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Quantum Entanglement for the layman?

  1. Nov 7, 2013 #1
    Quantum Entanglement... for the layman? !!

    This may be a tall order, but can anyone explain the basics of quantum entanglement (theory?) in words that a relative layman might have a chance of understanding.

    The reason I ask is that although I have a only very basic knowledge of quantum physics, particle physics and relativity, most of what I do understand I can't explain in layman's terms (yes, I know, "if you can't explain it so that the man in the street understands it, then you don't understand it properly either")- and I'm in the middle of editing a sci-fi novel involving (among other things) a development of quantum entanglement into a practical application that also involves a temporal displacement (sort of)... far in the future, obviously...

    Anyone like to have a go at putting quantum entanglement in words of not too much more than one syllable? So at least I might end up with a snowflake's chance in Hell (don't start the endothermic/exothermic argument, please) of not getting my author's book published with glaring mistakes that will have serious physicists rolling on the floor laughing. Unknowns are OK for sci-fi, of course, but the "impossible" and the "against the laws of physics" both need additional variables...

    Thanks.
     
  2. jcsd
  3. Nov 7, 2013 #2

    UltrafastPED

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  4. Nov 7, 2013 #3
    Thanks. Perfect for what I needed. And I understood it, at least to the extent I understood what happens, not why it happens! But there's enough fact there for my author's writing to be not completely unbelievable for the distant future... maybe!

    The only problem is... now I want to know more! Not because I need to know, but this is fascinating stuff.

    I guess it's all on the Net somewhere; the difficulty is always the separating of the too simplistic Web stuff from the too technical, and finding a happy medium that actually makes sense,

    Any other links would be appreciated.
     
  5. Nov 7, 2013 #4

    UltrafastPED

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    Hey ... I'm a professional researcher, so finding the right stuff is right up my alley:

    This site should keep you busy for a while: http://qubit.physics.ox.ac.uk/
     
  6. Nov 7, 2013 #5

    Duplex

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    I had a good laugh at that romantic "Quantum Entanglement Tango" in the second link in your first post. Alice and Bob in a tango? :smile:

    I've already made a loop of the song to play when I got stuck in a measurement problem in the lab. Sort of right stuff for me.
     
    Last edited: Nov 7, 2013
  7. Nov 7, 2013 #6

    ZapperZ

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    Try this post I made quite a while back.

    https://www.physicsforums.com/showpost.php?p=3262928&postcount=5

    Moral of the story here is that you can't really understand entanglement without understanding the issue of quantum superposition. And you can't really appreciate the "brouhaha" surrounding what EPR brought up without understanding the classical analog of the same situation.

    Zz.
     
  8. Nov 7, 2013 #7

    Duplex

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    Before someone points it out, the text of the quantum entanglement tango is obviously not correct, it contains several errors. However, I like the idea of ​​music + physics. Rhythms facilitates learning.

    I would consider the possibility of an entire musical with Nobel Prize theme with scientifically accurate, but lighthearted lyrics where even children can become interested in science.
     
  9. Nov 8, 2013 #8
    Lay man here too. But got a question on this teleportation jazz. Is it not merely a copy?
     
  10. Nov 8, 2013 #9
    Is that the locality jazz? You know with that Newton quote about absurdity and all that.
     
  11. Nov 8, 2013 #10

    atyy

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  12. Nov 8, 2013 #11

    BruceW

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    when the copy is identical to the original, and the original must get destroyed, I'd say 'teleportation' is a pretty good way to describe it. But yeah, maybe it is not exactly the same as what most people think of as 'teleportation'.
     
  13. Nov 8, 2013 #12
  14. Nov 8, 2013 #13

    ZapperZ

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    Don't confuse the Star Trek "teleportation" with quantum teleportation. There's no "copy". No object is being created remotely.

    No, this is not strictly locality. The superposition principle in QM has more to do with the incompatibility of QM with the concept of classical realism.

    https://www.physicsforums.com/showpost.php?p=1307660&postcount=40

    Again, look at the example I gave with the classical scenario, and see why the QM scenario is different.

    Zz.
     
  15. Nov 8, 2013 #14
    I never quite got the reason why the Bells Inequalities ruled out hidden variables. Not least because if there were such things they would be encoded in the wave-function amplitudes rather than the square of them. Why would you try to apply set theory to quantum probabilities which are probabilities of interactions and detections rather than something inherent in the particle?
     
  16. Nov 8, 2013 #15

    Nugatory

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    That's because it doesn't.
    It rules out local realistic hidden variables.
    (Strictly speaking it also rules out local realistic non-hidden variables as well, but that's irrelevant because if there were non-hidden variables we'd see them, and we don't so they're already ruled out).
     
  17. Nov 8, 2013 #16
    Thanks for making this distinction, but would the equality hold if you applied it to the amplitudes rather than the squares of them? With the 60 degree spin type type experiment it looks like it would, but I don't know if that would apply generally or not!
     
  18. Nov 8, 2013 #17

    Nugatory

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    I'm not sure why that should matter?
     
  19. Nov 8, 2013 #18
    Because if it holds for the amplitudes and they are interpreted as holding all the information pertaining to the particle there would be no conflict between set theory and QM. It doesn't hold for the squares of the amplitiudes or probabilities which in my understanding are effectively joint probabilities of the particle and detector being in the same place or aligned.
     
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