Please create an account to participate in the Slashdot moderation system


Forgot your password?
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. ×

Quantum Theory Experiment Said to Prove "Spooky" Interactions ( 257

universe520 writes: Albert Einstein was troubled by how two particles can communicate with each other even if they are on opposite sides of the galaxy. Today researchers in the Netherlands have closed the final two loopholes in how quantum entanglement works. The Times reports: "The new experiment, conducted by a group led by Ronald Hanson, a physicist at the Dutch university’s Kavli Institute of Nanoscience, and joined by scientists from Spain and England, is the strongest evidence yet to support the most fundamental claims of the theory of quantum mechanics about the existence of an odd world formed by a fabric of subatomic particles, where matter does not take form until it is observed and time runs backward as well as forward."
This discussion has been archived. No new comments can be posted.

Quantum Theory Experiment Said to Prove "Spooky" Interactions

Comments Filter:
  • by Arkh89 ( 2870391 ) on Wednesday October 21, 2015 @04:10PM (#50776371)

    "and time runs backward as well as forward."

    It had to be published today, right Doc?

    • Nah, it's ten days early.

  • by mrego ( 912393 ) on Wednesday October 21, 2015 @04:13PM (#50776389)
    and this is the basis of the flux capacitor and all of time travel. About time it got discovered.
    • Someone needs to tell Stanford to stop making donuts.

  • Does this mean faster than light communication is actually possible? Maybe the best way to connect with extraterrestrial intelligence is to figure out how faster than light communication works, then make a call. What do you have to do to pair the particles to begin with?
    • by darkain ( 749283 ) on Wednesday October 21, 2015 @04:20PM (#50776467) Homepage

      Just press the red button on each and wait for their red LEDs to start blinking to pair the particles.

    • Maybe the best way to connect with extraterrestrial intelligence is to figure out how faster than light communication works, then make a call.

      Why? Who you gonna call?

    • by Arkh89 ( 2870391 )

      No, with entanglement it would seem that you cannot force one particle to a state so that the other is switching as well. Thus, you cannot effectively use this as a communication channel.

      A very crude picture can be stated as the following : you send two letters containing the same unique number (0...9) to both Alice and Bob (who also know this rule). When Alice opens her letter and reads the number, she knows that Bob has the same number but she cannot use that to communicate a particular number to Bob dir

      • I've never actually heard a convincing argument as to why this explanation is wrong. It seems to describe the Bell inequality experiments perfectly.

      • This is easier for me to grasp in the many-worlds interpretation [] of quantum mechanics. There is a universe in which Alice is holding "0" and Bob is holding "1", and another universe in which Alice is holding "1" and Bob is holding "0". Those two universes separate the moment Alice (for example) looks at her bit. At that point she is certain that Bob got the opposite bit.

    • by myrdos2 ( 989497 )

      Not that we know of. If you measure your particle, you know the fellow on the other end will read the opposite measurement. It's like having random number generators at each end that are perfectly synchronized, but always produce inverse results.

      You can use it for unbreakable encryption though, by treating your random numbers as a symmetric key with unlimited length. The person at the other end can deduce your key from his own measurements, without ever having to send the key over the channel.

      • If we know it's the inverse result, can't we use it anyway? Using binary as an example, if one end reads "1" then it means the other ends reads "0".
    • by Lumpy ( 12016 )

      Knowing how humans work, we will make a UDP broadcast call giving our location with "hello" and a lot of annoying children in different languages saying hello.

      This will cause a galactic armada to come here and obliterate us for messing up the last half of the season finale of "glip Glopr the unstoppable".

      • Don't be silly. They're just here to construct a hyperspace bypass, which will require the demolition of the Earth.

        Oh, and don't bother complaining. The plans have been on file at the local office in Alpha Centauri, if you wanted to file a complaint, you should have done it then.
      • by sconeu ( 64226 )

        Said armada will, due to a scaling error, be promptly eaten by a small dog.

    • "Does this mean faster than light communication is actually possible?"

      Nope. See no communication theorem. Basically you cannot communicate *any* information whatsoever.
    • by Spaham ( 634471 )

      Actually it has been proven that no signal can be passed between the two events, even though they seem to be linked.
      So no communication or data.

    • by Tablizer ( 95088 )

      Quantum Mechanics is a Great Tease.

      At first it looks like you can do wonderful things, like send messages faster than light or travel back in time. BUT when you look at the details or actually try it, there's always a catch that limits the usefulness.

      Me thinks Quantum Mechanics was designed by Oracle lawyers: it looks like you got a great big powerful database...until you go to use it and find out the contract does something ridiculous like count "transaction" as each table cell read, NOT per query, filling

    • Does this mean faster than light communication is actually possible?

      Short answer: no.

      Longer answer: entangled particles can only be observed to be in a state, they can't be placed in a state.

      The coin analogy is a good one. Imagine that you and a friend a long distance away have two "magic" coins that are guaranteed to show opposite sides: one comes up heads, and you know the other comes up tails, and vice-versa. You can flip your coin, see it come up heads, and you know instantly that your friend sees tails. But here's the catch: you can't control which face shows up. You c

      • by Boronx ( 228853 )

        Hold on though. If I don't actually look at my coin (leave it spinning). Isn't my friend's coin still spinning? Can't we tell that statistically?

        Let's say we're firing off entangled electrons. We have a splitter based on the spin of the electron. We redirect the split electron beam at the same target. If our friend is *not* measuring spin with his entangled stream, won't our beam interfere with itself? Won't that interference go away if our friend starts to measure?

    • xkcd just covered this a few days ago: []

  • Distance? (Score:5, Interesting)

    by Viol8 ( 599362 ) on Wednesday October 21, 2015 @04:18PM (#50776459) Homepage

    Spooky action at a distance is only spooky if one assumes distance is real and not an emergent property of a projected/holographic universe. In the same way in a computer simulation/game the distance between objects in no way represents the "distance" between them in the computers memory, perhaps our universe works at a similar level of abstraction.

    • That was a thought I had as well, that this provides further evidence that we are actually living in a simulation instead of a "real" universe. I've heard the theory that the universe is not 3D but actually a holographic projection of a 2 dimensional universe, but in that case it seems like there would still be propagation delays for communication of information. My previous belief that we are living in a simulation was based on my being told that positions in space and time are inherently quantized; in a "
      • by tnk1 ( 899206 )

        Yes, but why do you think a "real" universe wouldn't be quantized? Having only seen one universe, our own, what evidence do we have of this scenario being somehow not basic?

        The fact that it resembles what we do in computer simulations does not imply anything about the reality of the universe. It may be the other way around: simulations work the way they do because the real universe is naturally quantized.

        It is an interesting and possibly even correct assertion that someone is running us as a simulation.

        • by KGIII ( 973947 )

          Sure, first they say Pluto is not a planet and next they're going to say it's not the universe. I see where this is going...

      • by Greyfox ( 87712 )
        Oh yeah, and not even a very good simulation. Clearly corners were cut. The dodgy temporal consistency between various points, the hard coded speed limit, the way parts of it just crash when you put too much mass in one place. I'm pretty sure it's just an n-dimensional undergrad project to demonstrate how to convert hydrogen into plutonium with nothing more than a few simple rules. Of course, now that some plutonium has been created, they'll probably shut the whole thing down as soon as someone notices.
    • by DogDude ( 805747 )
      You're right. It's also only "spooky" if time exists as we perceive it to.
      • by KGIII ( 973947 )

        When I was young, and thought I was wise, I had a saying that I'd write all over the place - I'd stated it while tripping sack and it kind of stuck. Anyhow, I said, "Time is nothing but man's measurement for the passage of reality." I might have been right.

    • Re:Distance? (Score:5, Interesting)

      by pr0t0 ( 216378 ) on Wednesday October 21, 2015 @04:32PM (#50776577)

      I've always assumed that the "distance" was merely due to our observations in three-dimensional space, but quantum entangled particles are "touching" at some higher level dimension. It's a guess.

    • It's probably more like a two ended whirlpool, like a really tiny wormhole. It just doesn't break apart until it's "measured".
  • by trout007 ( 975317 ) on Wednesday October 21, 2015 @04:47PM (#50776733)

    I thought all this means is that you can entangle two particles when they are close. Basically this means all you know is one is + and one is -. Then if you separate them and measure one you know what the other one is. That doesn't seem so spooky.

    • by ceoyoyo ( 59147 )

      You've essentially described a hidden variable theory (the particle is + or -, you just can't see it). This guy named Bell proved that if that's the way the universe actually works then it implies some even spookier things. []

      • by LesFerg ( 452838 )

        How is that a hidden variable theory?
        Its much the same as taking two balls of silly putty and pressing them against opposite sides of a coin. In a dark room. Then taking one of them down the road to your mates place, where he can look at it and know what the one you left at home looks like. Whats hidden? Its only the imaginary "I don't know" probability wave which you "collapse" by looking at one of them. All the rest is just a big mind-fuck. And Einstein was more concerned with the stupid theories pe

    • by slew ( 2918 )

      I thought all this means is that you can entangle two particles when they are close. Basically this means all you know is one is + and one is -. Then if you separate them and measure one you know what the other one is. That doesn't seem so spooky.

      That's only the "non-QM" entanglement. The spooky part of the problem occurs when the particles are entangled in a superposition of states.

      The difficulty is that it's hard to describe a non-QM analogy of an object in superposition of states (e.g., cat-is-half-dead). The so called QM bomb tester [] thought experiment is perhaps one of the easier way to understand how QM superposition might be different that simply an emergent property of an unknown or hidden underlying probability distribution function. Give

  • Wave functions don't collapse. They just evolve with time. A state of superposition is equivalent to oscillating between states in a reversible way. Some interactions lead to state changes that are functionally irreversible because changing back to an earlier state becomes exceedingly impossible. For instance emitting a real photon.

    As for observers this is just an interaction like any other. The observing particle becomes entangled with and interacts irreversibly with the observed. There is nothing sp

Consider the postage stamp: its usefulness consists in the ability to stick to one thing till it gets there. -- Josh Billings