Exactly why FTLC is impossible with entangled photons?

[bhobba]

]https://www.physicsforums.com/threads/a-simple-proof-of-bells-theorem.417173/#post-2817138. There is no need for probabilities in these proofs.

Well others don't seem to think so
https://arxiv.org/pdf/0709.3909.pdf

But if you want to discuss that one I suggest you start a thread posting the paper that supports the claim - the link you gave is not to a generally downloadable paper.

Regarding Nicks supposed simple proof it has been discussed before, as per the link you posted, many thinking as I do he is a bit of a crackpot (I repeat the link for reference):
https://www.physicsforums.com/threads/a-simple-proof-of-bells-theorem.417173/#post-2817138

For example he says: Most sources of light in nature are unpolarized (SPOT produces a 50/50 random sequence of "0"s and "1"s). However sunlight scattered in the atmosphere becomes partially polarized with a polarization angle and degree of polarization that varies across the sky. SPOT would be an good tool to measure the polarization pattern of scattered sunlight in the heavens but we will use SPOT instead to probe the nature of quantum reality here on Earth

Sounds like stats to me. But we have professors of probability that post here - I would defer to their view.

Thanks
Bill

 

[zonde]

Its simply the truth. Those that think otherwise misunderstand Bell. There is no controversy about it at all. Bell says nothing about particles instantaneously affecting others unless you want to view the world in a certain way some find more like common sense - but of course you do not have to. In fact QM says nothing about particles even existing apart from observation so even saying observing one particle affects the other is making assumptions the theory says nothing about. It's this very strange quirk of QM that is most likely responsible for the different statistical properties it has that classical probability like the slips of paper I mention does not. But regardless its still the same - just a correlation.

It seems you are arguing that there is no instantaneous effects in QM model.
So as I understand I should read your phrase "Nothing is affected instantaneously." as "Nothing is affected instantaneously in QM."
But then it does not seem that the book speaks about theory. After all individual photons are not elements of QM as you noted.

And btw Bell (I mean the author himself) speaks about remote operations (not exactly particles however) affecting measurement : "It is the requirement of locality, or more precisely that the result of a measurement on one system be unaffected by operations on a distant system with which it has interacted in the past, that creates the essential difficulty."

 

[zonde]

Well others don't seem to think so
https://arxiv.org/pdf/0709.3909.pdf

Khrennikov in his paper is not quoting Eberhard's paper to which I gave the link. And Khrennikov in his paper seems to be arguing about seriousness of "fair sampling loophole" in rather obscure and sophisticated way. But "fair sampling loophole" is closed in recent experiments. So it does not seem relevant IMO.

Regarding Nicks supposed simple proof it has been discussed before, as per the link you posted, many thinking as I do he is a bit of a crackpot

This is Ad hominem fallacy. The argument is simple enough that you should not relay on credibility of the author. I came up with very similar proof before I learned about Nicks proof. And I saw this type of proof discussed in one of the recent threads and it came from different source (book).

 

[bhobba]

I came up with very similar proof before I learned about Nicks proof. And I saw this type of proof discussed in one of the recent threads and it came from different source (book).

You miss the point - his proof, right or wrong, regardless of what you think of him, used probability.

If you want to discuss Eberhard' proof post the full proof and in another thread at least at the I level then it can be discussed.

Thanks
Bill

 

[Mentz114]

You miss the point - his proof, right or wrong, regardless of what you think of him, used probability.

If you want to discuss Eberhard' proof post the full proof and in another thread at least at the I level then it can be discussed.

Thanks
Bill

Khrennikov in his paper is not quoting Eberhard's paper to which I gave the link. And Khrennikov in his paper seems to be arguing about seriousness of "fair sampling loophole" in rather obscure and sophisticated way. But "fair sampling loophole" is closed in recent experiments. So it does not seem relevant IMO.This is Ad hominem fallacy. The argument is simple enough that you should not relay on credibility of the author. I came up with very similar proof before I learned about Nicks proof. And I saw this type of proof discussed in one of the recent threads and it came from different source (book).

I don't understand why you two are arguing when you both must believe that a separable conditional probability $P(xy|\alpha\beta)=P(x|\alpha)P(y|\beta)$ cannot reproduce the predictions of QT ? The least that is required is $P(xy|\alpha\beta)=P(x|\alpha)P(y|\alpha\beta)$ meaning there must be common up-to-date information sharing. This could be correlation or communication. Both look the same and we can't use the model to decide - or can we ?

 

[Karagoz]

Now suppose that Alice changes her angle to something else, which we'll call $\theta$. The stream of photons reaching Bob is made up 50% of photons polarized along the angle $\theta$ and 50% polarized along the angle $\theta+\pi/2$.

So when Alice changes her angle to Φ, and passes his photons through that filter, 50% pass through it and 50% don't. So The stream of photons reaching Bob is made up 50% of photons polarized along the angle Φ and 50% polarized along the angle Φ+1/2π.

Shouldn't it be that P=cos^2(Φ) of Alice's photons pass through his filter when he changes her angle to Φ?

 

[bhobba]

I don't understand why you two are arguing when you both must believe that a separable conditional probability $P(xy|\alpha\beta)=P(x|\alpha)P(y|\beta)$ cannot reproduce the predictions of QT ?

Beats me as well. All I am saying is the rules of normal probability theory are not respected in QM which is hardly surprising since it is a different probability model. If you want it to be like ordinary probability theory you need non-locality. But for some reason he thinks Bell has nothing to do with probability.

Thanks
Bill

 

[Mentz114]

So when Alice changes her angle to Φ, and passes his photons through that filter, 50% pass through it and 50% don't. So The stream of photons reaching Bob is made up 50% of photons polarized along the angle Φ and 50% polarized along the angle Φ+1/2π.

Shouldn't it be that P=cos^2(Φ) of Alice's photons pass through his filter when he changes her angle to Φ?

If a photon does not pass a filter it is gone. All the photons that pass a polarizer are aligned to the polarizer angle.

 

[Nugatory]

So when Alice changes her angle to Φ, and passes his photons through that filter, 50% pass through it and 50% don't. So The stream of photons reaching Bob is made up 50% of photons polarized along the angle Φ and 50% polarized along the angle Φ+1/2π.

Shouldn't it be that P=cos^2(Φ) of Alice's photons pass through his filter when he changes her angle to Φ?

The ones that arrive at Bob with polarization $\phi+\pi/2$ also encounter Bob's filter and contribute to the number passing through it. What is $\cos^2(\phi+\pi/2)$?

 

[Karagoz]

The ones that arrive at Bob with polarization $\phi+\pi/2$ also encounter Bob's filter and contribute to the number passing through it. What is $\cos^2(\phi+\pi/2)$?

We are talking aboit a new set of entangled photons when Alice changes his polarization filter. So almost same thing happens again.

Thanks, I think I got it if I'm not wrong.

 

[bhobba]

The question has been answered so its time to close it.

Thanks
Bill