Entangled Particles Seem to Communicate Instantly—and Befuddle Scientists

By Eliza Strickland | August 13, 2008 6:37 pm

light photon fiber opticsOf all the weirdness in the universe, the quantum mechanics phenomenon called “entanglement” may be the most mind-boggling. Physicists have long shaken their heads at the theory that two particles that become entangled will always and instantly mirror each other’s properties, no matter how far they are separated, which seems to go against all other physical understanding. In the everyday world, objects can organize themselves in just a few ways. For example, two people can coordinate their actions by talking directly with each other, or they can both receive instructions from a third source…. But quantum mechanics allows for a third way to coordinate information [Nature News].

Einstein rebelled against the notion of quantum entanglement, derisively calling it “spooky action at a distance”  [LiveScience]. Entanglement would look a lot less spooky if we could prove that an entangled object releases an unknown particle or some other signal at high speeds to influence its partner, giving the illusion of a simultaneous reaction [LiveScience]. But a new study shows that if some hidden signal is passing between the separated particles, it would have to travel at 10,000 times the speed of light. As this explanation seems impossible, the research team favors the alternate, weirder idea: that a measurement on one photon instantly influences the other [New Scientist].

Physicist Daniel Salart entangled [his] photon pairs using a source in Geneva, then passed them through fibre-optical cables of exactly equal length to the villages of Jussy and Satigny, which lie respectively east and west of Lake Geneva. Here, the photons’ entanglement was checked by an identical pair of instruments to reveal consistent entanglement of their photons, and the effects of the Earth’s rotation taken into account [Telegraph].

The study, published in the journal Nature [subscription required], shows that the particles did indeed mirror each other’s properties at the exact same moment even though they were 11 miles apart. The research team says their finding disproves the more comprehensible hypothesis–that the particles were sending signals at faster-than-light speed–and instead supports the stranger theory of instant communication. Dr Terence Rudolph of Imperial College, London, remarks that “any theory that tries to explain quantum entanglement… will need to be very spooky – spookier, perhaps, than quantum mechanics itself” [Telegraph].

For a look at what quantum entanglement means for the potential to teleport ourselves, check out the recent DISCOVER article, “Teleportation? Very Possible. Next Up: Time Travel.

Image: flickr/Photo Mojo

CATEGORIZED UNDER: Physics & Math
  • http://leftwingfox.blogspot.com Left_Wing_Fox

    Creepy, it appears Orson Scott Card actually wins a point in the “prescient Sci-Fi Author” column for the basic principle behind the “ansibles” used to communicate instantaneously in the Ender’s Game universe.

  • http://blogs.discovermagazine.com/sciencenotfiction Stephen Cass

    Left_Wing_Fox — I would throw some props as well to Ursula LeGuin, who coined the term “ansible” in the sixties. (OSC even had Graff explain in Ender’s Game that the “ansible” name for their technology had been lifted out of old book!) However, I believe LeGuin’s fictional technology requires at least one end of the communications link to be anchored on a planet or somesuch, while Card’s version does not. Of course the big problem with entanglement-based ansibles is that even if the particles are communicating instantaneously, our current model of quantum theory precludes the possibility of piggy-backing any additional information on the entanglement “carrier wave,” alas.

  • qbsmd

    Wikipedia claims Orson Card was born in 1951, and the quantum entanglement was first theorized in 1936.

  • Dan m

    qbsmd-

    Well done….is there a question in there, or nothing more than a random fact? OK, I have one too!

    Wikipedia says:

    “Bagpipes are a class of musical instrument, aerophones using enclosed reeds fed from a constant reservoir of air in the form of a bag.”

    Anyways, in Ender’s Game they claim that the buggers are why we figured out HOW to communicate faster than light. I guess now that means that we used them (the buggers) to figure out how to carry information using quantum entanglement as opposed to just taking measurments in two swiss cities.

  • http://www.bestsporecreature.com Spore

    Nitpick:

    “it would have to travel at 10,000 times the speed of light”

    Unless I misread the original article, 10,000 times the speed of light is the MINIMUM speed given the resolution of the equipment that was used.

  • MikeN

    These protons were separated by 11 miles through three dimensions in an arc that approximates the curve of the earth. We don’t know their exact distance from one another in terms of their x,y,z coordinates but these are not relevant.

    What was discovered here is that the entanglement of these particles took place across another dimension, and that in this extra dimension these particles were separated by 1/10,000 the distance in three “natural” dimensions. Information traveled, via the entanglement, across this distance in the extra dimension, at or below the speed of light.

    The real news here is that we can leverage this extra dimension for communication at the very least.

  • http://www.tonylandis.com Tony Landis

    Incredible stuff

  • Dietrich Epp

    Hate to break it to you, but you can’t make a communication system with this. You cannot make an ansible using quantum entanglement this way. Anyway, Card’s ansible has a problem: if you can communicate faster than the speed of light, then you can send messages back in time. Card didn’t predict jack squat, and he either didn’t think very hard about the implications of ansibles or he just doesn’t know very much about relativity.

    Let me put it this way: if the particles were really exchanging information, let’s have two spaceships flying by: one from particle A to B, the other from particle B to A. Both spaceships are at the midpoint, C, and travelling quite fast. One spaceship says, aha! information traveled from A to B, faster than the speed of light! The other spaceship says, aha! information traveled from B to A, faster than the speed of light!

    Not all interpretations of QM have “wave function collapse”… in these other interpretations, things make much more sense and nothing travels faster than light speed.

    Go take a look at http://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics

  • Myke

    “the particles did indeed mirror each other’s properties at the exact same moment”

    What exactly does this mean? They both vibrated in the same pattern at the same time? Are they 100% identical? If one particle was disturbed, does it affect the other one? If not, couldnt the particles influence each other when together enough to seemingly still “communicate” when separated?

    Am I missing something?

  • Jerome

    I saw in one of the links, ‘…Dr Charles Bennett of IBM and others theorised that entanglement can make a “quantum phoneline” that could “teleport” the details (quantum state) of one particle to another over an arbitrary distance without knowing its state.’

    While the article concludes that ‘the contents of those notes are beyond our control, and so can’t be used to transmit any useful messages.’, I certainly would rule it out. So, there’s a handy way to transmit binary data over arbitrary distances.. maybe? That would be nice.

    Myke, I think what they are saying is that altering the state of one electron affected the other one, for reasons that can only be explained by their theory?

  • http://eoarchitect@yahoo.com Edward Ozols

    Faster than light travel is an appealing idea, especially 10000x light speed. However, although my knowledge in this arena is by no means professional, might I suggest that travel between two ‘points’ might not violate any rules if the travel occurs in dimensions other than 1-4.

  • Mark

    I think the photons are separated in 3 dimensional space, but are in the same place in some other dimension. Extra dimensions also explains how small particles (e.g., electrons) can jump instantly from one place to another.

  • anon

    mark, very good, we also see how string theory is proposing to prove that there are something like 11 spatial dimensions in some of them time is reversed, which would also explain the electron equation.

    it just gets too crazy at this level of understanding, we aren’t living in 3 dimensions we’re living in 11 we just dont see anything but 3 spatial dimensions because of gravity. all other dimensions are overlayed on our space.

  • Wayne

    Among the many questions arising from quantum entanglement, there seems to be one concerning whether such knowledge could be *harnessed*. For example, could it lead to an advanced form of communication, even across cosmological distances? What about the possibility of ‘quantum-state telescopes’ and ‘quantum-state trancseivers’? It seems to me that some recent research may have brought us a step closer to realizing some of these ideas…

    Dr Lene Hau and her Harvard-based team has managed to non-randomly alter the quantum states of atoms via light, and, vice versa. The researchers have shown that light can be slowed to a bicycle speed and even stopped(!) within a laser-supercooled Bose-Einstein-Condensate (BEC) of sodium. The temperature of the condensate is a few billionths of a degree above absolute zero. At such a temperature the sodium atoms share the same low quantum state behaving en masse like a “super-particle”. The researchers then trained two lasers on this condensate: the first, a coupling beam; and the other a probe beam. Via their manipulation or ‘wavelength-tuning’ of the sodium condensate with the coupling beam, they were then able to get the condensate to slow down the probe laser light and bring the light to a complete stop within the condensate! During the deceleration, the laser beam light pulse shrank from a length of several kilometers to just tens of microns, fitting entirely within the sodium condensate cloud! The probe light left a kind of holographic imprint in the BCE atoms, and the researchers were able to manipulate/process that ‘stored light’ via electric- and magnetic fields. They were able to coherently transfer (change) BEC sodium atoms from one quantum mechanical state to another.

    For full article/discussion see here
    http://www.seas.harvard.edu/haulab/publications/pdf/OPN_Ultraslow_light.pdf
    mini video here of Dr Lene Hau discussing her work: http://www.nature.com/nature/videoarchive/trickofthelight/

  • .jad

    Loose the concept that communicating faster than the speed of light would be sending information back in time. You are confusing observation with time.

    If a mars rover uses an “entangled particle transceiver” to send data back to NASA saying it fell over the rim of a crater, the communication is more “real-time” than anything else.

    An astronomer watching the rover fall over the edge is getting the information after the delay caused by the limits of the speed of light.

    Nothing went back in time.

  • cam

    @ .jad

    Here is the reason why a faster-than-light signal would be travelling through time:

    If one were able to move information or matter from one point to another faster than light, then according to special relativity, there would be some inertial frame of reference in which the signal or object was moving backwards in time. This is a consequence of the relativity of simultaneity in special relativity, which says that in some cases different reference frames will disagree on whether two events at different locations happened “at the same time” or not, and they can also disagree on the order of the two events (technically, these disagreements occur when spacetime interval between the events is ‘space-like’, meaning that neither event lies in the future light cone of the other).[19] If one of the two events represents the sending of a signal from one location and the second event represents the reception of the same signal at another location, then as long as the signal is moving at the speed of light or slower, the mathematics of simultaneity ensures that all reference frames agree that the transmission-event happened before the reception-event.[19]

    However, in the case of a hypothetical signal moving faster than light, there would always be some frames in which the signal was received before it was sent, so that the signal could be said to have moved backwards in time.

  • cam

    And if that was a bit difficult to grasp (hence why Enstein was considered smart!), then understand that what you observe will always be different from what the person on Mars observes because of time dilation (time slows down as you move faster). So you can never agree on what is happening in “real-time” or “simultaneously”.

    And Since the two of you can’t agree on “when” things happen, it’s possible that you will get a faster-than-light message that seems to predict your future.

  • cam

    And to further simplify this explanation: Real-time or instantaneous communication is only possible if you live in a universe where time was constanst for every observer. But we don’t live in that universe. Time runs at different rates. It moves or slows down depending on how fast you’re moving relative to everything else.

  • http://www.lifecollege.org Ian Lewis

    This whole was a great thread and thanks to all. The last sence from you, Cam, says it all.

    The take for me is its application to consciousness and the creation of the/our universe – von Neumann, ‘We create our own reality.’ So let us keep looking for instantaneous messaging, that way we shall find it?

  • Jani

    Why isn’t quantum entanglement simply proof of deterministic behavior? Assuming the entanglement itself “resets” the state of both particles, and from that point on they tick independently but follow the same complex function.

    If this were the case, then the observed same state of both particles wouldn’t be any different from two computers calculating pi from the same moment and reporting the same decimal when queried.

  • mac

    @ cam (#16)

    “If one of the two events represents the sending of a signal from one location and the second event represents the reception of the same signal at another location, then as long as the signal is moving at the speed of light or slower, the mathematics of simultaneity ensures that all reference frames agree that the transmission-event happened before the reception-event.

    However, in the case of a hypothetical signal moving faster than light, there would always be some frames in which the signal was received before it was sent, so that the signal could be said to have moved backwards in time.”

    To elaborate:

    Consider two people standing 1LY apart, watching each other with telescopes. Each person has a box containing one half of an entangled pair. Both boxes have a light bulb which will turn on if a message is received via the spooky action of the entangled pair.

    1.) Person A presses his box’s button to send an instant communique to person B’s box.

    2.) While person B’s light turns on instantly, person A will not see the light or know the message has been received until 1 year later.

    3.) From Person B’s reference frame, his light will suddenly turn on, seemingly for no reason. When he looks through his telescope at Person A, he will not see Person A pressing the button for an entire year.

    4.) Therefore Person B, from *his own* reference point knows the future — that in one year his telescope will show Person A pressing the button.

    This doesn’t mean that causality has been violated from an absolute standpoint, but only that it appears to be violated from the reference frames of all observers involved. Unfortunately, Relativity theory is of the ideology that there is no absolute reference frame at all, therefore making the argument moot that causality is not violated from absolute standpoint. Following, if the only reference frames that exist are those of observers, and according to all observers involved causality appears to be violated, then logically causality is violated.

  • kim

    What a wonderful thread. As someone who left school at 14yr and can’t add up for nought ,even I could grasp the concept expressed in a manner that was obviously simplified. So true ” the more we learn the more we have to learn.”

  • chris

    @Jani: it has been proven that there are no hidden variables that work like your idea. When the entangled particles move a long distance (some miles are enough) it can be proven that the result of the measurement can be changed during the travel of the particles. So the state is not “reset” when they first get entangled. It happens when the state is measured.

    My idea is, because the particles move with speed of light, their distance in the dimension of time is 0.

  • Mike

    Isn’t the controversial (or perhaps I should say revolutionary) point of this discussion the notion that quantum entanglement raises the possibility that special reletivity is wrong (or incomplete in some way we don’t know yet?) Most of the “totally amazing” advances in the application of physics start with a rethinking of base level assumptions (the bomb being the most obvious but our ability to “shrink” silicon based transistors to the point where quantum effects apply and probably lots more I don’t know about). I think this is pretty amazing stuff – I’m hoping for new applications (which as several have point out) will seem “magical” or “paradoxical” at our current level of understanding but maybe perfectly explainable once new mathimatical models have been proposed and experiments designed, etc. Potentially very exiting times for the human race !!!

  • Jim

    can’t one observer, alice, convey a message to the other, bob, by choosing how to measure an entangled particle? then bob will see the results instantly as far as how it was measured and its results, because they are entangled. so, if one particle is measured by alice in one way and gives 1 result, it means to bob the british are coming. if it is measured and observed a different way, bob will know it means no british are coming, coast clear.

  • Victor

    I have several comments for this thread:

    1) Concept of Simultaneity: An astronomer would say Galaxy A which is 3 billion light-years away appears to us the way it was 3 billion years ago and today may look very different (for instance, we see a spiral galaxy today but in actuality it could be irregular or elliptical seen close-up due to collisions with other galaxies). However, the spiral picture we see would be considered by relativists to be occurring simultaneously with current time and be the galaxy “today”. This is not true communication to the past, only if we choose to call that spiral galaxy “today”. If this was true back in time communication, there would be a way to communicate with yourself in the past using this method, which I don’t see how this would be feasible.

    2) Causality Violations: Since the early 1990′s when I was starting to do physics, I have heard of the Causality Principle being discussed by physicists and have never heard a convincing argument for why this should hold besides personal belief that this should be so. We’ve known about the CPT Theorem for a long time which asserted antimatter particles would be identical to matter particles if considered traveling backward in time. Further, there has been very convincing recent experimental evidence utilizing laser amplification that future events can indeed affect the present. Actions taken by scientists a half hour in the future affected measurements taken a half hour before. It is likely that particles have time wave functions in addition to their space wave functions. In fact, relativity would seem to demand this to maintain the constant velocity of light as a speed limit. Some scientists have also put forward the idea that the reason quantum mechanics cannot predict exactly what a particle can do and instead uses probabilities is because some of the information needed is hidden in the future and that future events can affect the present. Sending messages to the past is no where forbidden by any physical laws I know and I believe Dr. Neil DeGrasse Tyson may have already discussed this being possible using frame-dragging such as what a rotating black hole does to space-time surrounding it.

    3) Hidden Dimensions: String theory has been putting forward the notion of 11 dimensions and the idea of compacted dimensions. I also thought at one time that entanglement may communicate across these compacted dimensions. We know all particles also have a wave nature and it’s this wave-particle duality which we should think in terms of since entanglement is intimately connected to the particle’s wave nature. Entanglement can be thought of in terms of superposition of waves. The two particles maintain this superposition irregardless of their spatial locations until some measurement affecting their spin orientation takes place (e.g. passage into a magnetic field). The question is how far can we separate the particles with this coherence being maintained.

    4) Use as a communication tool: I’ve had many discussions with physicists regarding this including attending a talk at the Kavli Institute for Theoretical Physics in Santa Barbara where the speaker concluded that it wasn’t possible because no matter what axis you measured along, you still had 50% probability for measuring either of two directions so no information could be conveyed. I still think there are ways of getting around this though using either an ensemble of particles or weak measurements. I still believe this area needs further research since we honestly don’t know quantum mechanics well enough to say FTL communication isn’t possible.

  • jeff

    The focus should not be the explanation of the possible FTL particle or unknown communication between two entangled photons. This is not happening. The particles are entangled at some point during or observation of them. That entanglement is an essential piece of information about those specific particles. The reason they don’t need time to transmit their current behavior to their fellow entanglee is because they are moving at the speed of light! They have no time. Everything is instantaneous. Those photons are zipping through the entire universe instantaneously from their perspective. Photons are difficult to understand, and should be used for many things, but not this. For this we need something slow. It must be possible to suspend some heavier entangled particles in lead or some more researched element while using basic on/off EM waves to change the state of the suspended particle at the same time monitoring the other particle at a distance. I’m sure if this worked, a more complex system could be developed to improve data transfer, something humans have become quite adept at in the recent years.

  • Ed

    Someone made the argument about the two people looking through telescopes then pressing the buttons on their “entangled” phone. The reason this looks like time travel is that two things are being confused. Think about what happens when you call into the radio station and talk to someone on the phone in real time – this is like the entangled transmitters. If you then turn on the radio, you hear something a few seconds later because of the delay of the the radio system – this is like looking through the telescopes using light. In the end, you and the person on the moon or Mars exist and are moving at relatively (pun intended) the same speed through space-time. A radio signal takes a few minutes to get from Mars because it is electronmagnetic manifestations of energy in 4-dimensional space-time. What entanglement may be is sort of a “tunnel” through the other dimensions where light or some other form of energy signal really has no speed limit at all. According to relativity, nothing can go faster than the speed of light in our perception of space-time. If this space-time offers some type of “resistance” to even electromagnetic radiation, then that is what we see and measure as the speed limit of light. We all know that the speed of propagation of light changes in different materials, I maintain that space-time is just some other “material” that dictates light speed. As of now, since we don’t believe that anything can travel faster than light, how can we even measure or recognize something that does, even if we see it. Entanglement may be that thing.

    As far as not being able to transmit information, it doesn’t seem impossible to then group multiple entangled items together to form bits and bytes. If I can even oscillate a single entangled pair (on-off/up-down/etc) then this stream of oscillations could be interpreted as information the same way we use fiber optics to communicate a 10+ Gigabits/sec. If the signals were entangled, the information would have a signaling rate, but if the measurements are correct, this information could travel from earth to mars in practically zero time. It just means that we can’t try to look at each other through telescopes while doing it. At least not optical telescopes. But maybe Entanglement-TV………

  • LenMontieth

    If anyone thinks this explanation is too “Spaced Out”, may I remind them of the crazy subject?

    This is an effect and an expected proof of a theory that our known universe is sitting on top of other dimensions. In essence that our universe is sitting on a singularity of a White Hole.

    In that singularity, of one dimension, absolutely everything is connected at “source” of the white hole that created the universe. It would not be possible to find field differences in a small “space-time area” like around Earth because ALL particles and space time, rests on top of the White Hole “source”.
    One side effect of a white hole, would be for particles to fizz into and out of existence… because of the radiation effect of the “source” being omni present.

    Proving connection within the omnipresent singularity “source” , could be tested by entangled particles the distance between particles and “Faster than light communication”.
    Since there is no way communication can travel faster than light, entangled particles would have to be in direct contact IF near instantaneous communication was proved with a suitable distance.
    The experiment suggests 10,000 times faster than light travel. This is not physically possible in our universe. It therefore supports the theory of our universe sitting atop a white hole singularity, by which everything is connected as part of our universal fabric.
    Connection by a singularity is not faster than light time travel and no law has been broken,
    entangled particles communicate via the singularity “short”.

    It would lead credence to near instantaneous “teleportation” or “communication” from one side of the universe to the other BUT boxes would have to be built at each end (via normal space). Again I say this would NOT be time travel, but INFORMATION transference via the singularity on which the universe is sitting.

  • steve

    What would be truly special is if the entanglement could be slowed. It would be the key to travel through another dimension.

  • pete dixon

    interesting reading….tho’ beyond my comprehension! and what about yesterdays news of neutrinos at CERN going at faster than light?

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