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Here are two You Tube videos from the last few days.

The first one from IBM’s Qskit explains Bell’s inequality and some of its implications. It also explains how the violation of the Bell test demonstrates that non-local correlations are not classical.

"Bells Inequality: the weirdest theorem in the word | Nobel …"

The first part of this video below is from Sabina Hossenfelder where she explains non-locality “Spooky action at a distance.’ and how it is real.

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The experiments of Bell, Aspect, and Clauser demonstrated that entangled particles are non-locally connected so that if you measure one entangled particle you instantly fix the quantum identity of its partner. Einstein was demonstrated to be wrong about his idea that any change to one particle could never affect a change to another distant particle without a direct physical, light speed connection.

The strange part of quantum entanglement is that when you measure something about one particle in an entangled pair, you immediately know something about the other particle, even if they are millions of light years apart. This odd connection between the two particles is instantaneous, seemingly breaking a fundamental law of the universe. Albert Einstein famously called the phenomenon "spooky action at a distance."

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15 minutes ago, bangstrom said:

The experiments of Bell, Aspect, and Clauser demonstrated that entangled particles are non-locally connected so that if you measure one entangled particle you instantly fix the quantum identity of its partner. Einstein was demonstrated to be wrong about his idea that any change to one particle could never affect a change to another distant particle without a direct physical, light speed connection.

The strange part of quantum entanglement is that when you measure something about one particle in an entangled pair, you immediately know something about the other particle, even if they are millions of light years apart. This odd connection between the two particles is instantaneous, seemingly breaking a fundamental law of the universe. Albert Einstein famously called the phenomenon "spooky action at a distance."

Nice account of how it is not spooky, it is not an action, and it is not at a distance. And the reason for the quotation marks in the title:

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What is quantum entanglement? A physicist explains the science of Einstein's 'spooky action at a distance'

You have to actually read it to see that, of course:

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Existing in multiple states at once

To truly understand the spookiness of quantum entanglement, it is important to first understand quantum superposition. Quantum superposition is the idea that particles exist in multiple states at once. When a measurement is performed, it is as if the particle selects one of the states in the superposition.

IOW => NOT(LOCALITY AND REALISM) => NOT (LOCALITY) OR NOT (REALISM)

Quantum mechanics has no underlying realism.

Are we there yet?

Let me guess: No.

Silly me for believing you were in a superposition of yes and no.

Just now, joigus said:

it is as if the particle selects one of the states in the superposition.

Funny. I did say exactly that. Only, I dropped the "as if."

On 10/5/2022 at 11:56 AM, joigus said:

"teleselection," "telefiltering," or even better perhaps "Q-teleselection," "Q-telefiltering," to further insist that these cannot be replicated by dice, gloves, or boots, would be far more honest-to-goodness terms than "teleportation."

On 10/5/2022 at 11:56 AM, joigus said:

The reason, of course, being that correlations after measurement involve selecting a basis which wasn't implied in the initial preparation of the state. I know by now that the reasons for this will fly right over your head.

And was I right, oh man, that it would fly over your head.

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1 hour ago, bangstrom said:

The experiments of Bell, Aspect, and Clauser demonstrated that entangled particles are non-locally connected so that if you measure one entangled particle you instantly fix the quantum identity of its partner. Einstein was demonstrated to be wrong about his idea that any change to one particle could never affect a change to another distant particle without a direct physical, light speed connection.

Thanks for the link. It confirms that no "faster than light" signal  "instant connection" "instant fix" or similar is involved:

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Importantly, there is also no conflict with special relativity, which forbids faster-than-light communication. The fact that measurements over vast distances are correlated does not imply that information is transmitted between the particles. Two parties far apart performing measurements on entangled particles cannot use the phenomenon to pass along informationfaster than the speed of light.

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8 hours ago, bangstrom said:

For example, when two particles A and B are entangled even though they might be light years apart. A measurement made on either one of the entangled particles instantly destroys the entanglement for both of the entangled particles and their quantum properties which were indeterminate before (superimposed) instantly become determinate.

You keep explaining these details as if the people in the thread are not aware of them.

8 hours ago, bangstrom said:

The repeated observation that entangled particles are anti-correlated when they drop out of entanglement suggests ...

...

This observation suggests...

...

This suggests some form of a non-local exchange of quantum information often called a 'signal'.

The part you keep ignoring is that this "suggestion" does not come from QM, but from notions being applied from other parts of physics.

Much like the conventional wisdom that all waves require a medium, and thus an aether must exist. But that idea was abandoned because the data did not support it, and we had a theory that did not require it.

QM has other examples of phenomena that exist that do not require an explicit interaction. The Pauli exclusion principle, for example, which e.g. leads to degeneracy pressure. That fermions can't occupy the same quantum state and bosons can doesn't arise from some interaction, but the allowable behavior for identical particles and the details of their wave function (symmetric vs antisymmetric). And yet this allows atoms to exist and prevents them from collapsing under gravitational pressure, up to a point. But there is no interaction in play.

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4 hours ago, bangstrom said:

However, if two events happen at exactly the same time...

OK, so we assume that in the reference frame of Alice, the source of entangled particles exactly in the middle, and Bob on the other side; nobody is moving against each other. So if Alice and Bob find a correlation between their measurements, it is impossible to say who was first. That is already problematic for you: in which direction is the signal/information/communication/effect/action/interaction going? The situation is exactly symmetrical.

Now observer1 flies with great speed from Alice to Bob. He will see that one of them was before the other, and could conclude that one sent a signal to the other.

Observer2 flies in the opposite direction, from Bob to Alice, and so concludes exactly the opposite, she will say that the other one was first.

If Observer1 and 2 know their relativity, they will recognise that the events are space-like separated, and the correlation must be caused by an event that exists in the respective light cones of Alice and Bob. And lo and behold, there is a one single source of entangled particles in the light cones of both. So the reason of the correlation lies in the past that Alice and Bob share. Like a pair of shoes... There is no signal/information/communication/effect/action/interaction needed to explain this correlation.

I have a dejà vu.

3 hours ago, bangstrom said:

The experiments of Bell, Aspect, and Clauser demonstrated that...

Another dejà vu... Bell did not do these kind of experiments. I assume you mean Zeilinger. You know, one of the three that got a Nobel prize.

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1 hour ago, Eise said:

OK, so we assume that in the reference frame of Alice, the source of entangled particles exactly in the middle, and Bob on the other side; nobody is moving against each other. So if Alice and Bob find a correlation between their measurements, it is impossible to say who was first. That is already problematic for you: in which direction is the signal/information/communication/effect/action/interaction going? The situation is exactly symmetrical.

Now observer1 flies with great speed from Alice to Bob. He will see that one of them was before the other, and could conclude that one sent a signal to the other.

Observer2 flies in the opposite direction, from Bob to Alice, and so concludes exactly the opposite, she will say that the other one was first.

If Observer1 and 2 know their relativity, they will recognise that the events are space-like separated, and the correlation must be caused by an event that exists in the respective light cones of Alice and Bob. And lo and behold, there is a one single source of entangled particles in the light cones of both. So the reason of the correlation lies in the past that Alice and Bob share. Like a pair of shoes... There is no signal/information/communication/effect/action/interaction needed to explain this correlation.

I have a dejà vu.

Another dejà vu... Bell did not do these kind of experiments. I assume you mean Zeilinger. You know, one of the three that got a Nobel prize.

Jumping in the wagon here but what about the hypothese that two events would be spacelike in the 4D continuum but also much closer to each other in an oblique, 5th dimension in which those two non-local events would be local ? As long as physical information is not allowed to transit tru it.

10 minutes ago, Mitcher said:

Bell did not do these kind of experiments. I assume you mean Zeilinger. You know, one of the three that got a Nobel prize.

A Nobel prize for an experiment they did 50 years ago while still at Berkeley ? woaw.

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13 minutes ago, Mitcher said:

Jumping in the wagon here but what about the hypothese that two events would be spacelike in the 4D continuum but also much closer to each other in an oblique, 5th dimension in which those two non-local events would be local ? As long as physical information is not allowed to transit tru it.

!

Moderator Note

Such speculation should go in its own thread

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48 minutes ago, swansont said:
!

Moderator Note

Such speculation should go in its own thread

Yes, in the thread about entanglement and non-locality. The one here or so it seems isn'it ?

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6 hours ago, Eise said:

OK, so we assume that in the reference frame of Alice, the source of entangled particles exactly in the middle, and Bob on the other side; nobody is moving against each other. So if Alice and Bob find a correlation between their measurements, it is impossible to say who was first. That is already problematic for you: in which direction is the signal/information/communication/effect/action/interaction going?

That is no problem because the timing is non-local (instant) no matter which way the whatever-you-call it is going.

That was the case with the early Aspect-Clauser experiment and many others but they were only looking for anti-correlation among entangled particles, in which case, it didn’t matter which detection came first. The signals were detected as anti-correlated before a light speed signal could reach opposite ends of the experiment indicating that the connections were non-local.

7 hours ago, Eise said:

If Observer1 and 2 know their relativity, they will recognise that the events are space-like separated, and the correlation must be caused by an event that exists in the respective light cones of Alice and Bob. And lo and behold, there is a one single source of entangled particles in the light cones of both. So the reason of the correlation lies in the past that Alice and Bob share. Like a pair of shoes... There is no signal/information/communication/effect/action/interaction needed to explain this correlation.

You are right right. That is a perfectly good explanation for correlation and there are many experts who would agree with you. Hold that thought and consider the implications.

7 hours ago, Eise said:

Bell did not do these kind of experiments. I assume you mean Zeilinger. You know, one of the three that got a Nobel prize.

Bell did the math and theoretical work. Aspect and Clauser did the experiments and Zeilinger came along much later.

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29 minutes ago, bangstrom said:

That is no problem because the timing is non-local (instant) no matter which way the whatever-you-call it is going.

Instant in one reference frame is 1 to 2 in another, and 2 to 1 in yet another for space-like intervals. The order of events is frame-dependent. Please, oh please, do learn some special relativity. At least the basics. "Instant doesn't mean anything in special relativity. That's the point. (Ahem, ahem, sigh.)

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6 hours ago, Mitcher said:

Yes, in the thread about entanglement and non-locality. The one here or so it seems isn'it ?

!

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Responses to speculations need to be mainstream science, not other speculation.

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15 hours ago, swansont said:

The part you keep ignoring is that this "suggestion" does not come from QM, but from notions being applied from other parts of physics.

I haven’t been ignoring the “suggestion”. I just don’t follow the practices here of saying you are wrong and confused and your idea is garbage if I disagree. Nor do I think unsupported personal opinions pass for expertise. I don’t find these things very convincing and many others in other science forums must not either since personal comments and unsupported opinions are less infrequent.

I keep saying the violation of the Bell test has ruled out the possibility that anti-correlation among entangled particles has a classical explanation So, the “suggestions” to the contrary are wrong and confused and garbage in case anyone feels ignored.

15 hours ago, swansont said:

You keep explaining these details as if the people in the thread are not aware of them.

The part you keep ignoring is that this "suggestion" does not come from QM, but from notions being applied from other parts of physics.

Much like the conventional wisdom that all waves require a medium, and thus an aether must exist. But that idea was abandoned because the data did not support it, and we had a theory that did not require it.

QM has other examples of phenomena that exist that do not require an explicit interaction. The Pauli exclusion principle, for example, which e.g. leads to degeneracy pressure. That fermions can't occupy the same quantum state and bosons can doesn't arise from some interaction, but the allowable behavior for identical particles and the details of their wave function (symmetric vs antisymmetric). And yet this allows atoms to exist and prevents them from collapsing under gravitational pressure, up to a point. But there is no interaction in play.

I don’t agree that these examples are without direct physical interaction and I can explain why but that is another topic.

5 hours ago, joigus said:

Instant in one reference frame is 1 to 2 in another, and 2 to 1 in yet another for space-like intervals. The order of events is frame-dependent. Please, oh please, do learn some special relativity. At least the basics. "Instant doesn't mean anything in special relativity. That's the point. (Ahem, ahem, sigh.)

The Alice and Bob analogy assumes a single reference frame. Your comment about other reference frames is a ridiculous obfuscation. And, please, oh please, do learn something about QM from this past half century. The EPR effect is dead and non-locality is real.

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21 hours ago, bangstrom said:

"Bells Inequality: the weirdest theorem in the word | Nobel …"

It is really amusing to see how you shoot yourself in the foot again and again. At about 10:05:

Quote

The way that most scientists have interpreted this, is that we have to give up on the idea of realism

2 hours ago, bangstrom said:

I haven’t been ignoring the “suggestion”. I just don’t follow the practices here of saying you are wrong and confused and your idea is garbage if I disagree.

It is not garbage, in the end even a lot of physicists thought we have to give up on locality. See my citation of Zeilinger from his Dance of the photons. But his book is from 2010. Now 12 years later, in 'your video', above is said. So it seems  the consensus is moving in the other direction.

Your counter argument against my relativity however, is garbage, as @joigusalso noted.

9 hours ago, bangstrom said:

You are right right. That is a perfectly good explanation for correlation and there are many experts who would agree with you. Hold that thought and consider the implications.

I did. In my opinion (maybe Swansont, Joigus, and MigL would not agree, that's why I say 'opinion') that in QM, more specifically the wave function, we have reached the limit of our our capacity to know and understand nature. In a Kantian way, one could say that we encountered the limit behind which the thing-in-itself (Ding-an-sich) is hiding. I have a hunge (even more vague than 'opinion'), that there will be no new experiments that will close some of the remaining interpretations (MWI, superdeterminism (of which Sabine Hossenfelder is a fan), counterfactual definiteness). But more Zeilingers will stand up, and will design more unbelievable applications of entanglement. And who knows, some day my hunge and opinion turn out to be wrong?

Can you tell us, why you are so attached to the idea of non-locality? Or what you have against loosening our conception of realism? You see, the moon really is there, even if we do not look up. But we cannot observe the wave function. It is only at this very deep level we must loosen our concept of realism, not in our daily life.

Edited by Eise
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3 hours ago, Eise said:
23 hours ago, bangstrom said:

Bells Inequality: the weirdest theorem in the word | Nobel …"

It is really amusing to see how you shoot yourself in the foot again and again. At about 10:05:

Quote
The video says nothing can travel faster than light and I have no objection to that statement. I understand that to mean no thing can travel faster than light and a thing is something with mass.
The conventional wisdom is that light can travel as fast as light because a photon is massless. A quantum wave function is also massless so a wave function should be able to travel at least as fast as light.
With entanglement, the wave function is considered to be able to connect entangled particles over any given distance which necessarily means that it extends across a space-like, measurable by a clock, span of time. The wave function can be considered to be either forward or backward in time depending upon from which end it is observed.
When entanglement is lost, it is lost instantly across both ends of the wave function and experiments have demonstrated that the changes to one particle are simultaneous with changes other particle. This is why the interaction is considered to be non-local and FTL. Since no physical connection is involved, that is what Einstein called “Spukhafte Fernwirkung” and he thought, That can't be right.
That is the 'realism' we have to give up.
3 hours ago, Eise said:

Can you tell us, why you are so attached to the idea of non-locality? Or what you have against loosening our conception of realism? You see, the moon really is there, even if we do not look up. But we cannot observe the wave function. It is only at this very deep level we must loosen our concept of realism, not in our daily life.

I think we need to abandon 'realism' at the quantum level but not at the macro level because that is where it works- nearly all of the time.

I never felt I understood the nature of light until I encountered non-locality and then all the things that never made sense before began to make sense. Non-locality also simplifies the explanations of SR without changing it one bit except that all of the light related paradoxes vanish. That is, things like the ‘Pole in a Barn’ paradox that only adds to the confusion.

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5 hours ago, bangstrom said:

The Alice and Bob analogy assumes a single reference frame. Your comment about other reference frames is a ridiculous obfuscation. And, please, oh please, do learn something about QM from this past half century. The EPR effect is dead and non-locality is real.

Nope!

4 hours ago, Eise said:

I did. In my opinion (maybe Swansont, Joigus, and MigL would not agree, that's why I say 'opinion') that in QM, more specifically the wave function, we have reached the limit of our our capacity to know and understand nature. In a Kantian way, one could say that we encountered the limit behind which the thing-in-itself (Ding-an-sich) is hiding. I have a hunge (even more vague than 'opinion'), that there will be no new experiments that will close some of the remaining interpretations (MWI, superdeterminism (of which Sabine Hossenfelder is a fan), counterfactual definiteness). But more Zeilingers will stand up, and will design more unbelievable applications of entanglement. And who knows, some day my hunge and opinion turn out to be wrong?

Can you tell us, why you are so attached to the idea of non-locality? Or what you have against loosening our conception of realism? You see, the moon really is there, even if we do not look up. But we cannot observe the wave function. It is only at this very deep level we must loosen our concept of realism, not in our daily life.

I think these comments get to the heart of the matter from a philosophical POV. My take on it is the wave function represents infinitely many occurrences we simply cannot tell apart from each other. IMO, up to a certain point, to the extent that the theory has been mathematically understood, choices may open up.

Don't forget that, even when quantum mechanics has given you a valid choice for your $$\left|\psi\right\rangle$$, there are infinitely many prescriptions equivalent to each other. Once we've written the state vector in the so-called position representation,

$\left\langle \left.x\right|\psi\right\rangle =\psi\left(x\right)$

we can still change the prescription point-wise as long as there is a gauge field accompanying it,

$\psi\left(x\right)\rightarrow e^{iq\theta\left(x\right)}\psi\left(x\right)$

$A^{\mu}\left(x\right)\rightarrow A^{\mu}\left(x\right)-\partial^{\mu}\theta\left(x\right)$

So right there gauge ambiguity is telling you your state object is very, very far away from being determined.

If I had to bet, I'd say the "mysterious part" --the persistent thwarting of any attempts on our part to determine the system-- is hidden under the carpet of gauge ambiguity:

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Gauge invariance: the results of the experiments are independent of the choice of the gauge for the potentials

Note that in these experiments, the only quantity that affects the result is the difference in phase between the two parts of the electron wave. Suppose we imagine the two parts of the electron wave as tiny clocks, each with a single hand that sweeps around in a circle, keeping track of its own phase. Although this cartoon ignores some technical details, it retains the physical phenomena that are important here.[17] If both clocks are sped up by the same amount, the phase relationship between them is unchanged, and the results of experiments are the same. Not only that, but it is not even necessary to change the speed of each clock by a fixed amount. We could change the angle of the hand on each clock by a varying amount θ, where θ could depend on both the position in space and on time. This would have no effect on the result of the experiment, since the final observation of the location of the electron occurs at a single place and time, so that the phase shift in each electron's "clock" would be the same, and the two effects would cancel out. This is another example of a gauge transformation: it is local, and it does not change the results of experiments.

The spin factor of the state being even more deeply non-realist than the space-time part. IOW: Spin variables cannot even be represented by commuting variables.

Edited by joigus
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47 minutes ago, joigus said:

Nope!

Why do you think I don’t understand? Initially, Alice think she is first and Bob thinks he is first but it maks nix. The wave function decides.

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9 minutes ago, bangstrom said:

Why do you think I don’t understand? Initially, Alice think she is first and Bob thinks he is first but it maks nix. The wave function decides.

Alice and Bob are sitting in the same reference frame. They can use laser to determine they saw it at the same time. They determine they saw it at the same time!!! (In their common inertial reference frame.)

Carla and Daniel, on the other hand, equipped with lasers too, are sitting each one on yet two more inertial reference systems. They infer different coordinates for the reception. From the POV of Carla, Bob's photon reaches Bob before Alice's photon reaches Alice; from the POV of Daniel, Alice's photon reaches Alice before Bob's photon reaches Bob.

Why do I think you don't understand? Because you don't. You simply don't understand it. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't.

Don't. Don't. Don't. Don't. Don't. Don't. Don't. Don't. Don't.

Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do.  Oh, please, do.

Edited by joigus
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1 hour ago, bangstrom said:

Why do you think I don’t understand? Initially, Alice think she is first and Bob thinks he is first but it maks nix.

Fully agree with Joigus. You just showed that you do not understand one single word that MigL, Joigus and I said when considering relativity in such entanglement experiments. And Joigus made such a beautiful drawing, exactly showing what I meant (+1).

You are nearing the troll-zone. Instead of sticking to your viewpoint, try to understand what here is said. Please do.

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9 minutes ago, Eise said:

Fully agree with Joigus. You just showed that you do not understand one single word that MigL, Joigus and I said when considering relativity in such entanglement experiments. And Joigus made such a beautiful drawing, exactly showing what I meant (+1).

You are nearing the troll-zone. Instead of sticking to your viewpoint, try to understand what here is said. Please do.

Jawohl! Es macht sinn!

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8 hours ago, bangstrom said:

I haven’t been ignoring the “suggestion”. I just don’t follow the practices here of saying you are wrong and confused and your idea is garbage if I disagree. Nor do I think unsupported personal opinions pass for expertise. I don’t find these things very convincing and many others in other science forums must not either since personal comments and unsupported opinions are less infrequent.

If you aren’t ignoring it, please show me where QM requires the signal you insist is present.

Not your personal unsupported opinion, mind you.

2 hours ago, bangstrom said:

Why do you think I don’t understand? Initially, Alice think she is first and Bob thinks he is first but it maks nix. The wave function decides.

You really have no clue about relativity and simultaneity, too.

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On 10/13/2022 at 11:52 AM, bangstrom said:

"Bells Inequality: the weirdest theorem in the word | Nobel …"

Some cleaning up of silliness seems necessary. I can't let this go. I don't know who said it, but it's sooo foolish...

Bell's inequality is certainly not the weirdest theorem in the world. It represents the common world. The world of "yes" and "no."

I'm not responsible for stupidity propagating around, nor is @Eise, nor is @MigL, nor is @swansont, nor is @Ghideon.

Bell's theorem is about classical propositions. How could it be "weird"? What's "weird" is, perhaps, its violation.

A = My cat is alive

Not A = My cat is not alive

B = My sweetheart is happy

Not B = My sweetheart is not happy

C = the kid is a girl

Not C = the kid is not a girl

Probability(A, not B)+Probability(B, not C)  is greater or equal than Probability(A, not C)

The CSHS inequalities are are more suitable version for experimental verification. Thanks to @Ghideon. +1

How is that strange? It's far from obvious, but not strange at all.

What's strange is that (colour for dramatic effect),

Quantum mechanical probabilities violate this!!!

This is because, for quantum mechanics:

Probability(Sx=up,S45º=down)+Probability(S45º=up,Sy=down) is less than Probability(Sx=up,Sy=down)

And how could that be? Only because a premise of the theorem is wrong. Which one? The assumption that variables are either this or not this. (The assumption of realism.) The premises of the theorem are so weakly-assuming that there is no other option. IOW, there's barely any other premise. It even includes as a possibility statistical dependence: A totally contained in not B, etc.

Because quantum mechanics allows for states for which my cat is neither alive nor dead, etc, with a probability amplitude that the cat is 1/sqrt(2) alive and 1/sqrt(2) dead, QM violates the otherwise simplemindedly-true, but devilishly astute, theorem due to Bell.

And that's almost all there is to it.

What are classical data? What happens when my sweetheart is definitely not happy? That's another matter.

Does decoherence arise "instantaneously"? (whatever that means.) That's another matter too.

Edited by joigus
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4 hours ago, bangstrom said:

When entanglement is lost, it is lost instantly across both ends of the wave function and experiments have demonstrated that the changes to one particle are simultaneous with changes other particle. This is why the interaction is considered to be non-local and FTL. Since no physical connection is involved, that is what Einstein called “Spukhafte Fernwirkung” and he thought, That can't be right.

No need anymore to comment on this.

4 hours ago, bangstrom said:

That is the 'realism' we have to give up.

But then, we see how you bend what is said, even in your video. At 7:55 she says that the only two assumptions that went into the CHSH inequality are locality and realism. See the screenshot I made from the video.

So it is locality or realism (or both) that we must give up. And to repeat: later on she says "The way that most scientists have interpreted this, is that we have to give up on the idea of realism".

Edited by Eise
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4 hours ago, joigus said:

You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't. You don't.

Don't. Don't. Don't. Don't. Don't. Don't. Don't. Don't. Don't.

Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do.  Oh, please, do.

Am going to try and read this thread this weekend, not only to better understand the scientific attitudes towards realism, but also how someone broke Joigus.  JK.

Years ago, I had this notion that entanglement was analogous too two distant astronauts tethered together.  When the tether breaks in the middle, there is no FTL signal, but their state changes instantly to "untethered." Nothing spooky.  Just a change such that, if we measure either astronaut for tetheredness, we will find them unmoored.  Yeah.  That was when I realized it was a mistake to map RW situations onto QM.

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There seems to a major misunderstanding here and it has nothing to do with SR.

I can give a simple example and, if it makes sense, we can go from there.

Suppose you take two firecrackers and twist the fuses together so when lit they both go off at the same time. You light the fuses and both firecrackers go off so close to the same time that there is no way of knowing which went first. It is next to impossible to get two firecrackers to fire simultaneously because one fuse might catch before the other, manufacturing differences, lengths etc. etc..

You have four observers, who because of SR have four different views of the timing and they may have even been able to observe which firecracker they think went first. The problem is which observer caused one firecracker to go before the other.

I would say none of them caused the event because all observations were made after the event. Is that clear?

Looking at an experiment, Alice and Bob are one light second apart.

A...................................................................Source...................................................................B

<-- one light second apart -->

The dotted line is the non-local wave function between the two entangled particles.  If Alice measures her particle one nano sec. before Bob, this instantly fixes the quantum identity of Bob's entangled particle so it is anti-correlated with Alice's particle.

If Bob measures his particle one nano sec. after Alice, somehow his observation should be anti-correlated with hers. It is not necessary that Bob know what Alice's observation was or that he know his observation was not first and he need not wait for a light speed signal to reach his location.

The entangled particles 'know' how to respond to the loss of entanglement and that is what matters.

The violation of the Bell test indicates that the quantum properties of the entangled particles are not established from the start so the first observation is random (Alice's observation in this case) and the second observation is instantly decided by the first. Even if it is beyond the range of a light speed signal.

The observations of outside observers do not switch which observation came first because the die is cast with the first local observation. I have explained this several times before in bits and pieces but here it is it is in one post