Exploring the Mysteries of Entanglement and Non-Locality in Quantum Mechanics

[rasp]

I’m reading in the lay literature that experiments on Bells inequality have shown that 2 entangled particles pass information simultaneously and therefore break the special relativity rule of c and therefore indicate a break from the concept of locality. I’m sure I didn’t phrase that sentence exactly correct, however, if I have the basic idea, then let me proceed to my question. How can we say information is passed between particles. What could be the material means by which basic particles communicate information? How is the information coded?

 

[Buzz Bloom]

I’m reading in the lay literature

Hi rasp:

The lay literature is quite often unreliable for accurately describing science phenomena. Your rendition of the lay text is not one of the several ways that physicists interpret experiments related to Bell's inequality. I recommend the lay book "What is Real?" by Adam Becker. It is mostly about the history of the development of ideas about QM, and it presents a very clear discussion the implications of Bell's inequality.

Regards,
Buzz

 

[StevieTNZ]

Another good book is 'Sneaking a Look at God's Cards' by Giancarlo Ghirardi - https://www.amazon.com/dp/069113037X/?tag=pfamazon01-20 , as well as 'Quantum Chance: Nonlocality, Teleportation and Other Quantum Marvels' by Nicolas Gisin - https://www.amazon.com/dp/3319054724/?tag=pfamazon01-20

 

[jfizzix]

I’m reading in the lay literature that experiments on Bells inequality have shown that 2 entangled particles pass information simultaneously and therefore break the special relativity rule of c and therefore indicate a break from the concept of locality. I’m sure I didn’t phrase that sentence exactly correct, however, if I have the basic idea, then let me proceed to my question. How can we say information is passed between particles. What could be the material means by which basic particles communicate information? How is the information coded?

What the experimental violation of Bell inequalities shows is that the correlations between measurements of two separated particles A and B cannot be explained away by common-cause events whose actions propagate at a finite speed (e.g., the speed of light). This non-local correlation is a very important fact about physical reality, but going from that to deducing that faster than light signals have to travel between the particles requires extra assumptions about quantum physics that are not universally agreed upon.

In any case, they don't communicate information in the traditional sense, because, if all you have is particle A, there is no measurement you could do on A or way that you can tell if particle A is half of an entangled pair. It's only when whomever is doing measurements on the particle B compares notes with you later on, that you can see that there are correlations, and nonlocal correlations at that.

 

[king vitamin]

How can we say information is passed between particles. What could be the material means by which basic particles communicate information? How is the information coded?

We actually cannot say that information is passed between particles; saying so violates an important theorem in quantum mechanics: https://en.wikipedia.org/wiki/No-communication_theorem

 

[rasp]

What the experimental violation of Bell inequalities shows is that the correlations between measurements of two separated particles A and B cannot be explained away by common-cause events whose actions propagate at a finite speed (e.g., the speed of light). This non-local correlation is a very important fact about physical reality, but going from that to deducing that faster than light signals have to travel between the particles requires extra assumptions about quantum physics that are not universally agreed upon.

In any case, they don't communicate information in the traditional sense, because, if all you have is particle A, there is no measurement you could do on A or way that you can tell if particle A is half of an entangled pair. It's only when whomever is doing measurements on the particle B compares notes with you later on, that you can see that there are correlations, and nonlocal correlations at that.

Thank-you. I’m understanding that “they don’t communicate in the traditional sense. “. Yet a to be measured particle separated by distance from its entangled pair somehow know the state of the first particle and will therefore restrict the second measurements so as, for example, not to violate the Heisenberg uncertainty principal. So, as the Bell inequality proved there are no hidden variables, how does the second particle know the state of the first?

 

[1977ub]

What the experimental violation of Bell inequalities shows is that the correlations between measurements of two separated particles A and B cannot be explained away by common-cause events whose actions propagate at a finite speed (e.g., the speed of light).

Isn't that too strong a statement, given the fact that superdeterministic hidden variables can't be fully ruled out? If superdeterminism is a "religion", isn't it similarly a religion to say that "it has been proven that reality is non-local" ?

 

[DrChinese]

... isn't it similarly a religion to say that "it has been proven that reality is non-local" ?

That is not what jfizzix said. He said: "correlations between measurements of two separated particles A and B cannot be explained away by common-cause events whose actions propagate at a finite speed (e.g., the speed of light)." There need not be realism or causality in the traditional sense. Else perhaps there are non-local influences. There are a variety of interpretations you can consider as viable, which address Bell's Theorem.

 

[DrChinese]

Thank-you. I’m understanding that “they don’t communicate in the traditional sense. “. Yet a to be measured particle separated by distance from its entangled pair somehow know the state of the first particle and will therefore restrict the second measurements so as, for example, not to violate the Heisenberg uncertainty principal. So, as the Bell inequality proved there are no hidden variables, how does the second particle know the state of the first?

There may be hidden variables, and if there are, they are non-local. That's Bell.

And no one knows the precise mechanism that allows separated entangled particles to behave as a single system.

 

[Spinnor]

There may be hidden variables, and if there are, they are non-local. That's Bell.

Bell in a nutshell, thanks.

 

[1977ub]

There may be hidden variables, and if there are, they are non-local. That's Bell.

And no one knows the precise mechanism that allows separated entangled particles to behave as a single system.

The local (super)determinism variables can't be 100% ruled out by Bell experiments. If someone really believe that experimenters can "freely" choose *random* measurements, then they were never a determinist to begin with. I'm just saying that these "reality is non-local" formulations seem too strong.

 

[jfizzix]

Thank-you. I’m understanding that “they don’t communicate in the traditional sense. “. Yet a to be measured particle separated by distance from its entangled pair somehow know the state of the first particle and will therefore restrict the second measurements so as, for example, not to violate the Heisenberg uncertainty principal. So, as the Bell inequality proved there are no hidden variables, how does the second particle know the state of the first?

That's a million dollar question, that I have no idea how to answer.

 

[zonde]

The local (super)determinism variables can't be 100% ruled out by Bell experiments.

Yes, superdeterminism based explanation can't be ruled out by Bell experiments. But if it's considered non-scientific then it can be ignored in science discussions. So I see nothing wrong with statements given by jfizzix and DrChinese.

If someone really believe that experimenters can "freely" choose *random* measurements, then they were never a determinist to begin with.

Experimenters do not have to have fundamental "freedom of choice". It's enough to have FAPP "freedom of choice". And this FAPP "freedom of choice" is justified by existence of chaotic systems.

 

[DrChinese]

The local (super)determinism variables can't be 100% ruled out by Bell experiments.

That's not entirely correct. Before you could say that, you'd have to have a superdeterministic model to consider. There currently aren't any. Current concepts in superdeterminism are akin to asking "where does God reside".

• For example: where are the (superdeterministic) local hidden variables? Can they be seen or modified?
• Did they exist at the beginning of the universe?
• How do they get passed to newly created photons in a laser?
• What happens to them when a photon is absorbed?
• How do they propagate when photons "split" during parametric down conversion?
• Does every particle contain a complete instruction set for all future measurements so they know to give results in accordance with QM?

These would just be beginning questions, as I would basically want to know what the "true correlation rate" is for particles in Bell tests, since the assertion is that Bell Inequality violation is just an elaborate illusion. A "conspiracy", if you will.

A suitable reference should be cited before discussing superdeterminism.

 

[rasp]

I was wondering (but not to take this discussion to the philosophical) but only to clarify terms. Is the idea of super determinism related to the idea that the observed and the observing mechanism share information to produce results, which lead humans to arrive at conclusions that are logically consistent but not correct? Is this the basis for some to postulate a universal conspiracy theory or even to go so far as to conjure a scenario in which our world is an artificial game played by super intelligences?

 

[1977ub]

Yes, superdeterminism based explanation can't be ruled out by Bell experiments. But if it's considered non-scientific then it can be ignored in science discussions. So I see nothing wrong with statements given by jfizzix and DrChinese.

Experimenters do not have to have fundamental "freedom of choice". It's enough to have FAPP "freedom of choice". And this FAPP "freedom of choice" is justified by existence of chaotic systems.

All the FAPP practical purposes can do is *hide* the chains of local cause-and-effect, right? They don't make them go away. No information is destroyed ?

 

[zonde]

All the FAPP practical purposes can do is *hide* the chains of local cause-and-effect, right? They don't make them go away. No information is destroyed ?

Chains of cause-and-effect in chaotic systems are not hidden. They are simply unpredictable in a long run. If you would try to come up with a model that includes as a factor output from chaotic systems you wouldn't get anything sensible out of such model.
Look, if you ask what Bell inequality says about physical reality itself, then there is no fundamental answer that you can squeeze out of it. But Bell inequality violations limit the possible set of (event by event) models that we can use to explain entanglement phenomena. And that is quite enough in scientific context.

 

[zonde]

Is the idea of super determinism related to the idea that the observed and the observing mechanism share information to produce results, which lead humans to arrive at conclusions that are logically consistent but not correct?

I would not say it this way. Rather I would say that some possible configurations of physical situation are considered unphysical based on some hypothetical relationship that is impossible to calculate from the information we have or could have, so this relationship is ad-hoc and does not lead to any other testable predictions.