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originally posted by: Arbitrageur
a reply to: Choice777
The short answer is:
Post-Quantum Correlations: Exploring the Limits of Quantum Nonlocality
That article goes on to describe how some experiments refine our understanding of nonlocality.
Despite advances in quantum research, physicists still don’t fully understand the fundamental nature of nonlocality.
It's a stretch to say that "information" is being exchanged, since there is no faster than light communication possible in entanglement experiments so far. I think it would be more accurate to say it's a "correlation".
When it comes to nonlocal correlations, some correlations are more nonlocal than others. As the subject of study for several decades, nonlocal correlations (for example, quantum entanglement) exist between two objects when they can somehow directly influence each other even when separated by a large distance. Because these correlations require “passion-at-a-distance” (a term coined by physicist Abner Shimony), they violate the principle of locality, which states that nothing can travel faster than the speed of light (even though quantum correlations cannot be used to communicate faster than the speed of light).
In physics, the no-communication theorem is a no-go theorem from quantum information theory, which states that, during measurement of an entangled quantum state, it is not possible for one observer, making a measurement of a subsystem of the total state, to communicate information to another observer. The theorem is important because, in quantum mechanics, quantum entanglement is an effect by which certain widely separated events can be correlated in ways that suggest the possibility of instantaneous communication. The no-communication theorem gives conditions under which such transfer of information between two observers is impossible.
How is this known? How many times do we need to say that nature is under no obligation to behave in a manner that humans would deem "logical"?
originally posted by: ImaFungi
now it is known there must be some logical mechanism, as regardless of distance, the correlation between entangled particles must occur at the speed of light or less
I'm not a researcher in this field and since it's an area of active research I'm sure an active researcher would have a better answer. But as far as I know, the hidden variables theory doesn't appear to be true because the results don't satisfy Bell's inequality.
so what I am asking for as a theory, is what is the theory of the now hidden variables, that is the physical/material/energetic structure which supports the entanglement of particles theory?
So the observed behavior conforms to quantum mechanics theory, without hidden variables.
A possible resolution to the apparent paradox might be to assume that the state of the particles contains some hidden variables, whose values effectively determine, right from the moment of separation, what the outcomes of the spin measurements are going to be. This would mean that each particle carries all the required information with it, and nothing needs to be transmitted from one particle to the other at the time of measurement. It was originally believed by Einstein and others (see the previous section) that this was the only way out, and therefore that the accepted quantum mechanical description (with a random measurement outcome) must be incomplete. ...
The hidden variables theory fails, however, when we consider measurements of the spin of entangled particles along different axes (for example, along any of three axes which make angles of 120 degrees). If a large number of pairs of such measurements are made (on a large number of pairs of entangled particles), then statistically, if the local realist or hidden variables view were correct, the results would always satisfy Bell's inequality. A number of experiments have shown in practice, however, that Bell's inequality is not satisfied. This tends to confirm that the original formulation of quantum mechanics is indeed correct, in spite of its apparently paradoxical nature.
To me, that creates an even bigger paradox (proliferating labels) than the one it tries to solve (the locality paradox), but nature is under no obligation to conform to my preferences either, so I try to keep an open mind
Bell's theorem depends crucially on counterfactual reasoning, and is mistakenly interpreted as ruling out a local explanation for the correlations which can be observed between the results of measurements performed on spatially-separated quantum systems. But in fact the Everett interpretation of quantum mechanics, in the Heisenberg picture, provides an alternative local explanation for such correlations. Measurement-type interactions lead, not to many worlds but, rather, to many local copies of experimental systems and the observers who measure their properties. Transformations of the Heisenberg-picture operators corresponding to the properties of these systems and observers, induced by measurement interactions, "label" each copy and provide the mechanism which, e.g., ensures that each copy of one of the observers in an EPRB or GHZM experiment will only interact with the "correct" copy of the other observer(s). The conceptual problem of nonlocality is thus replaced with a conceptual problem of proliferating labels, as correlated systems and observers undergo measurement-type interactions with newly-encountered objects and instruments; it is suggested that this problem may be resolved by considering quantum field theory rather than the quantum mechanics of particles.
You are onto something there mate
originally posted by: Choice777
originally posted by: Arbitrageur
a reply to: Choice777
The short answer is:
Post-Quantum Correlations: Exploring the Limits of Quantum Nonlocality
That article goes on to describe how some experiments refine our understanding of nonlocality.
Despite advances in quantum research, physicists still don’t fully understand the fundamental nature of nonlocality.
It's a stretch to say that "information" is being exchanged, since there is no faster than light communication possible in entanglement experiments so far. I think it would be more accurate to say it's a "correlation".
When it comes to nonlocal correlations, some correlations are more nonlocal than others. As the subject of study for several decades, nonlocal correlations (for example, quantum entanglement) exist between two objects when they can somehow directly influence each other even when separated by a large distance. Because these correlations require “passion-at-a-distance” (a term coined by physicist Abner Shimony), they violate the principle of locality, which states that nothing can travel faster than the speed of light (even though quantum correlations cannot be used to communicate faster than the speed of light).
What if we could make two antennas of entangled particles ? Instant communication across the planet, solar system, etc.
originally posted by: Arbitrageur
How is this known? How many times do we need to say that nature is under no obligation to behave in a manner that humans would deem "logical"?
I'm not a researcher in this field and since it's an area of active research I'm sure an active researcher would have a better answer. But as far as I know, the hidden variables theory doesn't appear to be true because the results don't satisfy Bell's inequality.
Quantum entanglement
So the observed behavior conforms to quantum mechanics theory, without hidden variables.
A possible resolution to the apparent paradox might be to assume that the state of the particles contains some hidden variables, whose values effectively determine, right from the moment of separation, what the outcomes of the spin measurements are going to be. This would mean that each particle carries all the required information with it, and nothing needs to be transmitted from one particle to the other at the time of measurement. It was originally believed by Einstein and others (see the previous section) that this was the only way out, and therefore that the accepted quantum mechanical description (with a random measurement outcome) must be incomplete. ...
The hidden variables theory fails, however, when we consider measurements of the spin of entangled particles along different axes (for example, along any of three axes which make angles of 120 degrees). If a large number of pairs of such measurements are made (on a large number of pairs of entangled particles), then statistically, if the local realist or hidden variables view were correct, the results would always satisfy Bell's inequality. A number of experiments have shown in practice, however, that Bell's inequality is not satisfied. This tends to confirm that the original formulation of quantum mechanics is indeed correct, in spite of its apparently paradoxical nature.
Locality in the Everett Interpretation of Heisenberg-Picture Quantum Mechanics
To me, that creates an even bigger paradox (proliferating labels) than the one it tries to solve (the locality paradox), but nature is under no obligation to conform to my preferences either, so I try to keep an open mind
Bell's theorem depends crucially on counterfactual reasoning, and is mistakenly interpreted as ruling out a local explanation for the correlations which can be observed between the results of measurements performed on spatially-separated quantum systems. But in fact the Everett interpretation of quantum mechanics, in the Heisenberg picture, provides an alternative local explanation for such correlations. Measurement-type interactions lead, not to many worlds but, rather, to many local copies of experimental systems and the observers who measure their properties. Transformations of the Heisenberg-picture operators corresponding to the properties of these systems and observers, induced by measurement interactions, "label" each copy and provide the mechanism which, e.g., ensures that each copy of one of the observers in an EPRB or GHZM experiment will only interact with the "correct" copy of the other observer(s). The conceptual problem of nonlocality is thus replaced with a conceptual problem of proliferating labels, as correlated systems and observers undergo measurement-type interactions with newly-encountered objects and instruments; it is suggested that this problem may be resolved by considering quantum field theory rather than the quantum mechanics of particles.
originally posted by: mbkennel
a reply to: Arbitrageur
Is there a locality paradox?
My position:
At the core, Einsteinian relativity is about imposing symmetry & transformation constraints on the underlying laws of physics. And quantum field theory obeys this 100%.
Those constraints, when applied to a *classical* field theory with differential operators only, for example, fluid mechanics or acoustics, result in light-cone locality restrictions on cause and effect. These just happen to be the types of physics which humans live in and experience day to day.
So, it's the expectation of locality which ought to be adjusted.
originally posted by: dragonridr
a reply to: ImaFungi
First i think you misunderstand entangled particles you do realize we cant change one and magically have the other change dont you? An entangled system means both systems no matter how far we separate them act the same, when we measure one we know the state of the other no matter where it is. In other words the other particle acts just as if we measured it even if we didnt. Because we know that quanta behave differently when measured for example the double slit experiment. But lets say we change say an electron in an entangled pair what happens to the other nothing at all. So basically what entanglement shows us is we can measure anything like spin etc and the other system will be the same id their any communication id have to say no. But as i said earlier there does appear to be a time independence that opens up some strange possibilities for communicating across different frames of reference, If that article i read was correct but again we arent making changes to the system just measuring it.
But is there even any conceivably hypothetical, rhetorical, theoretical blurb of a thought can offer as to how possibly in formation can travel instantly across any distance?
Entangled particles are not in fact separate entities but rather a projection of the same single entity within the computer. A shared memory area from which different manifestations of the same entity or information are created. Faster than light signaling is thus an illusion.
originally posted by: ImaFungi
originally posted by: mbkennel
a reply to: Arbitrageur
Is there a locality paradox?
My position:
At the core, Einsteinian relativity is about imposing symmetry & transformation constraints on the underlying laws of physics. And quantum field theory obeys this 100%.
Those constraints, when applied to a *classical* field theory with differential operators only, for example, fluid mechanics or acoustics, result in light-cone locality restrictions on cause and effect. These just happen to be the types of physics which humans live in and experience day to day.
So, it's the expectation of locality which ought to be adjusted.
But is there even any conceivably hypothetical, rhetorical, theoretical blurb of a thought can offer as to how possibly in formation can travel instantly across any distance?
That is what you are suggesting, even if you say we cant read that information faster than light, you are suggesting that at an infinite distance between 2 entangled particles, when one is observed, the other automatically reverts to the exact opposite state.
Now all this means, is there is another physical dimensional structural aspect of the universe, that we did not and could not take into account, while developing einstein speed of light is the fastest speed rule.
You now think you know that is a fact, that there is a systematic potential relationship between what are thought to be separate parts of a system
en.wikipedia.org...
n quantum mechanics, einselection, short for environment - induced superselection, is a name coined by Wojciech H. Zurek[1] for a process which is claimed to explain the phenomenon of wavefunction collapse and the emergence of classical descriptions of reality from quantum descriptions. In this approach, classicality is described as an emergent property induced in open quantum systems by their environments. Due to the interaction with the environment, the vast majority of states in the Hilbert space of a quantum open system become highly unstable to entangling interaction with the environment, which in effect monitors selected observables of the system. After a decoherence time, which for macroscopic objects is typically many orders of magnitude shorter than any other dynamical timescale,[2] a generic quantum state decays into an uncertain state which can be decomposed into a mixture of simple pointer states. In this way the environment induces effective superselection rules. Thus, einselection precludes stable existence of pure superpositions of pointer states. These 'pointer states' are stable despite environmental interaction. The einselected states lack coherence, and therefore do not exhibit the quantum behaviours of entanglement and superposition.
Advocates of this approach argue that since only quasi-local, essentially classical states survive the decoherence process, einselection can in many ways explain the emergence of a (seemingly) classical reality in a fundamentally quantum universe (at least to local observers). However, the basic program has been criticized as relying on a circular argument (e.g. R. E. Kastner [3]). So the question of whether the 'einselection' account can really explain the phenomenon of wave function collapse remains unsettled.
originally posted by: ImaFungi
a reply to: mbkennel
So hilbert space refers to the spatial domain in which the most fundamental quanta and forces operate? The effects of which, their interactions, are deemed 'the emergent classical world'?
So are you saying the emergent classical world is 'less real' than the most fundamental hilbert space quanta interacting?
Is hilbert space not also 3d space?
originally posted by: mbkennel
"Is hilbert space not also 3d space?"
No!
The notion of 'spaces' in mathematics extends far beyond Euclidean space or finite dimensional space and was/is a major subject since the middle of the 19th century.
The persistent illusion of the classical world is also real because the physics of decoherence and thermodynamics of large numbers of particles is just as real and unavoidable in our universe, even if it is an emergent property of microscopic dynamics.
Just as fluid mechanics is an emergent property of the underlying kinetic theory of particles---does that make the existence of things which behave like fluids, nearly universal in Earthly experience---unreal or invalid? Surely not. Even though we know the equations of fluid mechanics aren't always valid. For instance in a vacuum tube shooting electrons.
In this case I'm specifically denying that there's a requirement as you stated that "the correlation between entangled particles must occur at the speed of light or less" which is apparently your logic. As I said the MWI (Many worlds Interpretation) would allow this to happen, but I know of no absolute reason why "the correlation between entangled particles must occur at the speed of light or less", so I don't feel any compulsion to accept the MWI just because it allows a local explanation.
originally posted by: ImaFungi
originally posted by: Arbitrageur
How is this known? How many times do we need to say that nature is under no obligation to behave in a manner that humans would deem "logical"?
When you say, 'nature does not have to behave logical'. What is your understanding of the term 'logic' being used here, that you deny being appropriate?
Yes but Bell's inequality doesn't require us to know what the hidden variables are, it's only testing for whether such variables may exist.
The term 'hidden' in the concept hidden variables only applies to hidden from our awareness. It is saying there are variables that we are ignorant of.
I think there is a deeper explanation for entanglement behavior, and we don't know what that is, but again, I don't make any assumption that this deeper explanation must include locality. It may, or it may not, or I could be wrong and maybe there isn't a deeper explanation.
If non locality is true, if entanglement is true, there still must be variables as to HOW non locality and entanglement is physically working. This ties into my understanding of logic, that there must be a physical reason as to why something occurs, even if you dont think there is, even if you dont know what it is.
How do you rationalize this with Bell's inequality?
I think if there were hidden variables there would be the same results as are received. I think what matters is what is actually occurring when an entangled pair of particles is created. Hidden variables suggests they must be in some exact state (upon measurement we can deduce, opposite states). QM suggests each particle is in at the same time, 2 opposite quasi states.
The physicist in the OP video, Sean Carroll likes it, and while he may be in the minority, I think the minority may be growing. The way he puts it, it's just assuming the Schrodinger equation is actually correct, but it seems like a messy explanation. That doesn't mean it's necessarily wrong.
Yes it depends what it means. I have felt at times it has meant that a single system, say a person sitting in a chair in their room holding an apple, every single quantum action that takes place 'doubles' into an entirely new real universe, or that the entire universe is always physically multiplying. But the past few times I have come in contact with this theory, I feel it seems it might be instead suggesting that, merely the universe, or the sections and intimate systems within the universe are not entirely checked and captured and solidified in terms of all else, that the immediate relations of particles while they are not in contact with all the rest, it is as if they exist in another world, unto themselves. So then when particles are separated from this system, it is a part of that old system traveling into new territory, like an entire new world, a new system, but it still has the signatures, the breeding if you will, of the old system it was a part of. And perhaps they are suggesting this sort of thing happens or can happen all the time, mixing and matching and withholding signatures, and still be connected by some informational aspect even at a distance. Just like if you moved to south east asia, even though you would be away from the system you started and grew much in, you would still have some 'attachment' and relation to that old system. but this is me spitballing.
That was addressed to imafungi and I don't have a need for it, but I was curious...Do you agree with the paper I posted saying that the many worlds interpretation is local so one wouldn't need to give up locality with that interpretation? For me, giving up locality is easier than accepting the many worlds interpretation, but I'd still like to know if that assertion is correct.
originally posted by: mbkennel
Give up your need for locality. It ain't happening.
I didn't choose the word "paradox" very carefully. The source I quoted called lack of locality a "conceptual problem", is that better? I'm not sure if it's really a problem though, which is why I don't feel compelled to buy into MWI just because it claims to provide a local explanation.
originally posted by: mbkennel
Is there a locality paradox?
I tend to agree. Thanks for contributing your thoughts. I started the thread on this topic but we never really discussed it much in depth until now but I'm glad to see we returned to it to discuss it in more depth.
My position:
At the core, Einsteinian relativity is about imposing symmetry & transformation constraints on the underlying laws of physics. And quantum field theory obeys this 100%.
Those constraints, when applied to a *classical* field theory with differential operators only, for example, fluid mechanics or acoustics, result in light-cone locality restrictions on cause and effect. These just happen to be the types of physics which humans live in and experience day to day.
So, it's the expectation of locality which ought to be adjusted.
So you don't agree with the video but you're citing it anyway, is that what you mean?
originally posted by: ChaoticOrder
Well I prefer not to think we live in a computer, but the best explanation I have read is the following:
So, Cats are macroscopic meatbags and that explains why they can't be in a superposition of dead and alive states...makes sense to me.
originally posted by: mbkennel
So you don't have Schroedinger's entangled felines---his point was that there has to be some transition from quantum to classical in practical nature because actual cats are always classical and not entangled/mixed states in our experience.
I didn't think that was the main problem. I thought even if we weren't macroscopic entities with macroscopic measurement devices, the problem is that it's simply a correlation. You need to do more than just measure the state, you'd need to set it somehow, and you can't do that because the outcome of the measurement seems to be probabilistic, unless you're saying it's not really probabilistic.
originally posted by: mbkennel
We can't prepare and maintain in a deep quantum mechanical way two different macroscopic measurment apparatuses separated beyond light cones.
So, FTL communication is impossible to the degree that we are 60 kilogram meatbags of jillions of atoms at a positive temperature.
No doubt a lot of ImaFungi's questions could be answered in physics courses. However this question of how to interpret Quantum Mechanics wasn't answered in any of the courses I took nor was such a course even offered to my knowledge. Also as the OP video states there is quite a divergence of opinion even among professional physicists.
originally posted by: mbkennel
The notion of 'spaces' in mathematics extends far beyond Euclidean space or finite dimensional space and was/is a major subject since the middle of the 19th century.
It's time for you to stop bugging people here and actually work and learn real physics. You'll get some answers to your questions more reliably and with deeper understanding.