 said:
It is my understanding that the no communication theorem proves that the two particles cannot communicate to one another, however an outside source may communicate to both. I'm not sure of the mathmatical proof reguarding the theory, however this is what I've been told by a physicist.

The no-signalling theorem says that nothing you do to one particle will allow you send a message to someone watching the other particle.
The wikipedia article at https://en.wikipedia.org/wiki/No-communication_theorem is worth reading.
 
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