Testing Einstein's 'Spooky Action at a Distance'

smooth wombat writes "Travelling to a time in the past is, as far as we know, not possible. However, Einstein postulated a faster-than-light effect known as 'spooky action at a distance'. The problem is, how do you test for such an effect? That test may now be here. If all goes well, hopefully by September 15th, John Cramer will have experimented with a beam of laser light which has been split in two to test Einstein's idea. While he is only testing the quantum entanglement portion, changing one light beam and having the same change made in the other beam, his experiment might show that a change made in one beam shows up in the other beam before he actually makes the change."

Been there, Done that

[sconeu (64226)]

Didn't the Aspect Experiment [roxanne.org] back in the '80s demonstrate this effect?

Re:Been there, Done that

[MOBE2001 (263700)]

Didn't the Aspect Experiment back in the '80s demonstrate this effect?

Of course. Slashdot is getting weird by the day. First off, it was not Einstein's idea. Eisntein was against it and this was made famous in a paper he wrote with two other physicists who agreed with him. It's called the Einstein-Podolsky-Rosen paradox [wikipedia.org] or EPR paradox for short.

Re:Been there, Done that

[msevior (145103)]

Actually no. This new experiment is VERY interesting. The new experiment proposed by John G. Cramer aims to test an idea that might allow quantum signaling.

See this:

http://www.analogsf.com/0612/altview.shtml [analogsf.com]

The idea is to see if an interference pattern will spontaneously change from a single slit to a double slit merely by moving the position of where entangled photons are destroyed.

I think there is a reasonable chance this will work. This is interesting as it in principle allows FTL communication.

After that his ideas get REALLY interesting.....

Re:

[brunascle (994197)]

i knew [slashdot.org] that name sounded familiar.

dupe, sort of.

He's a quack selling snake oil

[gr8_phk (621180)]

He is talking about an issue I've raised before - there is no way to tell the difference between a particle whose entangled twin has been "measured" and one that has not. If you can tell the difference, this would allow faster than light communication. I contend there is no difference - physics has a lot to explain here. But he claims to have an experiment to confirm it - great. However:

Where do you get a laser that produces entangled pairs with the ability to separate the pairs into 2 coherent beams?

Then from TFA we have this:

Now brace yourself for the backward-causality part: Because Signal B followed a shorter route to its detector, the fiddling in Signal A could theoretically show up in Signal B before Cramer actually fiddles with Signal A. It would be as if Cramer's actions had an effect that worked backward in time.

This guy doesn't think that the detector for B will "fiddle" with the photons at A before they reach their fiddler?

He also seems to be getting money from people who believe his BS. Not to mention publicity.

If someone honestly believed they could send information back in time, the logical thing to do is fund the experiment any way you can while keeping it secret. You recover the funds by playing the stock market using future data (minutes to hours is the required time frame here). You keep it secret so "they" don't come after you - for whatever "they" you may be concerned about.

Re:"Faster than light"...

[mrpeebles (853978)]

A big criticism of quantum mechanics (still) is that nobody is exactly sure the minimum you have to do to one entangled particle to "measure" it, which determines what the person with the other entangled particle will he when he "measures" his particle. Schrodinger's cat paradox has never beeon completely satisfactorily answered. The existance of quantum entanglement is well established, though.

Nobody has ever found a way to use entangled particles to send FTL messages. In principle it is impossible. I have never even heard anybody else but this guy musing about ways it might be possible.

Re:Been there, Done that

[Brad1138 (590148)]

Didn't the Aspect Experiment back in the '80s demonstrate this effect?

Well, I looked it over, contemplated it, thought about it in depth for a while and I came to the conclusion that I have no fucking idea what that proves, and now I have a headache, thank you.

Re:Been there, Done that

[target562 (623649)]

Quantum teleportation and entanglement have been proven bunches of times. It's the basis for quantum computing, too -- I doubt folks would be wasting their time on THAT if it wasn't valid.

Re:

[brunascle (994197)]

it's already been tested, and passed. years ago.

while we're wasting time, let's test relativity theory :-/

and einstein had little to nothing to do with it. he didnt even believe in it. "spooky action at a distance" was meant as a derogatory term.

Quit it

[missing000 (602285)]

Einstein formulated the theory with 2 colleagues, Podolsky and Rosen.

It's called the EPR Paradox in the scientific community.

Einstein was no fan of it, and he believed it was a way to point out how silly the idea of Quantum Mechanics was, but he was very much the discoverer of it.

This is as important to understanding Einstein as "God does not play at dice", his basic objection to the probability implications of QM and EPR.

Re:Quit it

[kalirion (728907)]

Personally, I still believe that the outcomes of all the dice throws are predetermined. We just don't know how.

Re:Quit it

[thelexx (237096)]

I love how people grab on to that one phrase of his and make out like he was Mr Pious or something:

"It was, of course, a lie what you read about my religious convictions, a lie which is being systematically repeated. I do not believe in a personal God and I have never denied this but have expressed it clearly. If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it."

Albert Einstein, in a letter March 24, 1954; from Albert Einstein the Human Side, Helen Dukas and Banesh Hoffman, eds., Princeton, New Jersey: Princeton University Press, 1981, p. 43.

Re:Been there, Done that

[mattmatt (855592)]

Sure, we got the results years ago. But if this guy doesn't do the experiment, then we *won't* have got the results...

Re:Been there, Done that

[Harmonious Botch (921977)]

But he's already done the experiment. Didn't you read the dupe a few years ago?

Re:Been there, Done that

[fbjon (692006)]

Exactly. If a change is observed in the other beam, before the actual change has been made in the first beam, simply decide not to make the change in the first place, thereby causing an explosion of the scientists head and the implosion of the entire Universe due to catastrophic logic failure.

Unless you'd like to avoid this, of course, in which case I take payment in Visa, Mastercard, or hookers.

Causality

[GWLlosa (800011)]

Does this mean that once the effect shows up in the one light beam, before he does it in the other light beam, he is somehow locked in to his future actions? If not, what happens if he just turns off the device?

Re:Causality

[by Anonymous Coward]

Does this mean that once the effect shows up in the one light beam, before he does it in the other light beam, he is somehow locked in to his future actions? If not, what happens if he just turns off the device?

Fire and brimstone coming down from the skies. Rivers and seas boiling.
Forty years of darkness. Earthquakes, volcanoes...
The dead rising from the grave.
Human sacrifice, dogs and cats living together - mass hysteria.

Re:Causality

[BakaHoushi (786009)]

To me that sounds like changing the past.

As you said, event B requires event A. Event B precedes event A.

Let's say event A occurs when I press a button, just for the sake of simplicity. So if this formula is correct, event B will happen BEFORE I press the button. This is hurting my brain a little, but I think this would imply that event B could not happen unless I was truly planning on pressing the button. I can't "fake" the universe out by pretending to hit it, witness B, and then stop. Because if I were to do that, B would never happen. And... uhhh...

OW. See, as much as I support the fields of science and research into all things, I'm concerned about screwing with time. It makes my head hurt and the possible consequences scare me a little. Teleportation gives me similar worries.

Re:Causality

[G-funk (22712)]

If you can't fake the universe, and you can really see results before the action is taken, what happens if you decide wether or not to hit the button based on the flip of a coin? Does that make the coin flip result predicted by whichever result you see?

Re:Causality

[Verteiron (224042)]

Larry Niven wrote a short-story (surprise!) about how the universe protects causality. A clever man discovers that every civilization that has ever undertaken the task of building a time machine has vanished before they can finish it. He puts forth the idea that if plans for a working time machine were leaked to their current enemies, they would try to build it and therefore disappear as well. Before the plan can be put into action, though, the clever man's own (presumably stable yellow) star inexplicably goes nova, thus preventing the time machine plans from being leaked and protecting the nature of causality.

I sure hope Niven's wrong about that.

Re:

[loqi (754476)]

It seems that, if you subscribe to something like quantum immortality [wikipedia.org] and further assume that a violation of causality results in uniform annihilation, things would appear to an internal observer exactly as if the universe did protect causality.

Re:Causality

[MellowTigger (633958)]

I think that causality will be preserved, even if the effect occurs prior to the cause.

Consider: Researcher prepares to activate device, but researcher views results first. He already plans to perform an action (activate or not activate) in a way designed to contradict the results. He views the results, then takes the appropriate contradictory action. He succeeds in contradicting the theory. What does he prove? Not much, I think. How do you prove that the experiment was successful in sending an appropriate signal rather than it showing some false signal based upon noise or some other failure? In other words, how do you backtrack (forward-track?) the results to determine that the point of failure was actually the researcher's decision rather than some other mechanical issue?

Far more interesting would be an experiment in which a random number generator is in control of the device activation. Perform a long series of tests. Review the results afterwards. Does the activation always match with the pre-recorded results? Now that would be interesting. It still seems impossible to "backtrack" and prove no mechanical errors, but it would be possible to compile statistically important results this way.

Re:Causality

[fractoid (1076465)]

Or, alternately, reality and causality conspire to ensure that event A does happen, irrespective of any efforts made to stop it. Refer to the experiments conducted on resublimated thiotimoline [wikipedia.org]. by I.A. et al.

Re:

[RuBLed (995686)]

If he turns off the device as soon as he sees a result, he would be transported to the realm of Q where he would be tortured and made to drink the soup of earth's first would be inhabitants.. He would only be released when he agrees that he would not turn off the switch thus Q would send him back one second before he turns off the switch thus he would not turn off the switch he turned off in the future... or something like that..

Problems with classical intuitions.

[chub_mackerel (911522)]

Does this mean that once the effect shows up in the one light beam, before he does it in the other light beam, he is somehow locked in to his future actions? If not, what happens if he just turns off the device?

I'd guess we could never create such a paradox even if the effect is real.

Classical relativity imposes one set of constraints, and quantum mechanics another. Einstein was bothered because it seemed like the classical limits (think "light cone") would be inapplicable here. Quantum physics requires us to consider the actual mechanisms by which we measure and communicate as PART of the experiment.

Even if it works out that information at point B shows up "before" (in the same reference frame) an action at point A causes that message to be sent... it's possible that there's no practical way to detect this fact and use it in any way that would make for a "paradox." It may be that the best we can do is *record* the fact that such a backward transmission happened.

Example: Your instrument records a signal at B "before" the timestamp of the interference of the beam at A. This shows that entanglement is real, and gets you out of the "light cone" limits of classical relativity, which is what bothered Einstein. But if you go further and try to create a logical paradox, by using this information at A to stop the sending of the signal, then you will likely run into other, quantum mechanical limits... E.g. the actual means by which you detect the signal at B and send that information back to A will likely overwhelm or destroy whatever time differences we're talking about, bringing them back within classical limits...

This would be similar to things like the particle/wave experiments, where the experimental apparatus itself affects the outcome of the experiment.

So while something like "instantaneous" or even slightly "backward in time" messages may seem spooky in some ways may be possible, I'd bet that the time differences we're talking about wouldn't be large enough to make for any of the paradoxes people imagine using sci-fi based "time travel" notions.

Re:

[AdamWeeden (678591)]

Go watch Deja Vu [imdb.com]. The movie is not going to win any Oscars, nor are the physics 100% pristine, but it does have an interesting proposal on effects preceding causes and causal feedback loops.

Very neat and interesting!

[Kagura (843695)]

But we've already done it: Elitzur-Vaidman bomb-testing problem [wikipedia.org]

At the bottom, it says that the equivalent experiment has already been performed, and TFA sounds like it is nearly the same experiment.

Re:Very neat and interesting!

[Kagura (843695)]

Also see the Renninger negative-result experiment [wikipedia.org], in which it was postulated and proven that a particle need not be detected in order for a measurement to have occured.

Re:

[iminplaya (723125)]

But we've already done it...

Well there you go.

I think it is already working!!

[QuantumG (50515)]

Look, posting this article made this other article from June 12 [slashdot.org] with exactly the same content get posted!

The theory works!

Amazing

[INeededALogin (771371)]

Spooky Action at a Distance describes my sex life exactly.

Re:Amazing

[friedman101 (618627)]

faster-than-light describes mine.

Re:Amazing

[plover (150551)]

There once was a student named Frisk
Whose sex was exceedingly brisk.
So fast was his action
That the Lorentz Contraction
Reduced his tool to a disk.

Re:Amazing

[Bluesman (104513)]

Don't worry, you'll get another chance yesterday.

Re:Amazing

[EnsilZah (575600)]

Ha, while you're stuck performing Spooky Action at Distance I'm doing the Double-Slit Experiment.

(No, not really. =\ )

A True Hacker

[phantomfive (622387)]

John Cramer, the designer of the experiment, is really quite a colorful guy. He last got the attention of the press by simulating the sound of the big bang using Mathematica. Useless research of course, but who wouldn't laugh hearing that the big bang sounded like "large jet plane 100 feet off the ground flying over your house in the middle of the night?" At heart this guy is a physics hacker (in the true sense of the word hacker).

He also writes science fiction [wikipedia.org], so you can tell he completely enjoys science. Betcha anything he's doing this experiment, not because he thinks it will work, but just 'cause he wants to see what will happen. I can totally agree with that. It's the right reason to do research.
--
Looking for a C/C++ job in Silicon Valley? [slashdot.org]

Re:A True Hacker

[xPsi (851544)]

I worked with John on the STAR experiment at RHIC in the pion interferometry group. Your description of him as a physics hacker (in a good way) is right on. I do sometimes wonder about his sanity when I read about his latest projects (e.g. see TFA) -- but he is by no means a crank or crackpot. Oddly enough, he also does dog shows as an owner. His personality would fit right into Christopher Guest's movie Best in Show (I also mean that in a good way). So think of him as a dog trainer/quantum mechanic/science fiction author. He's basically a nerd renaissance man.

Spooky? (Couldn't resist)

[LordPhantom (763327)]

Well.... he would be successful with his "spooky action", if not for those meddlesome kids!

What happens when....

[ChronoFish (948067)]

"...his experiment might show that a change made in one beam shows up in the other beam before he actually makes the change...."

What happens when he notices the change, before he makes the change, and changes his mind and doesn't make the change?

-CF

Makes my head spin

[Traf-O-Data-Hater (858971)]

so I've just sat down and made myself a nice cup of instant tea. The list of ingredients on the teabag's packet say it contains 'Thiotimoline, resublimated, product of China.'

Paradoxes my a$$

[master_p (608214)]

I apologize for the colorful title, but I can not describe my feelings towards the so called theorem of 'no communication faster than light' in any other way. There are no time paradoxes if FTL communication exists, for the simple reason that when an event happens, it happens for all the universe. The fact that photons would not have arrived to the FTL communication target when the FTL signal reaches that target is totally irrelevant. And there is no way to perceive an event before it happens and change the outcome, for the single reason that effect always follows cause. So even if FTL communication is real, there would not be possible to avoid doing events that already have happened, for the simple reason that the events have already happened.

Re:

[master_p (608214)]

Nope. The theory of relativity states that there is no universal simultaneity for OBSERVING an event. It talks about OBSERVATIONS, i.e. about photons. It does not talk about when the event actually happens.

So it is quite possible for an event E to happen in system A, to use FTL comm to transmit the event to system B, system B to take an action depending on the information before observing E, and then finally system B to observe the event E.

The above is not violation of causality in any way. It's similar to

Re:Isn't all time travel impossible?

[FriendOfBagu (770778)]

If time travel into the past is impossible, then surely that means that all time travel must be impossible. In other words, time travel into the future must be impossible too.

Nonsense!

I, myself, am a time traveler from the past. I've been journeying into the future at a rate of sixty seconds per minute.

Re:Isn't all time travel impossible?

[hmccabe (465882)]

Relatively speaking, of course.

Re:Isn't all time travel impossible?

[Nyeerrmm (940927)]

As others have pointed out, we are in fact time travelling all of the time. However, to time travel as I'm sure you mean, significantly faster than our surroundings, Einsteins time dilation does the trick nicely, its just a matter of propulsion technology.

Note that also, too, we can observe the past due to the finite speed of light. Thus, given our current knowledge it is always possible to travel to the future and observe the past, but never the other way around (except maybe at quantum scales as discussed in TFA).

This, according to my random ponderings makes me think that if its possible to travel to the past, it will also be possible to observe the future, and in fact in some respects, they could be two aspects of the same thing.

Just for the record, I'm not a physicist, so beyond the first couple of facts this is all random amateur speculation.

Re:Isn't all time travel impossible?

[JaWiB (963739)]

Suppose an astronaut travels away from the earth at 99.9% of the speed of light. According to relativity, if he ever returns then everyone on earth will have aged considerably more than he has. But he has to turn around at some point in order for this to happen, hence he has to accelerate. And it doesn't take any reference points to judge that acceleration, so you can in effect say that he has travelled into (Earth's) future, and that the entire Earth has not travelled into the past.

Eternalism and Reverse Causality

[Pfhorrest (545131)]

Relativistic physics imply a sort of eternalism, whereby nothing is really "moving" through time at all - spacetime is a four-dimensional construct which is itself timeless, inasmuch as the four-dimensional spacetime does not change across some fifth "hypertime" dimension, so nothing in 4D spacetime really "moves"; there are just changes across the time dimension of spacetime (as a cone "narrows" in the vertical dimension even when it's not "changing" when considered as a 3D object in time, things "change"

Re:

[vux984 (928602)]

The images are already there and we see the progression. It is a kind of scary concept in that it seems to mean that free will is an illusion.

Only if you assume that their is only one set of ordered images. If every possible image is in the 'book' and every page is 'adjacently linked' to every other page that differed 'only a little', then free will may determine which adjacent page you (individually or perhaps your entire universes shared consciousness) go to at each step.

Re:

[by Anonymous Coward]

You are quite obviously talking out your ass.

When sending any signal, they need to consider that the signal grows weaker the further it travels. This is obvious with 3-dimensional travel but when adding that 4th dimension, it degragates exponentially.

Signal degradation is already exponential, and already takes into account time, "the fourth dimension." It is not possible for a signal to degrade without it being away from the source of its transmission, which necessitates its having propagated away, which re

Re:

[Control Group (105494)]

Strictly speaking, he could have been referring to the Earth's rotation. Since you can always detect if you're in a rotational frame, that's motion that's real in a more absolute sense than linear motion.

Of course, an interesting thought experiment is to consider a universe consisting of exactly one particle...and then ask if that particle is spinning.