# crowded quantum information

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2 hours ago, joigus said:

And it doesn't because all the alternatives that were coded in the quantum superposition in some sense disappear.

Sorry, I meant:  because all the other alternatives that were coded in the quantum superposition in some sense disappear. I'm sure most people understood that.

3 hours ago, NTuft said:

For illustrative purposes, even though this is a scienceforum; there's been a 17-page shootout here between a group on a bandwagon and a lone @bangstrom on a horse. @Mitcher tried to help but @swansont killed him by saying he couldn't speculate (and we wouldn't want him speculating in here against our conceptually Holey but well quantified Law of Relativity). I told you Murray Gell-Man got mad and left the wagon train to go off and was camping somewhere and devising consistent histories around the campfire. A.F. Kracklauer is now up ahead at the pass through the gorge about to blow the dynamite and close the pass on all your arguments regarding even needing to give up locality or realism.

Funny summary.

4 hours ago, NTuft said:

This other paper in, "Open Physics", is by Louis Sica who's been on this topic a while:

Funny too, but in the other sense. It is my impression that if you sit long enough and think about Bell's analysis, you're bound to eventually find yet another possible loophole for some kind of "weak realism", or another.

Maybe some kind of "emergent realism," or "fiduciary realism," as I tend to see Bell's beables, "superdeterminism," "hypercontextuality." I'm expecting new fancy concepts, most of them probably not very compelling, and having to face the inevitable sharp edge of Ockam's razor.

The inspiring mood being: Try to find a way in which you can weaken the reality hypothesis, and you can find a way out.

I was in the middle of writing this when @MigL's comment popped up, very much in that direction:

31 minutes ago, MigL said:

Joigus post above, reminds us of the many interpretations of QM.
All equally valid, and all equally nonsensical from our classical macro perspective.

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Fine

On 10/16/2022 at 4:12 AM, Eise said:

QM. Just QM.

[...]

Because, from a classical view, the results are outrageous. Two of the fundamental assumptions of classical physics are challenged, locality and realism (in the technical sense of those words, not of your vague interpretations of them, see CHSH). There obviously were physicists that trusted QM so much, that they did not find it necessary to do such experiments, e.g. Feynman.

[...]

I'm sure most realize it but to be explicit, we've branched from QM to Quantum Field Theory(QFT) which most often does bring along Special Relativity. And the CHSH game, or the version with two referees judging timing, may be drawing a line between the classical and quantum versions of Bell's inequality:

Quote

[...]In the following sections, it is shown that if Alice and Bob use only classical strategies involving their local information (and potentially some random coin tosses), it is impossible for them to win with a probability higher than 75%. However, if Alice and Bob are allowed to share a single entangled qubit pair, then there exists a strategy which allows Alice and Bob to succeed with a probability of ~85%.

Most of the experiments seem to use measuring polarized light as a proxy for entangled electrons as Bell had intended.

On 10/21/2022 at 12:56 AM, Eise said:

[...]

It is called the singlet state, and QM shows it can be created.

In that you shifted the meaning away from how it is used in the CHSH inequality. For you, realism includes locality. For CHSH it doesn't.

Here you are redefining it:

That simply is not what CHSH is about. It clearly distinguishes the two assumptions on which it is based: locality on one side, realism on the other side.

From reading Kracklauer, he seems to state that the only appropriate distinction regarding non-commutating measures in QM relates to the uncertainty principle. So one end of either momentum or position; joigus superbly explicates the math/physics formalism for locality.

On 10/21/2022 at 6:49 PM, MigL said:

Information, according to Relativity is constrained to stransfers equal to, or less than, the speed of light.
Are you saying Relativity is wrong ?

No, they did not demonstrate the 'reality of non-locality'.
They demonstrated the absence of local realism.

You can twist and bend that as much as you like, but they are NOT equivalent.

I don't think Relativity needs to come into the discussion regarding QM or QFT. It is brought out as a litmus test for trying to weigh an interpretation's plausibility but I don't think that's valid here. To point to the second postulate of S.R. is to sidestep the point of contention at issue here with regards to entanglement.

On 10/24/2022 at 3:58 PM, hoola said:

for some reason, my newer entries were not displayed on the last page, but the first, so let me re iterate what I said recently. If entangled particles can be considered as matter waves only until wavefunction collapse, and each matterwave  has a distinct, but inverted waveform, running parallel to each other, and proximate enough to induce cancellation, then an increase in spatial separation of the two data streams sufficient to cause them to not interfere would allow them to re appear as real data pertaining to both particles properties, allowing the collapse of the wavefunction into their particular structures. The fact of the two data streams being inverted offers the reason to expect the particles to have the opposite spins. I will go back to the bottom of page one to see if they are still there, as they have a more complete dialogue on what I am saying now....well, they certainly are not there, and since the idea will certainly be broadly panned, I will not persue the matter unless there is any interest of a further explanation.

So the idea of wave function collapse explained by the projection postulate as reality condensing to a certain possible superposition is the measurement problem in QM. I read your conjecture here to hinge on wave->particle duality taking a direction or shape as in going from a wave to a particle upon observation, is that what you're envisioning?

On 10/27/2022 at 3:18 AM, bangstrom said:

[...]

Correlation between distant points and under varying conditions requires some form of signaling. Violations of Bell's ineqalities and Zeilinger's teleportation rule out the possibility that particle's quantum properties are not unchanged from the start.

Entangled particles act as if they are side-by-side so any action on one end instantly affects the other as a single event. There is no space-like separation at the particle level, in the way there is at the macro level, so all interactions are essentially instant at the particle level for entangled particles.

Realism accepts that the cause of a physical change must be local in that it requires a physical interaction between a cause and effect. It also accepts that objects are real and exist in our physical universe independent of our minds. We live in an objective reality, not one which exists only in our minds or which takes form only upon our looking at it.

On further reading I am open to the possibility that instant action at a distance is 'local' since everything is instant and local for entangled particles and there is no space-like timing between them. I have always considered the emission and absorption of light to be simultaneous events from the perspective of light itself.

As Carver Mead explains, every electron, when the resonant conditions between permit, is capable of a direct interaction with any other electron on the same Minkowski light cone. I can understand that kind of locality but I don't recognize it as the same locality discussed here.

On 10/27/2022 at 4:36 AM, joigus said:

[...] It's not a minor point. It's very important.

It's the essence of the projection postulate, which is deeply non-local, but has no non-local consequences. Only problem: It's just a convention. It's not an evolution law for the state, and certainly not a law of physics. And most importantly, it has no experimental consequences. It was theoretically designed to do exactly that. Go back to my comment on FAPP's Bell's comment.

Most physicists that contributed to the formulation of QM had no problem in seeing the state vector as just an epistemic book-keeping device, reflecting our knowledge. That's why they had no problem in introducing a non-local, non-unitary mathematical convention of which no non-local consequences could be derived.

And last, but not least, as Eise has said above: No. Non-locality does not imply non-realism. They are very different assumptions. Example: Plane waves propagate in a totally local way. Yet, by virtue of selecting the momentum, the position is totally undetermined. That's local non-realism at its simplest, even before we start talking about entanglement.

[...]

Here, if momentum is zeroed to a finite precision, which is questionable, and the position is totally undetermined doesn' that equate to non-locality? I realize you later explain non-locality explicitly.

On 10/13/2022 at 9:49 AM, swansont said:
!

Moderator Note

Such speculation should go in its own thread

I can't get back all the quotes I had, but @Mitcher seemed to be referring to Kaluza-Klein theory when he mentioned an oblique 5th-dimension in which apparent long distances are effectively local, so I think he was not in unacceptable territory but was meeting some speculation with some well-supported science:

Quote

In 1926, Oskar Klein gave Kaluza's classical five-dimensional theory a quantum interpretation,[4][5] to accord with the then-recent discoveries of Heisenberg and Schrödinger. Klein introduced the hypothesis that the fifth dimension was curled up and microscopic, to explain the cylinder condition. Klein suggested that the geometry of the extra fifth dimension could take the form of a circle, with the radius of 10−30 cm. More precisely, the radius of the circular dimension is 23 times the Planck length, which in turn is of the order of 10−33 cm.[5] Klein also made a contribution to the classical theory by providing a properly normalized 5D metric.

3 hours ago, swansont said:

Correlation is not an interaction, and the correlation is present at the beginning.

This applies to you, too.

Will try to provide supporting evidence to assertions as should be required.

1 hour ago, MigL said:

[...]
All equally valid, and all equally nonsensical from our classical macro perspective.

[...]

I'm not an aether fan-boy; I see it as a useless ( and incredible ) add-on, much like I view non-local 'interactions'.

[...]

Bully, I say. As swansont also mentioned aether not being necessary, I would agree, but only because the patch-work put together is now effectively an elastic dielectric medium for wave propagation and the vacuum energy may even be non-zero (ok, crank-case speculations here). This is on par with higher education, so thanks.

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30 minutes ago, NTuft said:

Here, if momentum is zeroed to a finite precision, which is questionable, and the position is totally undetermined doesn' that equate to non-locality? I realize you later explain non-locality explicitly.

Not exactly.

The correct statement is: If momentum is zeroed-in with a finite precision of, say, $$\Delta p_x$$, x-position can be zeroed-in with finite precision no better than that given by HUP. That is $$\triangle p_{x}\geq\frac{\hbar}{2\triangle x}$$. When $$\triangle p_{x}=\frac{\hbar}{2\triangle x}$$, you get "minimal packets."

But even in this desirable situation, you cannot get perfectly defined momentum. And worse: even though packets left to free evolution tend to get "plane-wave" profile, and thereby more and more defined momentum, their position precision spreads as they go, like this.

So the situation is far from being as clean as Einstein would have wanted it to be.

I'm sure that's the reason behind the fact that David Bohm took the whole discussion to spin. In that case, you can devise a situation in which an observable is constructed by adding up two "statistically disperse" variables, while the sum of both is "statistically dispersionless."

This situation does not equate with non-locality, as it's just a matter of waves of different frequencies (and wave numbers) having different phase velocities, which becomes transparent when you do their Fourier analysis.

So no, this is not non-locality. Waves --that are not solitons-- on the surface of the water, also suffer the same kind of dispersion.

Edited by joigus
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1 hour ago, NTuft said:

I can't get back all the quotes I had, but @Mitcher seemed to be referring to Kaluza-Klein theory when he mentioned an oblique 5th-dimension in which apparent long distances are effectively local, so I think he was not in unacceptable territory but was meeting some speculation with some well-supported science:

It’s incumbent on a poster to make such connections and explain the relevance of it. In this case, some work that cites a work tying K-K theory to entanglement. Just seeing mention of a fifth dimension and knowing there’s a hypothesis with five dimensions is speculation without it. For you to think this is not speculation, surely you have a citation in mind. Please share it.

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On 10/29/2022 at 6:47 AM, swansont said:

Correlation is not an interaction, and the correlation is present at the beginning.

I will leave it to you to speculate about how a correlation is not an interaction?

The correlation may be present from the beginning but the quantum properties have been demonstrated to be random at the first observation and instantly predictable at the second observation. If the observed properties were unchanging from the first, then the instant correlation could have a simple classical explanation but it has been determined that this is not the case.

This makes it difficult to explain how a correlation can be constantly maintained from one end of the connection to the other, no matter what the distance between, without some kind of an instant signal common to both ends of the entanglement.

The conventional explanation is that the quantum properties are random, indeterminate and superimposed prior to the first observation. This explains the random nature of the observation but it doesn’t explain the correlation.

Some have described the connection between the two or more entangled particles as a Schroedinger wave-like connection and that implies some kind of a circular undulation like the one depicted with “Hoola’s” wave a few posts ago. If the two particles are always at opposite points of the wave function such that, when one particle is at a point that could be considered the ‘peak’ of the wave, the other particle will be at a point that could be considered the ‘trough’. This could explain how the entangled particles remain anti-correlated where opposite positions on the common wave function represent opposite quantum properties.

N. “Viv” Pope explained the connection as “swapping stools” much like two persons in a game of musical-chairs with two chairs. When the music stops, each one grabs a chair but they will always be anti-correlated.

The first observation is the thing that breaks the entanglement and the loss of a connecting wave function instantly ‘stops the music’ on both ends and this signals each particle to take on an identity that is appropriate for whichever its position on the wave function calls for at the time.

In this scenario, the connecting wave function is what maintains the correlation and the instant loss of entanglement is the signal that ‘stops the music’ and ends the entanglement leaving the particles on both ends of the former entanglement with the appropriate anti-correlated quantum properties.

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10 hours ago, bangstrom said:

I will leave it to you to speculate about how a correlation is not an interaction?

OK, that makes no sense.

10 hours ago, bangstrom said:

The correlation may be present from the beginning but the quantum properties have been demonstrated to be random at the first observation and instantly predictable at the second observation. If the observed properties were unchanging from the first, then the instant correlation could have a simple classical explanation but it has been determined that this is not the case.

This makes it difficult to explain how a correlation can be constantly maintained from one end of the connection to the other, no matter what the distance between, without some kind of an instant signal common to both ends of the entanglement.

For entangled spins, it’s because angular momentum is conserved.

Energy is going to be conserved, too. But nothing has be “constantly maintained” in order for that to happen.

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14 hours ago, bangstrom said:

I will leave it to you to speculate about how a correlation is not an interaction?

Again???

No room for speculation when something is obvious.

14 hours ago, bangstrom said:

The correlation may be present from the beginning but the quantum properties have been demonstrated to be random at the first observation and instantly predictable at the second observation. If the observed properties were unchanging from the first, then the instant correlation could have a simple classical explanation but it has been determined that this is not the case.

No problem at all in obtaining classical systems with random variables that are perfectly anti-correlated.

No need for causation at a distance to explain the correlations. You put, say, the single left-handed woman in one space pod and the married right-handed man in the other. You throw a coin to decide who goes where.

You can have as many random, compatible, anti-correlated properties as you want for boots, coins, umbrellas, dice, gloves, armadillos or astronauts.

No problem at all in obtaining classical systems with random variables that are perfectly non-correlated.

No need for causation at a distance to explain any non-correlations. You put the ambidextrous professor of Russian Literature in one space pod, and the left-handed Vegas hooker in the other.

What you can't get with classical systems is random variables that are perfectly anti-correlated for certain pairings of observables, while perfectly non-correlated for other pairings of observables. What you can't get with classical systems is both at the same time.

But again, no need for causation at a distance to explain the overall correlations. The quantum state has all you need, and it was prepared at one small region of space, and at one time.

I'm working on an example that's so transparent that even you will have to agree with it. Let's see what happens.

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On 10/31/2022 at 2:16 PM, joigus said:

But again, no need for causation at a distance to explain the overall correlations. The quantum state has all you need, and it was prepared at one small region of space, and at one time.

Again, are you saying the quantum properties of entangled particles are ‘fixed’ at the start and unchanging? This is contrary to the Bell test and Zeilinger’s teleportation experiments would be impossible if it were so.

This should be a yes or no question. More examples with macro objects will not answer the question since the question is about entangled “particles” and not macro objects after separation.

On 10/31/2022 at 9:40 AM, swansont said:

Energy is going to be conserved, too. But nothing has be “constantly maintained” in order for that to happen.

Energy, spin and all other properties are conserved but are the quantum properties unchanging? Are you saying they are fixed from start to finish?

On 10/31/2022 at 2:16 PM, joigus said:

I'm working on an example that's so transparent that even you will have to agree with it. Let's see what happens.

I'm waiting.

On 10/29/2022 at 4:33 AM, joigus said:

What people (sometimes, quite loosely, quite sloppily) call "quantum non-locality) is not that. Quantum theories allow you to prepare states that have no definite value of these locally-conserved quantum numbers Q, and then measure their value at the boundary. So you force the quantum state to "decide" (select, einselect) what particular value of the quantity Q it --for lack of a better word-- "encapsulates."

"So you force the quantum state to "decide" (select, einselect) what particular value of the quantity Q it --for lack of a better word-- "encapsulates."

How does that 'force to decide' not involve some kind of a signal?

On 10/29/2022 at 4:33 AM, joigus said:

You can do pairs of measurements for space-like separated events (so no light ray can join them) or for time-like separated events (so the time ordering between the events is observer-independent: the later one is in the light cone of the previous one). That really doesn't make that much of a difference. And it doesn't because all the alternatives that were coded in the quantum superposition in some sense disappear.

The individual quantum properties are binary, either one state or another, and they don’t disappear with the loss of entanglement. They become determinate. What happens with the others is unknown because we can only observe one property and that causes entanglement to be lost.

On 10/29/2022 at 4:33 AM, joigus said:

You can do pairs of measurements for space-like separated events (so no light ray can join them)

Would you say space-like separated particles interacting on the same light cone are local or non-local?

I would call that a non-local interaction. If that is 'local,' what would you call non-local? Or, are you saying nothing is non-local?

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3 hours ago, bangstrom said:

Energy, spin and all other properties are conserved but are the quantum properties unchanging? Are you saying they are fixed from start to finish?

Are you incapable of determining whether or not I said that? Or that I’ve repeatedly confirmed that the states are undetermined?

I guess reading comprehension is one of the issues here.

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2 hours ago, bangstrom said:

I'm waiting.

Yeah, sure. You're waiting. It takes half a minute to dismiss other people's careful arguments with no arguments of your own. But it takes a bit longer to prepare a carefully-thought argument.

3 hours ago, bangstrom said:

Would you say space-like separated particles interacting on the same light cone are local or non-local?

I would call that a non-local interaction. If that is 'local,' what would you call non-local? Or, are you saying nothing is non-local?

See my point? With this degree of carelessness it's gonna be hard. When one event is within the absolute future light-cone of another, you don't need to invoke non-locality/violation of relativistic causality to explain it. Maybe thowing a stone would suffice.

It's with spacelike-separated events that you do.

Do we have to go to the basics of SR every time you say something?

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5 hours ago, swansont said:
8 hours ago, bangstrom said:

Energy, spin and all other properties are conserved but are the quantum properties unchanging? Are you saying they are fixed from start to finish?

Are you incapable of determining whether or not I said that? Or that I’ve repeatedly confirmed that the states are undetermined?

I guess reading comprehension is one of the issues here.

We both know entangled particles are indeterminate before the first observation is made so why tell me they are indeterminate?

Quantum particles have observable properties BEFORE and or AFTER entanglement and you say they are coordinated or anti-coordinated after entanglement.

The Bell test and quantum teleportation experiments tell us that any AFTER property is not necessarily the same as the BEFORE. Do you agree with this observation or not?

5 hours ago, joigus said:

See my point? With this degree of carelessness it's gonna be hard. When one event is within the absolute future light-cone of another, you don't need to invoke non-locality/violation of relativistic causality to explain it. Maybe thowing a stone would suffice.

It's with spacelike-separated events that you do.

Do we have to go to the basics of SR every time you say something?

Entanglement is not SR and think about what you said in the above.

Every particle large or small is “within the absolute future light-cone of another.” If that is your understanding of ‘entanglement’ then every interaction is an entanglement so entanglement is no different from throwing a stone.

I don’t know if that is what you mean but that is what you appear to have been saying the whole time.

Do you recognize that there is a difference between entanglement and classical interactions?

5 hours ago, joigus said:

Yeah, sure. You're waiting. It takes half a minute to dismiss other people's careful arguments with no arguments of your own. But it takes a bit longer to prepare a carefully-thought argument.

I know the problem well so take your time.

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1 hour ago, bangstrom said:

Entanglement is not SR and think about what you said in the above.

Every particle large or small is “within the absolute future light-cone of another.” If that is your understanding of ‘entanglement’ then every interaction is an entanglement so entanglement is no different from throwing a stone.

I don’t know if that is what you mean but that is what you appear to have been saying the whole time.

Do you recognize that there is a difference between entanglement and classical interactions?

No. It is simply not true that every particle is within the absolute future light cone of another. This proves an absolute ignorance of the principles of special relativity. You know nothing about SR, that's clear enough for everybody here.

When the interval between two particles (instants in their respective histories, viewed as events) is of time-like character, then one is in the future light cone of the other, and the character of time ordering between both is observer-independent.

When the interval between such two events is spacelike, on the other hand, the time ordering between them is observer-dependent.

Of course there is a difference between entanglement and classical interactions. Do I have to go back to square one to explain it to you again?

This is the kind of babbling nonsense I have to put up with:

9 hours ago, bangstrom said:

Would you say space-like separated particles interacting on the same light cone are local or non-local?

I would call that a non-local interaction. If that is 'local,' what would you call non-local? Or, are you saying nothing is non-local?

Particles are neither space-like or time-like separated. Events are.

Local or not is not an attribute of particles. It's an attribute of interactions and/or evolution of the state.

When two events are on the same light cone, they are causally connected.

Can you get anything, anything!!! right???

Just one little elementary thing. Can you just get one little elementary factoid of SR right?

Edited by joigus
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He’s gotten a rise out of you, so from the perspective of a troll he’s done that right

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2 hours ago, bangstrom said:

We both know entangled particles are indeterminate before the first observation is made so why tell me they are indeterminate?

Because you asked “Are you saying they are fixed from start to finish?”

Now you admit to knowing that I was not. One wonders why you asked the question.

2 hours ago, bangstrom said:

Quantum particles have observable properties BEFORE and or AFTER entanglement and you say they are coordinated or anti-coordinated after entanglement.

The Bell test and quantum teleportation experiments tell us that any AFTER property is not necessarily the same as the BEFORE. Do you agree with this observation or not?

No. You can’t tell what the property was before, since you can’t tell identical particles apart, and/or there was no known “before” property. In parametric down-conversion, for example, the photons are created as entangled. There is no “before” state.

You’ve not shown an example of a system that has a “before” state that could be identified.

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10 minutes ago, iNow said:

He’s gotten a rise out of you, so from the perspective of a troll he’s done that right

You're probably right, but that's the last thing on my mind, as concerns this "debate."

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12 hours ago, swansont said:

Because you asked “Are you saying they are fixed from start to finish?”

Now you admit to knowing that I was not. One wonders why you asked the question.

I asked the question because your explanations of why the particles always appear anti-coordinated only work when one assumes that they are unchanging as with the 'gloves in boxes' example or how the particles are always anti-correlated with no signal between them. I wasn't asking about the quantum properties while they were entangled.

12 hours ago, swansont said:

You’ve not shown an example of a system that has a “before” state that could be identified.

Knowing the “before” state is not necessary to observe that changes in the quantum properties of entangled particles are taking place.

It is NOT necessary to know the ‘before’ state with the Bell test. The Bell test demonstrates that there are more possible outcomes of an ‘after’ observation when more than a single quantum property is observed than are possible with the classical model where the quantum properties are fixed and unchanging from the start.

Are you implying the Bell test is faulty?

Also, knowing the ‘before’ identity is also NOT necessary for quantum teleportation because a second entanglement can change the observation of a remote entangled particle from indeterminate to determinate.

If you understand how quantum teleportation, works you should know that the instant teleportation of a single quantum property from one particle to that of a remote entangled particle is only possible if the quantum property under observation is capable of being instantly changed (teleported) from one particle to a distant particle.

You may not know what the quantum property of the particle may have been without teleportation but you can reliably predict what it will be after teleportation because it will always be identical to the identity of the particle whose property you teleported. This requires some kind of instant signaling between the particles.

Experiments demonstrate that the quantum properties of entangled particles are random and anti-coordinated on both ends of an entanglement and become determinate when the first particle is observed. So how does a particle on one end of a remote entanglement 'know' it should be anti-coordinated with its partner when its distant partner is observed without some kind of an instant signaling?

12 hours ago, swansont said:

Edited by bangstrom
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4 hours ago, bangstrom said:

I asked the question because your explanations of why the particles always appear anti-coordinated only work when one assumes that they are unchanging as with the 'gloves in boxes' example or how the particles are always anti-correlated with no signal between them. I wasn't asking about the quantum properties while they were entangled.

Knowing the “before” state is not necessary to observe that changes in the quantum properties of entangled particles are taking place.

It is NOT necessary to know the ‘before’ state with the Bell test. The Bell test demonstrates that there are more possible outcomes of an ‘after’ observation when more than a single quantum property is observed than are possible with the classical model where the quantum properties are fixed and unchanging from the start.

Are you implying the Bell test is faulty?

Also, knowing the ‘before’ identity is also NOT necessary for quantum teleportation because a second entanglement can change the observation of a remote entangled particle from indeterminate to determinate.

If you understand how quantum teleportation, works you should know that the instant teleportation of a single quantum property from one particle to that of a remote entangled particle is only possible if the quantum property under observation is capable of being instantly changed (teleported) from one particle to a distant particle.

You may not know what the quantum property of the particle may have been without teleportation but you can reliably predict what it will be after teleportation because it will always be identical to the identity of the particle whose property you teleported. This requires some kind of instant signaling between the particles.

Experiments demonstrate that the quantum properties of entangled particles are random and anti-coordinated on both ends of an entanglement and become determinate when the first particle is observed. So how does a particle on one end of a remote entanglement 'know' it should be anti-coordinated with its partner when its distant partner is observed without some kind of an instant signaling?

Yeah, yeah... Blah, blah.

Every time you're caught in an embarrassing lack of understanding of the basics of this problem, you choose not to answer and keep blowing smoke in a different direction.

Do you or do you not understand the role that the light cone plays in the discussion of causality?

This is, of course, a rethorical question, as it's pretty obvious you do not:

19 hours ago, bangstrom said:

Entanglement is not SR and think about what you said in the above.

Every particle large or small is “within the absolute future light-cone of another.” If that is your understanding of ‘entanglement’ then every interaction is an entanglement so entanglement is no different from throwing a stone.

⁉️

On 11/9/2022 at 12:33 PM, bangstrom said:

Would you say space-like separated particles interacting on the same light cone are local or non-local?

I would call that a non-local interaction. If that is 'local,' what would you call non-local? Or, are you saying nothing is non-local?

⁉️

(my emphasis.)

For two arbitrary events, A and B, A can be in the future light cone of B, A can be in the past light cone of B, or A and B can be space-like separated --ie. either one of them is outside the overall light cone of the other.

Space-like separated events are never, --repeat, never-- on the same light cone.

Events in the same light cone are causally connected. It is for events outside their respective light cones that any discussion of non-locality would make any sense. You are shockingly ignorant of the concept of causality, and of many other physical concepts.

Do some explaining and self-correcting, please, because last time you said something about this, you got it completely backwards. And stop blowing smoke.

Bad as it is, ignorance is not your problem. Your problem is you think you actually understand something, and are incapable of acknowledging your ignorance. Your problem is the --highly intellectually toxic-- combination of hubris and ignorance.

Another possibility is that two space-like separated events are both on the same (future) light cone of a previous event thus including both in the absolute future of such antecedent event. Or both are on the same (past) light cone of a subsequent event, thus including both in the absolute past of such subsequent event.

None of these qualifications is in your language. You are either sloppy, or deliberately ambiguous, or both.

Edited by joigus
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On 11/9/2022 at 3:09 PM, joigus said:

No. It is simply not true that every particle is within the absolute future light cone of another. This proves an absolute ignorance of the principles of special relativity. You know nothing about SR, that's clear enough for everybody here.

This isn't what I said but close enough. What is so wrong about this statement? Essentially it says that every particle, given enough time, will eventually interact with another particle. I don't find that to be so controversial. This statement had something to do with how a thrown stone has an impact site in its future light cone but that doesn't mean it is entangled.

Also, I learned nothing from your excellent discussion about light cones because it was nothing I didn't know before. We appear to be in general agreement but you missed the points where our views part company.

One minor point is that particles can not have a space-like separation. I say that any two particles in different locations have a space-like separation.

The only major disagreement I see is the one below.

17 hours ago, joigus said:

Space-like separated events are never, --repeat, never-- on the same light cone.

There is one remarkable exception to the rule and that is with entanglement. When two similar charged particles, usually electrons, establish a two-way resonant connection and act as if they were side-by-side, even though they may be galaxies apart, that is entanglement.

Their connection is non-local and you could say they even reside in different light cones because they have no ordinary classical connection.

On 11/9/2022 at 8:38 AM, joigus said:

Do we have to go to the basics of SR every time you say something?

As I recall there are some basics of SR that you never explained if I may go back and review.

For one, if you have a source of entangled photons (usually a down converter) exactly in the middle of two synchronized clocks, so that two photons are generated simultaneously and they reach opposite detectors at exactly the same time, how do the observer-dependent views of outside observers affect the timing of the events.

I say they have no effect on the the timing at all.

Secondly, with the same setup, if one timer is closer to the source than the other so a measurement is made on the closer particle before the farther particle, that makes the closer particle the ‘first observed’ and the difference in the timing of the measurements both time-like as well as space-like.

Then, as before, if an observer closer to the farther particle sees the farther particle as the ‘first observed’, how does this change the order of events and make the farther particle the actual ‘first observed’ and the closer particle the ‘second observed’?

I would say the local view where the closest particle is the first particle observed still holds true and the view of an outside observer has no effect on the local observation of which came first.

What is wrong with these scenarios?

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2 hours ago, bangstrom said:

This isn't what I said but close enough. What is so wrong about this statement? Essentially it says that every particle, given enough time, will eventually interact with another particle. I don't find that to be so controversial. This statement had something to do with how a thrown stone has an impact site in its future light cone but that doesn't mean it is entangled.

Also, I learned nothing from your excellent discussion about light cones because it was nothing I didn't know before. We appear to be in general agreement but you missed the points where our views part company.

One minor point is that particles can not have a space-like separation. I say that any two particles in different locations have a space-like separation.

This shows you do not even understand what SR is about. The 'objects' in a space-time diagram are events, not physical objects of any kind, so not particles either. Important to note is that the measurements (that are events) both lie in (e.g. when using electrons) or on (when using photons) the future light cone of the event in which the entangled particles were created.

2 hours ago, bangstrom said:

For one, if you have a source of entangled photons (usually a down converter) exactly in the middle of two synchronized clocks, so that two photons are generated simultaneously and they reach opposite detectors at exactly the same time, how do the observer-dependent views of outside observers affect the timing of the events.

I say they have no effect on the the timing at all.

Of course observers have no effect on the timing. But when the measurements (events!) are space-like separated, there will be observers who see Alice's measurement first, and others that see Bob's measurement first. So that would mean that the first observer must, according to you, send a FTL signal to Bob, but for another observer Bob must send a signal to Alice. But under relativity, all observers agree on what physically is happening. A signal going into one direction for one observer, and into the other direction for another observer, cannot be a physical signal. A none-physical signal is no signal at all.

And this has nothing to do with:

2 hours ago, bangstrom said:

Secondly, with the same setup, if one timer is closer to the source than the other so a measurement is made on the closer particle before the farther particle, that makes the closer particle the ‘first observed’ and the difference in the timing of the measurements both time-like as well as space-like.

Observers can perfectly calculate the delay due to their distance of the measurements. And they still will observe that they see the measurements in a different timely order. Space-like separated events do not have a defined timely order, it depends on the observer.

And don't forget: the inertial frame in which the entanglement source, and the measurement devices of Alice and Bob are standing still, is not a privileged frame.

You really do not understand SR, and the relevance of it for understanding what the true impact of entanglement is.

Edited by Eise
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4 hours ago, bangstrom said:

Essentially it says that every particle, given enough time, will eventually interact with another particle.

No. Two photons parting away from each other will never meet.

Also, light cones refer to events, not to particles. Read @Eise's comments above, if mine seem obscure to you.

4 hours ago, bangstrom said:

There is one remarkable exception to the rule and that is with entanglement. When two similar charged particles, usually electrons, establish a two-way resonant connection and act as if they were side-by-side, even though they may be galaxies apart, that is entanglement.

No, there's no "remarkable exception." Again, you ignored something I said later. I made a significant addition because I fell in the trap of your ambiguous language of referring to "a light cone" without specifying the generating event, which of course, is meaningless:

22 hours ago, joigus said:

Another possibility is that two space-like separated events are both on the same (future) light cone of a previous event thus including both in the absolute future of such antecedent event. Or both are on the same (past) light cone of a subsequent event, thus including both in the absolute past of such subsequent event.

Here's a drawing of a generic light cone, with a particle trajectory for the purposes of illustrating its role in general.

And here's a drawing of the situation in the EPR experiment, with all the light cones that are relevant to it:

So, as you can see, every event "carries" its own light cone. Measurement 1 is outside of measurement 2's light cone, and conversely, measurement 2 is outside of measurement 1's light cone; while both are well within the antecedent preparation of the quantum state's big whopping light cone.

4 hours ago, bangstrom said:

Secondly, with the same setup, if one timer is closer to the source than the other so a measurement is made on the closer particle before the farther particle, that makes the closer particle the ‘first observed’ and the difference in the timing of the measurements both time-like as well as space-like.

Then, as before, if an observer closer to the farther particle sees the farther particle as the ‘first observed’, how does this change the order of events and make the farther particle the actual ‘first observed’ and the closer particle the ‘second observed’?

I would say the local view where the closest particle is the first particle observed still holds true and the view of an outside observer has no effect on the local observation of which came first.

What is wrong with these scenarios?

What's wrong is that, for space-like separated events, time ordering is ambiguous. So the thing that's "happening" before or after, as the case may be, has to be completely ineffectual (for all intents and purposes, just a re-definition of the wave function,) and only in your mind, really. Eise has just explained how the ordering is ambiguous. If it had any consequences --measurable ones, interactions, etc.-- it would be very bad for SR. It doesn't happen.

Edited by joigus
minor correction
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On 11/9/2022 at 12:33 PM, bangstrom said:

I'm waiting.

Finally. Here it is. I'm sorry that the explanation is quite lengthy. But I hope it's transparent.

In order to explain why non-realism is all that's going on, I will try to work out an example that very much amounts to reverse-engineering Bell's deductive formulation of the contradiction between QM and hidden-variable models. I'm going to do it inductively, instead of deductively, trying to figure out what kind of (realist) collectivities you would have to postulate in order to explain quantum correlations.

Here's how you do it. Let's take pairs of astronauts, and two space pods. We pick both astronauts from certain cohorts, arranged is some way or other --we'll see about that in a moment-- so that we may hopefully reproduce the quantum correlations.

Let's introduce three basic observables for the astronauts: $$\mathcal{G}$$ (gender,) $$\mathcal{H}$$ (handedness,) and $$\mathcal{M}$$ (marital status.)

Let's assume the observables to be sharply dichotomic in their spectrum (possible outcomes of observing each property):

Gender: $$\leftarrow$$ (female), $$\rightarrow$$ (male)

Handedness: $$LH$$ (left-handed), $$RH$$ (right-handed)

Marital status: $$M$$ (married), $$S$$ (single)

Let's also assume that these properties are mutually incompatible, in the sense that I am allowed to ask the question, "is the astronaut a married person?" But then I'm not allowed to "experimentally ask" whether it's a woman, or whether it's LH or RH. We must ask one, and only one question. This is meant to crudely replicate the concept of incompatibility in QM.

Let's also represent our "hidden internal states" with round brackets. Eg. a female, right-handed, married astronaut would be $$\left(\leftarrow,RH,M\right)$$. BTW, this is what's not going to be possible.

Einstein's hope to claim these internal states as "real" (elements of reality) was that we perfom the experiments for incompatible properties by exploiting a conservation law, and asking the two incompatible questions in different sub-systems. Eg.: Gender for astronaut (1), and handedness for astronaut (2).

Let's represent pairings of experimental outcomes with square brackets: Gender for astronaut (1) and marital status for astronaut (2) would be $$\left[\mathcal{G},\mathcal{M}\right]$$, while a possible outcome would be $$\left[\rightarrow,M\right]$$, which reads: "Astronaut (1) is a male, and astronaut (2) is married."

We can, of course, decide to measure for both astronauts the same property. In our notation, that paired measurement would be represented by, eg, $$\left[\mathcal{H},\mathcal{H}\right]$$ (handedness, handedness.)

Now we select two astronauts, put one in one space pod, and the other one in the other space pod, at random: We throw a coin to decide.

Very important observation: Now we can have the space pods fly in opposite directions, or we can decide to conduct the experiment in the same place. It doesn't matter. Whether the pods are in the same place or light years apart when we do the measurement is not an issue. Quantum computations give the same result no matter what we decide at this point. That's key.

Another very important observation: At some point, you've put your finger on a real conundrum, which is what happens after we measure the properties, and the question of how the quantum state is updated. This is known as the "measurement problem," and it's part of the reason why some kind of formal non-locality could be invoked. "Formal," because no measurable consequences can be extracted from it. But that's another story. It's the story of how Copenhagen's interpretation of quantum mechanics cannot be taken but as a useful practical rule.

Now, back to our "experiment." I said:

On 10/31/2022 at 8:16 PM, joigus said:

No problem at all in obtaining classical systems with random variables that are perfectly anti-correlated.

For this to be the case, you would have to measure pairs of compatible properties. That is:

$\left[\mathcal{G},\mathcal{G}\right]$

$\left[\mathcal{H},\mathcal{H}\right]$

$\left[\mathcal{M},\mathcal{M}\right]$

As is well known, in this case the results are perfectly anticorrelated (but random!!). Examples:

$\left[\mathcal{G},\mathcal{G}\right]:\left[\rightarrow,\leftarrow\right],\left[\leftarrow,\rightarrow\right],\left[\rightarrow,\leftarrow\right],\left[\leftarrow,\rightarrow\right],\cdots$

$\left[\mathcal{M},\mathcal{M}\right]:\left[M,S\right],\left[S,M\right],\left[S,M\right],\left[M,S\right],\cdots$

$\left[\mathcal{H},\mathcal{H}\right]:\left[LH,RH\right],\left[RH,LH\right],\left[LH,RH\right],\left[LH,RH\right],\cdots$

If you think about it, in order to get this results alone, and if you insist on the triplet of properties being "real" all along, you would have to pick a cohort like,

Or perhaps others, like all $$\left(\leftarrow,LH,S\right)$$ in one sub-cohort, and the exact opposites for every property, $$\left(\rightarrow,RH,M\right)$$ in the other. There is no other way. It's the assumption of realism that leaves you no other way out.

On the other hand, I also said:

On 10/31/2022 at 8:16 PM, joigus said:

No problem at all in obtaining classical systems with random variables that are perfectly non-correlated.

And here's how. The totally uncorrelated outcomes for incompatible pairings are like,

$\left[\mathcal{G},\mathcal{M}\right]:\left[\rightarrow,M\right],\left[\leftarrow,M\right],\left[\rightarrow,S\right],\left[\leftarrow,S\right]$

$\left[\mathcal{M},\mathcal{G}\right]:\left[M,\rightarrow\right],\left[M,\leftarrow\right],\left[S,\rightarrow\right],\left[S,\leftarrow\right]$

$\left[\mathcal{M},\mathcal{H}\right]:\left[M,LH\right],\left[M,RH\right],\left[S,LH\right],\left[S,RH\right]$

$\left[\mathcal{H},\mathcal{M}\right]:\left[LH,M\right],\left[RH,M\right],\left[LH,S\right],\left[RH,S\right]$

$\left[\mathcal{H},\mathcal{G}\right]:\left[LH,\leftarrow\right],\left[RH,\rightarrow\right],\left[LH,\leftarrow\right],\left[\rightarrow,RH\right]$

$\left[\mathcal{G},\mathcal{H}\right]:\left[\leftarrow,LH\right],\left[\rightarrow,RH\right],\left[\leftarrow,LH\right],\left[\rightarrow,RH\right]$

All equally likely. Now, if you think about it, in order to get these results, and you insist on having them from statistical cohorts or picking from subcohorts that hold these properties all along, as real attributes, you have no other way but doing it from,

IOW, there is no way that you can obtain both statistical behaviours at the same time with any reasonable assumption of cohorts that hold these properties as real.

That's my reverse-engineering of Bell's theorem --or its violation by QM, to be more precise-- for you.

Note: Sorry, the usual symbols for male and female don't work here, so I've edited the Latex with $$\leftarrow$$ for "female" and $$\rightarrow$$ for male.

(Except in the pictures.)

Edited by joigus
Latex editing
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22 hours ago, Eise said:

This shows you do not even understand what SR is about. The 'objects' in a space-time diagram are events, not physical objects of any kind, so not particles either. Important to note is that the measurements (that are events) both lie in (e.g. when using electrons) or on (when using photons) the future light cone of the event in which the entangled particles were created.

The outer bounds of a space-time diagram are the propagation distance of a light flash and the inner contents of a light cone can include anything within the entire visible universe. The light cones themselves are imaginary constructs and it is legitimate to populate the cones with any ‘objects’ relative to the discussion.

The contents of a light cone are not limited to events alone and other contents frequently include particles, world world lines, smaller cones, and even space travelers as with illustrations of the twin paradox so your assertion that the addition of anything other than events alone in not kosher with SR is without merit.

19 hours ago, joigus said:
On 11/11/2022 at 2:52 AM, bangstrom said:

Essentially it says that every particle, given enough time, will eventually interact with another particle.

No. Two photons parting away from each other will never meet.

OK, but that is not what I said.

19 hours ago, joigus said:

No, there's no "remarkable exception." Again, you ignored something I said later. I made a significant addition because I fell in the trap of your ambiguous language of referring to "a light cone" without specifying the generating event, which of course, is meaningless:

The generation of an entanglement event is like the generation of a light flash. It can be anywhere an origin is possible and it makes no difference where the origin may be if you are just speaking of entanglement or light flashes in general.

A major difference with entanglement is that it can begin at a single point when two particles are generated from a common source or it could be generated at more than one point as when two electrons in different locations spontaneously entangle. In that case, it would be the origin of two separate light cones but with electrons sharing a common non-local wave-like connection.

Your second picture of light cones illustrates that sort of an event.

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20 hours ago, joigus said:

What's wrong is that, for space-like separated events, time ordering is ambiguous. So the thing that's "happening" before or after, as the case may be, has to be completely ineffectual (for all intents and purposes, just a re-definition of the wave function,) and only in your mind, really. Eise has just explained how the ordering is ambiguous. If it had any consequences --measurable ones, interactions, etc.-- it would be very bad for SR. It doesn't happen.

Yes, for space-like separated events, timing is ambiguous but the ambiguous nature of SR events for different observers can not reverse or even slightly affect the order of time-like events. You and others were trying to tell me some discussions ago this is possible but I still say outside observations can not go back in time and reverse the order of events that have already happened. I thought this was eventually understood but you raised the issue again.

16 hours ago, joigus said:

IOW, there is no way that you can obtain both statistical behaviours at the same time with any reasonable assumption of cohorts that hold these properties as real.

That's my reverse-engineering of Bell's theorem --or its violation by QM, to be more precise-- for you.

I agree with Bell that the many kinds of variations such as those found in your "Collectivity (2)" are observed with observations involving entangled particles. The observation of one quantum property can not indicate the possible nature of any other of the several quantum properties. They can all vary independently and this indicates that they are not fixed from the start.

There are no cohorts among quantum properties as there are among classical properties and every observation is random.

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4 hours ago, bangstrom said:

OK, but that is not what I said.

Yes, it is. It is exactly what you said. Are you suggesting I'm tinkering with the quoting function, or I'm lying?:

On 11/11/2022 at 9:52 AM, bangstrom said:

What is so wrong about this statement? Essentially it says that every particle, given enough time, will eventually interact with another particle. I don't find that to be so controversial.

It is simply not true that every particle, given enough time, will eventually interact with another particle. Two photons that are being lost beyond the cosmic horizon in opposite directions, eg, will never meet again, or interact in any way.

It is false. What you said, you said, and it's false.

4 hours ago, bangstrom said:

A major difference with entanglement is that it can begin at a single point when two particles are generated from a common source or it could be generated at more than one point as when two electrons in different locations spontaneously entangle. In that case, it would be the origin of two separate light cones but with electrons sharing a common non-local wave-like connection.

False, shockingly ignorant statement. Entanglement always occurs as a consequence of local interactions. Particles must be brought together for them to entangle. Here. Simple Google search of "what causes particle entanglement":

Quote

Entanglement is usually created by direct interactions between subatomic particles. These interactions can take numerous forms. One of the most commonly used methods is spontaneous parametric down-conversion to generate a pair of photons entangled in polarisation.

In the case of parametric down conversion, it's the (non-linear) response of the crystal to a laser at a particular location in the crystal.

4 hours ago, bangstrom said:

Your second picture of light cones illustrates that sort of an event.

No. It illustrates the moment when the particles disentangle.

3 hours ago, bangstrom said:

Yes, for space-like separated events, timing is ambiguous but the ambiguous nature of SR events for different observers can not reverse or even slightly affect the order of time-like events. You and others were trying to tell me some discussions ago this is possible but I still say outside observations can not go back in time and reverse the order of events that have already happened. I thought this was eventually understood but you raised the issue again.

You're misquoting here, or just plain lying. Point to me where anybody said that "the ambiguous nature of SR events for different observers can reverse the order of time-like (separated) events." This, most likely, is a new half-digested regurgitation from your mind of what others have actually said.

3 hours ago, bangstrom said:

I agree with Bell that the many kinds of variations such as those found in your "Collectivity (2)" are observed with observations involving entangled particles. The observation of one quantum property can not indicate the possible nature of any other of the several quantum properties. They can all vary independently and this indicates that they are not fixed from the start.

Missing the point again. I will rephrase correctly your gazpacho of words and, with any luck, you will see what you said wrongly:

The observation of one quantum property cannot indicate the possible outcome of any other incompatible quantum property.

The observation of one quantum property completely determines the possible outcome of the compatible quantum property that's tied to it by a conservation law.

And that, my friend, is why realism has no business in explaining quantum mechanics.

Never underestimate the value of repetition.

Edited by joigus
minor correction
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On 11/11/2022 at 9:52 AM, bangstrom said:

One minor point is that particles can not have a space-like separation. I say that any two particles in different locations have a space-like separation.

Here you show where you do not understand space-time diagrams. If you would draw a simple space diagram, yes, then there is a space distance between particles at different locations. But that is not the same as a space-like separation between 2 events in a space-time diagram! One could call a space-time diagram also a causality diagram. Events that are space-like separated cannot have a causal connection. Events that are time-like separated can have causal relationships. And because of the 'law of conservation of causality', i.e. every observer agrees what event was the cause, and what event is the effect, every observer agrees about the timely order of events. And as there is no possible causal connection between space-like separated events, there is no problem that different observers see them in a different timely order.

And this is the crux of Aspect's experiment, where it improved on Clauser's: Aspect set up the experiment in such a way that the measurements could not even influence each other with the speed of light. In other words, they were space-like separated, i.e. outside each other's light cones.

This (italics) is definitely false:

5 hours ago, bangstrom said:

Yes, for space-like separated events, timing is ambiguous but the ambiguous nature of SR events for different observers can not reverse or even slightly affect the order of time-like events. You and others were trying to tell me some discussions ago this is possible but I still say outside observations can not go back in time and reverse the order of events that have already happened.

Nobody here defended that there are observers that see time-like separated events in a different timely order.

Your first sentence is correct, except that it is not relevant precisely because the essential improvement of Aspect was that the measurements were space-like separated. Recall, the measurements, i.e. events, were space-like separated. Not with Clauser's experiment. There of course there was a spatial distance between the measurement devices, but the measurements were not space-like separated, in the sense of SR.

All this confusion arises because you are so sloppy with what a space-time diagram depicts, namely events, not physical objects. A physical object A in a space-time diagram is a chain of events, A being at x1 at t1, at x2 at t2, etc. Drawn all infinitesimal positions and times, the physical object A will show as a world-line, never as an individual point.

Again, your use of the concepts in your arguments are so vague, that they are, well, not even wrong. They miss the matter under discussion completely.

Edited by Eise
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