FIrst, I have been thinking quite a bit lately about the language used to describe various areas of science. Two words that come up frequently in popular communications about Nature are "Magical" or "Miraculous," which both, for obvious reasons are problematic!

That said, Nature often faces us with a very *real* sense of Awe at how it is constructed or acts, and I think it is worth attempting to find a philosophically neutral word or phrase that conveys the amazing, astonishing, confounding, bewildering, counter-intuitive features of real empirical models, the math and the experimental evidence that is found.

Second, I do not believe entanglement is magical. There are, at least with current understanding, fairly substantial limits on what it can and cannot do. There have been, as yet, not experiments that allow for *information* in the strictest sense to travel faster than light. The literature largely gets around this by calling it not information, but *correllation*.

Entanglement does beg for a coherent explanation of just *how* correlation is maintained at a distance. I haven't found many truly satisfactory explanations for the "how" aspect is explained, though I would like to be directed to some if they exist. I have read much that indicate the mathematical formalisms that lead to concern that entanglement might exist, right through the experiments that are very close to closing any last loopholes that would allow Local Realism to still be possible. Anton Zeilinger's group is very active in closing the remaining loopholes.

This still leaves us with the "how". I'm not sure the answer necessarily lies in redefining movement. In a rather pathetic submission to last years FQXi contest, I suggested that one way to keep entanglement from violating universal speed limits (c, the speed of light), entanglement could be considered a *structural* component of Nature. Thus, the entanglement itself, the *correlation* storing link, doesn't move all! There is a wavefunction that describes the PAIR of Alice and Bob's particles, but the leap I took was suggesting that Alice's particle links to the PAIR wavefunction. Bob's particle links to the PAIR wavefunction, but the parts of the wavefunction describing their individual *motion* do not directly link Alice's particle to Bob's particle. That link is a structural element, largely not concerned with or participating in the spatial/time evolution of the individual particles.

Also, little discussed is how ubiquitous entanglement really is, at least if the math is to believed. While reading Roger Penrose's "Road to Reality" I was stunned to hear him say that all electrons are, in some way, entangled with each other. Electrons are *identical* to each other, which is one of the reasons chemistry functions so well! I may make a muddle of this next bit, but in terms of the wavefunction, identical particles are always entangled. This entanglement does not seem to be easily exploitable experimentally. Practical experiments engtangle *aspects* of pairs of electrons, which does exploit the identical nature of electrons, but by teasing out very specific correlations that can be "purified" for experimental purposes.

When a photon or electron used in an entanglement experiment reaches a detector, revealing the correlation with its partner, Penrose says that the electron or photon rapidly becomes hopelessly entangled with the wavefunction of the detector.

So, my point is that while contemporary experiments are fo...

Sorry. The end of my comment seems to have gotten lopped off during an edit.

So, my point is that while contemporary experiments are focused on "purified" states, there are a lot of interesting things going on in the background. A recent paper talks about how Dark Energy might be the result of entanglement between different *eras* of the universe. Also, I saw something talking about how entanglement may be able to surive passing the event horizon of a black hole! Think of the implications of that!

Dean

I admit that the question was formulated in a provocative manner – but I tried to discuss with people who don’t look at entanglement to see magic. Our eyes and our brains face a real challenge when examines phenomena at scales different from those which formed our way of thinking. Cosmology and the quantum world are governed by the laws of physics – but these laws are scale-dependent. The illusion of magic arise at the interfaces of these scales – we should try to see how things are doing beyond these boundaries.

„There have been, as yet, not experiments that allow for *information* in the strictest sense to travel faster than light.” – you say. And I agree.

But can you define information in the strictest sense? We trid to make some approaches in a paralell discussion on the Quality of Information – but I’m not yet satisfied with the result. We did not arrived to mention the special issues of entangled information, the laws of conservation of information and the simmetries generated by this law (see Noether th).

I have just downloaded your FQXi essay and will try to take a look at it later.

From the phrase in your comment „That link is a structural element, largely not concerned with or participating in the spatial/time evolution of the individual particles. ” I suppose that it may contain some similarities with my thoughts related to entanglement with conservation of local reality. The difference is that I call the space/time evolution of particles *motion* - but the motion of elementary particles differs essentially from the motion which is observable to naked eye (and even to eyes dressed with eyeglasses, microscopes or telescopes and other fancy instruments)

Interesting remarks about dark energy and BH horizon. I have to think about that (think-experiment, because hands-on experiment...)

Salve,

András

Andras,

Thank you for the feedback. I too have concerns about entanglement not being information. I am careful to not "speak out of turn" on this as I have not found a clear way around the subtleties.

I am also somewhat obsessed with discovering ways to convey the vast differences in scale that we need to imagine/visualize in order to really comprehend our universe. I am concerned that one of the reason there is a decline in real public understanding of science is the mind-boggling quantities and distances involved. Quarks are so unimaginably tiny and remote. Early galaxies are so huge and remote. The number of atoms in our body, the number of photons spewing from a flashlight are so huge that we have very little human experience we can use as reference points.

I consider my self a Generalist, which is still a bit of dirty word in some academic and corporate circles, but it's almost genetic for me, so I've stopped fighting my need to research broadly, but I've also tried to couple it with intense bursts of learning the "proper" language of specialties. One interesting thing I've discovered is that when you focus on something like Entanglement, there are 'camps' that use different terminology to describe the same phenomena. I expected this in broad-stroke science, when Many Worlds meet the Copenhagen Interpretation for instance, but was surprised by how *casual* the interpretive writing has become in published papers. The evidence is presented clearly, but when I read something like, "we can determine *which-way* the particle went," I find this to be disturbingly old-school and clumsy language to be used in what are the most beautiful and cutting edge experiments.

When I see this I begin to think that you are right, there is still a lot of Magical Thinking that may need to be penetrated before even the scientific community grasps the implications of science, much less the general public.

@Dean

I’ve just finished reading your essay and found it very interesting.

Actually I had some difficulty in breathing when I saw your phrase “there is no separation between ‘particles’ even at great distances”.

That’s exactly my point of view detailed in a manuscript sent to a publishing house in sept 2012. (and apparently the manuscript has found a safe hiding place there). So, if we are talking about crazy ideas, you’re not alone! But as I read further, I realized that your craziness is somehow different of mine (no offense!).

You make a parallel between the special relativity (c=const) and entanglement, based on the fact that both phenomena would be frame-dependent. Which is true in the case of SR, and as a consequence the Lorentz-transformations are needed to switch between the reference frames. But in case of entanglement (further Entg) there is no formula for such switch: the detected quantic operator becomes unavailable to the other particle instantaneously. Obviously this means for me that the notion of *movement*,* motion* is somehow different in the case of Entg-d pairs compared to the particles in relativistic motion. Should we call it super-relativistic motion? Maybe we’ll find a better term…

One of your essay’s basic idea is to see Alice directly latched to the Pair’s wave function, meanwhile Bob is latching to the same wave function from a different reference-frame. I have problems visualizing the wave function as something with little handgrips on it to make possible for some particles to latch to that wave front. Even with closed eyes I keep seeing a wave front as a probability distribution in an abstract space (as you correctly state later), which describes with complex numbers some quantic operator of the involved particle and the operator’s probable behaviour in space and time. Maybe you should give more details how you see this *latch*. On the other hand you admit that Alice and Bob are latched to the wave front from different reference frames. But if there is no separation between the particles, why should they have different ref frames?

I hope, you won’t find these questions too crazy : )

Salve,

András

I would like to propose a discussion on interpretation of entanglement beyond the view offered by Copenhagen’s interpretation (which regards the vawe-function as a description of the observer’s knowledge about the quantum-system) about an attempt to describe quantum reality. In my oppinion we have to bestride Copenhagen’s in order to get rid of the limitations sprang from its anthropocentrism, and discuss separatly about the isolated quantum system – and later about the interactions of this quantum system with the measuring devices, the observers and Wigner’s friends. The alternative interpretations (many worlds, density matrices of environmental decoherence, pilot wave, consistent histories, etc) are dealing mostly with the interpretations of what is measured and perceived – and not concerning very much, what is real.

Of course, I know that quantum reality the time beeing is beyond the grasp of our perception and understanding – but I hope, is not beyond our imagination. That is why I propose to imagine what kind of processes could be unfolding in the quantum realm which can lead to the impression of non-locality in case of entanglement.

To start I would separate the four phases of an experiment whith entangled particles.

In phase I two particles (A and B) are emitted in a process which correlates their quantic operators: polarization plane in case of photons, spin for electrons, etc. – which has to be opposite measured along the same axis due to Pauli’s exclusion principle.

In phase II these particles are moving freely – without interaction with their environment. Phase II is finished when one of the particles comes in interaction with its environment.

Phase III starts if one of the entangled particles interacts with a measuring device which can determine the quantic operator used for entanglement (polarization plan, spin measured along an axis, etc). Phase III ends when the second particle is measured with a similar device on its path.

In phase IV the perception of the observers enters in the arena: Alice and Bob will try to understand the meaning of what they read on their devices capturing particle A - respectively B. What they know: the result of their measurement is unpredictable, but as they learn the result obtained along a randomly chosen axis, they come to know that their partner’s particle is ortogonally polarized/spin is the opposite if it would be measured on the same axis. Helas, the information regarding the chosen axis can not travel FTL – so, causality is maintained in the macroscopic world of phase IV.

The apparent paradox of non-locality springs from the events of phase II – not discussed by Copenhagen’s interpretation or the alternatives. Without this discussion, the result is mind-boggling: the correlation between the particles seems instantaneous - even if the particles are reciprocally excluded from their partner particle’s light-cone. Quantum Mechanics does not explain what is really happening – just offers the mathematical formalism to describe the result and warns that the apparent FTL speed which correlates the quantic operators of the particles can not be used in phase IV to communicate information FTL.

In my oppinion, the explanation resides in the fact that in phase II the entangled particles are forming a closed system. In phase II the particles A and B are moving on the boundaries of this system, but nor energy, nor matter – and consequently, nor information – are crossing this border: this is a definition of closedness. Thermodynamics allows for closed systems to maintain their enthropy at a constant level – so phase II resists until one (or both) particle interacts with its environment (phase III starts if this interaction is a measuring device – otherwise the experiment can be considered as failure from the viewpoint of Alice and Bob). During phase II the system’s enthropy is stable – so external time’s flow (observed by the outsiders, namely Alice and Bob, as a steady increase of the Universe’s enthropy) is irrelevant for particle A and B. They are “flying” in a happy, timeless state which preserves their correlation concerning those quantic operators determined in phase I. As time being frozen, nor the space between the particles can disturb the idyll: correlation acts instantaneously on whatever axes Alice and Bob chose to set their devices during phase III. The space inside the closed system with particle A and B on its growing boundary of phase II acts differently compared with the space which separates Alice and Bob. Information can not travel FTL between the observers, because they are excluded from the closed, timeless system of phase II: the explorer’s interaction with the particles are the start-signal of phase III. Outside the closed quantic system space acts as an insulator for information, and the insulator capacity depends on the enthropy of the intervening medium: in vacuum (minimum enthropy) photons can convey information with speed-light. In opaque media, with higher enthropy, speed falls drastically.

Inside the closed system formed by the entangled particles enthropy is almost zero (the fewer entangled particles, the lesser the enthropy) – so the speed of correlation’s spreading amongst the particles is almost infinite in case of 2 particles, somewhat slower in many-particles system. But anyway, the closed system behaves as if it would be extremly rigid: if Alice interacts with her particle A here, she will learn instantly what would measure Bob on particle B, if he would measure along the same axis. Even if Bob would be light-years away – which means FTL.

Well when I do not understand something, I actually do look to the maths for an honest naked expression of truth, and to the master papers of old. Those people really did know how to express grand concepts simply. But don't worry. The unification of physics will happen within the next five years. All the signs are there for the students of history of physics to see. History is repeating right now, but don't expect Copenhagen to be wrong or misguided in any practical sense.

I come to this from more of a mechanics background, but it seems to me not hard to understand that the correlated state variables in phase space are essentially a spatial phenomenon therfore time is of no account. The fact that it takes time to separate parts of the wave function in our space-time does not negate this intimate connectedness in phase space, which must have some basis in reality else it would not happen!

I do agree that the relationship between spacetime, the speed of light, and quantum mechanics could be better explained, but hardly anyones day job paying the bills depends on such interactions between GR and QM.

It might help if you think of communication at light speed not so much as seeing a photon from an object four light years away, but rather an instantaneous communication with an object four years old. Suddenly entanglement in the moment is not so strange to understand after all. From the reference frame of the photon it is instantaneous! From our reference frame it appears to take four years for one electron to lose energy, and the one in our eye to gain it. Go figure! It is actually this reference frame issue I find far more interesting than entanglement to ponder.

Andrew, thank you for sharing some ideas on this thread.

I observed some similarities between our approaches above in the sense that you say

“the correlated state variables in phase space are essentially a spatial phenomenon therefore time is of no account”

In my formulation

“external time’s flow (observed by the outsiders, namely Alice and Bob, as a steady increase of the Universe’s enthropy) is irrelevant for particle A and B. They are “flying” in a happy, timeless state which preserves their correlation”

Furthermore, I understand your suggestion to examine the importance of reference frames: timeless correlation between different reference frames are a hint that some other mechanism is hidden in space.

I don’t think that Copenhagen’s is wrong or misguided. It is a state-of-the-art scientific approach to the curious phenomena of quantum mechanics: observation – hypothesis – experiment – verification and start-over of these cycles. But I also think that this is a kind of black-box approach.

We don’t know, what is in the box (we can’t open it), so we are testing it with different inputs and observing the output of the box - using the mentioned cycles. Copenhagen’s is operating with this approach and the result is expressed in the terms of the black box’s output – that is, with the information, knowledge learnt by the experimenter about the quantum system, expressed in terms of probabilities of the wavefunction. That is why I called this approach anthropocentric: is not concentrating on what is happening IN the black box, but with the knowledge obtained by the bystanders. I recognize that the Copenhagen’s was tho engine of the first and second quantum revolution – but I suspect that for the next revolution an other interpretation will be necessary. An approach which will permit to open the lid of the black box. At least as part of a think-experiment for start. My previous post was an attempt to imagine: what could be INSIDE the black box?

Well what is inside the black box is Hamiltonian mechanics. As an engineer we were very well trained in mechanics (one of the more trivial aspects of our jobs thanks to the brilliance of those who came before us) and we know nothing further is hiding in the box. In physics, I am far more concerned with what is being fed into the box - that is where the value lies in new interpretation. I get accused all the time of fiddling with the black box, when this is the last thing I need or want to do! Which just goes to show how bad I must be at explaing the work I am attempting in this field.

I have read somewhere that in physics what is difficult to understand is not its math, but the physics. Probably this goes also for the formalism which describes physical phenomena.

In classical multiparticle systems, of course, the symplectic manifolds of phase-space offers a generous context to describe Hamiltonian dynamical equations.

What is this thread about, is not classical – and perhaps not multiparticle. Even if we think that in our black box we have 2 particles, they are behaving as one. Maybe we should imagine the two entangled particles as one system – spread over the entire phase-space. If the phase-space is big enough, its interaction with the outer world can create the illusion of magic (EPR paradoxes). But you’re right affirming that the size here doesn’t really matter. As time is not flowing in this phase-space, it would look like „frozen” Hamiltonian. An interaction with the external world (Alice and Bob making quantum measurments) will lead to the „meltdown” of the entangled system, and liberates the Pauli principle’s djinn – which in turn correlates instantly the quantic operators at the boundaries of the phase-space. To the great amazement of Alice and Bob.

This could be a simple explanatory mechanism of entanglement: no magic, no mystery whatsoever. So, what do we have in our black-box?

Deep-frozen hamiltonian phase-space.

Human brain is always better than a computer or super computer.