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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."
Didn't the Aspect Experiment back in the '80s demonstrate this effect?
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
He better bloody watch out he doesn't end up stuck in the 8th dimension!
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?
But we've already done it: Elitzur-Vaidman bomb-testing problem
At the bottom, it says that the equivalent experiment has already been performed, and TFA sounds like it is nearly the same experiment.
Look, posting this article made this other article from June 12 with exactly the same content get posted!
The theory works!
How we know is more important than what we know.
he sees the change and it startles him to not make the change? therefore will a paradox be created that either consumes our local universe into a giant black hole created at the point of origin or will the researcher cease to exist?
Will Schrödinger's cat have the answer to the question?
Do not look at laser with remaining good eye.
Consider if this was not the case... A and B start out together. A travels into the future (from B's perspective). Surely, from A's perspective that is the same as B travelling into the past. The only way to tell the difference is if you have a bunch of cues/landmarks that you use as a time reference. If we remove those cues then it is no longer easy to tell what is happening.
Lets suppose we make A = the whole universe - B. Then shifting A into the future is indistinguishable from shifting B into the past.
Engineering is the art of compromise.
Spooky Action at a Distance describes my sex life exactly.
I'm not knocking scientific experimentation, but this looks like just another test for the finer details of a well-understood phenomenon: quantum entanglement. Wake me up if anything even slightly unexpected happens.
I have no problem with your religion until you decide it's reason to deprive others of the truth.
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, 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?
Qxe4
This solves about every communication problem that man has ever come up. Long-distance space communication not only becomes trivial.. our future explorers will be playing WOW all the way to Alpha Centauri.
Well.... he would be successful with his "spooky action", if not for those meddlesome kids!
This is a possibility: The effect will happen AFTER the change is triggered by the researchers, but it will simply show up in the untouched beam before it does in the "touched" beam. By a few nano or femtoseconds perhaps. Then it will show up in the "touched" beam.
But I can't be sure, I'm no Emmet Brown, and I didn't RTFA.
I can travel through time, although it's only in one direction, and very slowly ;)
i've always had trouble with this idea. my primary reason, is that the future hasn't happened so how can it exist before the present?
If you mod me down, I will become more powerful than you can imagine....
"...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
as he would of just needed one to do the test in 1-5 min.ed
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.'
He also formulated the transactional interpretation of quantum mechanics. He claimed support for this interpretation in its ability to explain the results of the Afshar experiment. I have not seen any consensus concerning the experiment's setup, data, interpretation, or significance.
r etation
http://en.wikipedia.org/wiki/Transactional_interp
You mean he was born a 70 year old man?!?!
www.purevolume.com/martyd
so, let's say Beam A and B are split from one beam.. you change beam A, B changes before you changed A so then B's change should change A before you changed it and it would recur ...
so how would you be able to measure a change that would effectively be happening in an infinitely small amount of time?
On a hardwood floor? Nope, don't know anything about it I'm afraid...
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.
What if the paradoxes occurred? They may seem like paradoxes to us, but it may mean that time is not just the 4th dimension, but rather, there's more than one dimension of time. This could be our first step into actually seeing ourselves as more than just 4 dimensional entities. If this discovery actually happens, I don't know about the rest of you, but I would definitely be calling it the first Singularity. A historic moment soon to happen!
Heh... I said historic... how quaint that word sounds now, this may be one of the last times it's used with quite the same meaning.
As mentioned before, this has already happened. if you don't believe me, check wikipedia or read a book about quantum physics/string theory such as 'fabric of the cosmos'
If I had a poltergeist in my house at the other side of the state. Would that be considered Spooky Action at a Distance too?
The game.
BTW, wasn't Traf-O-Data the first foray of Gates and Allen into the biz world???
the "Einstein's Bridge" John Cramer who's proposing this test?
Just wondering...
CUR ALLOC 20195.....5804M
no idea what you are talking about.
Wacking off to anime tentacle movies OTOH.........
Please sign petition to restore sanity to our banking system!!!
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We will have Subspace communication!/a
i take it that soon, i will be able to clone (/split) myself, and my clone will go to work before i actually do it? i wonder how far ahead we'll be able to get it.. hours? days? years? will people be able to retire after graduating from elementary school? we should lobby congress for funding.
this is VERY exciting!!
not only is time travel possible, it's irrelevant.
"Observations on entangled states naively appear to conflict with the property of relativity that information cannot be transferred faster than the speed of light. Although two entangled systems appear to interact across large spatial separations, no useful information can be transmitted in this way, so causality cannot be violated through entanglement. This is the statement of no communication theorem."
-- Wikipedia article on Spooky Action
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.
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. They also need to consider the displacement that occurs as well. Obviously, the Earth is not in the same exact place a few seconds ago as it is now. As such, they would need to conpensate for that as well. They should also consider that there is bound to be interference by all of the signals bouncing around these days and should use an untouched frequency. And finally, they should have the reciever up and running way BEFORE they ever attempt to send that signal.
As for avoiding paradoxes, I would suggest creating the message/recording/whatever and sending it to a point before it was sent but AFTER it was created. Also, they would need to have the device set up to send the signal no matter what, where transmission cannot be interupted after reception. Otherwise, the paradox will stop the reception from ever happening. I like to think of paradoxes as time's way of fixing itself by fizzling out/destroying such events from ever occuring. I would best describe one as a trick knot in a string (time) where each time the loop reoccurs (from happening to not happening to happening, etc) the string tightens and the loop shrinks until it 'pops' out of existance and the experiment fails. If scientists can avoid causing a paradox, their experiment will be a success otherwise time itself will adjust to keep it from happening at all.
DEAD DEAD DEAD DELETE ME
Bastard. Now I'm hungry and it's hours to home time. :(
As a footnote, hardwood floors are bad but not as bad as nylon carpets. Carpet burn sucks.
Rampant carbon sequestration destroyed the Dinosaurs' tropical paradise. I'm here to help repair the damage.
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" across the time dimension of spacetime even though spacetime itself never change when considered as a 4D object). So in a sense, yes, if the relativistic model is completely correct, we cannot travel to the past OR to the future, because nothing's really moving at all, four-dimensionally. Things are just different in the four-dimensional construct of spacetime at different points in time.
...and your particles then reverse their temporal direction, travel haphazardly back in time, safely within the backward-moving containment field, until such a point as they collide with an identical bunch of antiparticles (or, viewed in forward time, regular matter), annihilating with them, or as viewed in 4D time, turning around and becoming them, and then being reassembled by some helpful scienti
So when you talk about backward time travel, really all you're talking about is backward causation: can I, now, make it the case that something happened in the past, the way I seem to make it the case that things will happen in the future? This, interestingly enough, happens all the time, for antimatter is nothing but time-reversed matter. An electron and a positron being created and then annihilating with each other looks, in the four-dimensional model of spacetime, as a causal loop; the electron moves forward in time, then releases a ton of energy and turns around to go back in time - or, when you play things the other direction, a ton of energy converges on the electron to make it turn around. this electron (now with various properties reversed when viewed "forward", appearing to us as a positron) then travels back in time until it turns around, releasing a ton of energy - or, viewed the other way around in "forward" time, when a ton of energy converges upon it, turning it around. Of course, as this particle doesn't exist in times before or after its turn-around points, it doesn't look to us like we shoved a bunch of energy in with a positron and turned it into an electron; it looks to us like we shoved a bunch of energy together and a positron and an electron were created.
So, if you were to successfully travel back in time, there would have to be a backward-moving anti-you around somewhere, with whom you would have to annihilate, perfectly; from your perspective the world would then seem as antimatter, moving backward in time, and you'd somehow have to avoid annihilating yourself by touching anything, get back to the past that you want to go to, and then find another perfect anti-you to annihilate with to turn around. In forward time, this would mean that somehow, a copy of you with your future memories, and his antimatter clone, would have to be created somehow in the past; the antimatter clone would then have to be slowly changed and preserved in a precise way such that its evolution is the reverse of the normal processes that a person witnessing an antimatter universe moving backward around him would undergo, until it reaches such a state that it is a precise antimatter clone of future-you at the moment that future-you collides with it. Of course, since experiencing the trip backwards in time really isn't all that important, then the people in the past could just create a bunch of matter and antimatter, arrange the matter into a perfect clone of what you'll be like in the future when you decide to travel back in time, and then just leave the vat of antimatter in containment until that time comes that you want to travel back in time, whereupon you jump into the vat of antimatter and are annihilated...
-Forrest Cameranesi, Geek of all Trades
"I am Sam. Sam I am. I do not like trolls, flames, or spam."
Or effect and cause? Maybe the entangled photon was actually already in that state. Isn't it likely that the state of the photons is not affected at all by observation, but that it's the nature of two entangled photons to be in the same state and we just happen to be noticing the state now? I think we're attributing too much significance to observation. Quantum physics is probably more about the predicting of the states of two semi-related photons and less about anyone observing those states. Nothing spooky about that at all. In fact, I'd like to coin the term "Not-spooky action" to predict that if one related photon is spinning one way, its relative will also be spinning that way."
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
...double-slut experiment.
Beam A does some stuff. Beam B does some corresponding stuff. Sounds like cause and effect to me.
...or equally, we can say that invisibly small pixies used time machines to do all this tweaking of beams...
Now either we can throw Copenhagen away, and state that B must have anticipated what A was going to do, and change B's own state 'in advance,' which appears to be what all the hullabaloo is about here...
But to some dude tweaking A and watching AND IN ALL CIRCUMSTANCES -WAITING- to see what happens to B... it doesn't matter what the mechanism is. Decoherence, Bell, pixies, or whatever, there is no way to surface the mechanism and use it to influence the chain of events, with time's arrow or against it.
If you are watching B there is no way to confirm B's behaviour relates to A, unless you also know what A did and you sit down and correlate it. In other words you cannot infer anything from B until you have looked at what A was doing anyhow...
Everyone is very free with the word 'before' in this discussion... before with regard to whom, what cones, and what worldlines?
"... and more and more now there are all kinds of electronic goodies available" -- Pink Floyd 1972
In quantum entanglement you have to objects with an entangled quantum state. That is, one of their properties is always the same (or always the opposite, depending on the kind of entanglement). On the other hand, this property is not already fixed when the objects get separated. Only when you measure the state of one particle you actually stipulate its state, and due to entanglement the state of the other partcle as well. As this happens instantaneous an the objects might be separated by a great distance, you get this 'spooky action at a distance'.
But, as been shown before, since you have no influence on the outcome of the measurement, there is no data tranmission involved (and also no reverse causality).
The article claims, that one can actually set the state of one object at will, thereby forcing the other object to have the same predetermined state. The problem is, that while you can actually force a light beam to behave like a particle (when you look at it how it behaves as a particle) or to behave like a wave (when you look at it how it behaves as a wave), and this actually has an effect on the entangled beam, it is not possible to measure if a light beam behaves like a particle or a wave!
Let's say you make the two slit experiment and observe which slit the beam will choose (thereby forcing the beam to behave like a particle). If you make the same experiment on the entangled beam, you will observe, that it will go through the same slit. (This is an ordinary EPR experiment without faster than light communication and reverse causality). If, on the other hand, you choose to look at the entangled beam as it behaves as a wave, it will behave as a wave. It still has both, the particle and the wave nature!
Unlike the spin, that could be either up or down, the particle or wave nature of a quantum object are two properties that coexists!
What if he sees the change and because of that he chooses not to alter the laser beam. Will he create a parallel universe?
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.
For the litle amount of knowledge i have from quantum mechanics, the experience might work, but only in certain conditions. time is non-linear, for every-action observed, reality colapses to one reaction, be it in the future or past, so if you want a reaction in the past, you can not be the one that creates the action in the present, since you dont really know if you gona do it until you see yourself doing it.
so what you're saying is: munch the hard wood on the carpet floor, munch the carpet on the hardwood floor.
lets say you split/entangled a beam and shot the 2 beams in different directions. double-slits for Beam A would have a device that allowed you to enable/disable the ability to detect which slit the photon went through. Now lets say you arrange/distance the slits and detectors so that when the device on slits A (if you had it enabled) measures the photon as it passes through the screen it will effect/measure Beam A BEFORE Beam B passes the Beam B screen. If my very basic understanding of quantum physics is correct this would reveal information about Beam B causing it to collapse before the Beam B slits and change the detection pattern on detector B to indicate no interference pattern. If you disable the device on slits A the beam A photons would pass through allowing both Beams to remain in quantum states and interfere with themselves as they pass through the slits. Now because Beam B would be measured BEFORE Beam A due to the detector arrangement could you not in effect communicate in morse code from point A to point B almost instantaneously by way of measuring wether or not Beam B was interfering with itself and controlling the time the interference pattern showed up? if you create 2 of these systems you could have instantaneous 2-way communication could you not?
I like the bit "his experiment might show that a change made in one beam shows up in the other beam before he actually makes the change"
Get a whole bunch of these things
join them end to end
then remember to feed in the lottery numbers encoded in binary at one end just after the results are read out on TV
read the results out before it's announced
fill in ticket
proffit!
I don't pretend to be (remotely) an expert on quantum physics, but it's the main problem with quantum entanglement that they don't know how it works, and are trying to figure out it's capabilities, limitations, and explanation? If that's the case, then it seems a little off the mark to call it "faster than light". Couldn't it be working much slower than light, in a way we don't yet understand -- say, by "short-circuiting" spacetime through another dimension, or by spreading waves through time so that the waves reach other points in spacetime "quickly"?
In one sense, it's still "FTL", but the distinction is important too, no?
Is this the "Einstein's Bridge" John Cramer who's proposing this test?
:)
If you follow the link from the article you'll see the answer.
Also, from TFA: "If this experiment we're doing works, then I will follow up and push it as hard as possible. And if it doesn't work, I will write a science-fiction novel where it does work," he said. "It's a win-win situation."
In which a Slashdot article is directed through a hlaf-silvered mirror. On one path it may interact with a reader. If the reader is a dud, its quantum state (and head) collapses. Otherwise, its head explodes. By measuring the comments on the article at a site where the reader has not yet read it, we can determine if the article makes the reader's head explode or not without actually exploding it.
I suggest an extension to the Schrödinger's Cat thought experiment to investigate this situation. In the original experiment, you lock up a cat, along with food and a gun that fires when a radioactive atom decays. In quantum theory, the cat is both alive-and-dead, until the box is opened and an observer looks in.
Now suppose the cat is pregnant and the box has a door big enough for a kitten to escape. In quantum terms, the kitten is entangled with its parent, because a dead cat cannot have given birth. So if the observer looks in and sees a long-dead cat then the kitten will vanish!
Reduce, reuse, cycle
Hmm something I don't quite get about the experiment: So the beam is split into 2, say signal A and signal B, and signal B goes through a long detour. If signal B gets meddled with at the end of the detour, doesn't signal A get the same effect at the time when signal B gets meddled with?
It's like the whole universe is one of those gadgets that have all those hundreds of little bars held in a frame that when you push your hand into it, it's image is extruded on the other side...
They had the flux capacitors, but he couldn't find a DeLorean.
Forget thrust, drag, lift and weight. Airplanes fly because of money.
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:
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.
For the uninitiated:
e rties_of_Resublimated_Thiotimoline
http://en.wikipedia.org/wiki/The_Endochronic_Prop
Almost as obscure as that recent User Friendly cartoon where, to celebrate Heinlein's birthday, one of the characters tries to get a free lunch.
Best on-topic, factually accurate, one-word post...ever.
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
I can feel a bit smarter today.
If the experiment turns out to show that is true, then some math is wrong, or some theory is wrong (verified, but interpreted wrongly for example).
So why I say that doesn't work? Because if the 2nd light changes before the 1st light changes, it can be that the action that causes the 1st light to change start changing it, but not detectable, or not changing it yet, but that action starts to have effect on it in a way that affects the other light. The effect on the 1st light is not detectable or know at this point of age. That is just 1 explanation.
Here's the nail in the head. If the experimenter decided to not change the 1st light after the 2nd light change, would that mean the 2nd light just change?
Also, for the record, while Einstein used the expression "spooky action at a distance", he did not "postulate faster than light" action. In fact, Einstein was intent on disproving the validity of quantum mechanics and dismissed many theories associated with QM, thus the use of the 'scientific' term 'spooky'.
I'm quite happy to believe in non-local signalling between signallers in the same reference frame, but not otherwise.
You don't need to break relativity.
Thus, you may well appear to communicate as if a telegram travelled faster than light, but that doesn't mean you can communicate back in time.
In other words two signallers at rest with respect to each other may signal non-locally no matter how far apart, but relativistic effects still apply when the signallers have a relative velocity.
Somehow I get the feeling like this isn't so much information traveling instantaneously, but more generated in one place, split in to two identical pieces, and sent in opposite directions. For example say I fliped a coin, then without looking covered it with a sheet, clips two halves of the coin down and cut it in two with tin snips. Then, again without looking or disturbing it within the clip, I ship one half of the unrevealed coin off to Timbuktu. I call up the person holding the coin and check mine and presto: they're both heads!
I'm obviously missing some mysterious aspect to the experiment here since I'm dense on quantum entanglement. But, is anyone saying that the photon reacts in some way at the exact same time, like it's sitting there in it's funky indeterminate state and on it's own it observably goes 'poof' to pick a quantum state at an exact point in time? We can observe that moment in time it changes independent of knowing when the other is being measured? That is, opposed to the photon going 'poof' whenever I happen choose to measure it, like an hour later? Seems to make a big difference. One can be explained by saying the two halves were always in fact in a given state but we couldn't know about it until we measured at least one half (cause the other one always matches). The other way actually entails synchronized moments in some sort of "absolute time". Which, seems somewhat impossible to me as there is no such thing as absolute time according to relativity..
In theory, there is no difference between theory and practice. In practice, however, there is. -Berra
I'm still not sure how this backward causality is suppose to work. We've demonstrated quantum entanglement, and it is indeed spooky, but I see no reason why the length of one cable vs. another cable proves a violation in basic causality.
We split the input beam into "A" and "B".
At some distance "X" after the split, we modify "A".
Beam "B" is allowed to travel "X + Y" before it hits a detector.
Beam "A" is allowed to travel "X + Z", where "Z > Y", before it hits a detector. "A" has longer to travel.
The change is detected in "B" first. That seems natural to me, if we accept quantum entanglement which has been demonstrated. How does this violate causality? Does the researcher "emperor" have no clothes? Why aren't people talking about this?
Yeah but you're operating under a close proximity assumption here.
Say instead that the photon pulse for Device A is being fired are from Earth to Mars and then back again on a round trip, or around the earth many times in a flawless optical cable. Meanwhile Device B's laser is earth bound over a short distance. You can extend this range to whatever is needed to make the photons in Device A take 1 minute or longer to reach the detector.
You could then fiddle with Device A, see result in Device B way before Device A detects it's result, and have lots of time to turn off Device A, thus creating the paradox.
I can understand that a large mass such as earth, can displace time. It's also very easy to grasp that looking at the stars at
night. or photos from telescopes from hubble we are looking back in time since light travels at a constant speed, sure it can be bent by gravity but for the most part it's pretty damn constant. So... if an object your looking at is 10,000 light years away your are looking 10,000 years back in time. But... my simple mind does not believe that matter can not travel faster than light.
But... if you can fold space/time then possibly you can shorten the path from point a to point b. But to do that would require
an enourmous amount of energy and mass. Can I picure it.. sure, do I think it's possible, no. That's the only way I can visulize
traveling back in time. fold space/time, travel from point a to point b 10,000 light years away, travel back 10,000 years in time. Now... to go home, fold space/time.... go back to point a... travel 10,000 years back to future, but originating time.
I can not picture traveling to a future time from origination. I can not visualize that at all.
So I'm just a little confused about this article. To perform the experiment, you take a beam and split it into two. One beam (A) goes toward a target and crosses the distance in, say, 5 milliseconds. The second beam (B) takes longer and requires 60 milliseconds to reach the goal. If the researcher changes A, B is changed due to entanglement and vice versa.
What he's proposing is that changing B results in a change in A before B is actually changed. For the sake of example, we'll say A registers a change 55 milliseconds before B is modified - the difference between both beams. As he is researching causality, he would still have to modify B to verify that A and B match. Like any good researcher, he will continue with additional attempts at modifying A before changing B. But each time, he would require changing A in any case to see if A and B match.
Is that about correct?
Which leads me to believe that there's something akin to the conservation of mass something like a conservation of causality. He could never prove that A changed before B without actually modifying B in any case. Leaving the experiment half-done would cause doubt, let alone a paradox. It would be akin to cracking into a server to leave the message, "im in ur server, hacking ur systemz"
If this experiment is correct, and both communication systems are using this setup, then merely intending to leave the message would leave the message. But you would never be certain, because, really, are you going to trust thinking about leaving a message to leave a message? Not at all, you'd be certain to leave the message so that the public can see it.
As the "Uncertainty Principle" is already taken, perhaps it could be called the "Human Conditioning Principle."
He's using several kilometers of fiber-optic cable to increase the delay to 50ms. This makes me wonder how slow you can make light travel without destroying its quantum properties. You don't want to have to wrap the planet with fiber-optic cables to send a messages a week into the past!
The wrong points are so many, I will name just a few.
The idea that photons (and electrons) are both waves and particles have nothing to do with quantum entanglement.
The "being a particle or a wave" property is not a physically observable one. It's not like spin, position or momentum.
All photons are waves. period. They can be counted due to indetermination principle, which provides that the electromagnetic field moves around orbits in the configuration space that are quantized. This has nothing to do with slits.
Moreover every "particle" is just a field which evolves like a wave. The particle-like behaviour comes in some particular conditions, under which the field has a compact spike in one position and is quite absent in any other position. This provides that it can be seen as a single point moving.
Still its equations are those of a wave.
Saying "a superposition of it being a particle or a wave" is just like saying that we can choose whether it will follow Galilei's or Einstein's relativity. It will follow Einstein's. In some cases it will seem it is following Galilei's, it is still following Einstein's.
This is nothing but a sign of how badly the experiment is explained. Yet it gives some suspects.
To confirm that this is not science I could point out that even if he will use spin (a much simpler and precise measure, and it is even a proper observable) he will demonstrate nothing.
Or that no energy transport will happen, so it's not really violation of causality.
Or that the two photons start together so that they interacted while causality violation require they did not.
Or that he will not be able to choose which result to get from signal A after signal B will be measured, so no paradox is involved (RTFA for definitions).
Or that he failed to provide calculations of how this thing works. Physics is not done with buzzwords. That's interpretation. You can't do physics by reading divulgative works nor understand how it really works. A good divulgative work explains nothing but the thing it speaks of and cannot be used as a source for experiments. Nothing can be logically deduced from buzzwords. E.g. the "ball over cloth" explaination of general relativity does not suggest that you can "cut the cloth". This guy is doing this kind of things.
Instead I will just point out one of the first lines in the article: "thanks in part to tens of thousands of dollars in contributions sent in by his fans".
People, please...
I've been reading up on and following this experiment for a while now. Personally, I don't think it will "work" in the sense that back-time signaling will be demonstrated. However, the experiment is still well worth doing, because we learn as much from how it "fails" as from success. Plus, it's just so interesting.
The proposed experiment is based on another experiment by B. Dopfer that has already been done and the results published. The original experiment shone a UV laser into a special crystal that split each incoming photon into two entangled photon going in different directions (you need a laser to get the right frequency of light into the crystal.) One photon (B) went through a double-slit and then to a, well, camera. You expect to see one of two patterns on the detector: if the photon is acting like a particle, then there's a 'hump'. If it's acting like a wave, there will be a diffraction pattern.
Now the other photon (A), goes through a lens and onto another detector. With the lens in the right position, you can observe A and tell which slit photon B went through. Move the lens and you can't tell anymore. What's interesting is that the pattern detected for B depends on where the lens is at detector A. This is exactly the 'spooky action at a distance' that Einstein pointed out.
Now, the original experiment filtered out all the noise by using a 'coincidence detector'. This also, in effect, re-synchronized the two signals via classical communications, eliminating any exciting possibilities like FTL communication. Unfortunately, the Dopfer paper doesn't say what happens without the coincidence detector.
Cramer is proposing two modifications to the Dopfer experiment.
First is to remove the coincidence detector. This will degrade the pattern that shows up at detector B, but (according to the QM math), not enough to make it go away. That means that a change in the setup at detector A will 'instantly' effect the pattern seen at detector B. Simply by looking at what pattern is seen at B, you can tell what the physical setup is at A.
Even if this is as far as the experiment goes, it will be extraordinary. Theoretically (yes, I know) A and B can be as far apart as you want, far enough to demonstrate that FTL communication is taking place.
The second modification that Cramer is proposing is even more radical. If you look closely at the original experiment, you can see something really unusual: the distance that photon B travels to it's detector is SHORTER than the distance photon A travels to it's detector. So what? So it looks like a change in how A is measured effects the measurement of B, even if B is measured before changing A. This is quite a bit like the 'delayed choice' experiment, except with much more measurable results.
Now the difference in path lengths between A and B in the original Dopfer experiment was on the order of centimeters, too short to measure directly. Cramer wants to route the A photons through a fiber optic cable, introducing enough delay between the A and B detectors that it can be measured. This is where the 'retrocausality' (I hate that term) comes in.
I doubt (and I'm pretty sure Cramer is skeptical too) that back-time signaling can be demonstrated. But you can work the experiment just via the math, using standard QM equations, to see what the predicted outcome is. And there's nothing in the math (so far) that prevents the experiment from working. QM predicts that it will work. If the experiment doesn't work, then we learn more about Quantum Mechanics. If it only partially works, then we get FTL communication. If it goes all the way, we've invented time travel (for information, anyway).
THAT'S why the experiment is so fascinating.
... and it's called deja vu. Deja vu would be an example of changing signal A ("the real world"), and seeing the change in B (your subconscious). Then, dreaming would be an example of the "bilking paradox." If deja vu is a result of quantum entanglement, then maybe other forms of this exist. See http://science.slashdot.org/article.pl?sid=06/12/0 8/0123218, where someone asserted blind people experience deja vu through their other senses.
Can I use this to determine Powerball numbers before they're drawn?
"It's the height of ridiculousness to say for those 9 lines you get hundreds of millions."
We're too late, here's the worst thing about time travel will have already been coming to pass when he will have been already doing this experiment then.
Now wait for it....
"or the simple reason that when an event happens, it happens for all the universe. "
no, actually it doesn't. As has been proven NO information can travel faster then light.
So if the sun disappeared, it's effects would not reach use for about 8 minutes.
I'm not just talking about the light stopping, I am talking about the fabric of the universe changing, and reality.
Cue spooky music.
"for the single reason that effect always follows cause. "
maybe...but no one is sure. QM allows for the possibility that cause can create an effect before itself, hence the eperiment.
yes, it's weird..one might even say it's 'spooky'
"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."
That's a very nice assumption you got there.
The Kruger Dunning explains most post on
was 'Time Cop'
The Kruger Dunning explains most post on
This basically states that paradoxes are impossible. Say you build a device such as the one in your post: When you press the button, the light will blink five minutes ago. The above principle says that if you suddenly see the light blink, *somehow* five minutes from now with absolute certainty the button will be pressed. More than likely however, the light will never blink; our decision-making processes would probably never allow for a consistent loop to take place.
If however this principle is true, and if sending information back in time is possible, it does allow you to do some shit-awesome things with computers. Time Loop Logic is a field of computing in which you program a computer which can send information back in time.
Obviously this principle is unproven, and may turn out to be useless if time travel is proven to be impossible, but still, it's quite an elegant solution to the whole paradox business.
When you hear about a realitivly small experiment in time and scope in the media before it is done and the results have been reviewed history has shown me anyway its ususally a safe bet such an experiment is the result of crackpot science without genuine motivation and simply won't work.
n /comm_02.asp
Having said that anyone who is willing to perform experiments to validate their ideas are not beyond saving.
But for crying out loud entanglement can not be used to transmit information. I know thats a bit counterintuitive however this whole theme is getting old.
People who should know better are failing to see the underlying issues with entanglement for information transfer... No matter how creativly you arrange permanent magnets you simply will not create a perpetual motion machine.
On the other hand anyone serious about building an interstellar FTL communications network should see this article:
http://www.eve-online.com/background/communicatio
How will Verizon charge their $.02/$.0002 for long-distance data communication? Will their reps mangle your bill before you even start using the bandwidth?
Gravity is a contributing factor in nearly 73 percent of all accidents involving falling objects. -Dave Barry
From nocat.net
Of course if it was Schrodinger's Cat http://en.wikipedia.org/wiki/Schrodinger's_Cat the signal would have a quantum probability of getting there, but Einstein wouldn't accept that as possible.
Oh, I'm sorry sir, I thought you were referring to me, Mr. Wensleydale.
If you can tell the difference, this would allow faster than light communication.
Remember this is only a problem as we understand 4-D space-time. I'm reminded of Flatland, where creatures living in a 2-D world have a sphere pass through their universe. They see a series of small discs that appear, get larger, then get smaller, then disappear. They ask, "WTF?"
If we had a 4-D sphere show up here it might look like a ball that gets larger than smaller and disappears, and we'd be like, "WTF?".
Similarly, we've got these strange 'entangled pairs' of photons that can be sent across the universe and still maintain a connection, and we _might_ be able to hack them to communicate FTL. And we're like, "WTF?"
It's at least worth considering that these things aren't what we think they are. Maybe a laser can produce a N-D 'thingy' that when traveling through our universe looks like a pair of photons, or maybe all photons are capable of such properties but something about a laser turns that property on. Who knows, my brain can't grasp what an 11-dimensional universe looks like - all I know is it's usually wrong to say, "that's impossible because we understand everything."
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
I predict another inconclusive result.
I hate all this "what if" causality crap they throw into these articles. "What if I measure the event and then don't do it?" is the stupidest thing I've heard in a while... and I work in IT! If you were able to measure the event, then that means the event occurred. Whether or not you've caught up to the point in time that it occurred doesn't matter. Equally, if you decide you don't want to do it, then there will be no event for you to measure, because it never occurred. Is this really so hard?
And this isn't the same as the grandfather paradox, they shouldn't be compared. This is "if I make a choice to do something, can I choose to not do it after the effect happens but before the event does?" (answer, NO, imho, ymmv). The grandfather paradox is different. (tangent) Personally, I'm in favour of the "alternate realities" view on time travel... if you go back in time and change something, that reality splits off into a separate reality, with events there unfolding in their new, special way, while you still belong to your original timestream. So the "new" reality unfolds of dead granddad, but you still belong to your original stream where grampa was around to promise he'd pull out, and thus begat daddy.
Of course, I'm generally in favour of the "infinite realities" view, where every choice in life splits off into it's own reality, but that's a mostly separate discussion.
If I knew the wedgies I gave you back in 6th grade would have resulted in this . . . I might have taken a moments pause.
I think personally (with my layman's quantum physics background) what is more likely to happen than see the result "in the past", is that the process of the destruction of the first arriving photon when it is measured will cause the longer-arriving entangled photon to change such that the "observed value in the past" is NO LONGER the actual value the longer-taking photon will have when it reaches it's destination.
Thus both "sending a message into the past" AND avoiding a paradox simultaneously - because the sending of the message into the past changes the message being sent, which no longer makes it a message into the past.
IMO this fits with my personal view of reverse time travel as I understand relativity and quantum mechanics - time travel int othe past is totall ypossible n theory, but not reverseable. That is, if you travel into the past, you would never then reach the future from which you came; rather you would reach a different future since the quantum probabilities the universe will take are now different. T
Thus no paradoxes are created.
Don't you have to actually manipulate one of the entangled particles/waves in order for the other particle/wave to change? Isn't it also the case that there's no way of knowing how a change in one particle/wave is going to affect the other particle/wave until you do it?
http://en.wikipedia.org/wiki/Proton_pack
now that's some spooky action.
oh marmalade.
I would suggest the following scenerio
You have a timeline with two dependent events, A and B. B cannot happen without A. Therefore B does not happen until A has occurred. The problem and confusion in this case is simply that one perceives these events in reverse order, B before A. I think it is a faulty assumption to assume that the past is less malleable than the future and would imagine that the outcome would happen more like this...
Scientist waits to record Event B, no sign of Event B is evident. Scientist proceeds with experiment (Event A) and now has data and memory of Event B having already happened. The scientist would simply cease to be aware of any alternate timeline in which Event B did not occur. Probably through some destructive mechanism in which this timeline was destroyed... which would hint that this type of event would cause the destruction of our universe as we know it.
That kind of thinking simply brings into question the notion of existence and continuity relative to human perception and various metaphysical musings on the human soul and whether it exists or not.
That's probably why this sort of thing is so interesting, it has so many implications to the real nature of our universe.
All the "paradoxes" it would cause are just arrogance.
"What if I got a message from my future self, and then decided not to send it?" Sorry, Pal: If you got the message, then it'll get sent. There just wouldn't be any significant alternatives in the wave function.
We already know that non-local communication exists between particles (Aspect experiment). People only have trouble with the possibility of non-local communication between people, because it conflicts with our notions of free-willed decision making.
--
Corrollary: Never ask a psychic about your future -- if they're not full of crap, you'd be giving up any say in it!
Is that when God takes a poop?
Because the Schroedinger Wave Equation predicts that it will, and the SWE is all there is. The Copenhagen Interpretation (collapse of the wavefunction) is dead. The MWI is the only decent interpretation left that makes sense; Cramer's Transactional Interpretation is interesting, but poses too many new effects, like backwards causality. The MWI says the SWE is all there is; it implies (no, demands) that worlds split whenever anything happens. In one world, the laser "behaves as a particle" (handwaving, but it's from TFA) and in the other as a wave. Deutsch has a good paper on the EPR experiment and how the MWI explanation works (see section 4).
In this experiment (basically garden variety EPR with some small twists), experimenter EA performs a measurement on beam A. EB performs a measurement on EB. Now what the MWI says happened is this: as soon as the entangled beams left the laser, there were already two worlds. One of each polarization, let's say (for simplicity -- the current experiment is more complicated but the theory is the same). In one world both beams are polarized vertically, in the other they're polarized horizontally. Now when EA does her measurement, the Copenhagenists say this "collapses the wavefunction". MWI says nothing special happens; in those worlds where the beam was vertically polarized and EA's polarizer what vertical, the beam gets through. In other worlds, not. All the measurement tells EA is, which world is she in. Now EB does the same thing; so far nothing superluminal has happened. There are now (at least) two versions of EA and EB each. Now, at regular subluminal speeds, they take their rockets back to earth and communicate their results to each other. When they meet, "magically" their results match all the time! Why? Superluminal signaling? No; just because the ones who can meet to match results are (obviously) the ones who were in compatible worlds to begin with. The incompatible ones decohere rapidly, and can't be detected by the others within picoseconds. In other worlds, the alternate EA and EB meet and also confirm their results (opposite to the original pair) also match.
Oh well, that's way too much for a quick slashdot article. Read e.g. Tegmark at Arxiv for a nice readable overview of the current state of the world.
He would send one of the entangled beams (call it Signal A) through a circuitous detour - say, a few miles of fiber-optic cable - then fiddle with it when it came out of the cable. If the principles behind nonlocal communication held true, the evidence of that fiddling should be detected at a corresponding place in the other entangled beam (call it Signal B).
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.
I just don't understand what this experiement consists in, practically, if someone could re-word it in a simpler way. My main problem is with the word "fiddle", I'm not getting what it means in this context.
You just got troll'd!
Every time I see this experiment brought up, I feel compelled to point out that Ashfar's own experiment showing that one can demonstrate both the wave and particle "duality" simultaneously basically means that regardless of this gentleman's results, he will not have shown anything conclusive.
What you're talking about reminds me how Tipler came up with some theories for 'time travel' having something to do with the gravitational effects near an infinite cylinder.
Here's a interesting thought I had for a way to observe past events, that doesn't require any new understanding of space/time:
Light can be bent by the gravity of a massive object, which we can observe (e.g. gravitational lensing). Theoretically, a massive enough object can bend light enough so that it travels 180 degrees back to the point of origin. Alternatively a series of massive stars could each bend a light beam a few degrees to accomplish the same thing. So essentially you could observe light from your point of origin in the past. So assuming we can find the right alignment of stars, we can see the entire history of the Earth as it was.
Now, granted, even if we could resolve every individual photon that managed to make it that far, it may be too few to see anything at a very high resolution. But, I think it likely there would be enough to at least make out the atmospheric composition and get some useful data out of the exercise. Kind of cool, I think, if it would work.
The sending of this message pretty much inconveniences everyone involved.
okay. I haven't read nearly enough about physics yet, and school doesn't start until late august, so I'm just going to have to be as humble as I can, but I'm just wondering, if anyone can tell me: is there any reason why quantum entanglement can't be explained by higher dimensional space (essentially, isn't a wormhole actually a fold through four dimensions [not necessarily spatial], allowing FTL in a non-technical sense? which is something I've been wondering about lately*)? would this or would this not gel with some of the string theory variants, if it were possible? and if it's not possible, what's the reason? some sort of intricate mathematical difficulty?
* if m-theory talks about gravitons being able to traverse branes (in 11 dimensions, I think?), then why couldn't gravity be a higher dimensional form of light, since light exhibits similar properties (although I do know that Einstein thought this and later had to change his mind since the EM force and G force are quite different!) -- it could potentially even be that FTL is possible outside of the three spatial dimensions we're confined for, if relativity allows for that?
I hope someone can answer. thanks.
How does this "by September 15th" time limit translate to the past?