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NIST Physicists Show Ion Pairs Perform Enhanced 'Spooky Action'

nist.gov

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Re: NIST Physicists Show Ion Pairs Perform Enhanced 'Spooky Action'

#11

One think I've been wondering about spooky action is if entanglement reactions are bound to the speed of light. As in, if one particle of the entangled pair is manipulated, is there a "signal" that is "transmitted" at some speed? Or is it "instant" in the sense that it transcends lightspeed? Or does this question even make sense in this context? Quantum stuff gets weird fast since we have very little basis in which t…

Although I'll certainly butcher the phrasing, my understanding is: measuring a property of one of the entangled particles lets you know the same property of the other particle (an experiment showed this happens faster than the speed of light by measuring the two particles when they were 1.3km apart). This is particularly mysterious because it seems that the property of the particle is not determined before this measurement.

Here are some quotes from a piece on the experiment I mentioned above. from https://www.sciencenews.org/blog/context/entanglement-spooky...

> Einstein insisted that the handedness of the glove must be determined in advance by some physical law. He was perplexed by the possibility that Alice’s choice of hand could have something to do with whether Bob’s glove would fit his fingers.

> Suppose you prepared entangled photons and sent them to Alice and Bob in such a way that if Alice measured hers to be vertically polarized, she instantly knows that Bob’s will be horizontally polarized. . . .

> . . . The photon does not have an orientation until Alice detects it. Same for Bob’s. But once Alice makes a measurement, the outcome of Bob’s measurement is certain.

> Here’s where a lot of confusion clouds entanglement commentary. Contrary to what you might have read in a magazine with “New” and “Yorker” in the title, Alice’s measurement does not “instantaneously” influence Bob’s photon. No signal is sent, no influence transmitted. For all Alice knows, Bob might have measured his photon first. In fact, if the measurements are made at nearly the same time, there might be no objective way to say who made the first measurement. (A space traveler flying along at nearly the speed of light might see Bob’s measurement first, while another traveler flying in a different direction would see Alice’s first.)

Re: NIST Physicists Show Ion Pairs Perform Enhanced 'Spooky Action'

#12
post #6

susskind described entanglement in a bit different way than I'd heard - "that entanglement allows one to know everything there is to know about a system of particles (the whole), while knowing nothing about it's parts." In the classical version of an information experiment, if i randomize placement of objects A and B into 2 boxes, and send one of those boxes to someone else - upon opening my box I instantly know whet…

So to me, that doesn't suggest that something "traveled" to the other box, just like in the Classical version. Rather, somehow I only "knew" the system at the beginning without knowing "any of it's parts" (due to entanglement & superposition). Then, just observing a degree of freedom in one the parts finally reveals what the corresponding degree of freedom in the other part was. This (intuitively) makes more sense to me than saying "information traveled" and "action at a distance"

But exactly this is not the case, exactly this is the difference between classical physics and quantum physics. Classically you place one coin in each of the two boxes, heads in one, tails in the other. Nothing strange happens here, the outcome is determined when setting up the boxes. When you look in one of the box, you will see either heads or tails as determined by the setup. The other box will have the coin showing the opposing side, also determined by the setup.

The quantum case is very different. You again place one coin in each of the two boxes, again one heads and one tails, but this time the coins are constantly flipping. It is no longer predetermined whether you will get heads or tails and only when you look in one of the boxes does the coin in there stops flipping and you see either heads or tails. But more importantly the other coin stops flipping at the very same time so that you will see the opposing side when you look into the second box.

The correlation is in both cases established when the boxes are setup, the coins will always show opposing sides. The quantum cases of course also requires both coins flipping synchronously. But in the classical case the exact outcome is also established during the setup while in the quantum case the exact outcome is only established when one looks in the first box.

Re: NIST Physicists Show Ion Pairs Perform Enhanced 'Spooky Action'

#13
post #6

susskind described entanglement in a bit different way than I'd heard - "that entanglement allows one to know everything there is to know about a system of particles (the whole), while knowing nothing about it's parts." In the classical version of an information experiment, if i randomize placement of objects A and B into 2 boxes, and send one of those boxes to someone else - upon opening my box I instantly know whet…

Very little about QM is intuitive at the ontological level; what matters is that it's logical at the mathematical and practical level. Lasers work, the math works, the ontology doesn't.

Re: NIST Physicists Show Ion Pairs Perform Enhanced 'Spooky Action'

#14
post #12
post #6

susskind described entanglement in a bit different way than I'd heard - "that entanglement allows one to know everything there is to know about a system of particles (the whole), while knowing nothing about it's parts." In the classical version of an information experiment, if i randomize placement of objects A and B into 2 boxes, and send one of those boxes to someone else - upon opening my box I instantly know whet…

So to me, that doesn't suggest that something "traveled" to the other box, just like in the Classical version. Rather, somehow I only "knew" the system at the beginning without knowing "any of it's parts" (due to entanglement & superposition). Then, just observing a degree of freedom in one the parts finally reveals what the corresponding degree of freedom in the other part was. This (intuitively) makes more sense to…

> the coins are constantly flipping ... the other coin stops flipping at the very same time

I'm not sure this corresponds to my understanding of the wave function before observation.

Just because the probabilities for each state is less than 1, to me doesn't mean that it's "constantly flipping". Only that upon measurement there's a probability that one of those states gets defined/constrained.

This is what i think susskind meant by understanding the whole (probabilities of the wave function of the whole system), without understanding the parts "the particles" i.e. it's kind of not right to think of just the parts here. It's only the system+parts that must be thought of together (which of course is why one of the reasons no-one truly understands it).

Re: NIST Physicists Show Ion Pairs Perform Enhanced 'Spooky Action'

#15
post #13
post #6

susskind described entanglement in a bit different way than I'd heard - "that entanglement allows one to know everything there is to know about a system of particles (the whole), while knowing nothing about it's parts." In the classical version of an information experiment, if i randomize placement of objects A and B into 2 boxes, and send one of those boxes to someone else - upon opening my box I instantly know whet…

Very little about QM is intuitive at the ontological level; what matters is that it's logical at the mathematical and practical level. Lasers work, the math works, the ontology doesn't.

sure, but I'm not sure we should be saying that it doesn't have an ontology (even if it is a very weird one), just because the only model that we've been able to come up with thus far is mostly a calculational one (as QM "calculates" probabilities).

Re: NIST Physicists Show Ion Pairs Perform Enhanced 'Spooky Action'

#16
post #14
post #12

Earlier quoted context omitted.

So to me, that doesn't suggest that something "traveled" to the other box, just like in the Classical version. Rather, somehow I only "knew" the system at the beginning without knowing "any of it's parts" (due to entanglement & superposition). Then, just observing a degree of freedom in one the parts finally reveals what the corresponding degree of freedom in the other part was. This (intuitively) makes more sense to…

> the coins are constantly flipping ... the other coin stops flipping at the very same time I'm not sure this corresponds to my understanding of the wave function before observation. Just because the probabilities for each state is less than 1, to me doesn't mean that it's "constantly flipping". Only that upon measurement there's a probability that one of those states gets defined/constrained. This is what i think su…

I'm not sure this corresponds to my understanding of the wave function before observation.

This was only meant as a classical model how the outcome is not predetermined, I did not want to imply that the wave function oscillates back and forth between two states or something like that. I could also have said that you place two coins in each box and one randomly explodes when you look in the box. And of course the corresponding coin in the second box also explodes simultaneously.

Re: NIST Physicists Show Ion Pairs Perform Enhanced 'Spooky Action'

#17
post #15
post #13

Earlier quoted context omitted.

Very little about QM is intuitive at the ontological level; what matters is that it's logical at the mathematical and practical level. Lasers work, the math works, the ontology doesn't.

sure, but I'm not sure we should be saying that it doesn't have an ontology (even if it is a very weird one), just because the only model that we've been able to come up with thus far is mostly a calculational one (as QM "calculates" probabilities).

It doesn't have an ontology with a current prayer of being falsifies, which is the same thing if you're interested in the science and not the popsci. Exceptions exist, hence AdS/CFT correspondence and M-Theory, but they are exceptions. Even then, all that can be said is various tools have been created with value beyond their fields, not that they're in any way falsifiable yet.

At any rate, "intuitive" strikes me as a bad test for QM.

Re: NIST Physicists Show Ion Pairs Perform Enhanced 'Spooky Action'

#18
Why does this not describe the "entanglement" phenomenon:

1) Alice, Bob, and Charlie are in a room.

2) Alice has only an apple and a pear, seen by Charlie.

3) Charlie leaves the room.

4) Alice gives one of the two fruits to Bob.

5) Bob leaves the room to meet up with Charlie and starts eating the pear.

6) Charlie instantly knows that Alice has the apple, no matter where she has ended up in the universe (which is not spooky at all).

Re: NIST Physicists Show Ion Pairs Perform Enhanced 'Spooky Action'

#19
post #18

Why does this not describe the "entanglement" phenomenon: 1) Alice, Bob, and Charlie are in a room. 2) Alice has only an apple and a pear, seen by Charlie. 3) Charlie leaves the room. 4) Alice gives one of the two fruits to Bob. 5) Bob leaves the room to meet up with Charlie and starts eating the pear. 6) Charlie instantly knows that Alice has the apple, no matter where she has ended up in the universe (which is not…

Because Bob leaves the room with either an apple or a pear and this choice is made inside the room. In quantum physics Bob would leave the room with half an apple and half a pear, Charlie would ask Bob to eat the pear, and in this moment Bob's half of the apple would teleport to Alice and Alice's half of the pear to Bob. Charlie could also have asked Bob to eat the apple.

Very roughly speaking, this picture is actually flawed. Charlie can not choose the fruit to eat in quantum mechanics. In this picture you would also transmit Charlie's choice to Alice faster than the speed of light which is not possible in quantum mechanics. The important part of this picture is that Bob does not leave the room with a predetermined fruit, the choice happens later outside of the room but Alice still always ends up with the other fruit, Alice and Bob never end up with the same fruit.

Re: NIST Physicists Show Ion Pairs Perform Enhanced 'Spooky Action'

#20
post #18

Why does this not describe the "entanglement" phenomenon: 1) Alice, Bob, and Charlie are in a room. 2) Alice has only an apple and a pear, seen by Charlie. 3) Charlie leaves the room. 4) Alice gives one of the two fruits to Bob. 5) Bob leaves the room to meet up with Charlie and starts eating the pear. 6) Charlie instantly knows that Alice has the apple, no matter where she has ended up in the universe (which is not…

It would be spooky if, in the middle of step 5, Malory exchanged Alice's apple for a banana. And Charlie knew that.

Edit: I like danbruc's answer better.

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