Quantum Entanglement: No Comm Thm & Counterfactual Def

[Physicsunderstand1]

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 theorm 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.

 

[yeezyseason3]

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?

 

[Physicsunderstand1]

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.

 

[yeezyseason3]

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.

 

[Jeff Rosenbury]

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?

 

[Nugatory]

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.