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...
"Many worlds" makes this "instantaneous" communication moot, which is why I'm surprised so many physicists are barking up the other tree. In "many worlds" what actually happens when a thing "decoheres" is that the experimenter gets pulled into its superposition. So now instead of a dead-alive cat and one scientist, you've got one dead cat, one alive cat, one sad scientist, one happy scientist. Or from another perspective, a dead-alive cat and a sad-happy scientist - the superposition still exists, but the number of things inside it has increased.
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.
As I understand it, the "spooky action" is completely an artifact of the perception of randomness in the initial process.
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.
I don't know how "spooky action" differs from this except in the way the process gets described.
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.
There are two answers to that; both the same. One them is "simple" fact, the other one is the same with a whole lot of explanation and maths and all sorts that, to be honest, I wouldn't trust myself to get right even given a day to dig it all up and write it out, and ultimately it finishes in the same place anyway. So I'll just give you the "simple" fact version, without supporting documentation, I'm afraid.
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.
Yes, one would do better with some less dogmatic assertion.
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.
I remember years ago, back in highschool, when I studied quantum mechanics, our professor suggested this idea (he used a blue and a red ball in two briefcases) as a comparison to entanglement and then disproved it explaining that it's not quite the same.
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.
Your view was Einstein's view articulated in the 1935-1936 EPR Paradox paper. It proved that you need either local, real, hidden variables to account for quantum entanglement or FTL communication between particles was necessary--widely believed to be in violation of special relativity.
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.
Many worlds is also my preferred interpretation, but it really puts the weirdness of super position into perspective. If we really are splitting entire universes all willy-nilly like, maybe some of the other possibilities aren't so weird in comparison. Is causality-breaking FTL travel really more improbable than the universe splitting into infinite pieces just from the act of observing particles?
What I don't like about many worlds is that it's spectacularly inefficient w.r.t. energy. A whole new universe is created for each option. That's very wasteful and doesn't gel with so much of what we see around us. Sure, you can say that energy is fixed within each universe but not in the whole system, but that sets off my internal Occam's Razor.
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.
I know beans about this, but am intrigued and read as much as I can understand. For whatever reason this reminded me of the bitcoin protocol where they take measures to ensure a coin isn't duplicated in the system. From a personal perspective, I don't like the idea of more than one of me and would take steps to stop duplication of me if I could...
Interesting, but that still violates the principle of locality. Inside each world, the scientists are experiencing spooky action at a distance because information in their world is moving faster than light.
edit: removed my question after reading joe_the_user's question.
From the "outside", it doesn't end. But consider world A and world B. They are pulled apart from interacting with each other, so they can't do anything to the A-B superposition like they used to. From inside world A, the entanglement seems to have ended because no matter what scientists(world A) do to coin_1(world A), it doesn't affect coin_2(world A). Likewise in world B.
I tried to read the article, but the first paragraph already compelled me to rant.
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.
The Einstein quotes are rather apt. There was a famous disagreement between some well known physicists about what quantum entanglement meant for the principle of locality. The argument that you explain above is the same as that used by some of the brightest minds in physics in the 1930s, including Einstein: http://en.wikipedia.org/wiki/Bohr-Einstein_debates#The_argum...
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.
Notice that I say 'I shoot' above, so the moment you start to look at correlations, I start to decide into which pockets I shoot. ( For example determined by the results of an EPR experiment.) However, my rant is not so much about details of entanglement as it is about science journalism, after I have read the entire article, I still have no idea what the paper is about.
If that's all there was to entanglement, we would just use the term "ignorance of the actual state". The issue with entanglement is that the system will show properties of being in _both states at once_, which is distinct from being in one unknown state, which is your analogy. There's really no classical analogy that I know of that correctly fits entanglement in QM.
You are misunderstanding the physics. Suppose A and B are two quantum entities that result from a collision. They are entangled and moving away from each other. The math very clearly says that a modification of A's state will alter B's state after the time of collision. In fact, it must do so, since A and B do not have separate states. Their states are the same one little chunk of math.
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.
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.
I think you're misrepresenting this. In your example, the colour of both balls is fixed the whole time. In entanglement, it isn't fixed the whole time. It's not fixed until observed. We take them a light-year apart, and they don't have any value. When we look, one will be "up" and one will be "down," but until we look, it's not decided.
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.
I don't think that I am misrepresenting this, however I should perhaps have made clearer what I mean by classical vs. quantum. So I take the view, that entanglement can be traced back to the smaller than naively expected state space, which is something that can be constructed in classical physics. If you then quantize such a system, then the system would be in a superposition of the classical states.
The problem of local realism then arises from this smaller state space and the collapse of the wave function during the measurement.
So are you saying it is, or is not, odd that a decision made here can affect something a light year away? If you don't find that odd that's great for you; you obviously have a far more intuitive understanding of the universe than most people.
Assuming that it actually effects a particle at a distance, it is odd. But I simply see it as a oddity of the collapse of the wave function, which is no more surprising than finding just one photon in a double slit experiment even when the detectors are space like separated.
If that's all it was, it wouldn't be so mysterious. It's been shown that the billiard ball can be either red or white up until the point you check it, and that the other ball will spontaneously resolve.
That's based off what I know, though, I may be wrong.
> But what enables particles to communicate instantaneously — and seemingly faster than the speed of light — over such vast distances?
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.
You are correct, information (at least in the classical sense) isn't traveling faster than light with entanglement. The marble analogy is good, but like most analogies, it breaks down at the edges. Quantum entanglement is a little bit more magical than just revealing the discreet state of an object, because it turns out the probabilities we expect don't match the probabilities that we measure when we do certain entanglement experiments: http://en.wikipedia.org/wiki/Bell's_theorem#Bell_inequalitie...
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.
entanglement does not allow faster than light communication, but it's also not like your boxes, which have a "hidden variable" (a known real answer).
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).
> As I have heard, entanglement doesn't provide FTL comms. [...]
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
The "you" column shows what angle you set your filter to for each coin outcome. Second column is for me. They key here is that when we both see H, we are setting our filters 67.5 degrees apart, and so the probability that they will produce the same outcome is cos(67.5)^2, which is 15%, and so we win 85% in the H/H case (remember, we want to mismatch in that case). When one of us sees a T, our measurement angles differ by 22.5 degrees, so we match 85% of the time.
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.
Since this seems like a good place to ask: Does anyone know of an interactive simulator for replicating some of the tests of Bell's Theorem?
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?
Thanks for posting this. I'm not a physicist but I do enjoy reading about new explanations that simplify things.
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.
So, yeah, theory, and pretty far-out theory at that. I'm pretty sure the "holographic duality" thing is purely a theoretical device as well.
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.
Definitely pure theory, of a very abstract variety.
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.)
Could I ask someone with the necessary patience to explain why quantum entanglement as described here doesn't allow faster-than-light communication? I've been told that I'm misunderstanding something by guessing that it might, and if it can be expressed in layman's terms, I'd love to know why.
try inventing a system using the marbles i describe in an answer above. you just go round in circles. the problem is that there's no "useful" information "coming out".
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...).
Quantum entanglement allows you to know something about a far-away system that you couldn't have been told by communication, but you can't control what information is passed. Essentially, you both get a random result, it's just that you both happen to know what result you both got. That doesn't allow you to communicate anything to each other. The best it does is allows you to both get the same random number at the same time.
Try constructing an experiment where one side answers a predetermined question, and you'll notice that you can't.
Why can't I combine quantum entanglement with the two slit experiment? Observing one particle will collapse the other's quantum state, so lead to a classical result for the dual split experiment rather than a quantum one?
That's true that it allows faster-than-light communication is some sense, however it is not clear if it is possible to use quantum entanglement for faster than light information transfer: to extract the particle stat one has to perform a measurement which immediately destroys the state it is in.
It is unlikely that quantum entanglement allows FTL signalling of any kind. I also believe it is accepted among physicist that it doesn't allow actual FTL communication.
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.
It says it does travel faster than light - instantaneously. He's just saying that according to Einstein's theory (nothing is faster than the speed of light), that shouldn't happen.
The "nothing faster than light" thing has been repeated so much that people just take it verboten. Its actually not specifically true.
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.
When I read this kind of (serious!) physical therories I really find it rather difficult to isolate them from crackpot theories (some crackpot theories are even more imaginative than this one). The only way I found is to consider from what institute/person the article is.
To me this almost sounds like some crazy kinky joke. (Maybe I've just got a sick mind though.) I had to re-read it a couple of times until I remembered that latex is a way to lay-out formulae etc. :P
The best way is to learn the material yourself and then it becomes easy to separate real and crackpot theories. That said, that can take quite a lot of time, so reputation is indeed probably a good proxy.
Exactly. But that they said FTL is a violation of general relativity made be doubt the article. General relativity does not disallow FTL, special relativity does. But that is about my extends of knowledge about these things.
Also, while FTL is not allowed in general or special relativity, that's not why general relativity is incompatible with general relativity (since quantum mechanics depends on special relativity, which also doesn't allow FTL). The actual reason is more complicated and comes down to a certain mathematical trick (renormalisation) which is needed for quantum mechanics to not predict absurd probabilities failing to work when you try to construct it in general relativity.
I'm not sure why general and special relativity are called like that. Special relativity is about movement and how that causes length contractions, time dilations and a change of mass of the moving object. General relativity is about how mass (even at rest) dilates spacetime. So general relativity is about black holes and worm holes and how space itself maybe "moves". There is no speed limit on how fast a region of space itself can move in relation to another region, thus it is ok that the universe expands at a speed where two regions are "moving" away from each other faster than the speed of light.
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).
Under the assumption that panzi's statement is correct (I'm no physicist) in the limited context of special relativity FTL travel is impossible. But general relativity considers a more general context.
A portal, you can see it on the game Portal and Bugs Bunny ACME black holes, they only exist entangled.
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.
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...