Is action at a distance possible as envisaged by the EPR Paradox.

[DevilsAvocado]

Unfortunately for us, your reaction is typical :-)

I'm afraid it's worse -- there is no "movement," of any 'thing' any 'where'.
...
This means there is no empty spacetime -- there are no material objects without space and time, and there are no space and time without material objects.

Amazing, just amazing. Hollywood cannot keep up with SFX to beat this one...

I realize you and your partners didn’t come up with this idea just from the "pop-up top hat" , you’ve spent a lot of time and effort, and in this process you must have tested a lot of 'scenarios'. Still, I have to ask – How do RBW handle CMB, if there is no "movement," of any 'thing' any 'where'?

Photons are subatomic particles or quantum waves interacting via forces, and the only explanation for the measured redshift, are that the waves gets stretched during the long travel in the expanding space... and we can measure photon by photon when they arrive from their long journey that started ~370 000 years after BB. How do RBW explain this?

There are no "quantum objects" (sometimes referred to as "screened off" objects) in our interpretation -- all material objects have trajectories and are therefore "classical." However, you don't model objects via ever smaller objects, you build them with their commensurate spacetime using graphical relations in an "all at once" (blockworld) fashion. Just look at the first four figures of our QFT paper in the arXiv.

Okay, I understand this, sort of, the QM wavefunction do not exist. But... when we perform a measurement on e.g. an electron, hitting a detector screen – doesn’t the electron 'exist' then?

When you want to explore the distribution of relations comprising some objects (typically, beam splitters, sources, detectors, etc), then you're doing quantum physics. If you want to discuss large-scale average behavior, then you're doing classical physics.

I think I have to stop 'yearning', and just accept the fact... maybe a sledgehammer will do the work...

I don't know what the "right" answer is. All I can say is that our interpretation solves all the quantum mysteries and is now being used to solve those of QFT as well. If it's successful (ultimately accounts for all quantum and all classical phenomena), then we're stuck with an adynamical picture. I don't care what the picture is as long as it accounts for all our experiments in a coherent fashion. We don't have such a picture now, so we must switch between incongruous pictures when working in formally incongruous theories (quantum and GR).

Time for the "sledgehammer" again... seriously, do you think that the fact that QM <> GR (at extreme levels), is an indication for, or better, a reason for what we perceive as "quantum mysteries"? I.e. do you think that we (even a layman) someday will say – Ohhh sh*t, is it all that simple!? Now it makes sense all the way!

(...or is it just a layman’s "wet dream"... )

Zeilinger has created interference patterns with buckyballs (buckminsterfullerene C60, a molecule with 60 carbon atoms).

WOW! Some time ago I was asking about "macroscopic EPR" in this forum, and was almost banned as the biggest crank in history... () Thanks for the info! Very interesting! Would it be possible to perform EPR with buckyballs...??

[PLAIN]http://upload.wikimedia.org/wikipedia/en/2/22/CntHAADF.jpg
Electron micrograph showing a single-walled nanotube (buckytube)

I don't think there is a Schnitt, you can create interference patterns with elephants if you can "screen them off."

Okay, no Schnitt on interfering elephants is maybe bad news for me... or maybe not... ()


PS: Just a coincidence? RUTA in Swedish = SQUARE ≈ BLOCK...

 

[DevilsAvocado]

About Frame Dragger: Events do have a cause

I finally found the "last" FD post, and it looks like a temporary ban. Maybe someone with more "banning experience" can provide the "final prediction".

Anyway, it happened in the thread https://www.physicsforums.com/showthread.php?t=391197" that drifts off-topic into education, religion, politics, racism, migration, culture, etc.

No attention about the post from PF ADMIN GB, whatsoever.

The discussion is now entering "US Domestic policy & language"... quite a bit from "Overpopulation"...

PF ADMIN GB has now had enough, and tell the guys to – "Please keep this thread in a productive state, thank you."

FD misjudges the situation and https://www.physicsforums.com/showpost.php?p=2692904&postcount=80" ...

The rest we know.

 

[RUTA]

I realize you and your partners didn’t come up with this idea just from the "pop-up top hat" , you’ve spent a lot of time and effort, and in this process you must have tested a lot of 'scenarios'. Still, I have to ask – How do RBW handle CMB, if there is no "movement," of any 'thing' any 'where'?

Photons are subatomic particles or quantum waves interacting via forces, and the only explanation for the measured redshift, are that the waves gets stretched during the long travel in the expanding space... and we can measure photon by photon when they arrive from their long journey that started ~370 000 years after BB. How do RBW explain this?

Actually, we're hoping to account for redshift this summer and reevaluate the galactic rotational velocity profiles. But, it's true that as permanently "screened off entities" photons are never "there." Lucky for us, famous physicists, including a couple Nobel Laureates (A. Bohr and B. Mottelson) and Zeilinger, have already proposed this one :-)

Okay, I understand this, sort of, the QM wavefunction do not exist. But... when we perform a measurement on e.g. an electron, hitting a detector screen – doesn’t the electron 'exist' then?

Yes and no. There is something different about the detector upon a detection event, but what's different about a CCD when it clicks due to an "electron" isn't the same as what's different about a cloud chamber when a track appears due to an "electron." People want to picture one and the same (screened off) 'thing' responsible for what they observe in both cases, but the situations are discernible so their descriptions differ and the descriptions are all we have (not to sound like an instrumentalist).

Time for the "sledgehammer" again... seriously, do you think that the fact that QM <> GR (at extreme levels), is an indication for, or better, a reason for what we perceive as "quantum mysteries"? I.e. do you think that we (even a layman) someday will say – Ohhh sh*t, is it all that simple!? Now it makes sense all the way!
(...or is it just a layman’s "wet dream"... )

Absolutely, once you "get it" you realize it's not at all difficult.

Would it be possible to perform EPR with buckyballs...??
Okay, no Schnitt on interfering elephants is maybe bad news for me... or maybe not... ()

Assuming there is no quantum cut (not everyone agrees), you can entangle anything you want as long as they're "screened off." Just replace the interferometer atoms in an interaction-free measurement device with elephants and you can entangle them like Elitzur's quantum liar experiment.

Elitzur, A.C. and Dolev, S. (2005). Quantum phenomena within a new theory of time. In A. Elitzur, S. Dolev and N. Kolenda (eds.), Quo vadis quantum mechanics? Berlin: Springer Verlag, 325 – 349.

Elitzur, A.C. and Vaidman, L. (1993). “Quantum mechanical interaction-free measurements.”
Foundations of Physics, 23, 987 – 997.

PS: Just a coincidence? RUTA in Swedish = SQUARE ≈ BLOCK...

A student in my boundary value problems class took to calling me Captain RUTA in reference to the fact that the problems we solved were "nasty." Rather than his (crude) acronym, I'll claim the Swedish origin to keep myself out of trouble :-)

 

[yoda jedi]

Events have no cause.

We do know "one guy" who absolutely suffers bad right now from this very fact...

good joke !
...laughs...

Okay yoda jedi, can you help me reconvert my omelet into 4 eggs, I want to return to the past future?

if i have to go to some city, say... the netx month, that "fact" can change the order of things to do, today...
and change the order of things today can change things in the future and so on... of course we see more "natural" the last possibility...

 

[DevilsAvocado]

Actually, we're hoping to account for redshift this summer and reevaluate the galactic rotational velocity profiles. But, it's true that as permanently "screened off entities" photons are never "there." Lucky for us, famous physicists, including a couple Nobel Laureates (A. Bohr and B. Mottelson) and Zeilinger, have already proposed this one :-)

Cool!

... an "electron" isn't the same as what's different about a cloud chamber when a track appears due to an "electron." People want to picture one and the same (screened off) 'thing' responsible for what they observe in both cases, but the situations are discernible so their descriptions differ and the descriptions are all we have ...

Aha! The "cloud chamber" is good one, I do understand that! (and I remember it well, when as a freshman I saw it for the first time, wonderful...)

Absolutely, once you "get it" you realize it's not at all difficult.

Okay... but still QM <> GR... so maybe we (I) have to wait a 'while'...

Assuming there is no quantum cut (not everyone agrees), you can entangle anything you want as long as they're "screened off." Just replace the interferometer atoms in an interaction-free measurement device with elephants and you can entangle them like Elitzur's quantum liar experiment.

I think I just have had a 'revelation'! It’s not about SIZE, it’s about "screen off"!You can’t disturb the system/'object', because then all the 'magic' goes away!

My business idea, to fill Wembley Stadium, presenting – The Two Outrageous Entangled Elephants! – will of course not work. No one is allowed to see... is has to be all black on Wembley for TOEE to work...

Thanks for making me understand that!

(This maybe belongs to the "Philosophical forum"?) Isn’t it strange... weird... kinda... I definitely don’t believe in any "higher being", but still it looks like 'someone' is laughing big time at humans "trying to understand"... at the 'smallest level' – we are forbidden to watch... and at the 'biggest level' – we can’t see beyond the surface of last scattering... someone must be laughing? Agent Smith??

I'll claim the Swedish origin to keep myself out of trouble :-)

Yeah, absolutely, right! It’s always safest with some "Nobel-compatibility"... you never know...

 

[DevilsAvocado]

good joke !
...laughs...

Well, huum, not a 'joke'... more like paradox/irony... but if "one guy" leaves permanent... it’s just sad...

if i have to go to some city, say... the netx month, that "fact" can change the order of things to do, today...
and change the order of things today can change things in the future and so on... of course we see more "natural" the last possibility...

Okay, but I was not thinking about the ordering of events. I was thinking about the macroscopic irreversibility of time:
egg -> omelet = TRUE | omelet -> egg = FALSE

 

[ThomasT]

I haven't seen you derive your coincidence rate. If you've done that, please tell me the post number. If not, please derive it now.

You can disregard my little exercise in translating |a - b| into ||a - L| - |b - L||. It only works for certain values of a, b, and L. For other values it's ||a - L| + |b - L||.
Of course it must be possible to express |a - b| in terms of the individual angular differences. Anyway, it doesn't matter. We still haven't accounted for the cos^2 term.

Afaik, it's empirical in origin and empirically applied -- based on, as you've mentioned, the equipment that's used, and the experimental setting.

The photon coincidence rate is the intensity of the light transmitted jointly by the polarizers. Do you agree that the cos^2 Theta rule regarding resultant intensity applies in certain optical Bell tests where, in each trial (ie., wrt each pair of entangled photons), identically polarized optical disturbances are jointly analyzed by crossed linear polarizers? (For the purpose of this discussion, we're considering an ideal setup.)

If so, then do you think that the application of this rule is in accord with the principle of local causality and c as a propagational speed limit?

If so, then there's a problem with the interpretation of Bell's theorem which says in effect that the observed cos^2 dependency between the angular difference of the polarizer settings and photon coincidence rate can't be due to a c-limited local common cause, ie., an emission produced entanglement.

And yet the emission model(s) accompanying the QM account say that the entanglement is produced via the emission process.

So, let's try a different interpretation of Bell's theorem:

Bell's theorem says that lhv accounts which meet certain formal requirements can't possibly reproduce the QM predictions and the observed cos^2 dependency between the angular difference of the polarizer settings and the photon coincidence rate.

This seems ok. So, which formal requirements are, effectively, at fault?

c-limited locality can't be explicitly formalized without having some variable (hidden or not) to express it in terms of. But it seems rather illogical to require an account of joint detection rate in terms of a variable, L, which doesn't determine it. The variability of P(A, B) is solely a function of variations in a global measurement parameter, the angular difference of the polarizer settings. To say that an explicitly local hidden variable account is impossible misses this point. Of course a viable lhv account is impossible, but the reason for this precludes inferring or positing from it that >c propagations exist in Nature.

Since NONlocality isn't a physical mechanism, and since positing ftl propagation speeds (to allow the entangled entities to 'communicate ' with each other) based on Bell, GHZ, etc. theorems is unwarranted, then we're left with the assumption (of mainstream physics) that we live in a c-limited, locally causal universe.

Hence my attempt at a local explanation or understanding (of sorts), but not an explicitly local formalization, for at least a certain class of entanglement experiments -- and a rather more physical understanding of quantum entanglement than can be gotten via the formalism(s) of it.

Quantum nonlocality and quantum superposition refer to formal terms and transformations. EPR, Schrodinger, and many others have pointed out the problematic and sometimes even absurd entailments of taking this as a literal description of the states, configurations, and behaviors of physical objects.

The physical essence of quantum entanglement is better understood than some commentators on the subject would lead one to believe. It has to do with relationships between and among the motional properties of entangled entities that result from these entities' interaction with each other or with a common disturbance, or having a common origin, or being part of an encompassing system. These relationships, when subjected to physical analysis via global measurement parameters, are revealed in the form of correlations predicted by the QM formalism. The entangled entities don't have to be 'communicating' with each other.

So, considering the above, I still think that the correct answer to the title question of this thread is no, spooky action at a distance (or nonlocality) as envisaged by EPR (or anybody else), isn't a physical possibility.

Are ftl propagations a possibility? Yes, wrt certain worldviews. But they're not necessary to understand the correlations associated with quantum entanglement.

 

[RUTA]

And yet the emission model(s) accompanying the QM account say that the entanglement is produced via the emission process.

Not quite, entanglement is a property of the entire experimental arrangement to include outcomes and a particular type of source.

So, let's try a different interpretation of Bell's theorem:

Bell's theorem says that lhv accounts which meet certain formal requirements can't possibly reproduce the QM predictions and the observed cos^2 dependency between the angular difference of the polarizer settings and the photon coincidence rate.

This seems ok. So, which formal requirements are, effectively, at fault?

c-limited locality can't be explicitly formalized without having some variable (hidden or not) to express it in terms of. But it seems rather illogical to require an account of joint detection rate in terms of a variable, L, which doesn't determine it. The variability of P(A, B) is solely a function of variations in a global measurement parameter, the angular difference of the polarizer settings. To say that an explicitly local hidden variable account is impossible misses this point. Of course a viable lhv account is impossible, but the reason for this precludes inferring or positing from it that >c propagations exist in Nature.

Since NONlocality isn't a physical mechanism, and since positing ftl propagation speeds (to allow the entangled entities to 'communicate ' with each other) based on Bell, GHZ, etc. theorems is unwarranted, then we're left with the assumption (of mainstream physics) that we live in a c-limited, locally causal universe.

Hence my attempt at a local explanation or understanding (of sorts), but not an explicitly local formalization, for at least a certain class of entanglement experiments -- and a rather more physical understanding of quantum entanglement than can be gotten via the formalism(s) of it.

Quantum nonlocality and quantum superposition refer to formal terms and transformations. EPR, Schrodinger, and many others have pointed out the problematic and sometimes even absurd entailments of taking this as a literal description of the states, configurations, and behaviors of physical objects.

The physical essence of quantum entanglement is better understood than some commentators on the subject would lead one to believe. It has to do with relationships between and among the motional properties of entangled entities that result from these entities' interaction with each other or with a common disturbance, or having a common origin, or being part of an encompassing system. These relationships, when subjected to physical analysis via global measurement parameters, are revealed in the form of correlations predicted by the QM formalism. The entangled entities don't have to be 'communicating' with each other.

So, considering the above, I still think that the correct answer to the title question of this thread is no, spooky action at a distance (or nonlocality) as envisaged by EPR (or anybody else), isn't a physical possibility.

Are ftl propagations a possibility? Yes, wrt certain worldviews. But they're not necessary to understand the correlations associated with quantum entanglement.

What you're discovering for yourself is that there are two independent ways to account for QM's violation of Bell inequalities -- causal non-locality and/or non-separability. You're correct in saying "the entangled entities don't have to be communicating with each other," because, for example, you could view the entangled quantum system as "one entity" rather than "entangled entities." Another way to instantiate non-separability is get rid of the quantum entities altogether and simply understand the wave function as a description of the the locations, types and orientations of all the experimental equipment from the initiation to the termination of the experiment.

Anyway, the bottom line is that you don't HAVE to invoke FTL communication to account for QM's violation of Bell inequalities. You can rather invoke non-separability.

 

[DrChinese]

If so, then there's a problem with the interpretation of Bell's theorem which says in effect that the observed cos^2 dependency between the angular difference of the polarizer settings and photon coincidence rate can't be due to a c-limited local common cause, ie., an emission produced entanglement.

And yet the emission model(s) accompanying the QM account say that the entanglement is produced via the emission process.

...The physical essence of quantum entanglement is better understood than some commentators on the subject would lead one to believe. It has to do with relationships between and among the motional properties of entangled entities that result from these entities' interaction with each other or with a common disturbance, or having a common origin, or being part of an encompassing system. These relationships, when subjected to physical analysis via global measurement parameters, are revealed in the form of correlations predicted by the QM formalism. The entangled entities don't have to be 'communicating' with each other.

The common cause you push is not generally accepted as occurring at the time of emission. As RUTA says, it is the context of the entire setup that is relevant. What QM says is that spin is conserved. It does not say there is a cause, or that it is definite independent of observation.

Not sure what you mean when you say entanglement is "...better understood...", as I don't think it is all that well understood. However, there is in fact a lot of theory around entanglement precisely because a lot can be directly derived from QM. Experiments can be performed using the tools of the trade. If that is what you mean, then I would agree with you.

As to global parameters, you won't find much agreement with your position on that. At least, not in the sense you intend.

 

[ThomasT]

DrChinese and RUTA, thanks for your replies. I might have some questions or comments regarding them, but for now I'm curious about DrC's comment:

As to global parameters, you won't find much agreement with your position on that. At least, not in the sense you intend.

I was just referring to the crossed polarizers. The global measurement parameter is their angular difference. What sense of global parameter did you think I intended?

 

[DrChinese]

DrChinese and RUTA, thanks for your replies. I might have some questions or comments regarding them, but for now I'm curious about DrC's comment:

I was just referring to the crossed polarizers. The global measurement parameter is their angular difference. What sense of global parameter did you think I intended?

The crossed polarizers are not considered global. On the other hand, c is global.

 

[ThomasT]

'AFTER' was the last nail in the coffin for LHV. There was a theoretical possibility that the entangled photons had 'spooky tentacles' that could 'sense' the settings of the polarizer, to pre-agree on LHV, and then run to 'mimic' the QM predictions.

Why would they need to 'pre-agree on LHV'? The value (the polarization angle) of the LHV can be anything. It doesn't matter. The correlations are solely a function of the angular difference of the polarizers.

Why else all this work on randomizing the polarizers??

In order to close the 'communication loophole'.

It was necessary to do the experiments. And by doing them it was learned that closing this loophole would have no effect on the results.

As we seem to agree, closing all of the loopholes will have no effect on the results -- except to bring the QM predictions closer to the raw data.

(I googled "Bell's lhv ansatz" and got 2 hits, both point at you at PF ... is this your own 'invention'?)

The word ansatz just means formulation. There's at least one other active thread in this forum discussing Bell's lhv ansatz.

As I understand you dismiss LHV and "spooky action at a distance" and loopholes. What's left?

ftl locality ? -- but then, I 'dismiss' that too. That leaves c-limited locality -- which seems to work for pretty much everything.

Nothing is just being dismissed out of hand. If you disagree with the reasons, then we can discuss that.

You mentioned Local Hidden Constants in an earlier, but that doesn't work either ...

That just refers to the relationship between the entangled optical disturbances. It does 'work' in that it's part of the QM treatment. And, given that the application of the cos^2 Theta rule doesn't contradict locality, then we have a simpler and more physical understanding of entanglement than saying that "nonlocality (or ftl) did it".

It's quite strange to see the strong argumentation against Alain Aspect et al.

Who's arguing against Aspect? I like to use his Bell test(s), considered in the ideal, because the setups are easier to understand than most of the more recent one's using SPDC photons.

Don't you think it's quite farfetched to dismiss the official conclusion, and replace it with your 'personal speculations', based on an optical law from 18th century - basically saying "some light is lost in the polarizer"...?

Yes that would be farfetched.

I can't do the calculations, but I suspect that the probabilities for the 18th century Malus Law too by chance reproduce exactly the expected results predicted by QM, is even more 'miraculous' than "Spukhafte Fernwirkung"...

Consider an Aspect-like setup where polarization-entangled counter-propagating photons are analyzed by crossed polarizers. Now visualize both polarizers on the same side. The results are the same as with one polarizer on each side. The side with the two polarizers is called a polariscopic setup and it's the sort of setup where Malus discovered the optical law that bears his name. Now visualize the original setup again. Do you see why this optical law applies? If so, then I would agree that that would be a miracle.

the latest discoveries by Bell & Aspect prove that if we look at one particle here - it immediately settles the properties of a twin particle, on the other side of the universe?

It depends on what you mean by "settles". It really is important how these things are phrased. Somebody might get the wrong idea.

Wrt the Bell test, if it's known that the polarizer settings are aligned or perpendicular (if the angular difference is 0 or 90 degrees), then if the detection attribute at one end is known, then the detection attribute at the other end can be deduced. These are the only two settings where such deductions are possible. Do the photons really need to be communicating with each other?

Wrt EPR, if one particle of an entangled pair is detected at a certain distance from the emitter at time, t, then the position of the other particle at t can be deduced from this information.

I assume you've read the EPR paper. Where does the spooky nonlocality that you seem so enamored with come from?

 

[ThomasT]

The crossed polarizers are not considered global. On the other hand, c is global.

How about their angular difference? If you change the setting at one end or the other, then |a-b| is instantaneously altered.

 

[DrChinese]

How about their angular difference? If you change the setting at one end or the other, then |a-b| is instantaneously altered.

That is a fact. But no one would know that for a while. a and b are local parameters, and their difference does not constitute a global parameter. Neither is the difference between my bank account and my desired spending...

 

[ThomasT]

That is a fact. But no one would know that for a while.

It's a fact of the experimental setup. We know it independent of whether it's actually done or not.

a and b are local parameters, and their difference does not constitute a global parameter.

What would you call |a-b| then?

 

[ThomasT]

The common cause you push is not generally accepted as occurring at the time of emission.

I didn't know that. Anyway, the emission model(s) can be interpreted that way. What do you think? Do the emission preparations enable the photons to 'communicate' sometime after emission via some ftl means, or are their motions related during the emission process.

As RUTA says, it is the context of the entire setup that is relevant.

Of course it's relevant. But the deep cause of the correlations is that the motions of the particles are related -- and the best assumption as to when this relationship is created is that it's created during the emission process.

What QM says is that spin is conserved. It does not say there is a cause, or that it is definite independent of observation.

The way QM is formulated, the experimental setups, and the observations allow certain rational assumptions regarding the deep reality of things. If we assume that there are no deep causes, that there is no underlying reality, then what are we doing?

Not sure what you mean when you say entanglement is "...better understood...", as I don't think it is all that well understood.

I think it's well enough understood to say what I've said about it, which I think is a better understanding of it than attributing it to nonlocal or ftl communication between entangled entities or simply saying that it's due to the experimental setups that produce it.

 

[ThomasT]

Not quite, entanglement is a property of the entire experimental arrangement to include outcomes and a particular type of source.

Recall my statement that entanglement has to do with relationships between and among the motional properties of entangled entities that result from these entities' interaction with each other or with a common disturbance, or having a common origin, or being part of an encompassing system?

The relationship between, say, counter-propagating optical disturbances in the Aspect experiments is the deep cause of the entanglement that is a property of the entire experimental arrangement, and the way I read the emission model is that this relationship is produced via the emission process and therefor exists prior to filtration of the optical disturbances.

What you're discovering for yourself is that there are two independent ways to account for QM's violation of Bell inequalities -- causal non-locality and/or non-separability.

I don't think so. I think that 'causal non-locality' is a contradiction in terms. It's not a physical account of anything.

My physical interpretation of quantum nonseparability is that the emission-produced motional relationship between the optical disturbances makes them 'nonseparable' wrt the analysis of this relationship via a common or global measurement parameter (the angular difference of the polarizer settings).

The fact that it's this relationship that's being analyzed in the joint context, and not the polarization angle (which is what's being analyzed in individual measurements), is what renders Bell's lhv formulation an inadequate (read: incorrect) representation of the experimental situation, and is therefore what causes Bell inequalities based on the predictive limits of that formulation to be violated by QM predictions and experimental results.

This nonseparability is adequately represented in QM in the nonfactorability of the joint, entangled state.

You're correct in saying "the entangled entities don't have to be communicating with each other," because, for example, you could view the entangled quantum system as "one entity" rather than "entangled entities."

The entangled quantum system can be viewed (physically interpreted) in terms of physically separate entangled entities that don't have to be communicating with each other if their motions are related via the emission process.

The usual response to this is something like: "But Bell proved that there can't be a local common cause for the entanglement." However, as has been shown, Bell didn't prove this. What he did prove was that no lhv theory meeting his formal requirements for an lhv theory can reproduce the full range of QM predictions.

Unfortunately, and to reiterate, Bell's formal requirements for an lhv theory simply misrepresent the experimental situation. Since the determining hidden parameter in the joint context (the photons' motional relationship) is different from the determining hidden parameter in the individual contexts (the photons' polarization angle), then the joint context can't possibly be viably represented in terms of the individual contexts.

 

[IcedEcliptic]

Recall my statement that entanglement has to do with relationships between and among the motional properties of entangled entities that result from these entities' interaction with each other or with a common disturbance, or having a common origin, or being part of an encompassing system?

The relationship between, say, counter-propagating optical disturbances in the Aspect experiments is the deep cause of the entanglement that is a property of the entire experimental arrangement, and the way I read the emission model is that this relationship is produced via the emission process and therefor exists prior to filtration of the optical disturbances.

I don't think so. I think that 'causal non-locality' is a contradiction in terms. It's not a physical account of anything.

My physical interpretation of quantum nonseparability is that the emission-produced motional relationship between the optical disturbances makes them 'nonseparable' wrt the analysis of this relationship via a common or global measurement parameter (the angular difference of the polarizer settings).

The fact that it's this relationship that's being analyzed in the joint context, and not the polarization angle (which is what's being analyzed in individual measurements), is what renders Bell's lhv formulation an inadequate (read: incorrect) representation of the experimental situation, and is therefore what causes Bell inequalities based on the predictive limits of that formulation to be violated by QM predictions and experimental results.

This nonseparability is adequately represented in QM in the nonfactorability of the joint, entangled state.

The entangled quantum system can be viewed (physically interpreted) in terms of physically separate entangled entities that don't have to be communicating with each other if their motions are related via the emission process.

The usual response to this is something like: "But Bell proved that there can't be a local common cause for the entanglement." However, as has been shown, Bell didn't prove this. What he did prove was that no lhv theory meeting his formal requirements for an lhv theory can reproduce the full range of QM predictions.

Unfortunately, and to reiterate, Bell's formal requirements for an lhv theory simply misrepresent the experimental situation. Since the determining hidden parameter in the joint context (the photons' motional relationship) is different from the determining hidden parameter in the individual contexts (the photons' polarization angle), then the joint context can't possibly be viably represented in terms of the individual contexts.

I believed that Bell Inequality had ruled out all of the Local Hidden Variable theories that existed. What theories are left, that have what QM offers of predictions?

 

[DrChinese]

...Unfortunately, and to reiterate, Bell's formal requirements for an lhv theory simply misrepresent the experimental situation. Since the determining hidden parameter in the joint context (the photons' motional relationship) is different from the determining hidden parameter in the individual contexts (the photons' polarization angle), then the joint context can't possibly be viably represented in terms of the individual contexts.

That sounds all well and good, but:

0, 120, 240: give me the dataset. The rest is just words, like "pigs fly". Easy to say, give me an example that addresses these. I learned this from Bell, so if it doesn't apply, it should be easy to come up with.

 

[DevilsAvocado]

Why would they need to 'pre-agree on LHV'? The value (the polarization angle) of the LHV can be anything. It doesn't matter. The correlations are solely a function of the angular difference of the polarizers.

ThomasT, I must say that it’s not only "Spukhafte Fernwirkung" that’s a mystery to me – your 'interpretation' of EPR & Bell test experiments is a 'mystery' as well (no offence).

First: When talking about angle (and settings), I think that most interested folks here understand that it’s the angles of the analyzers we are talking about, and not LHV. When talking about 'pre-agreement' and LHV, it’s the 'presetting' of the particle spin (of the pair) that’s addressed, which can be spin up(+) or spin down(-).

Second: The bright geniuses Albert Einstein & Niels Bohr had a discussion for decades about EPR. There was no way (or at least extremely difficult) to tell the difference between QM predictions and LHV in a 'static' EPR setup, and that’s why Einstein & Bohr never were able to finally settle the question. They never thought that EPR could be solved by an experiment/test – this was all a matter of interpretation in 1935.

Third: 30 years later John Bell introduces the absolutely brilliant idea to 'enforce' probability into the measurement of EPR, to be able to distinguish LHV from QM predictions, and this is implemented in form of varying angles of the analyzers.

The spin of the particle pair could be any combination of spin up(+)/spin down(-), i.e. correlated (+,+) (-,-) or non-correlated (+,-) (-,+).

When Alice and Bob measure the spin of entangled particles along the same axis (180°), they get identical results 100% of the time (= correlation of 1.0).

When Bob measures at orthogonal angles (45°) to Alice’s measurements, his measurement matches hers 50% of the time (= correlation of 0.0).

I think that we all agree that QM and Heisenberg's uncertainty principle is valid, and that we can only relay on probability distributions when predict the behavior of QM particles:

The QM probability distribution makes a 'footprint' in Bell test experiments, in the form of a cosine curve from correlated at 0° and anti-correlated at 90°. In contrast, Bell’s theorem places a straight-line limit on the curve that any LHV model can follow from 0° to 90°:

The most obvious difference between any LHV theory and QM predictions is when the analyzer alignment is 22.5°; QM gives a 0.71 correlation, whereas the LHVT "straight-line-limit" is 0.5.

(I know, it’s the second time I show this picture, but it really says it all...)

Now back to 'pre-agree on LHV': I do hope that you now clearly see the logic in a 'pre-agreement' to make the LHV theory work?? The ONLY way to 'compete' with QM, when the analyzer alignment e.g. is 22.5°, is for the 'magic LHV' to make 'pre-agreement' on a 0.71 correlation – before leaving the source!

I.e. for the LHVT to work at 22.5°, sending 100 pairs of photons, 71 pairs must pre-agree on a correlated result (+,+) and 29 pairs must pre-agree on a non-correlated result (+,-) (-,+).

(AFAICT this must also lead to some "LHV Global Counter", which makes the LHVT even more troublesome...?? )

IF the analyzer alignments are settled AFTER the LHVT photons LEFT the source – they can pre-agree on anything (from building a house on Mars to making gold) but they CANNOT be saved – the LHV correlation can NEVER compete with QM predictions in this kind of Bell test!

If the LHVT make a decision later, after they left the source, we’re back to "Spukhafte Fernwirkung" again, and the L in LHV must be replaced by NL (nonlocal).

That’s why 'AFTER' and angle is "des Pudels Kern" in Bell test experiments. Get it?

In order to close the 'communication loophole'.

Meaning exactly what I just explained + 400 meter, right?

Who's arguing against Aspect?

Is the 'Malus Law Theory' embraced by Aspect as well??

Do you see why this optical law applies? If so, then I would agree that that would be a miracle.

No sorry, I don’t see how the MLT applies to Bell test experiments? And my best argument is that Bell test experiments have been executed using ⁹Be⁺ ions (an isotope of Beryllium, steel-gray, strong, lightweight brittle alkaline Earth metal, passing the optical MLT to the closet), with the same successful correlation result. Bell’s own idea was not to use photons (I think it was 'atoms'?), so there is no direct connection between Bell test experiments and photons, except for that’s the easiest way to perform the experiment.

It depends on what you mean by "settles". It really is important how these things are phrased. Somebody might get the wrong idea.

I agree, we really don’t know exactly what’s going on. There are different interpretations, trying to explain, but no 'official explanation'. I do hope that we all agree that 'something happens' that seems to violate locality, and don’t blame all on good old Etienne-Louis Malus!

I assume you've read the EPR paper.

You mean Dr. Bertlmanns Socks?

Serious, I’m only a layman and I have not mathematically penetrated every 'angle' of EPR & Bell's theorem, but I persuade myself I got the "Big Picture" fairly correct. There are scary examples of people who https://www.physicsforums.com/showthread.php?t=399795", that make them think it’s physical impossible to have one red and one white card in a box, and take them out to inspect the colors, because the probability for one card/color (according to their "homemade probability chains") is not 0.5, but 0.25??

But when I get the time, I’ll do all my 'homework', promise...

Have you read the EPR paper?


@RUTA – I did https://www.physicsforums.com/showthread.php?p=2701710#post2701710" your reply, though very late (sorry), just wanted you to know...

 

[zonde]

When Alice and Bob measure the spin of entangled particles along the same axis (180°), they get identical results 100% of the time (= correlation of 1.0).

If you mean that QM predicts that then yes that is so.
But if you mean that this prediction is experimentally tested then no this is not tested. There is only experience that you can get close to this prediction under certain conditions and certain assumptions. But common experience is not scientifically verified fact.
To verify this prediction in scientific fashion you have to test what happens when you vary conditions and if variations in results are justified by theoretical model or not and whether results agree with assumptions to testable limits or not.

 

[DevilsAvocado]

If you mean that QM predicts that then yes that is so.

Correct, and to be fair – LHV can also produce this correlation, but then it all goes 'bananas'...

But if you mean that this prediction is experimentally tested then no this is not tested.

Okay...?? If you are correct, then this must mean Alain Aspect is an imposter?? Presenting false data on public lectures!?

Here’s one of Alain Aspect’s own slide:

Alternatively: Alain Aspect is one of your "who-cares-it-doesn’t-bother" scientists... ??

By the way, I did answer your "not bother"-assumption in https://www.physicsforums.com/showpost.php?p=2697161&postcount=208".

 

[zonde]

Therefore, your "not bother" assumption is quite farfetched. The man or woman, who does find this limit of QM will get a Nobel, lots of fame, and money – besides the scientific thrill and satisfaction.

To "not bother" in this case, is to not be a real scientist. I’m sorry.

From this paper:
http://arxiv.org/abs/quant-ph/0402001"
"On the other hand, the fair sampling assumption is very reasonable, and easy to express."
I call this "not bother".

That must be Alain Aspect!

From the same paper:
"Clear violations of Bell’s inequalities have been found, under the assumption that the « fair sampling hypothesis » holds."
Seems that it's not Alain Aspect who is wearing the tin foil hat but someone else.

 

[IcedEcliptic]

From this paper:
http://arxiv.org/abs/quant-ph/0402001"
"On the other hand, the fair sampling assumption is very reasonable, and easy to express."
I call this "not bother".


From the same paper:
"Clear violations of Bell’s inequalities have been found, under the assumption that the « fair sampling hypothesis » holds."
Seems that it's not Alain Aspect who is wearing the tin foil hat but someone else.

Are you seriously making the fair sampling loophole argument?! Really, I was not aware this was still even marginally accepted anymore.

 

[RUTA]

Are you seriously making the fair sampling loophole argument?! Really, I was not aware this was still even marginally accepted anymore.

It's been at least 10 years since I saw someone present this argument at a foundations conference. The community has moved on.

 

[IcedEcliptic]

It's been at least 10 years since I saw someone present this argument at a foundations conference. The community has moved on.

Thank you RUTA, reading your discussion with Dr. Chinese has been very elucidating. I feel I have a deeper understanding of of non-locality as a result. Not a decision on my part, but so much to ponder.

 

[ThomasT]

I believed that Bell Inequality had ruled out all of the Local Hidden Variable theories that existed. What theories are left, that have what QM offers of predictions?

There's good reason to believe that, not just due to Bell inequalities, lhv representation of entanglement is impossible.

What I'm trying to explore is why, and I think that the correct answer to that will have nothing whatsoever to do with nonlocality or ftl locality or any of the rather exotic explanations that have been offered over the years.

Of course, we're not all on the same page here.

And, sorting things out can be a bit tedious.

 

[IcedEcliptic]

There's good reason to believe that, not just due to Bell inequalities, lhv representation of entanglement is impossible.

What I'm trying to explore is why, and I think that the correct answer to that will have nothing whatsoever to do with nonlocality or ftl locality or any of the rather exotic explanations that have been offered over the years.
<snip>

Why do you believe that?

 

[DevilsAvocado]

Why do you believe that?

Because ThomasT has his own version of the 'scientific model': First you decide how the world should work according to your personal taste, and nothing else – then you make up pseudo-mathematical theories that seems to fit your personal view.

That’s why we have seen a long discussion on how the 18th century optical Malus Law can reproduce QM predictions, which has no connection to reality. For Malus Law to work at 22.5°, sending 100 pairs of photons, 71 pairs must agree on a correlated result (+,+) and 29 pairs must agree on a non-correlated result (+,-) (-,+).

And not only that - the 18th century optical Malus Law must keep a Global Counter on the correlated/non-correlated result for 100 pairs of photons! Amazing, isn’t it!?

And when ThomasT is proven wrong – he just refuse to reply – blaming on things being a bit tedious.

And I agree – this is getting tedious – in the manner this debate is performed.


Finally: I must point out that I from the beginning had the same view as ThomasT – this "spooky action at a distance" can’t be true! This is just mathematical mumbo-jumbo from physicist trying to raise more funding by presenting spectacular theories!

But I changed my mind. And I can assure ThomasT – it didn’t hurt at all...

 

[my_wan]

To the OP question: In practice no. In principle we can't be sure. Reading the debate here should make that clear, but I'd like to add something to the debate that appears to have poor representation thus far.

I have a predisposition toward looking for so called loopholes to avoid 'spooky action at a distance', but when I see the case for these classes of models overstated and pinned on distinct ontologies within a class it gets painful. I'm going to attempt a description of the general features of this class of model, but it must be understood that the only justification is that Bell's Theorem fails to rule them out. It's not even a claim that any model in this class exist that's capable of superseding the Standard Model. This thread is the wrong place for anybody that possessed that. RUTA's Blockworld interpretation appears to fit within this class, in an ontologically inverted sort of way. The fact that it run counter to my predispositions in no way limits my fascination with it.

First let's look at the assumptions of Bell's Theorem. Using a list provided by DrC:

a. Realism - a la EPR's "elements of reality".
b. Hidden Variables - Essentially a deduction from realism.
c. Non-contextuality - the context of an experiment does not matter to the realism of an observable.
d. Counterfactual Definiteness - you can speak meaningfully about unmeasured observables.

DrC expressed a distaste in discussing the implications of these terms due to semantic arguments. I wish to describe only the class as clearly as possible, the semantic choices are not a legitimate issue in this context. RUTA's Blockworld is a massive distortion of my prejudices, but apparently remains within this class.

The notion behind a 'hidden variable' is that a variable exist that is 'hidden', obeys Einstein realism, and local. EPR experiments obviously can't perform experiments directly on these variables that are presumed 'hidden', else the argument moots itself. Instead we take a measurable variable, such as spin, make some assumptions about the relationship between the hidden element and the measurable variable, and use the measurable variable as a proxy for probing the hidden variable. Thus we are basing our results on this presumed relationship between these hidden and measured variables. This is in general what's referred to when it's said that counterfactual definiteness is a basic assumption of Bell's Theorem. Essentially it presumes that the measured variable is an observer independent absolute property defined by the hidden variables. Thus non-contextuality is related to counterfactual definiteness by the property of observer independent absolutes. What Bell's Theorem proves, from my perspective, is that, if such hidden variables exist, all known measurable variables must be emergent properties of these hidden variables, not inate properties of them.

This in no way proves it is possible to contextualize 'hidden' variables in such a way to recover QM, and people can argue forever on the semantics of how to do that. It merely identifies a class of 'hidden' variables which Bell's Theorem fails to rule out. There are a great many unrelated variables which are obviously contextual. One of the simplest being velocity. Temperature also qualifies, as any given molecule in a gas may be considered at rest between collisions. There's nothing strange about contextual variables in general, except in classical cases we can define definite symmetries relative to known parameters. In the QM case we have only correlations in randomness that interferes with itself. This is further complicated by the nature of quantization itself and the inability to directly observe the processes. Instead we are stuck with inferences from point observations in which our experiments to observe them play a role in the outcomes, for reasons that can also be debated.

I like to think that sub-Planck physics is involved, which not only contains QM/GR but allows QM/GR to be derived. Yet what I like is of no consequence to physics. Ontological claims of what will work, as well as claims of the impossibility of avoiding non-locality, etc., is mooted by the facts as we know them at this time, in spite of the excellent work of Bell and many many others.

 

[DevilsAvocado]

... or we could just make it simple and say:

Local Hidden Variable Theory = Norwegian Blue Parrot

https://www.youtube.com/watch?v=<object width="640" height="385"><param name="movie" value="http://www.youtube.com/v/npjOSLCR2hE&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/npjOSLCR2hE&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="640" height="385"></embed></object>

 

[DevilsAvocado]

Frame Dragger is BACK!

 

[Frame Dragger]

Frame Dragger is BACK!

Heyo DevilsAvocado! Love the Montey Python reference, "...it's gone and joined the choir invisible, this, is a DEAD PARROT!."

 

[DevilsAvocado]

...it's gone and joined the choir invisible

Yeah! You got it! Choir Invisible = Hidden Variable !

Great to have you back FD! I was real worried there for awhile... Now let’s get real ironic AGAIN!

(got to go now, see you later terminator)

 

[DrChinese]

DrC expressed a distaste in discussing the implications of these terms due to semantic arguments...

The notion behind a 'hidden variable' is that a variable exist that is 'hidden', obeys Einstein realism, and local. EPR experiments obviously can't perform experiments directly on these variables that are presumed 'hidden', else the argument moots itself. Instead we take a measurable variable, such as spin, make some assumptions about the relationship between the hidden element and the measurable variable, and use the measurable variable as a proxy for probing the hidden variable. Thus we are basing our results on this presumed relationship between these hidden and measured variables. This is in general what's referred to when it's said that counterfactual definiteness is a basic assumption of Bell's Theorem. Essentially it presumes that the measured variable is an observer independent absolute property defined by the hidden variables. Thus non-contextuality is related to counterfactual definiteness by the property of observer independent absolutes. What Bell's Theorem proves, from my perspective, is that, if such hidden variables exist, all known measurable variables must be emergent properties of these hidden variables, not inate properties of them.

This in no way proves it is possible to contextualize 'hidden' variables in such a way to recover QM, and people can argue forever on the semantics of how to do that. It merely identifies a class of 'hidden' variables which Bell's Theorem fails to rule out. ...
I like to think that sub-Planck physics is involved, which not only contains QM/GR but allows QM/GR to be derived. Yet what I like is of no consequence to physics. Ontological claims of what will work, as well as claims of the impossibility of avoiding non-locality, etc., is mooted by the facts as we know them at this time, in spite of the excellent work of Bell and many many others.

I realize there may be some differences in what kind of hidden variables might exist. My thing is to avoid getting into a semantic argument (I would rather focus on the physics). The key to that is to FIRST accept that there cannot be local hidden variables of the type identified by EPR (i.e. no objective elements of reality). I think you can then move on to extend the scope further, to include hypothetical classical components of elements of reality (i.e. where the element of reality is an observable, but the component may not be).

In Relational BlockWorld, I like to say the the hidden variables lay in the future. RUTA will probably choke on that description. If you accept that, then you would probably end up concluding that the future influences the past and causality is lost. RUTA would probably be OK with that, because he considers RBW to be acausal.

There also could be all kinds of weird rules at the subatomic level that are hidden from us. But the problem with that "escape" is that where else do they manifest themselves? Were there other evidence, it would make more sense.