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Comment by bdamm | Hacker News Reader

The part I don't understand is the "spooky action at a distance." Isn't this just the same as if the qbits were already in whatever their final state was as soon as they were entangled? Or in other words, is there any experimental basis for determining that the "cat" stayed alive at all? It seems a lot less magical when we just determine that in fact the value is the same no matter when or where you measure it, although it may not be predictable. And since the "entangled" qbit always had the same value, no matter when you measured it, then there is no "spooky action at a distance". The action occurred when d=0, and what you actually have is two copies of the same ROM.

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The idea that the qbits choose which value they'll collapse to at time of entanglement is called local hidden variable theory, which John Bell disproved in 1964: https://en.wikipedia.org/wiki/Local_hidden_variable_theory

In more practical terms, the theory also falls apart when you start doing more complicated things with entangled qbits than just measuring them, like quantum teleportation or error correction.

So, it's kind of like closures in JavaScript?

"A Bell test experiment or Bell's inequality experiment, also simply a Bell test, is a real-world physics experiment designed to test the theory of quantum mechanics in relation to two other concepts: the principle of locality and Einstein's concept of "local realism". The experiments test whether or not the real world satisfies local realism, which requires the presence of some additional local variables (called "hidden" because they are not a feature of quantum theory) to explain the behavior of particles like photons and electrons. According to Bell's theorem, if nature actually operates in accord with any theory of local hidden variables, then the results of a Bell test will be constrained in a particular, quantifiable way. If a Bell test is performed in a laboratory and the results are not thus constrained, then they are inconsistent with the hypothesis that local hidden variables exist."

Spooky private method scope is spooky.

It’s also worth noting that as of 2015[0], this has been experimentally verified.

We’ve made real-world measurements here that correlate with measurements made at the exact same time over there in a way that mathematically cannot be accounted for without some species of intuition-violating spookiness. It’s all very real.

0: https://en.wikipedia.org/wiki/Bell_test_experiments#Hensen_e...

Big deal. There's nothing shocking or spooky about two billiard balls being made to spin in arbitrarily opposing directions, selecting only one (omg! without discovering which way it spins, you guys), then separating them, and then noticing the spin of one, in order to reliably grasp that the other is the reversal.

I have two guitars. I place the guitars facing one another, such that plucking the HIGH E string on one, also plucks the LOW E string on the other. We put ear plugs in our ears, such that I can separate the two guitars, without us ever hearing them. I pluck the guitars, give you one, and take the other one and travel far away. I then listen to my guitar. It is the HIGH E guitar. Now I know you have the LOW E guitar. Wow. Incredibly unspooky. Not teleportration.

https://en.wikipedia.org/wiki/Local_hidden_variable_theory

https://en.wikipedia.org/wiki/Bell_test_experiments#Hensen_e...

These links are intended to suggest something contrary to what I've said, but they do not suggest any contradiction.

Im not an expert so from my outside viewpoint

I think by taking the guitar far away you are implying possibility of faster than light communication, which is thought to be not possible, so his links address that? Hard for me to understand so I'm just saying my thoughts out loud to get clarified, thanks

The quantum state of interest is induced when plucking the conjoined "guitars". (analog for particles)

That state is induced at the moment the guitars share "locality" because entanglement requires locality for initialization of polarization.

So then, we say we are as yet unaware of the qualities of the polarization we, ourselves, induced. Very mysterious.

So spooky, yes? We do not measure, because we choose not to, so we do not yet know.

Even if we prevent ourselves from having the capacity to measure, the results hold true, but so what? And so what, if we ask others to do the same. Imagine that we ask two waiters to tape two coins together in the kitchen, flip the linked coins, peel the coins apart while preserving the outcome of the coin flip, then take one coin to your table, and one to mine. Now I know which side of the coin you are looking at, without walking over to your table. So what. Nothing about this claims transmit information superluminously.

In reality, with instrumentation, carrier signals relay an electromagnetic transmission in such a way that one cannot peek or tamper (the waiters can't change the coin flip, we cannot hear the ringing guitar), but this does not invalidate the premise of the analog. For the purposes of the analogous guitar example, we say that our couriers (electromagnetism itself) are prevented from touching or listening to the ringing guitars, or disclosing what they might sense.

With the guitars, we say the guitars move away from the place where they were entangled. We'll say that our instrumentation rang the guitars at the grand canyon. Our couriers then transported the guitars to you, at the top of the Empire State Building in New York, and me on the Golden Gate Bridge in San Francisco. I receive the guitar, and discover that the LOW E string is ringing, it can only mean that you guitar's HIGH E string in ringing in New York.

There are no local hidden variables in this example. The premise of polarity as a corollary for guitar strings is modeled in the exact same manner. Six strings on a guitar maps to the same essential parameters of each of two directions for all three axes of spin.

You are missing the point of Bell test experiments. Such experiments demonstrate that which guitar is the high E one and which is the low E one is not decided when they are still together. It is not that you and everyone else just don't know which way it is until someone listens to one of them, it is actually not yet decided until someone listens to one of them.

It's just an expression of the conservation of energy. Much in the same way the double slit experiment conflates a particle transporting itself through two windows at once, so too, do these experiments conflate the polarizers as causing the effect.

Ask yourself: if you construct a gun, with two diametrically opposed barrels, with exactly opposed rifling twists, and you aim the gun at two opposing (but identical) abrasive knurled metal rasp targets, such that if the bullet spins one way, the ricochet off rasp target will send it to a blue target, but if the bullet spins the other way, the grain of the rasp target is such that the bullet is sent to an orange target, will you be surprised to find that the behavior of the projectiles remains consistent?

Fire those bullets out of that gun, and as the bullets leave the opposing twists of the barrel, and the spin of the bullets encounters the friction of the knurled surface, they will consistently be sent in whichever direction the spin of the barrels rifling puts them. When one side sends spins the bullet to hit the blue target, the other barrel's twist always puts the other corresponding bullet onto the orange target, by bouncing it off the polarizer rasp.

So, now, to shrink downward to the realm of particle physics, what we find is that the ballistic particle guns are such that the emitter source is an array of many guns with varying rifling twists, but like pulling a lever on a slot machine, we cannot know which of the guns embedded in the radiation source will fire next.

We won't know the turn of the rifling of the gun's barrel prior to whichever one happens to go off. We stick out our rasp target to have it send the bullet to a colored target, and we declare that the polarizer rasp directed the bullet particle, but not really. The emitting source's gun barrel imparted the spin. The polarizers induced behavior on particles that would have behaved as reciprocals anyway.

No, no, no. There is almost half a century of experimental evidence against you. The experimental results of Bell test experiments are incompatible with the assumption that the states of both particles are fixed when the pair is generated and are only classically correlated because of the way their states are fixed. All your analogy attempts are flawed and bound to fail exactly because entangled pairs of quantum particles do not behave like pairs of classical particles. You are making up classical experiment and assume that quantum particles will behave in the same way, but they don't. And that's the entire point.

EDIT: I just came across an illustration which might be helpful. I will place three coins on a table and cover them so that you can not see whether they are heads or tails. You get to pick two of them and I will reveal them for you but you can never look at the third one. Your task is to figure out by which rule I am placing the coins on the table.

In the first round you pick coins one and two, I reveal them to be heads and tails. In the second round you pick coins one and two again, now they are tails and heads. You continue picking coins one and two for a few thousand rounds and always see heads and tails or tails and heads, they are never the same.

Then you switch to picking coins two and three for a few thousand rounds and again they are always heads and tails or tails and heads, they are also never the same. Now you have figured out what I am doing, I am randomly choosing between heads, tails, heads and tails, heads, tails for coins one, two, and three.

So in the next round you pick coins one and three and I reveal them to you. Heads and tails. WtF?!? They should have been the same if I always choose between heads, tails, heads and tails, heads, tails. You try again. Heads and tails. Again. Tails and heads.

No matter what you try, you never get to see two coins with the same side up. That's ridiculous, you think. There are only two sides to a coin but three coins on the table. At least two of the coins have to have the same side up in each round and if you select the two coins to reveal at random, then you should at least sometimes get to see two coins with the same side up no matter which rule I use to place them. But you don't.

Assuming that I choose heads and tails for each of the coins when I placed them on the table and before you make your choice is incompatible with your observation that you never see two coins with the same side up. But if you assume that I can magically turn the coins around at the moment you tell me which two coins to reveal, then you can explain your observation. It may however trouble you because your explanation now involves magic.

And that is roughly how entangled pairs in Bell test experiments behave. Or more formally, classically P(1=2) + P(2=3) + P(3=1) >= 1, at least two coins always have the same side up no matter what the underlying distribution is. Entangled pairs in Bell test experiments violate this inequality, the probability of two coins having the same side up is less than 1. Not 0 as I portrayed it but 0.75.

Except you can't tell me what the spin is without polarizers. This is like telling me I have to measure the orientation of a fidget spinner with a fitness club's treadmill set to the brisk pace of an uphill jog.

None of the experiments don't use polarizing lenses to make a determination of results on both sides. This is where the experiments are fundamentally flawed and propose weak evidence.

To simply read about the fundamentals of light polarization is to understand that quantum wave function collapse is much ado about nothing, and it becomes obvious that all this contention is total bullshit, and none of it is magic.

https://en.wikipedia.org/wiki/Polarizer

https://en.wikipedia.org/wiki/Polarizing_filter_(photography...

https://en.wikipedia.org/wiki/Photon_polarization

If you read through the list of Bell test experiments [1], you will discover that not all of them are done with photons, for example »Violation of Bell’s inequality in Josephson phase qubits« [2].

[1] https://en.wikipedia.org/wiki/Bell_test_experiments#Notable_...

[2] https://web.physics.ucsb.edu/~martinisgroup/papers/Ansmann20...

https://en.wikipedia.org/wiki/Inconsistent_comparison

Josephson phase qubits aren't even utilizing the same fundamental concepts to examine the qualities of the mediums that quantum uncertainty affects.

https://en.wikipedia.org/wiki/Phase_qubit

https://en.wikipedia.org/wiki/Josephson_effect

https://en.wikipedia.org/wiki/Josephson_voltage_standard

You complained - without providing any substantive arguments why this might be an issue - that all Bell test experiments use polarizers, I pointed out that you are wrong. I have no idea what you are complaining about now, what is »[...] qualities of the mediums that quantum uncertainty affects [...]« even supposed to mean? You are obviously far outside of your area of competence. If not, just do the experiment, write the paper, and collect your Nobel Prize, no need to argue with clueless people on the web.

A Josephson junction doesn't even trap any single actual physical particle. It's just a standing wave of electrical current trapped in a bounded array of geometrically crafted slabs of superconductors and insulators. It's a phenomenon that arises from the construction of the device.

Unlike fundamental particles such as photons and electrons, there is nothing substantial about the state represented by the standing wave qubit trapped in a circuit operated by a Josephson junction device. Destroy the device (or nevermind that, just never place it in a dewar flask chilled to 4 degrees kelvin, to activate it) and the phenomenon doesn't even exist. So much for whether or not matter or energy can never be created nor destroyed.

To sit there and state that, on paper, this is the same thing as an individual electron emitted as beta decay is, well... fundamentally flawed.

Just to be clear, these are experimental results that are statistically impossible assuming a classical physics. Are you actually worried that they are somehow studying the wrong self-evidently non-classical thing, or what?

Quote from the "Phase_qubit" Wikipedia article:

"The zero voltage state describes one of the two distinct dynamic behaviors displayed by the phase particle, and corresponds to when the particle is trapped in one of the local minima in the washboard potential. [...] With the phase particle trapped in a minimum, it has zero average velocity and therefore zero average voltage. [...] The voltage state is the other dynamic behavior displayed by a Josephson junction, and corresponds to the phase particle free-running down the slope of the potential, with a non-zero average velocity and therefore non-zero voltage."

So, we're not even talking about actual fundamental subatomic particles anymore. We're talking about phase oscillations, and renaming that as if it were a "particle" because, hey, particle/wave duality, so why not?

Hand-wavey math permits us to equivocate that a current induced on a wire, by way of the transfer of many actual electrons across substrates, can serve to prove the premise of a "teleportation device" also.

See? If we play our game of three-card monte, change phase oscillations, wiggle our noses, and tilt our heads a little, it's all very obvious that faster-than-light information transfer can be generalized to fit in the same picture, because this tuning fork makes that tuning fork ring in harmony, but only when we choose to notice.

I’m not sure I follow your argument, but if I understand you right, I don’t believe what you’re quoting is relevant. From the article you are (I think?) criticizing:

We measure a Bell signal S of 2.0732 ± 0.0003, exceeding the maximum value |S| = 2 for a classical system by 244 standard deviations. In the experiment, we deterministically generate the entangled state, and measure both qubits in a single-shot manner, closing the “detection loophole”[11]. Since the Bell inequality was designed to test for non-classical behavior without assuming the applicability of quantum mechanics to the system in question, this experiment provides further strong evidence that a macroscopic electrical circuit is really a quantum system [7]. https://web.physics.ucsb.edu/~martinisgroup/papers/Ansmann20...

That says in plain English that they have not assumed that this system behaves according to quantum principles. In fact, it is precisely the opposite: the quantum nature of this system is a conclusion of their results. It would be statistically impossible for any system following classical rules to produce the same data.

(It bears repeating that the math underlying that conclusion is truly not very complex, and it is very, very well studied. If you can show that it’s flawed somehow, don’t bother publishing— just post your proof here and I’ll, uh... pick up the Nobel for you.)

The only caveat is that this experiment closes the detection loophole, but not the locality loophole; it is theoretically possible that a classical signal could be sent from one qubit to the other quickly enough to fabricate this data. There’s no particular reason to suspect a secret signal is in play, but it isn’t theoretically prohibited.

Assuming you haven’t found a flaw in their mathematics, and that you aren’t alleging that the researchers deliberately fabricated their data, the locality loophole is your best (and likely only) avenue to dispute their conclusions. However, if you wish to pursue that, you should keep in mind that there are many other experiments which close the locality loophole but not the detection loophole, and, since 2015, several that close both. Three-card monte may be a better investment of your time.

Uh, wow, at no point have I made the claim that an electrical circuit is not a quantum system. Nor have I claimed that they are incapable of simulating quantum phenomena. Quite the very opposite.

What I did clearly state, and insist as quite relevant, is that entanglement and double slit experiments are hocus pocus and irrelevant distractions. In fact, I stated that this experiment says basically nothing because it merely simulates quantum phenomena within a circuit.

Hello? Yes. Electrons are quantum entities, and assuredly interact with photons which are also quantum entities. This is demonstrated by the photo-electric effect, which we can all notice by placing tin foil in a microwave. Therefore a circuit is indeed a quantum system, since it assuredly deals in electrons.

Wow! Didn't even need to publish a paper about qubits to draw that conclusion! Amazing!

The implication here is that Bell is waste of time, and so is his theorum: such that emission doesn't determine state, especially when you don't look at it.

Great, thanks Bell. I'll be sure to not look at anything until I want to know what it is. True genius at work.

The experiment demonstrates quantum entanglement. I gather you don’t believe this. So how about this: I don’t believe you.

I don’t believe that you could, even theoretically, produce the data from a loophole-free Bell test without invoking superdeterminism, superluminality, or quantum entanglement.

Can you describe how this would be theoretically possible?

The experiment certainly demonstrates "something" in terms of how not to "measure" relativistic effects with macroscopic tools...

And yet, with relativistic particles, the wild claims are made that splitting photons through a substrate, and then passing them through the wall of a polarizing lens, means we can declare ourselves capable of rewriting and erasing history. Eh, not quite.

But hey, where there's smoke, there's fire, so something must be true, right? Let's just make up whatever.

1. Do you think all Bell test experiments ever done were flawed, i.e. none of the observed Bell inequality violations were real?

2. If so, do you think a non-flawed Bell test experiment could be done?

3. If so, do you have a definite opinion about whether or not it would yield a Bell inequality violation?

4. If so, would it yield a Bell inequality violation or not.

5. If you think all Bell test experiments ever done were flawed, can you pick one, preferably one commonly considered a good one, and point out what exactly you think the flaw in the experiment is?

6. If you think Bell inequality violations are or could be real, how do you want to explain them?

Note that those are all yes no questions, well, at least all but the last two. I don't need and want more than a yes or no for the first four because from your comments alone it is not clear, at least to me, what your position actually is.

It's not about getting correlated outcomes when the measurements are made, that would be unsurprising. It's that the correlations (or more precisely, the distributions) of the outcomes conditioned on seemingly random measurement choices suggest that the outcomes are not from independent measurements.

Now there are several ways you can interpret that: 1) the measurement choice at one site is superluminously conveyed to the other site and causes an effect; 2) the measurement choices are not independent and random despite the best attempts of the experimenters; 3) the wavefunction over the two sites is physically real and both measurement choices are necessary to sample it.

> There's nothing shocking or spooky about two billiard balls being made to spin in arbitrarily opposing directions, selecting only one, then separating them, and then noticing the spin of one, in order to reliably grasp that the other is the reversal.

Okay. So now, make two billiard balls so that they're spinning opposite directions, and separate them to opposite sides of the table. Then, go to ball A and do something to it that reverses its spin. Then observe the spins of the two balls. Are they the same?

For billiard balls, yes. If ball A is spinning clockwise and ball B is spinning counter-clockwise, and you reverse the spin of ball A, then you will observe both balls to be spinning counter-clockwise.

For quantum particles, no. If we manufacture two entangled electrons such that observing them will reveal them to have opposite spin, you can reverse the spin of one of them, and then observe them, and they will both still have opposite spin.

Unfortunately I don't think this is true. The moment you observe them, they are no longer entangled. So they have opposite spin at that point, but if you reverse one, it behaves classically and both electrons then have the same spin.

I'm still trying to wrap my head around why there isn't some hidden variable though which determines which spin they'll have. Like with Bayes' theorum, I keep learning it but for whatever reason my brain won't remember it and I have to look it up again hahah.

Correct, this only works if you can reverse the particle's spin without observing it. This is a descriptive example - the real experiment is slightly more complicated - but it was experimentally verified by Alain Aspect in 1982. If you want a more detailed explanation I recommend http://scienceblogs.com/principles/2007/02/22/spooky-action-...

Something else worth noting: an entangled state is itself a superposition of two non-entangled states. This is obvious when you look at the math: the entangled state |10> + |01> is the superposition of the factorizable (non-entangled) states |10> and |01>. But physically what this means is that entanglement is intimately related to interference. Interference happens when a photon "goes both ways". Entanglement happens when a pair of photons go in such a way that you can't tell which photon went which way. (There's more to it than that, but the point is that entanglement and interference are closely related phenomena. This fact is often overlooked, particularly when it comes to explanations of entanglement directed at lay audiences.)

Also, the idea that collapse is a physical phenomenon that propagates faster than light is not universally accepted. There are other ways to interpret these results. None of them take a toll on your intuition, but personally I like this one:

http://www.flownet.com/ron/QM.pdf

(There's a video too: https://www.youtube.com/watch?v=dEaecUuEqfc)

Can someone tell me if I understand this correctly. So Bell famously proved that it is not the case that the correlation we see between 2 entangled particles A and B is because of some common cause C. Therefore we concluded that it must be that A => B or B => A and we called it a spooky action at a distance. But aren't we forgetting that there's a one more way to get a correlation between A and B without resorting to spooky action at a distance - conditioning on a common effect, aka collider: http://www.the100.ci/2017/03/14/that-one-weird-third-variabl... Has anyone proven that this is not the case?

What you're proposing is essentially what Bell's inequalities contradict. That's why they're surprising.

I think the many-worlds picture is a clearer way to think about this than "spooky action at a distance".

Bell inequality proves (or is used to show) that the shared/correlated state of "entangled" particles cannot be fixed before the act of measurement. It has nothing to say about "A => B" or the likes. If there exists a third "C" it'll still have to set the state of A and B, at the moment of measurement, regardless of distance.

Yes, this is more or less what Bell's theorem disproves, although it's kind of a poor metaphor, because entanglement deals with indeterminate states, not just unknown ones.

The explanation you're supposing for the "spooky action at a distance" is called a hidden variable theory, and as others have said, this explanation has been disproven. You might be wondering how, and I'll tell you the scenario (adapted from The Elegant Universe) that helped me understand.

Imagine you and I each have a device: a small box with one openable window on the top, one on the front, and one on the back. When one of these windows is opened, it shows either white or black. Further, I tell you that these boxes are entangled: if we both open the same window, the same color will be displayed on both boxes. This only works for the first window opened and only if we both open the same window: if a second window is opened or if we open two different windows, the colors shown will no longer be correlated in any way.

I actually have many of these pairs of boxes, each pair numbered uniquely to identify its matching twin, and we run the experiment for an arbitrarily large number of them until you're satisfied that my claim holds true. You see nothing special about these boxes and argue that they're simply preprogrammed from the factory to display a set of colors the first time a window is opened (for example, BWB or WWB). I counter that entanglement is special and the boxes are not preprogrammed from the factory. In fact, they decide at random which color to show right at the moment one of the boxes' windows is opened!

My claim seems crazy and at first glance possibly even unprovable! But it turns out with a bit of cleverness we can test this.

We take an arbitrarily large number of boxes and begin independently opening their windows at random (without consulting or coordinating with each other when deciding which window to open), recording box numbers, window choices, and the resulting colors. When finished, we compare notes. Sure enough, when we both open the same window on entangled boxes, the colors match as expected. Upon a closer look at the data, we discover something surprising. Ignoring which window we opened, each pair of entangled boxes showed the same color exactly 50% of the time. How is this surprising? A little bit of probabilistic analysis conclusively demonstrates that such a result is fundamentally incompatible with any hidden variable theory.

Assume for the sake of argument that the boxes are preprogrammed. The only possible programming for each box is some form of XXX or XXY. Consider: if both boxes are programmed WWW (or BBB) and we both open a window at random, it will show the same color 100% of the time. If both are programmed WWB (or BWB, or BWW, or any equivalent variant), 2/3 of the time there's a 2/3 chance of displaying the same color when choosing windows at random and 1/3rd of the time there's a 1/3 chance. Combined, whenever the colors are in an XXY configuration, there's a 5/9 chance of showing the same color when windows are chosen at random. Note that in both scenarios the odds of seeing the same color from randomly-chosen windows are greater than 50%! Assuming the preprogrammed colors are chosen at random, some form of XXX will be chosen 2/8 of the time and XXY will be chosen 6/8 of the time, we see that the total odds of seeing the same color if the boxes were preprogrammed should be 2/8 * 100% + 6/8 * 5/9 = 2/3. In theory, our data should have shown a 66% agreement in color, but our experiment consistently shows colors matching 50% of the time.

A hidden variable theory—any hidden variable theory—runs into this probabilistic hurdle.

What I draw from this is that polarized light doesn't quite work the way we think, and the investigation should be into the modes of polarity.

Are you seriously dismissing offhand theoretically sound and experimentally-verified core tenets of quantum mechanics?

It's not like they're making this stuff up. It falls very straightforwardly out of the mathematics underpinning quantum mechanics, we have tested these things, and we have conclusively disproven the existence of any type of hidden variable theory.

That's not to say quantum mechanics is faultless and complete, but any new theory is going to have to incorporate these results rather than throw them out entirely (much like how Newtonian physics "falls out" of general relativity at low speeds and small masses.

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