You can’t get entangled without a wormhole
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The paper mentioned in the press release that it's directly building on (by Jensen and Karch) is: http://arxiv.org/abs/arXiv:1307.1132
And the earlier research on entangled black holes that these studies of particles are extending is here: http://arxiv.org/abs/arXiv:1306.0533
Now, none of that is likely to be readable to people who aren't string theorists: this is some pretty cutting edge pure theory, largely aimed at solving one of the major current puzzles in theoretical physics. One (older) collection of links to more accessible discussion of the firewall paradox is here: http://www.preposterousuniverse.com/blog/2012/12/21/firewall...
So, "I flip a coin and whichever it comes up, heads or tails, the other entangled coin flipped at the same instant comes up the the opposite, with instantaneous communication" is the wrong view. Rather, the coins are entangled (in the past), and observing them pulls the observers into the entanglement one atom at a time as the informational contagion spreads, so now you have world A, where scientists saw "heads, tails" and world B where the same scientists saw "tails,heads". The scientists got slurped in, but they are simply observing an entanglement that existed and still exists and which was established in the past. Only now they are observing it from inside.
Quantum spooky action "at a distance" is local in "many worlds" and never needs to be faster than light.
You also don't just have two worlds, you have infinite. In the coin-flipping example, whenever a coin is flipped there are many other universe-splitting this-or-that events happening elsewhere in the universe at the same instant. So each instant there are infinite worlds created (or infinite x infinite to describe each combination), and again a split in each universe in the next instant for every next possibility. Mmm. Dodgy.
My favourite: John Cramer's Transactional Interpretation. Doesn't require infinite universes' worth of energy, doesn't require an observer to collapse multiple possible waves. Does require you to accept backwards-in-time communication (breaks causality) but brings some very interesting what-if questions.
Take a black stone and a white stone, shake up in your hand, put one in one sealed container and one in a second sealed container. Take the two containers a hundred light year apart. Open one and "suddenly" you know the contents of another container light years away.
I don't know how "spooky action" differs from this except in the way the process gets described. You could say "wow, until you know whether there's a black stone or a white stone in there, it's like the stone is half white and half black." You could but how does that help? I mean quantum seems to take a "because it absolutely can't be measured till, it absolutely doesn't happen till later" but that seems to just contradict ordinary understanding in gratuitously unnecessarily fashion.
Bell's inequality paper in 1964 proved that the predictions of a local reality system and a quantum entanglement system are in fact different for certain polarization experiments.
Subsequent experimentation proved the two theories to be mutually exclusive and results back up FTL communication. An FTL mechanism has not been found experimentally, however we know that special relativity is not violated because quantum uncertainty prevents information from being transmitted via entanglement at FTL speeds.
Unfortunately, too many years passed and I don't remember the counter-argument that explains why you can't apply that logic to entanglement but it involved Bell's theorem[1] and the EPR Paradox[2]. Actually I think Einstein himself made a counter-argument similar to that (just not with stones/balls but with actual particles) and was disproved later on. Sorry if I can't give more details, I'm not a physicist.
[1] https://en.wikipedia.org/wiki/Bell%27s_theorem [2] https://en.wikipedia.org/wiki/EPR_paradox
Because, when you put the white stone in one jar and the black stone in the other, it's decided. One of them does contain a white stone. One of them does contain a black stone. The universe "knows" which is which. The decision has been made.
With the entangled particles, it's not decided. You separate them, and you do NOT have one particle in "up" state and one particle in "down" state. That decision has not yet been made. It's not the case that one of them is "up" and you just haven't checked yet; one of them is not "up". One of them is not "down". The decision has not been made. One will be "up" and the other "down" when the decision is made, but that random decision has not yet been made.
You then move them a long way apart, and look at one of them; the decision is now made for BOTH of them, even though they're very far apart.
Here it is; because that's how the universe works.
That decision doesn't get made until "something" checks it/depends on it/interacts with it (the English language, at heart a way of telling macroscopic monkeys about tigers and bananas, does struggle a bit here). If you go digging yourself, you'll be able to go as deep as you like. I apologise for not presenting a better answer, but I'd really be doing you a disservice.
Edit: It's really not a good answer at all. I'm digging through old reddit threads to see if RobotRollCall ever talked about this. Her explanations were generally very accessible.
I asked the original question and I've harassed people with this question enough that I vaguely recall the answer.
In terms of the boxes, the answer is you wind-up breaking open the boxes over time in different ways that wind-up with being incapable with the perspective that "just" a black stone or "just" a white stone is in each box.
http://en.wikipedia.org/wiki/EPR_paradox#Mathematical_formul...
edit: removed my question after reading joe_the_user's question.
There is nothing 'mysterious' or 'strange' or 'bizarre' about entanglement. Lets look at the classical version, suppose there is a red billiard ball at the middle of a billiard table. I shoot a white ball, such that one ball ends up in the upper left pocket and the other ball in the upper right. Then the state space is white ball in the left pocket and red ball in the right pocket or the white ball in the right pocket and the red ball in the left pocket. Because of momentum conservation it is impossible to have both balls in the same pocket and billiard balls also do not spontaneously change their color. So the moment I do look at one ball, I know the color of the other. It is exactly the same thing with 'quantum entanglement,' some conservation law demands that certain outcomes are impossible, and therefore the possible states of the system are restricted compared to a 'arbitrary' configuration. ( In the billiard example, I put one ball in one pocket. And then roll a dice two determine where to put the second.) But on the other hand, claiming that entanglement is somehow 'bizarre' lends itself to a Einstein quote. And we know that Einstein quotes are the pinnacle of modern science journalism.
[Edit] The parentheses are misleading. I mentioned a dice as a shorthand for arbitrary, not to imply that it has anything to do with some quantum process. So the point is, that in the classical case I follow a specific process, which leads to outcomes which are restricted compared to the case where I just put the billiard balls into arbitrary pockets.
It was a hotly debated topic for several decades. Until 1964 we weren't even sure we could ever resolve it, then a fellow named John Bell published a testable theorem showing a divergence between quantum mechanics and the classical explanation you have above (http://en.wikipedia.org/wiki/Bell's_theorem). In 1972, the first successful experiment of this theorem was performed, and incredibly, it showed entanglement is in fact more complicated than can be explained with classical mechanics http://en.wikipedia.org/wiki/Bell_test_experiments. The experiments have been repeated and refined over the years and little by little, the once common theory of local variables is now almost completely dead.
That's based off what I know, though, I may be wrong.
This even works if the states are known! This is how quantum cryptography works. You put two particles into Bell state with each other, give one to someone else, and then decide later what message you want to send.
I recommend learning the math. It is pretty simple if you already have linear algebra.
s_e= a |+-> + b |-+>
s_n= a |+-> + b |-+> + c |--> + d |++>
a|+-> + b|-+> is a very special-case entanglement. Yes, you'll see that one mentioned in Wikipedia (and quantum cryptography and etc) because it's very simple.
The general form for the states of two photons is exactly as you have listed for s_n. For some coefficient values of a, b, c, d, the photons are "entangled", for some, they are not "entangled". How do you know which is which? It is whether you can factor the polynomial into two separate expressions of the form (x|+> + y|->). If you can do this, the photons are not entangled; if you cannot do it, they are entangled.
Since most sets of (a, b, c, d) represent unfactorable expressions, you would expect almost any expression chosen at random to represent an entangled pair. Clean un-entanglement is the rare exception.
This is true only for pure-state entanglement (which itself is a rare exception ;-).
Then we look at one, and it is decided. If someone a second later looks at the other one, a light year away, it will be the opposite state. That has also been decided. Us looking at something over here caused a decision about what state something is in to be made over there, a light-year away. How did us doing something here affect a decision a light-year away? Two seconds ago the state of that particle a light year away was undecided; the "universe" had not given it a value. Then we did something here, and that particle a light year away had its value fixed. It did not have that value the whole time while we were moving the particles apart, but now it does.
The problem of local realism then arises from this smaller state space and the collapse of the wave function during the measurement.
As I have heard, entanglement doesn't provide FTL comms.
It's like putting a red marble in one box, and a blue marble in another box, and shuffling them so you don't know which is which. Then you give one to a friend. Your box has a marble that's red with p 0.5. When your friend opens his box and says, "Hey, thanks for the cool red marble!" then your box now contains a marble that's blue, not red at all, as if by magic.
But it's not magic, it's just how probabilities work as we learn more information about a system.
That said, IANAQP, and Feynman gives some stern warnings against classical analogies for quantum stuff in his lectures, so big cube of salt.
entanglement is a non-local effect that is deeply weird. both marbles are "bled" (or "rue") when they are put in the boxes. when the boxes open, one becomes red, and the other blue. even though they are now far apart.
(and what this new work suggests, afaict, is that this is no longer so weird - they're actually close together if you go "through the wormhole", but that's just my vague understanding).
It seems that measuring a particle does indeed have some kind of effect on the particle that it is entangled with (or, at least, with the universe we are measuring it from) beyond just revealing information about some discreet state.
Right, if by communication we mean some system where one party can specify a bit value and have that bit value be transmitted to some other party.
> But it's not magic, it's just how probabilities work as we learn more information about a system.
No, it is much more than that. A good illustration of entanglement occurs in the CHSH game.
Here's how the game is played. You and I are playing as a team against the house. We are taken to separate locations, very far apart. There is a game master at each of the locations. We each play 1000 rounds of the game with the game master at our location.
Each round consists of the game master stating the round number, and then flipping a (completely fair and perfectly random) coin and revealing the result (H or T). The player then says "1" or "0". The game master writes down the round number, the coin flip result, and the number the player stated.
After 1000 rounds, we all return to a common location, and the score is calculated. For each round, we get a point if either (1) both game master's coins came up H and we picked different numbers, or (2) at least one game master's coin came up T and we picked the same number. The higher our total score for the 1000 rounds, the bigger our reward.
Before we are taken to the separate locations and play starts, we are given as long as we want to plan how we want to play. We can make any preparations we want, and bring anything we want with us. The only constraints are that we are not allowed to do anything that will mess with the coin flips. We will be far enough apart that the speed of light limit stops any communication between us during play.
If we adopt the simple plan of "always say 1", we'll score a point in 75% of the rounds. Another simple plan is that I always say 0, and you say 0 on T, 1 on H. That also scores 75% of the time for us. Can we do better?
With a little thought, you can probably convince yourself that we cannot. In a world without entanglement, that would be correct.
With entanglement, we can score in 85% of the rounds!
Consider a photon that has just come through a polarizing filter set at a 0 degree angle. That photon is polarized at 0 degrees. If you try to send it through another polarizing filter also set at 0, it goes through. If the other filter is at 90 degrees, the photon is blocked. If the other filter is at some angle in between, say T, then the photon goes through with probability cos(T)^2, and if it does go through, it is now polarized at T.
What we do is prepare 1000 pairs of photons. The two photons in each pair are polarized the same way and entangled. We number these pairs from 1 to 1000, and you take one from each pair and I take one from each pair.
Now when we play the game here is what we do. When your game master flips his coin and shows you the result, you take your photon for that round and send it through a polarizing filter. You set the filter to 0 degrees if the coin came up H, and 45 degrees if the coin came up T. If the photon passes through the filter, you say 1, else say 0.
I do almost the same thing. The difference is I set my filter at 22.5 degrees if my game master's coin is T, and 67.5 degrees if it is H.
Let's look at what happens. In the following I'll assume you send your photon through your filter before I send mine through my filter, but it doesn't actually matter who goes first (or even if we happen to act simultaneously). It is just easier to talk about if we do it sequentially.
Suppose you see H and I see H. You measure with the filter set at 0. If your photon gets through (and so you say "1"), its polarization becomes 0, and since mine is entangled with it mine also becomes 0. When I measure with my 67.5 degree filter, there is only a cos(67.5)^2 chance (15%) my photon also gets through, and a sin(67.5)^2 chance (85%) mine gets blocked. So, 85% of the time you say "1" I say "0" in the H/H case. Remember, we want to say different numbers on H/H, so this is good for us.
Same on H/H if your photon gets blocked and you say "0". Because they are entangled, my photon becomes polarized at 90 degrees (so that it would also be blocked by a 0 degree filter), and when I measure it with a 67.5 degree filter, the difference between my filter angle an the photon is 22.5 degrees, so it will pass my filter cos(22.5)^2 of the time, or 85%.
Here's a little table to help see what is going on here:
You Me
H 0
22.5 T
T 45
67.5 H
If we were NOT using entangled photons, this would not work. Suppose, for instance, that all the photons were polarized at 0 degrees and they were not entangled. In the H/H case and H/T case, we'd still do well (85%). On T/H and T/T we'd bomb. You would be measuring a 0 degree photon with a 45 degree filter, and it is 50/50 whether it goes through or not. You are effectively just flipping a coin, and nothing I do matters--we win half these and lose half these. Our overall win rate is only 67.5%, which is worse than if we had went with "always say 1" and not bothered with all this photon crap.
Only with entangled photons are we able to beat 75%. If I see heads and so measure at 67.5 degrees, it was something that happened when you measured that "told" my photon whether it should have a high or a low probability of making it through my filter. Something happened FTL after you made your measurement that let my photon "know" whether or not it should go through the 67.5 degree filter with an 85% chance or a 15% chance.
This cannot be explained with models like your red and blue marble example, where all the state is finalized when the marbles are together and then it is simply revealed to us when the marbles are far apart. In the CHSH game, the state is not finalized until after the photons are far apart, because it depends on our actions after we see the coin flips.
No, it is not like that at all. I've got other comments here explaining why, but suffice to say here; it's not like that at all.
I've seen lots of explanations and a fair number of computer simulations to show the disagreement between QM theory and local hidden variables, but none that are interactive.
I'm thinking some simple web app with a diagram showing an entangled photon emitter with some polarizers and detectors. I could set the polarizers and detectors to arbitrary angles, emit entangled photon pairs one by one (or maybe even triplets) and have it accumulate the results side by side with the hidden variable predictions. I've fancied writing one for awhile, does it sound awesome to anyone else or just me?
Theoretical physicists are so cute.
I don't believe anyone is generating entangled quarks here; all of this was done on something isomorphic to a blackboard.
It wasn't clear from the article if this is all theory, or if there was some actual experimental use of electric fields and holographic mapping of particles?
If so, can I see those maps? I would love to see the closest thing we have to a picture of a microscopic wormhole.
Now an MIT physicist has found that, looked at through the lens of string
theory, the creation of two entangled quarks — the building blocks of
matter — simultaneously gives rise to a wormhole connecting the pair.
It would be nice if they could get an experimental prediction out of this that could verify/falsify string theory without requiring a particle accelerator the size of the solar system.
Spoil sport. I was looking forward to RFHPC in the next millenia or so.
But that being said, don't devalue gauge/gravity holography too quickly. Holographic arguments can be used to connect physical theories pretty similar to known, measurable particle physics to a gravitational/stringy theory (not a "theory of everything" variant, mind you) where some results are easier to calculate. Those methods are actually within spitting distance of being experimentally relevant today. (But even if these methods were to give an experimental prediction that was confirmed at RHIC or the LHC or somewhere, it would only be evidence supporting the math of string theory. It wouldn't be directly related to whether string theory is a correct theory of quantum gravity.)
Electromagnetic fields can only propagate through a vacuum at roughly a max of 299,792,458m/s.
Its super easy to slow light down. Sunlight does not travel at its max speed when it hits the ground. Its been slowed down by the atmosphere.
The one thing that most definitely can, and has travelled faster than 299,792,458m/s is space itself. Indeed, space is expanding as we speak.
You only have to worry about causality and referential frame violations if you physically are trying to move at high velocity. Wormholes are shortcuts through points in space. Its a different part of physics that doesn't get into the whole "faster than light" thing. Just sidesteps around it.
The classic EPR experiment run thus: magically create a pair of entangled photons, send them in opposite directions. Have them pass through polarised filters of the same direction. Now, the instant a scientist on one side see the photons pass through the filter, she knows the photon on the other side won't get through (and vice-versa). You will notice that the photons don't travel faster than light. So, the obvious explanation will be some kind of common cause. A "hidden variable", that will kinda determine in which direction the photons goes through.
Turns out, there is no hidden variable (Bell's Theorem). So, FTL? Not yet: there may be a third alternative: Many Worlds. Remember Schroedinger's cat? Well, after the experiment, there are two of them: the dead one, and the live one. (No, you don't get to see the other cat, just like your other self doesn't get to see yours.)
Likewise, in the EPR experiment, the scientist merely learn in which blob they are. Though I believe we don't know exactly how decoherence works in this particular case. I'd be surprised however if it actually involved something as complicated as wormholes, or even another dimension.
two people are both observing random processes. they happen to see related results, but they don't "know" that unless they get together and compare notes.
it's like you and i both flip a magic nonlocal coin, and we both flip heads. how does that let me tell you something? it doesn't. all you know is that i just flipped heads (and really you don't even know that - you only know that if i had flipped the coin, i would have seen heads...).
Try constructing an experiment where one side answers a predetermined question, and you'll notice that you can't.
So if you could move space itself you could implement FTL travel, because this is not movement at all in the sense of special relativity. Some scientists say one could do that if you could create matter with a negative energy density, whatever that might mean. I think our understanding of the universe does not exclude the possibility for such matter, but it doesn't predict it either. So unless new discoveries are made that lead to new theories that predict such matter FTL is in the realm of wishful thinking.
That's what I could piece together from various (non science journal) news publications and YouTube videos (by PhDs, aimed at laymen).
On a more serious note, maybe there is some underlying truth to that. The intense gravitational pull is actually something on the other side of a wormhole.