Quantum entanglement

Can you post an experiment?

Please stop posting this.
It is just incomplete and confusing for no reason, and no you don't need a retrocausal account.

please shut up

The strange thing is that there is correlation in ANY basis you measure in. It's like having spins that can be red or blue as well as up or down. If I decide to measure color and find red then you would find blue. However, if I measured red and you decided to measure spin instead, yours would be equally up or down. Likewise, if I measured spin up you would get spin down but if you picked the wrong basis you would get red or blue with equal probabilities.

Physically, color would correspond to measuring in the [math] \sigma_{x} [\math] basis instead of the [math] \sigma_{z} [\math] basis. These two operators do not commute, just as position and momentum do not.

The following is a rather thorough yet very accessible overview:

quantamagazine.org/20160428-entanglement-made-simple/

this. Einstein didn't oppose QM directly but realized it was incomplete

It's called Bell's Inequality, pretty famous.

>butthurt clockwork determinist detected

>I don't understand the delayed choice QE is just a trick with the coincidence counter
wew

Unfortunately for you the mainstream has moved on past billiard-ball Newtonian physics.

You don't understand the quantum eraser experiment lad.

You don't even understand normal erasers,
rubbing one out isn't what you think it is

would you be so kind and explain the experiment?
Are you referring to the fact that it can work without retrocausality because the result is only "determined" from your viewpoint at the moment you observe the data?

coincidence counters only impact what we can do with the information of an experiment. it has no influence on the essential mechanisms underlying the experiment itself

It is in fact you who does not comprehend the experiment.

Yes, and the "retrocausal" account is only made possible because you're selecting after the fact with the coincidence counter.

I'm reffering to the fact that if you asked Bohr or Heisenberg to work through the delayed choice QE experiment as a gedanken, they'd come up with the exact same result, without at any point invoking retrocausality.

Ok I'm reading through this article and I genuinely fell like a retard because I don't understand the paradox here.

>The interesting effects, which EPR considered paradoxical, arise when we make measurements of both members of the pair. When we measure both members for color, or both members for shape, we find that the results always agree. Thus if we find that one is red, and later measure the color of the other, we will discover that it too is red, and so forth. On the other hand, if we measure the shape of one, and then the color of the other, there is no correlation. Thus if the first is square, the second is equally likely to be red or to be blue.

Why would we expect there to be a correlation in this case? I measure the color of the first one, it's red. I know that red circles and red squares both exist. Therefore I know that the fact that the one I measured is red is meaningless when it comes to the shape of the other one right? So what's the paradox?

Bumping in the hopes someone can clarify here. I am retarded.

That used to be the thinking about quantum entanglement in the 20s and the 30s, but after some guy found a paper about how hidden variables will lead to a particular probability distribution when adjusting the equipment used to measure entangled particles, he actually made an experiment to test that (in, like, the 50s or 60s). What he found is that the probability distribution he got from tweaking the settings of his equipment between individual tests was nothing like the probability distribution calculated by the paper, leading to the conclusion that hidden variables cannot explain quantum entanglement, making the concept pretty counter intuitive. Further experiments have shown that large distances don't effect entanglement, removing any possibility of a light speed particle sending information between the entangled particles.

You're missing the main point of what makes it 2spoopy4me.

In your example, you have two balls that have a predetermined color, right? One of them is definitely red and one of them is definitely blue (or some such bullshit). The ball you take out will have always been that color, and the ball in the bag will have always been whatever color it is.

Now here's the quantum analog to this: You have two balls in a bag, and they can be either red or yellow, but there's no way to know which is which, so both might as well be both colors (this is just superposition, right?). The spoopy part is that once you take out one ball and measure its color, the other ball BECOMES the other color. That is, its wave function also collapses to the opposite state.

Do honestly not see how weird that is? That you've basically acted on one thing that could be a universe away instantaneously by observing another thing?

If not, then as one other user said, you don't fully grasp what's going on. Or if you don't understand what non-locality is.

>he other ball BECOMES the other color.

Now this is the part I don't get. How do we know it BECAME that color and wasn't just that color all along?After all, we haven't measured it yet, so clearly we didn't SEE it changing color.

btw I'm not pointing this out as a flaw, I'm aware I'm misunderstanding something and want to know what.

Please someone answer this I'm losing it.

Not him, but you're honestly not misunderstanding much. QM, especially quantum entanglement/superpositions, certainly wins no awards for making sense.

The way I conceptualize entanglement is like this:

Let's say a particle with spin zero spontaneously splits into two new particles while inside of a closed system. According to conservation of angular momentum, this zero spin state must be preserved -- so the two particles now have opposing spins that "cancel" out. In QM, quantum states are additive. So the initial quantum state of the closed system remains the same through this splitting event, the individual quantum states of the two new particles "add" together. Now, in a departure from classical analogs (read: leap of faith), we need to understand how QM explains this system. It's not that one particle has spin -0.5 and the other +0.5, but rather that in the closed system, before any interaction with the environment, the particles' spin states are superposed. They are both spin - and spin + at the same time. Once we take a particle out and observe its spin, you collapse this superposition and measure the two particles to have opposing spins, as expected according to our classical understanding of conservation laws. The "spook" is that these particles, even though initially occupying all spin states, will appropriately assume the proper spin state once measured.

In QM, the act of observing is like bringing the system out of the quantum world and into the real world that follows our rules, but not necessarily rules imposed by QM.

en.wikipedia.org/wiki/Bell's_theorem

It's complicated, but essentially there are certain observable quantum phenomena that couldn't work if the universe actually ran on so called 'hidden variables', i.e. the balls already being red and blue and us just not being aware of that fact.

>quote from 40+ years ago or something
Yeah, calculus was shocking too, 300 years ago.

I think I understand it now. While both are in the bag, they both are real objects and both currently have some state that we don't know.

So we say because we don't know whether either ball is red or blue, we will say both are currently "redblue." And we consider this redblue state a real state. That is the current "unmeasured" state of both of the balls.

Then that means we have something like this:

Before measurement

If we pick out one ball and see that it's red. It becomes this

After measurement: (intermediate)

Because we know that the other must be the opposite, making that first measurement justifies changing the second redblue state to just blue. And if you remember that we're considering the redblue state just as real as any other, then taking the first measurement caused the second one's color to change from the real color redblue to just blue.

It's a way to assign a physical value to the balls while they exist in this unmeasured state. And because you're assigning a physical value, any change from that value is a physical change. Even though you can come to that conclusion using basic logic, how do you explain what happened physically, rather than just, "I know that it's the other one because they're opposite."

>Once we take a particle out and observe its spin, you collapse this superposition and measure the two particles to have opposing spins, as expected according to our classical understanding of conservation laws. The "spook" is that these particles, even though initially occupying all spin states, will appropriately assume the proper spin state once measured.
But that's because of the mathematics of quantum mechanics, since we describe everything probabilistically, we can only describe then as being sums of probabilities of states, the particles aren't actually in both states at once, but we describe it like that, of course once you measure it, you know exactly what state it is in (hence collapses, because you know which state it is in, the probabilities of the other states become 0), and thus you know what the other one is.

That's how I understand it, like this I feel there's nothing to it.

You have a better understanding than you think you have. Dont get confused by the quantum woo retards

>the particles aren't actually in both states at once

There is a 100% probability that is in at least one of the states, and that state of 100% certainy of being either one or the other state is a state in itself, the superposition of both states is a real, physical state.

If you choose not to interpret the quantum state realistically, then that's your prerogative. But an antirealist has to account for the seemingly miraculous accuracy of the formalism in predicting the outcomes of experiments. If the math gives us the right answer, why don't we take what it says as a literal description of the world?

>even though initially occupying all spin states, will appropriately assume the proper spin state once measured.

Thank, but this just brings me back to my initial problem, how do you know they both initially occupied all spin states? You haven't measured them.

You keep making statements about what the particles are like BEFORE they are measured. Where is this knowledge coming from?

i gotchu senpai

so even if it looks red or blue, you cant say it is until you measure it?!

I have only ever seen the word 'woo' used by posters with a very similar style to yours, but across multiple boards. Do you just get around a lot or is there some link that I'm missing?

That's just mathematical abstraction for our lack of knowledge of what state it is in.
I'd say its a real mathematical state, but much like all the wave functions we throw to fit our conditions, we also throw these double states when actually measuring it.

Essentially for the same reason.

>If the math gives us the right answer, why don't we take what it says as a literal description of the world?
That's simply an abstraction.

The superposed state literally says, x% chance of being in a certain state, y% chance of being in another. etc

How do you physically interpret the state of being undetermined? If you have something that's either 0 or 1 but you don't know which, but you still want to assign a physical state to it, what is your choice?

Quantum is fucking stupid
The only useful shit yields are orbitals

I say "I don't know what it is". I don't assign a state to it. Why must it be different on the quantum scale? Are you telling me that "occupying all spin states" is just another way of saying "we don't know what spin state is because we haven't measured it"?

No, because the former causes the particle to have observable physical properties that are different than those that would be observed if it was already in a particular state and we just didn't know what that was.

No because the wave function that describes it in this unmeasured state is entirely different than any singular one.

Once again, how do you know it CAUSED the particle to have that physical property when you didn't know it's properties in the first place? How do you know they weren't that way already?

The entire system behaves far differently unmeasured than when you do measure it and determine the states.

upload.wikimedia.org/wikipedia/en/e/e2/Bell.svg
>The best possible local realist imitation (red) for the quantum correlation of two spins in the singlet state (blue), insisting on perfect anti-correlation at zero degrees, perfect correlation at 180 degrees. Many other possibilities exist for the classical correlation subject to these side conditions, but all are characterized by sharp peaks (and valleys) at 0, 180, 360 degrees, and none has more extreme values (±0.5) at 45, 135, 225, 315 degrees. These values are marked by stars in the graph, and are the values measured in a standard Bell-CHSH type experiment: QM allows ±1/√2 = ±0.7071..., local realism predicts ±0.5 or less.

>The entire system behaves far differently unmeasured than when you do measure it and determine the states.

Well THAT'S interesting, but it makes me seriously question the usefullness of "red ball yellow ball" analogies, which refer only to the properties of the individual particles and not the system as a whole, in describing the novelty of the quantum world. I feel none the wiser still.

In this existence, which is to say the absolute underlying base reality of everything even a 'god' could possibly reach or interact with (if given my theory that other existences should be entirely impossible to reach for any definition of a god or being), it is simple a multidimensional (relative to our perceptions) firmament with infinite stretching and contracting abilities; of which no resistance exists in an absolute sense nor an absolute limit on how it can be molded or turned; what we view as strings are actually simply folding of this firmament upon itself, which also creates spinning, and this spinning upon a zero-point is infinite, and it more or less pulls itself. the interactions of the folding and spinning upon itself are what makes our relative rules exist, but in actuality the rules of this firmament are a far cry from what we see today and create the spooky nature of the quantum.

entangled particles do not need an individual particle to communicate information because both particles are actually a single object; like a really long pole, any movement on one end of course instantly changes the other end. as for why the chance makes it opposite this most likely has to do with the spinning factor from the folding.

This spinning is the very ground base of what gravity and electromagnetism are from, albeit at a level far smaller than string theory defines reality to be as.

I could explain better, possibly, but this is just what I was able to type in a short time.

It's just retrocausality.

aeon.co/essays/can-retrocausality-solve-the-puzzle-of-action-at-a-distance

>both particles are actually a single object
That's what I thought too until I read this

ur not intelligent, sorry, now fuck off retard

specifically entangled particles are a single 'pole', but normal particles are more so the relativity between multiple 'poles', thus retro-causality and the non-relative instantly changing pole that two entangled particles exist as are both valid at once. The singular pole is that which allows the 'future' information to instantly become the 'present' information for the other particle; as past present and future are one in the same, so distinguishing a difference at the primary level of existence is simply not possible as there is no difference at that level.

Reality on it's most base level follows extremely basic 'rules', ie it's far 'simpler' in how it operates to such an extent that our very old existence's interactions with itself don't seem to make sense compared to it.

"a sufficiently complex system will be indistinguishable from it's components"

Like, basically, there's a near infinite amount of steps and stages of interactions between the basest level and even string theory, let alone the reality we can see with our eyes.

>on one end of course instantly changes the other end.
But user, that's not how it goes.

The information from one side of the pole to get to the other side takes time to travel.
Hence you can have the parabolic solutions to the pole paradox in relativity.

>Anyone not shocked by electricity has not understood it

It doesn't "influence" the other particle though. The phenomenon is no more spooky than superposition itself. You know something about the pair of particles. That's all entanglement is. Knowing something about a pair of particles in superposition works the same as knowing something about a pair of gloves.

At the basest level of reality, everything is in absolutes. The firmament instantly pulls every other part of itself with every fold and spin that occurs. It is a single object; it isn't a thing of "okay one part near it moves first, and then the next" it is all ONE part, JUST one. So ANY small or big part that is moved, moves the entirety of it at once. It has no limitation on how much it can be pulled or contracted; since the ideas of such limitations just don't exist at this level.

It's the same as when, with your eyes, you see that when you pull a piece of paper, the entirety of the paper moves at once. Except, even though this isn't true at the quantum level; it is literally the case at the basest level.

gloves have definite states before measurement, the particles do not.

Another way to put it: when a single particle or string moves; the entire string moves at once, doesn't it? Imagine reality as simply one gigantic elementary particle or string. There are no multiple parts underneath; thus it is a SINGLE piece, and so there is no mechanism at that level which would make it so some parts move at different times, since it is just ONE part.

wat

Precisely not, we haven't actually mesured it yet, but we think it might send light speed to the level of a turtle.
uh, did you know the chinese have sent a satellite in order to experiment communications with entanglement. The idea is that they send a photon, keep another one which is entangled to the sent one, and when it comes to the receiver, they alter it. In case it is catched by someone else, they just destroy the one they kept, so the sent one self destructs.
Basically, that's it. (if I remember correctly). So you have super secured communications. Cryptography can go back to its cave and les the quantics do the job.

In QM red squares and red circles do not exist--it is like saying you have a spin pointing in +z and +x direction simultaneously.

We expect correlation because the objects exist as a pair, e.g. a pair of gloves has one left hand and a right hand. The paradox is that if you measure in slightly different ways this correlation disappears; there is no sense of handedness anymore.

Put another way, you and your friend each have this box containing a color door and a spin door that it can be opened from (once it is opened it cannot be ''opened'' again). If you both open the same type of door, the results are correlated. If you open different doors, it's totally random. It is paradoxical in the sense that these two same boxes when opened differently give two completely different answers.

Yes, I already said this in the very first reply in this thread. The difference between gloves and particles is irrelevant because the fact that we know something about them is the only reason measurement appears to "influence" the other. As I said, the only spooky part is the superposition itself. Entanglement is actually completely normal behaviour that we should expect from any objects.

Michio and Neil have already independently explained quantum entaglement.

Say you have two gloves of a pair. You place one glove in a box and the other in another box.

Then you separate the boxes using two planes. Once sufficiently far away you open the box and see which glove it is.

Now you know which glove is in the other box, but you can't tell anyone faster than light, so it's not useful.

You could probably find their papers online if you wanted.

Once you alter the photon you break entanglement. Entanglement doesn't send information.

t. physicists who have been brought up generation after generation by other physicists who try to take the path of least resistance in their studies of mathematics

QM is LITERALLY just hilbert spaces and probability measures. operator theory is all about non-communtativity but suddenly we see one nontrivial application of those ideas to nature and we make a big fucking deal about it?

count me the fuck out. i have no idea why they call it heisenberg's uncertainty principle, btw, when it's literally a trivial result of fourier transformations on L2 functions.

>i have no idea why they call it heisenberg's uncertainty principle, btw, when it's literally a trivial result of fourier transformations on L2 functions.

people of yesteryear were so dumb, i would totally have invented

its obvious if photons can have particle nature than particles can have wave nature i would totally have figured out wave particle duality

i would totally have come up with special relativity

i would totally have figured out gravity and newtonian mechanics

wow people are dumb how could they not have realised that radiation is bad for you, i would have known

""""geniuses"""" like newton and neumann were so dumb if i was alive then i would totally have discovered everything first, everything they disocovered was so simple and intuitive i cant believe im part of the same race as the humans of yesteryear

i find everything easy and simple once i'm told the answer, it all makes intuitive sense to me

can i have my nobel prize now

There is information transfer in entanglement. You just can't use it to send signals

No there isn't user. Why are you pretending to know QM when you are clearly just making shit up? Why does Veeky Forums attract these people?

Bell's Inequality wasn't an experiment. The actual experiment to go along with it didn't come along until nearly a decade after (1973?).

It's not the formalism that's confusing, it's more the fact that real physical things even behave like that in the first place.

>i have no idea why they call it heisenberg's uncertainty principle, btw, when it's literally a trivial result of fourier transformations on L2 functions.
Yeah, my QM professor did that, it comes straight from assuming that matter behaves as a wave.

Though the implications of your other points I don't follow.

atoms have no other property other than just some numbers ( same goes for pretty much all particles ) - so red and blue would translate just in numbers, and until you don't measure them - you don't have their numbers.

t. someone who hasn't understood entanglement

The difference between gloves and particles is very relevant. If two particles are entangled in the state
[eqn]\tfrac{1}{\sqrt{2}}(|\uparrow\uparrow\rangle_z+|\downarrow\downarrow\rangle_z)[/eqn]This is the same as
[eqn]\tfrac{1}{\sqrt{2}}(|\uparrow\uparrow\rangle_x+|\downarrow\downarrow\rangle_x)[/eqn]That means that no matter which direction you choose to measure in the spins will [math]always[/math] match. This is spoopy because there's no way the particles know which axis is going to measured along.

Solid answer.

For those who don't understand spin, in quantum, internal angular momentum is quantized - it can either be up or down. That doesn't mean it doesn't have components that aren't along that axis, it just means that you can only measure one component at a time. In large scale applications (such as MRI), the combination of all the (proton) spins is known as the magnetization, and because it is the sum of many proton spins, it's not quantized - both components can be measured. So even though it's made up of a lot of things that have quantized spins in one axis, the average of all those spins isn't quantized.

>You have the uncertainty principle which says you can't know a particle's spin along both the x and y axis simultaneously, if you try it gets fucked up.
thats not what the uncertainty principle is fucktard

It's not just momentum and position numb nuts

>You have the uncertainty principle which says you can't know a particle's spin along both the x and y axis simultaneously
Stop watching popsci crap and read an actual QM book that derives the uncertainty principle

I think the information you have is incomplete, because what happens in the lab is that the states of the particles don't always correlate. In some configurations of equipment, you will always get that one particle has the opposite state of the other particle, but, in other configurations, the two never seem to correlate, and you get red/red, blue/blue, red/blue, and blue/red combinations regularly. The spooky thing about quantum mechanics is that Bells theorem shows that if hidden variables are behind quantum entanglement, then there should be a probability distribution that changes in a particular way as the lab configurations change. However, experiments have shown that quantum entanglement violates the Bell inequalities, so it has to be spooky.

Sx and Sy are non-commuting operators. What is wrong with what that poster said?

...

That doesn't respond to what I said. I said we know something about the particles just as we know something about the gloves. This does not imply anything about one particular angle of measurement. I can see you understand what entanglement is but you aren't grasping the point.

...

LOL spot the brainlet chemist

>implying that quantum theory is not shocking
>implying that they FULLY understand it

whatever you say, man

t. engineer who just plugs and chugs existing formalisms

But how can a particle know it's state was measured?

idk man

No matter how far apart they are, once you measure the first particle in the Z direction, the other particle will collapse into a definite 100% state pointing in the Z direction and once you measure the first in the X direction the other particle will collapse into a definite 100% state in the X direction. The thing is, what the second particle turns out to be is entirely dependent on what happens to the first one and it's not just due to the fact that we already know something about both of them because the direction we choose to measure in is completely unrelated to the state we prepared them in so there is no way that the second "knows" what direction to point itself in for measurement so it's spooky.

It's even spookier if the second particle is measured in a basis rotated 135 degrees from the first particle, that's where Bell's Theorem comes into play.

That experiment where they photographed a cat-figure and then used entangled photons that never hit the cat to view the same image... Did that information move FTL? (obviously not, but wtf).

news.nationalgeographic.com/news/2014/08/140827-quantum-imaging-cats-undetected-photon-science/

That's fuckin wild

The papers on it are behind a paywall so if anyone wants to read them have a look here:

drive.google.com/open?id=0BwJFVEbHtYrccE81eDFLNHdGZ0k

drive.google.com/open?id=0BwJFVEbHtYrcWF9MT2RodVZBRGM

Fuckety fuck fuck. I thought it was because they were the same fucking particle.

Of course it does. Superluminal information transfer occurs when one entangled particle is collapsed and other follows suit. Otherwise how does the other particle know what properties to take?

It's not information tho. Not the way it's properly defined.

You are not simply measuring one and making the other conform, you are measuring the pair as a single state as well. It's as simple as the math itself.

no bully