Einstein’s ‘spooky action at a distance’: 10,000 times faster than light

http://www.extremetech.com/extreme/150207-chinese-physicists-measure-speed-of-einsteins-spooky-action-at-a-distance-at-least-10000-times-faster-than-light

by mynameismiek • 13 years ago

43 49 13 years ago

extremetech.com

jerf• 13 years ago

"If it turns out that we actually can communicate data via quantum entanglement, we now know that it’ll be much faster than the speed of light."

No, no, no, no, no. No. No. No. Quantum entanglement can not be used to communicate in that manner, on its own. This is well-established, and given the how mathematical the establishment is, it's not going to change anytime soon.

No. No. No. Stop that. No.

olgeni• 13 years ago

Too bad - it could have saved a few telecommuters at Yahoo!.

abstractbill• 13 years ago

Earlier on, the article says:

"As of our current understanding of quantum mechanics, though, it is impossible to send data using quantum entanglement, preserving the theory of relativity. A lot of work is being done in this area, though, and some physicists believe that faster-than-light communication might be possible with some clever manipulation of entangled particles."

Shame it's so vague about those some physicists!

cwzwarich• 13 years ago

There are skeptics who maintain that the various "no-signaling theorems" in physics are simply "begging the question" and rely on hypotheses that are too strong, e.g. http://people.uleth.ca/~kent.peacock/FQXi_v2.pdf

nessus424• 13 years ago

Yes, they shouldn't get their hopes up too much. Since the Many Worlds Interpretation is the simplest one, it is also the most likely one. With MWI there is no spooky action at a distance, and nothing is actually transmitted faster than the speed of light.

wamatt4• 13 years ago

> Since the Many Worlds Interpretation is the simplest one, it is also the most likely one

The simplest defeasible claim in 2013, is still: "we don't know".

Consider, 'How does the sun come up every day?'

Answer A: God makes it happen.

Answer B: The earth is a spinning geoid that rotates eastwards, once about it's axis, roughly every 24 hours. However most of the effect is not related to the orbits of either the sun or earth, with respect to each other. The sun "rises" is more an observational effect of a stationary observer on the surface of the earth, having their field of view rotated.

(For the record, answer B can be improved of course, though that's not the point here)

"Simplicity" does not mean a catchall (Answer A). It also does not necessarily mean linguistic brevity either. There is debate around what it means and it's beyond the scope of my comment[1]. This is the problem with string theory, that also tends to be popular among the MWI crowd too. It's overly broad and the math looks pretty, but those are not sufficient conditions for a good scientific theory. (Oblig xkcd [1])

MWI, like string theory, makes little if any falsifiable and testable claims.

[1]http://plato.stanford.edu/entries/simplicity/

[2]http://xkcd.com/171/

OGinparadise• 13 years ago

But the title leads people to click. Why let about the little details like truth and math interfere with that?

alanctgardner2• 13 years ago

Maybe I'm mistaken, but I thought Einstein coined 'spooky action' sarcastically, to try and point out that it was absurd and violated his theories. I guess there aren't any better, sexy physicist names to put in the headline to attract clicks.

Scriptor• 13 years ago

I think that's what happend. Schrodinger's cat was also initially conceived to ridicule the idea of quantum superposition.

ars2• 13 years ago

The name Big Bang was also coined to ridicule the idea.

ISL• 13 years ago

Poisson's (Arago's) Spot was meant as ridicule, and ultimately became one of the definitive experiments to justify the wave theory of light:

http://en.wikipedia.org/wiki/Arago_spot

Amaze your friends! Shoot light through steel ball bearings with a laser pointer.

jivatmanx• 13 years ago

The speed of light ought to be enough for anyone.

Xcelerate• 13 years ago

Well, actually it poses a lot of problems. Communications that have back-and-forth transfers can be very slow.

For instance, if I wanted to do a distributed computation with a server on the other side of the world, it would be limited by the speed of light. From where I am to Australia is about 48 ms. So if I want to communicate there and receive a reply, that's about 1/10 of a second right there. I can only do that 10 times a second then. Not so good.

Not to mention the Mars mission has to wait anywhere from 8-19 minutes to get data between earth and the rover.

We could certainly use > c if it was possible.

martindale• 13 years ago

I believe the poster of this comment was being sarcastic, in the spirit of Bill Gates' [debatably misattributed] quote: "640K ought to be enough for anybody."

Zimahl• 13 years ago

On Earth, it's fine. Communicating with elements outside of Earth, the speed of light is way too slow. Talking with Mars is anywhere from 3 minutes to a 22 minute delay[1]. Wouldn't it be nice to be able to control a rover or talk with Mars settlers in real time?

[1] http://en.wikipedia.org/wiki/Colonization_of_Mars#Communicat...

a_p• 13 years ago

It's not fast enough for high frequency traders. That's why all the major HF traders pay large sums of money to rent space for their servers at the site of the exchanges.

mdda• 13 years ago

I thought that HF traders are just paying to be faster than their competitors. If the exchange servers had a 1 mile (or 10ms, or whatever) exclusion zone around them, everyone would be huddling up against that instead.

ChuckMcM• 13 years ago

Except HFT traders. I'm sure somewhere some poor ops guy is being harangued with "Hey I hear the Chinese have this tech that is faster than light, I want that shit on my fiber right now dammit, I don't care if its alpha quality ok? What? No I don't need to know about physics, I pay you guys to know about physics, get me that tech now."

stcredzero2• 13 years ago

> I want that shit on my fiber right now dammit, I don't care if its alpha quality ok?

Tell your boss you found a company with a scheme that can transmit bits over a quantum optical link, but only with a fidelity of 50%. Then get a friend to found that company and charge your boss' company $5 million for the device.

kevint8• 13 years ago

We need the ansible to head off into the final frontier.

smoyer• 13 years ago

Our communications run at about 90% of the speed of light through copper and about 66% through glass. Even at terrestrial distances, the latency is noticeable.

wjnc• 13 years ago

It's even better in German: "spukhafte Fernwirkung"

nolanpro• 13 years ago

Screw that, faster than the speed of light should be back in time. I want the information before it was sent!

ars2• 13 years ago

How does this rule out hidden variables?

I am aware of Bells inequality, but how do they show that for this specific experiment there were no hidden variables in play?

fjorder2• 13 years ago

They test a CHSH Bell inequality in this paper. This rules out local hidden variable theories. Non-local hidden variable (NLHV) theories are another matter entirely. Indeed, some NLHV theories may reproduce the predictions of quantum theory exactly.

oneandoneis2• 13 years ago

> One half of the pair was then observed, and the time for the other half to assume the same state is measured.

How??

How is it possible to observe whether or not an entangled particle has had its state resolved by the other particle being observed?

sbashyal• 13 years ago

In a pair of quantum particles [1], when one is spinning-up, other is spinning down even when they are separated. Therefore it is possible to find out about the state of one by looking at the other.

[1] http://en.wikipedia.org/wiki/Quantum_entanglement#Concept

colanderman• 13 years ago

Yes but doing so collapses the wavefunction. Hence there's no way to observe when the wavefunction collapses.

lnanek2• 13 years ago

Well, for entangled light, figuring out the path taken by one part of the pair forces both to produce no interference patterns. Their superpositions both collapse into a set state. I assume there's a similar effect for electron deflection or whatever they are using. Electron beams can similarly produce interference patterns.

pdonis3• 13 years ago

They're using photons, not electrons, but they're not using any interference patterns for detection since they're not bringing the entangled photons back together. They are detected separately.

pdonis3• 13 years ago

How is it possible to observe whether or not an entangled particle has had its state resolved by the other particle being observed?

It isn't. All they can detect immediately (i.e., when each photon is detected) is the measured polarization of each individual photon. They can't know the correlation between the two, which is what tests the entanglement, until the results from both measurements are brought together, which happens slower than light.

fjorder2• 13 years ago

Contrary to the claims of the extremetech article, they have not closed all loopholes in this experiment. Specifically, the detection loophole has not been closed. This loophole is caused by not being able to detect a high enough portion of the photons your source emits. A paranoid person might argue that the ones you do detect are not a representative sample. For example, some devious third party could be choosing which photons you detect in such a way that your results are skewed. Yes... This is a paranoid suggestion, but closing loopholes is all about satisfying the paranoid.

In this paper they invoke the assumption of "fair sampling". i.e. They assume what they do detect is representative. Ergo, they have not closed the detection loophole in this experiment. Fair sampling is a perfectly reasonable assumption to make and is very commonly used, so this should not be interpreted as invalidating their results. It just leaves room for improvement in the future, since single photon detectors with sufficient efficiency to close the detection loophole do now exist (They are very bleeding edge).

Note that the paper is correct and does not make the claim that "all loopholes" have been closed. The extremetech article got it wrong.

pdonis3• 13 years ago

the detection loophole has not been closed.

Not completely, but if I'm reading the paper correctly, they claim a detection rate of 91%, which is pretty high. Previous experiments had much lower detection rates. So while it may not completely close the loophole, it does make the detection loophole argument ("the photons you detected weren't a representative sample") much more "paranoid", to use your word.

Raz0rblade• 13 years ago

It is so simple, this is the same object seen over 2 places. Think of a fishing tank, the side glass wall and the front glass wall show the same fish. And that's i hope an easy to understand example of an extra dimension, it solves many physics problems add a dimension.. As the fish swims in the tank, both walls show change in position to and no need for communication at all, its just one fish.

you need proof for extra-dimensional existence just take all those experiments that could be solved by it .. double split... spooky action .... and many more.. (even quantum computers inner working)

bornonmars• 13 years ago

Quantum internet is "starting to become feasible"? It will be in their daily lives so much faster than that.

Einstein’s ‘spooky action at a distance’: 10,000 times faster than light

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