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Aug 13, 2008 06:21 PM | 70
No matter how many times researchers try, there's just no getting around the weirdness of quantum mechanics.
In the latest attempt, researchers at the University of Geneva in Switzerland tried to determine whether entanglement—the fact that measuring a property of one particle instantly determines the property of another—is actually transmitted by some wave-like signal that's fast but not infinitely fast.
Their test involved a series of measurements on pairs of entangled photons (particles of light) that were generated in Geneva (satellite view at left) and then split apart by optical fiber to two villages 18 kilometers (11 miles) apart where the team had set up photon detectors. (In 2007, researchers transmitted entangled light 144 kilometers between two of the Canary Islands.)
The idea in the new experiment is that the photons in each entangled pair are hitting the distant detectors simultaneously, so there's no time for them to exchange a signal. By comparing results from the two detectors, the researchers determined whether the photons were entangled or not, using a test known as Bell's inequalities.
The photons were indeed entangled, the group reports in Nature. But in reality, no experiment is perfect, so what they end up with is a lower limit on how fast the entanglement could be traveling: 10,000 times the speed of light.
To appreciate the weirdness of entanglement, consider that the outcome of a single quantum measurement is random. By all tests, a photon *has* no definite polarization until it hits a detector capable of measuring it. So it's like the entangled particles share one big quantum state.
There's one other subtlety to the experiment. If entanglement is traveling through space like some kind of faster-than-light wave, that would violate Einstein's theory of special relativity, which says the laws of nature are the same no matter which way you're moving with respect to anything else.
So the group had to run their experiment repeatedly for more than 24 hours, counting on Earth's rotation to sample all the different orientations relative to the stars. (Imagine a laser pointer shining into space along the direction of the optical fiber.)
It's always conceivable that quantum mechanics might break down (read: show some signs of everyday normalcy) if experimenters could test it the right way. In a 2007 study, researchers in Vienna tested the idea that maybe the instantaneous-ness of entanglement (called nonlocality) was consistent with hidden "variables" that can explain the randomness of quantum measurements. But no dice for that idea.
Theoretical physicist Terence Rudolph of Imperial College London, author of a commentary on the new paper, says that putting bounds on faster-than-light entanglement is useful for researchers trying to imagine theories that might extend beyond quantum mechanics.
What might such a theory look like? Rudolph says we're probably stuck with instantaneous entanglement, which seems impossible to us because we're stuck in everyday space and time. "We need to understand how quantum mechanics sees space and time," he says. "I think there's probably much deeper issues."
Related: Space Station Could Beam Secret Quantum Codes by 2014
Image credit: NASA Earth Observatory
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70 Comments
Add CommentEat that, Einstein!
Reply | Report Abuse | Link to thisWeird is'nt the word for it. It seems the rules are constantly changing as they are expected to do. So what is next?
Reply | Report Abuse | Link to thisWell if this effect is a function of just space and not space-time then I would say that Einstein's theory of special relativity still stands as it is based on propagation of information between two points within a specific time interval. Whereas this entanglement is operating simply between to points instantaneously or as observed 10k times the speed of light at the minimum , this definition of speed could simply be the result of propagation of information through space-time and not the result of the theoretical instantaneous transmission through entanglement which is just space (no time).
Reply | Report Abuse | Link to thisSo Einstein can eat his cake and have it to, so to speak.
I find this stuff very annoying. The crucial fact that these reports never make clear is that entanglement *cannot be used to transmit information*. When you have two entangled particles, measuring the state of one tells you what the result of measuring the state of the other will be, no matter when the measurement is made -- but unless you can *control* the state of the particle, instead of merely measuring it, there is no way to use this phenomenon to send a signal.
Reply | Report Abuse | Link to thisAh, that's where that idea of information cannot exceed the speed of light that was bouncing around in my head came from. To me it seems like it can but we can't do it... yet. A method for controlling an entangled particle and doing so in such a fashion that it could survive relativistic time dilation would be the patent of the century. Suppose if this *could* work and you had a system on earth and one on mars; how would they keep the data clocks in sync. A 1mhz clock on both planets would be running at different rates due to being in separate reference frames. But what confuses me about this is, would entangled particles connecting two reference frames act in sync within each frame or would their timing be dominant on one or the other end? And if there is dominance which end would be dominant?
Reply | Report Abuse | Link to thisI'd still like to see someone perform the following experiment; Set up the experiment as in this article but also set up the double slit experiment at the sending station with a splitter behind each slit. One output from each splitter would go to one of the distant receiving locations and the other output from each splitter would go in the other direction to the other distant receiving location. At one of the receiving locations set up detectors so that the slit that the photon went through could be determined when the detectors are on. At the other distant receiving location the two fiber optic cables could be set up to produce the interference pattern there if the slit that the photon went through is not known. Then, by switching the detectors on and off at the first distant receiving location, maybe the interference pattern could be produced or not at the other distant receiving location. I think that it would be interesting to see if faster than light communication could be achieved with this sort of arrangement.
Reply | Report Abuse | Link to thisIt's not so 'weird' under the many-worlds interpretation. In fact, it makes perfect sense. It's a shame this article makes no reference to the TWI but instead falls back on the old 'look how WEIRD quantum mechanics is!' science journalism saw.
Reply | Report Abuse | Link to thisIt sure was 'weird' that planets were seen to retrograde before Copernicus.
TWI is not without its problems, but it deserves the light of mainstream media day.
"...transmitted by some wave-like signal that's fast but not infinitely fast." Why not infinitely fast?
Reply | Report Abuse | Link to thisDoesn't QED address this? Particles have a probability for moving through time, and as such a particle can be in multiple places at the same time. i.e. Young's experiment. Perhaps this applies with the entanglement somehow?
Reply | Report Abuse | Link to thisi cut a penny in half , putting the heads side in one envelope, the tails in another. I send the envelopes to two villages 18 km apart. I open the envelope in one village. lo! I know which half is in the other village! the fact that measuring a property of one particle instantly determines the property of another happened here. where was the exchanged signal????
Reply | Report Abuse | Link to thisthere's noting weird or quantum about the above, and yet. it fits your defn of entanglement. your article misses the point.
your explanation needs to explain more about the particular bell inequality or the correlations to be valulable.explanation. this ludicrous signaling notion is even dumber: entangled particles can't be used to convey information--so there's no such signaling happening.
allison, I don't think that you quite understand the concept of quantum indeterminacy. You should look it up in Wikipedia for a good explanation.
Reply | Report Abuse | Link to thisMy name is Terry Kennedy. I have the answer to all existance. It is as simple as 1,2,3,A,B,C. There was never a Big Bang, we see Thermal Energy as well as visible light, and the understanding of the structure of Music is wrong. There is no diatonic comma. Energy opperates through a system of Octaves.Through this system,all is compareable, and all is predictable. Bode was right. He just didn't see the whole picture.
Reply | Report Abuse | Link to thisIt's restrictions are due to sympathy. It can only follow it's own Octave steps.This is why Energies seem to make such large jumps, yet are still similar.
Reply | Report Abuse | Link to thisParticle can be a Pulse form (B), as well as any other. In this form, Energy can travel any distance, but only through a allignment. In this form, there are no 'phsyical' barriers. This is how we will transport.
Reply | Report Abuse | Link to thisSo what they're *basically* saying is that they have no idea why the universe does what it does. How much, exactly, did they spend to reach that conclusion?
Reply | Report Abuse | Link to thisAll energies charteristics are dictated by that which forms them. This thing that's called 'Entanglement', is simply sympathetic Key's of smypathetic Octaves. Sympathetic Vibratory Phsyic's folk's !!
Reply | Report Abuse | Link to thisAny value is a product of lessor values, and visa versa. Sound a note in a room, and everything sympathetic to it, will sound as well. And off that, an harmonic will result. This is what we have come to know as phenomenon in the Electromagnetic Spectrum.
More about the stuff in Vasily Yanchilin's "The Quantum theory of Gravitation". I suggest that Scientific American asks him to write an article since his book dates from five years back already and his research may have continued. Interesting is also his explanation why time runs in one direction only.
Reply | Report Abuse | Link to thisCould the author please answer luckycharm�s question why he assumes, that the entanglement-effect was not provoced infinitely fast. To my knowledge, the researches have not ruled out this option, they could only say, that an interaction-signal must have travelled with more than 3 mill. km/sec. This speed-issue is critical, I believe - especially considering J.G. Cramer�sTransaction Interpretation which - in my view - is a much more convincing explanation than the Copenhagen interpretation or the far fetched multi-universe assumption
Reply | Report Abuse | Link to thisINSIGHTBD, the article said that the interaction-signal must have traveled at least 10,000 times the speed of light. Wouldn't that would mean that it must have traveled at least 3 billion km/sec, not just 3 million km/sec which would only be 10 times the speed of light?
Reply | Report Abuse | Link to thisAnd - in my view - I rather prefer the multi-universe interpretation. But I'm sure that nature will decide what interpretation SHE prefers and my own preferences will have no effect whatsoever on her decision. ;-)
Also, I would like to know if the experiment set up that I suggested in my earlier post on this article would be possible and, if so, what the outcome would be.
i believe the ' problem' with quantum mechanics has nothing at all to do with quantum mechanics but people's inability to stop trying to validate their personal theories about why entanglement 'shouldn't be working' as entanglement does work. what i find annoying has nothing at all to do with quantum mechanics but people's unwillingness to change their thought flow and just embrace quantum mechanics as perhaps that 'necessary metaphor' for how reality 'chooses to work...'. perhaps what quantum mechanics does eat at would be the rather difficult terms that many individuals what to view reality as 'must being...' in order to make 'sense' of reality. i personal choose to believe that within this lifetime - entanglement will become the foundation from which information will be transported: imagine (as you should..) a cellphone that works at all times at ANY place without drop off and with a clarity that can't be found no matter how much they try to sell the same line of advertisement of 'the network' always being there with you when you make a cellphone call..... and i would advise that instead of trying to 'make sense' of reality, that you embrace what reality will ultimately give to those willing to step and see the ongoing stage unfold...
Reply | Report Abuse | Link to thisthese entangled particles constitute a volume in space, and the volume of the 2 entangled particles interfere
Reply | Report Abuse | Link to thisthese entangled particles constitute a volume in space, and the volume of the two entangled particles interfere
Reply | Report Abuse | Link to thisBy the name of allah , the biggest
Reply | Report Abuse | Link to thisThe respectful teacher,
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If both Einstein's speed of light limit and quantum entanglement are correct (we have no reason to doubt either), then it is obvious that physicists are making an assumption about reality that is wrong. There is only one way to resolve this dilemma, in my opinion. Space (distance) is an illusion of perception. It simply does not exist. Nonspatiality is a concept whose time has come. Note that entanglement is not the only evidence that points to nonspatiality. There is also the phenomenon of quantum tunneling in which particles go through physical barriers in ways that defy classical physics. They even seem to do so at speeds faster than c! My hypothesis is that there is no travel at all through the intervening distance and thus no invalidation of Einstein's position. The particles simply disappear and reappear somewhere else, as if by magic but there is no magic. I predict that, in the not too distant future, we will have long-distance jump technologies that will allow us to "move" from anywhere to anywhere instantly. Suddenly, the dream of visiting distant star systems and galaxies beyond does not seem as far-fetched as it used to.
Reply | Report Abuse | Link to thisNasty Little Truth About Space:
http://www.rebelscience.org/Crackpots/nasty.htm#Space
Re: "a photon *has* no definite polarization until it hits a detector capable of measuring it...". Is this true? Doesn't it have an electric and magnetic component as it propogates, even before it hits any detector?
Reply | Report Abuse | Link to thisRe: "a photon *has* no definite polarization until it hits a detector capable of measuring it". Is this true? Doesn't the photon have an electrical and a magnetic component as it propogates, regardless of whether it gets detected?
Reply | Report Abuse | Link to thisc laird478 : I think that the point that allison was making is that there is no need to invoke faster-than-light transfer of information to explain how two separated observables are simultaeneously linked. Occam's razor suggests that the simpler explanation is the more likely.
Reply | Report Abuse | Link to thistuit: The analogy that Allison was using, though, was of matter on a macro scale, not the scale of quantum phenomenon like quantum indeterminacy. That is why Allison's analogy was not applicable regardless of Occam's razor.
Reply | Report Abuse | Link to thisCould be the photon case is the first example seen of a future event. Photon B already has a predetermined result by knowing what is going to happen to photon A of the entangled pair. It is programmed to perform the future change which we interpret as instant.
Reply | Report Abuse | Link to thisCould be that the entanglement case is the first evidence of an observed future event.
Reply | Report Abuse | Link to thisPhoton B is predetermined to change because it already knows the fate of
photon A of the entangled pair. We conclude that they communicate instantaneously.
Could be the photon case is the first example seen of a future event. Photon B already has a predetermined result by knowing what is going to happen to photon A of the entangled pair. It is programmed to perform the future change which we interpret as instant.
Reply | Report Abuse | Link to thisThis supports my hypothesis that entangled particles share the same macroscopic locality and thus the distance between them doesnt matter.
Reply | Report Abuse | Link to thishttp://www.helium.com/items/1271816-epr-paper-bells-inequality-delayed-choice-faster-than-light-communications
my hypothesis: the entangled particles at both ends of their communications systems are also in the same macroscopic locality.
Reply | Report Abuse | Link to thishttp://www.helium.com/items/1271816-epr-paper-bells-inequality-delayed-choice-faster-than-light-communications
Before the blogs were canceled here on Sci Am I had a blog under the username "PHAYEZ" which dealt with, among other things, time and measurement. I put forward that time only exists as a feature of three dimensional existence. Time is the "velocity/distance of 3D matter relative to the velocity/distance of other 3D matter". Outside of three dimensions "TIME" as such does not exist and infinity is equal to zero "time". Also outside of three dimensions measurements cannot be made of anything which makes mathematics, with all due respect, irrelevant since the language of mathematics has, as a syntax, products of measurement. The existence and non-existence of time is a spatial relationship oxymoron which is difficult to grasp when you are an entity who is wholly dependent on being made up of atoms which are moving through space.
Reply | Report Abuse | Link to thisOne final comment, if I may, on the speed limit of light and the fact that even information cannot exceed the speed of light. At the speed of light time is zero, in other words for the light there is no time that passes so that regardless of where it arrives, it arrives instantaneously. Nothing can move faster than instantaneously, even information...
Pierre
username: PHAYEZ (Edmonton,Alberta,Canada)
agree with Dave- we will find that matter that is separated in 3 dimensions is infinitely close in some of the other eight dimensions- if this was true the closer the items are together the closer they approach the speed of light, the father apart the items are, the greater the number of times faster than the speed of light information seems to move. The transfer of information does take a tiny bit of time - but that time is a constant whether an inch apart or a million light years apart.
Reply | Report Abuse | Link to thisCan we transmit information following way? The entangled photons released in modulated bursts let say group of ten with precise time gap between each within the group. Two entangled groups sent to separate physical locations. In TRANSMIT location we measure the state of only odd photons. In RECEIVE location we measure the state of every photon within the group. The altering state of the odd photons in the TRANSMIT location will be registered in the RECEIVE location instantly. Does this work?
Reply | Report Abuse | Link to this- Galilean relativity is correct. Einstein relativity is wrong.
Reply | Report Abuse | Link to this- The speed of light is not relevant to the observer.
- The speed of light is related to the properties of ether. As the speed of sound is related to the properties of air.
- The speed of light is the speed of electricity. The speed of light is not relevant to the magneto speed.
- Speed of magnetic waves is related to the magnetic properties of ether. So it is much greater than the speed of light. As the speed of gravitational waves is much greater than the speed of light. 10 ^ 24 times.
- That is right, space (not spacetime) is made up of pieces, like light is made of photons. For the structure of these pieces, please contact us: a.vaseghi@hotmail.com
I propose that the reason there is no signal being detected is that the photons are not separate. I think the hidden properties of quantum mechanics will reveal that while the photons seem to be in two locations, and indeed, for all intents and scientifically measurable purposed they are, the photons are fundamentally the same particle. It's likely this particle, given the state "entanglement", could be found in a higher dimension, and it's quantum properties allow it to appear in multiple locations in our lower 3 dimensions ( or 4 including time).
Reply | Report Abuse | Link to thisWell, the book Flatland by Edwin Abbott (1884) is helpful in trying to imagine the effects/capabilities of an N+1 dimensional object/entity in the Nth dimension. In our case, N = 3 (or 4 if Time is truly a separate dimension).
Reply | Report Abuse | Link to thisFor a 2D world, we can imagine instantaneous travel as possible in a simple fashion: fold the 2d space until the starting and ending point are next to each other in 3d space and then poke/step through. However, this "instantaneous" travel can only be accomplished by traveling along a 3D axis (which I believe is perpendicular to the folded 2D space). In 2D space, the points are still the same distance apart and a 2D inhabitant cannot necessarily detect that their entire universe has been folded.
Similarly, suppose the 2D space is folded so the 2 points are adjacent in 3D space. Now a 3D object is placed at the juncture so that it pokes through 2D space at both points. It is the same object, but because the 2D space is folded, this same object appears to be in two 2D spaces at the same time. Measure the object at Point A and Point B and of course you get the same result because you are measure the same projection of a N+1 dimension object onto dimension N. In this example, it would seem you could fold the 2D space into a wave or several waves all smashed up against each other so that the N+1 dimensional object can appear to be simultaneously at any number of points on the 2D space. The 2D space is not "smashed" up by this folding, because the folding is in the 3rd dimension (does not exist on the 2D plane).
I believe the concept of a "wormhole" is the 3D equivalent of "folding" space so that two 3D locations that are potentially great distances apart in 3D can be reached by traveling a short distance along an N+1 dimensional axis..."4D" in this case. Again, for us 3D creatures to be able to utilize such a mode of travel, we will need to travel along a 4D path. Is such a feat possible? Obviously I don't know :)
However it may be possible, and "entangled" pairs may be the gateway to understanding it. Using my analogy of a 3D object poking through 2D space at the same time and thus appearing as an entangled "point" or circle/polygon in 2D space. If we can change the location of one half or another of an "entangled pair", what we have really done is changed the location(s) at which an N+1 dimensional object is poking through our N dimensional world.
Another thing to note from Flatland:
Reply | Report Abuse | Link to thisA 3D object passing through a 2D plane appears to do things that are "impossible". A sphere for example starts as a point, then appears as a circle of increasing and then decreasing diameter, and finally back to a point before "disappearing".
This could lead us to theorize that anything we observe in our 3D world that seems to defy explanation within our 3D rules/physics is actually a 3D projection of an N+1 (or higher) dimensional object onto our universe or "plane" of existence. So all of this quantum "weirdness" could be the effects of an N+1 dimensional effects projecting into our universe.
Hmm...our consideration of "Time" as another dimension should allow us to consider that higher dimensions do not have to be "physical" or at least not phyically represented when projected into 3D.
The Tralfamadorians of Vonnegut's Slaughterhouse-Five could be N+1 dimensional creatures (perhaps 5D, if the 4th dimension = Time) for which all Time (as perceived by us 3D creatures living in a 4D plane?) exist at the same time as a "physical" property. If they pass through a 3D plane, only a projection (one instant of time) can be represented. If they pass through our 4D plane (3D + Time), only a linear sequence of Time can be represented?
So, is it possible that we ourselves are 4D projections of 5D creatures?
Hmm, this could explain some "paranormal" phenomena, especially those that could perhaps be explained by being able to perceive (subconciously) a portion of the totality of Time....especially if such perception is more of a glitch (not reproducible on demand, so not scientifically provable).
Suppose something (say a higher dimensional creature or device), has folded the space-time of our universe in order to pass from one point in Time to another. Suppose that a person happens to be at one end or another of such a folding of Time and at least subconsciously, are able to perceive it and store some sort of memory of the event (loosely referenced in the brain, so not recallable on demand per se).
So somewhere lost in their brain is knowledge of the past OR future that they would not normally have had if time had not been folded around them. This could be an explanation for "psychic" knowledge of the future or of the past (knowing where a body is buried a la the TV show "Medium").
Anyway...just letting my mind wander on the subject of extra-dimensional existence and the manifestation of such in our "universe"
The Beatles explained quantum weirdness in Within You/Without You more than 40 years ago.
Reply | Report Abuse | Link to thisI think your example, though true is not an apt analogy, therefore it misrepresents the entanglement phenomenon, Allison. The fault dear friends is not in our reality but in our mathematics. Mathematics is nothing more than a reflection of our human mode of perception. The infinitesimal calculus already has to make allowances for our (our brain's) need to view continuity in discrete increments. (For that we had to invent a discrete interval we call the infinitesimal, which really means practically zero.) In order to understand the true nature of space/time we need to take a look at the axiomatics of Bertrand Russell and Frege. This suggests (roughly speaking) that all our mathematical predictions change according to what we select as the basis for our calculations hence our perception of zero. In physics, we have arbitrarily selected the photon as (the equivalent of) our infinitesimal by ascribing to it zero mass. To break out of this we will simply have to use axiomatics to ascribe to the photon other massess (theoretically), even negative, and investigate what that does to our predictions about the universe. By examining the difference between these predictions we will then come up with a much better picture of the nature of the continuum that is our universe, and ideas as to how we might negotiate its mysteries. Suppose we ascribed a mass of zero to the neutrino instead for example, that would create an alternate (theoretical) universe which would certainly explain one or two other mysteries I can think of. The latest description of a neutrino as having a mass greater (slightly) than that of a photon, fails to explain the FACT that neutrinos from a stellar event reached earth before the photons of light did. Entanglement certainly provides an explanation, but our arbitrary use of the supposed zero mass of the photon as the basis of our calculations makes it all moot. (I think Bill's explanation above describes a specific of the approach I'm describing.)
Reply | Report Abuse | Link to thisDoesn't seem like a string should be required to obey lower-dimensional distances.
Reply | Report Abuse | Link to thisNot that string theory ever provided anything remotely testable.
I suspect that answers to the puzzle of quantum entanglement will come from validation of theories that the universe is in fact a sort of enormous holographic projection. In other words, particles which appear to be separated by great distances are in fact still occupying the same point on a lower dimensional level. Communication is therefore instantaneous and there is no violation of the universal speed limit.
Reply | Report Abuse | Link to thisThere are other things faster than the Speed of Light. Starting in the first seconds of the Big Bang particles were traveling faster than the Speed of Light. I also believe that 'Thought' is also as fast or faster.
Reply | Report Abuse | Link to thisWell, then, this explains chaos.
Reply | Report Abuse | Link to thisSometimes the simplest explanation is the best. The two particles are not separated by any distance at all in the underlying reality, we just only experience distance in 'our' limited view of the way things are.
Reply | Report Abuse | Link to thisSo now is the time to start looking for nonrandom wave function drop in the spectra analysis of starlight.What might appear to be noise may in fact be an entanglement signal.At the moment we are hunting for Earth like planets,if there are other species as advanced as or more so than us,it would be surprising if they were not doing the same thing,We may have already been found by one or more other species and they may be trying to contact us via entanglement.In other words they have found a star the same distance from them as it is to us.The starlight being from the same source is thus entangled,and now with them setting up a two slit experiments,we can watch for wave function drop that means they have a detector turned on in their two slit experiment and when the wave function is present their detector is off,ON=0 and off=1and we can be doing the same thing on this end.Of course it will start slow,most likely the message will be a string of prime numbers such as 1-3-5-7 and so on.Then the language of mathematics would follow,and then with more literate communication to follow.But we will never know until we start.For all we know we have already been found by others eagerly awaiting our response,and when we do so we can communicate instantaneously.Now let us take this next great step,for it will change or world more ways than we can imagine.
Reply | Report Abuse | Link to thisWhat's most weird is that this article from Aug 13, 2008 suddenly heads the 'most popular' list.
Reply | Report Abuse | Link to thisAlso weird is the assumption that photons traveling through a pair of optical glass fibers will arrive at any destination simultaneously. The speed of light is specified to be constant only in a vacuum. Not only must this light propagate through a glass medium, but it's a curved pipe through which light is reflected along its walls. I didn't even see a statement indicating the lengths of fiber were identical, but even if it were variations in its curvature would produce varying path lengths. Could be the two groups of photons don't arrive simultaneously...
Also weird may be that I thought that the test for quantum entanglement included the alteration of the particles' characteristic properties, spin or charge, then measuring the other particle's property to determine if it also changed. But maybe that's just me...
The only other thing that seems to be this fast is gravity.
Reply | Report Abuse | Link to thisWhy would this work / not work?
Reply | Report Abuse | Link to thisIf you and I continuously sent entangled particles That we measure ourselves as they go out to each other on a time based (TDM multiplexing) then you could signal me by selecting which particle you read. I would see the flip (based on my read as the particle went out to you) You could then send information by reading or not reading a particle at a given time. This would be a series of 1's and 0's.
sunwukong - As I understand, the transmitted entangled photons travel (in a perfect vacuum) at the speed of light to their individual destinations. It is purportedly only the control information that keeps the entangled particle properties in sync that is supposed to travel faster than the speed of light.
Reply | Report Abuse | Link to thisSo far, no test has directly intercepted or detected this hypothetical control information, much less used it to encode any meaningful information. Anyone please correct me if this is wrong - I don't think it is.
Sorry I only found this thread. I'm probably the last person on earth to go online and I'm not even sure how I found this...
Reply | Report Abuse | Link to thisIt is the same photon. In superposition. Propagate one, and N number of 'one's' have been propagated. Split the 'one' or don't split the 'one'. Here, there, and everywhere you want to measure the 'one', make a 'one' with chosen characteristics and you have made N number of 'measurable' presentations of that 'one'.
Just as Einstein demonstrated the boundry of Newtonian mechanics, and Quantum Mechanics limited the usefuleness of Einstein's advances, so too, Bell's Theorem (1964, CERN) and the Clauser-Freedman experiment (1972, Lawrence Berkeley Laboratory) may have established the limit of Quantum Mechanics. New topic for SciAm contributors: "Is LHC a Dinosaur Before I'ts Time?"
Now, 2010 c.e., 'time' seems to be showing limited usefulness (Scientific American, June 2010, "Is Time an Illusion"). Eliminate time from the equations and results above my pay-grade happen. Grand Unfied Theory (GUT) and String Theory are more recent developments that attempt to include Bell's Theorem. As of yet, there is no GUT and String Theory has no testable hypothosies.
Quantum Mechanics is not a description of reality. It is a pragmatic theory. Just as we aren't really sure what gravity is, but we know how to use it, so it is with quantum phenomena. Numen, anyone? Nyah, too spooky for me.
Honestly, jtdwyer, I'm not stalking your comments, you just seem to already have been where I tend go. Your questions are valid. Quantum correlation seems to be very unstable. I don't have any idea how they could verify their results under the conditions you mention. Got beer? Very old beer?
tichead - No problem - I welcome your better sourced input. I never read the book, only glanced at the the instruction manual.
Reply | Report Abuse | Link to thisMy wiki source, though, says the quantum non-local connection is a system of two or more objects linked in such a way that describing the quantum state of physical properties for one member produces non-classical correlations among all members.
From that I'd guess the superposition state provides a more theoretical description of the same thing: a single entity is 'highly correlated among more than one physical location. In practice I understand that a mirror is often used to produce an entangled photon pair. Maybe I'm confused - I'm playing outside the sandbox.
The faster than light communication people are referring to here is actually the unspecified correlation between particles. If this was provided by some physical link that could be controlled, others reason, then remote messages could be sent at faster than light speeds, they think. Unless I misunderstood...
There goes those dog-gone teenagers again exceeding the speed limit. Where are the light cops when you need them...someone is gonna end up getting hurt?
Reply | Report Abuse | Link to thisjtdwyer: If think I understood what I think someone just said... anyhow, not being a phizicist, I'm just a parrot here. 'tichead' stands for 'thought I could have earned a doctorate'. So like you I'm playing out of the sandbox also. But I think you are correct. We are either dealing with one 'doodad' in two places at the same time, or two 'doodads' that seem to 'know' what the other is doing. Superluminal communication. Einsteins's 'spooky action at a distance'.
Reply | Report Abuse | Link to thisBell's Theorem quantified what is generally known as the Einstein, Podolsky, Rosen (EPR) thought experiment that resulted from double slit interference pattern experiments during the development of Quantum Mechanics (QM). Apparently a photon going through one slit 'knew' whether the other slit was open or not. Since this implied faster than light communication Einstein was not happy.
After James Bell elegantly expressed the phenomena according to the terms of QM, Clauser and Freedman tested Bell's hypothesis and validated his arguments within the terms of QM. Now it appears that the University of Geneva team have put a minimum 'speed limit' on the phenomena.
Faster than light communication implies that the objects (in this case photons) are actually seperate entities. Superposition, the same object appearing in multiply locations at the same time, is currently only demonstrated at near absolute zero temperatures in Bose-Einstein condensates. Such condensates also have the characteristic of slowing light to walking speeds.
JamesDavis: I just hit the wall. The peddle got stuck, I swear it wasn't my fault. Call 411, hurry, I ruptured a neuron...
tichead - You make perfect sense to me. What does that mean?
Reply | Report Abuse | Link to thisIn this experiment, I propose that the timing difference is primarily the result of differing transmission speeds of each of the physical light paths, since they are not traversing space in a perfect vacuum.
In my universe, all material energy traverses space as a waveform. At rest, which occurs when 'a particle is detected' or it otherwise interacts with matter, for example, it is manifested as localized particle energy.
When a quantisized single photon is emitted, it propagates as wave energy. That wave energy is simultaneously absorbed and reemitted as separate waves by 'n' number of slots (within wave dimensioned distances). All waves are focused on the receiving backboard.
Since the slot material absorbed singular light wave is simultaneously reemitted, the photons that materialize at the backboard detector are probabilistically identical in the characteristic properties.
They are <not> the same photons received, but they <are> material manifestations of the same light wave transmitted. The detected photons are separate material instances of a singular light wave.
Not that I have to make sense to you... Thanks!
It can be inferred from this interpretation that:
Reply | Report Abuse | Link to this--- There is no 'infortmation' exchanged at particle detection.
--- The information is transmitted along with each singular wave and probabilistically determined for each particle absorption and wave emission event.
--- Received particles are not quite separate instances of the same particle, but highly similar manifestations of a single energy wave.
jtdwyer: your really get around these discussions for someone who is so "uneducated". I just read your posts on the 'What are Laws of Physics' discussion. Cool idea on the space-time dialation in transit causing the red-shift to appear more pronounced.
Reply | Report Abuse | Link to thisBut back to this. If I understand what you are saying then it would be like a wave in water propagating past an infinitely thin wall parallel with the direction of travel. The wall would cause the wave to appear as two seperate manifestations of the original wave, each with the characteristics of the original single wave. Thus, any measurement of either of the two seperated waves would display the same results such that they would appear to have been 'communicating' with each other.
While I'm not sure what the parameters were for the experiment in this article, in previous experiments the 'spin' state of a particle was used. In those experiments entangled particles were generated, sent off in different directions, and while in transit the spin of one particle was changed, then the spin of the particle that went the other way was measured. Invariably, the 'other' particle changed spin to correlate with the spin of the 'one' particle. Refering back to my analogy of what I think you are descibing, it would be as if the wave in the water on one side of the wall hit a large piling causing it to change it's pattern and the wave on the other side of the wall didn't have a piling in it's way but changed it's pattern just as the one did.
Part of the problem with what we are discussing is that quantum phenomena are innately non-intuitive. Also, our brains, in the absence of the math that descibes such events, tend to be limited to rather Newtonian type mechanical models of reality. We want the theory to describe reality when in fact it doesn't. As a pragmatic theory it only describes how we can use what is measured. When we think of particles we want to see them in our minds eye as something occupying a definite region of space. When we think of waves we see them as spread out across a less definite region of space. But when we measure the particle properties of stuff we get particle results and when we measure the wave properties of stuff we get wave results. I can't picture this 'stuff' in my mind so I just accept what the people with equations tell me.
I am inclined to believe that understanding this entanglement thing will bust open the doors to a whole new realm of physics much like the Michelson-Morley experiment lead to Einstein's stunning breakthroughs.
tichead - Thanks for your generous remarks.
Reply | Report Abuse | Link to thisI wholeheartedly agree with your 'uncertainty' about the experiment (not very well) described in this article. The 'clocking' of the entanglement 'communication' is apparently a measurement of the difference in the arrival of entangled particles at the same location, or something. At any rate I question this clocking using glass fibers...
I also agree with your description of QM as a pragmatic theory, yet I think it is commonly presumed to represent the physical processes producing the observed effects. Oh well. Thanks!!
A more complete description of this experiment is posted at:
Reply | Report Abuse | Link to thishttp://arxiv.org/abs/0803.2425
Again, I have to object to an experimental procedure that is dependent on the time of detection for entangled (reflected) photons, following transmission over separate glass fiber channels. Since the light is transmitted through the glass by reflection along cable walls as determined by cable curvature and actual path taken, the actual path length of transmitted light varies from the measured 17.5 km lengths of the two cables.
This distant glass fiber transmission length variation most likely introduces a far greater error than would found for a short distance atmospheric laser transmission in a controlled laboratory environment.
Thanks for the link to the paper being discussed. Even though the math and technical info are slightly farther down the rabbit hole than I have been I'll take a shot at this anyhow.
Reply | Report Abuse | Link to thisI agree that the fiber optic link could and probably does induce variables in the photon state during transmission. In addition to the internal reflection you mention, minute density variations of the glass medium, exact physical lenth of the line, and quality of intervening connections at nodes could induce variables in timing and/or decouple the entanglement of the photons completely.
However, the experiment uses the Michelson interferometers to validate the timing and verify entanglement at the destinations and reports long arm-short arm results as errors. If I understand the paper well enough, the long-long and short-short results validate accurate timing and verify entanglement.
Since the experimenters appear to have accounted for so many other variables, I have to assume they accounted for the quality of the transmission medium as you describe even though the article does not specifically mention it.
tichead - Yeah, I'm really using a top-down conceptual analytical approach, but I no longer have the stamina to reach completion. Thanks for forcing me onward...
Reply | Report Abuse | Link to thisI don't understand how the Michelson interferometers validate timing, only validate the reception of entangled photons. In fact, I get the impression that the only time measurement is to confirm that the detection/polarization determination process at a receiver is completed before a EM signal could be received from the remote detector (to adjust polarization).
If this interpretation is correct, the experiment only confirms that a light speed entangling signal does not align the properties of the two particles. The precise transmission path length is not not critical, since it is only used for macroscopic confirmation, not direct timing.
In this case, it's this article that incorrectly asserts that the experiment determines the speed of a faster than light entangling signal.
My earlier hypothesis is consistent with these results: the entanglement information is contained within the singular wave function from which both detected photons are materialized. Thanks.
By the way, the singular wave interpretation would have seemed to Einstein to conflict with his 'proof' that light (at rest) is composed of particles. As a result, he could not consider the conflicting singular wave interpretation (if it had occurred to him) and had to consider this 'spooky action at a distance'.
Reply | Report Abuse | Link to thisI suggest that material energy is not at the same time an uncertain wave and particle, but that it is a wave in motion and a particle at rest. We are only uncertain whether it is in motion or at rest: it is not. Our 'detection' of its location halts any motion, producing a particle; measuring the velocity of its wave identifies its energy dispersed among space and time locations. But, I'm just guessing...
I'm sorry if I accidentally kicked you farther down the rabbit hole than you wanted to go, but welcome to Wonderland.
Reply | Report Abuse | Link to thisAccording to the text of the paper: "Finally, we find that the
time of collapse is tD = 1s, using Eq. 1 [9] with d=12.6
nm and taking just the mass and volume of the mirror.
The total time is then tM = 7:1 s, almost one order
of magnitude shorter than the 60 s the light needs to
cover the 18 km between the receiving stations. Note
that taking into account the motion of the piezo itself
would even shorten this conservative estimation of tM."
If I understand this correctly, and I'm not sure I do, then the movement of the mirror is at least one order of magnitude less than any time differential imposed by the medium, be that medium air or fiber optic cable.
I think the main purpose of the experiment was to show that quantum events can have macroscopic effects and that any experiment describing non-local phenomena without measurable macrosopic effects is invalid. In this experiment it would appear that that they have demonstrated that entangled entities can effect macroscopic objects in non-local fashion. I got a boot tred imprint on my forehead just from reading this.
As to the 'wave in motion, particle at rest' hypothesis you propose, Einstein suffered no confusion or delusion. He understood the particle measurements to be events and wave measurements to be probabalistic, ie. interference patterns. He didn't like that light could be experienced and described as both and neither, but he could never refute the facts. And the QM folks understood and used relativity to define the rest mass of 'particle/wave's that they saw in their experiments.
Bottom line here, I think you are on the right track with the singular wave concept despite getting sidetracked by the technical details of the measurement process. Regardless, numerous experiments indicate that non-local information exchange is real and it is BIG. Bigger than relativity or quantum mechanics alone or together. Welcome to Wonderland.
No, it's been fun - I just don't have enough energy nowdays.
Reply | Report Abuse | Link to thisI think I agree: I tried to say earlier that the objective was to "confirm that the detection/polarization determination process at a receiver is completed before a EM signal could be received from the remote detector." close, anyway.
This article's interpretation, though, seems to be considered valid. If fact I found following papers that seemed to infer all kids of things from this experiment. Seems almost like anything goes...
I found a paper in Science v323 p598 "Sudden Death of Entanglement" (early dispersal of entanglement) that referred to the entangled pairs of atoms (in cavities) in addition photons and spin qubits, continuous Gaussian states and subsets of multiple qubits and spin chains. How atoms can be entangled was not explained. I think I'd better sleep on it...
OK, you lost me on the Gaussian states and qubits, more food for thought. I'll check out the article. See you 'round the discussions, thanks for the mental exercise on this one, it's been awhile since I pumped any quantum of iron.
Reply | Report Abuse | Link to thisWell done!
Reply | Report Abuse | Link to thisWhat is it that leads people to believe there is some sort of communication happening? If you synchronize two stopwatches they will read the same at a later time, how is that wierd? I suppose if you didn't know that a stopwatch kept time and you did such an experiment one explaination could be that the stopwatches instantly communicate with each other in order to give the same results. But since we do know of such things why the crazy instant communication theory??
Reply | Report Abuse | Link to thisIt seems to me that entangled pairs are in the same place on another axis. Our assumed x, y and z axis of space seem to me to be actually one dimensions that appears as three due to the vector attribute of forces. The photons could be in the same place at the same time in the other dimensions so it appears that information is traveling faster than light when it is not. Also the speed of light limit is only limited to the dimension of space.
Reply | Report Abuse | Link to thisThe speed of light is calculated from Eo, the strength of the electrostatic force and the u, the strength of the magnetic interaction. Eo is 8.854187817 x 10^12 coul^2 / (joule-meter) and u is 4 x pi x 10^-7 N / amp^2. The speed of light, c = 1/(E0 x u)^0.5. What this demonstrates is that the speed of light in the space that we are used to describing is limited because of the dielectric of space itself. Space, or how we perceive it, is a result of photons traveling through it and the speed limit, c, is a result of that observation. When there is no space measured in meters and velocity in meters/second then the speed of light becomes meaningless. The other dimensions are not dimensions of space but of different kinds of forces. If an entangled pair has the same component particle that particle does not have to exist in the same point of space.