
You can’t get entangled without a wormhole - geuis
http://www.mit.edu/newsoffice/2013/you-cant-get-entangled-without-a-wormhole-1205.html
======
Steuard
It looks like the original research paper that this press release is talking
about is here:
[http://arxiv.org/abs/1307.6850](http://arxiv.org/abs/1307.6850)

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](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](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...](http://www.preposterousuniverse.com/blog/2012/12/21/firewalls/)

------
JulianMorrison
"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.

~~~
joe_the_user
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.

~~~
EliRivers
_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.

~~~
zipfle
Maybe this is a silly question, but if you haven't looked at them, how do you
know the decision hasn't been made?

~~~
EliRivers
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.

~~~
joe_the_user
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.

[http://en.wikipedia.org/wiki/EPR_paradox#Mathematical_formul...](http://en.wikipedia.org/wiki/EPR_paradox#Mathematical_formulation)

------
yk
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.

~~~
flebron
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.

~~~
frede
Entanglement arises from the mix of mutual exclusive states and superposition.
Superposition of two states is what is missing in the classical world.

------
brownbat
> 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.

~~~
tzs
> 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.

~~~
jchrisa
Thanks for this- I described this game at dinner tonight. It as a bit.

------
gibybo
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?

------
DustinCalim
Maybe they're the same particle... sort of like the single electron
theory(since all electrons have the same mass/charge):
[http://en.wikipedia.org/wiki/One-
electron_universe](http://en.wikipedia.org/wiki/One-electron_universe)

------
mcguire
" _To see what emerges from two entangled quarks, [Sonner] first generated
quarks using the Schwinger effect...._ "

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.

------
jchrisa
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.

~~~
andrewflnr

      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.

~~~
Steuard
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.)

------
monitron
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.

~~~
pcmonk
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.

~~~
CJefferson
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?

------
wolfgke
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.

~~~
yk
Quite simple, physicists use latex and crackpots use word.

~~~
Ellipsis753
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

------
nsxwolf
How do you entangle a pair of black holes?

~~~
drawkbox
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.

