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Particle seen in two different places simultaneously

  1. Nov 25, 2006 #1
    We were watching a video last year called 'What the bleep do we know?' and they said that there had been an experiment where a particle had been seen simultaneously in two separate places. Is that possible and if so, how?
     
  2. jcsd
  3. Nov 25, 2006 #2
    No, that is wrong. WRONG, WRONG, WRONG, WRONG.

    And btw, that movie is a load of crap.
     
  4. Nov 25, 2006 #3

    vanesch

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    According to how you see QM, you can conceive that the particle *is* in two separate places at once. However, you will never be able to *see* it in two different places at once.
     
  5. Nov 25, 2006 #4
    vanesch:"According to how you see QM, you can conceive that the particle *is* in two separate places at once. However, you will never be able to *see* it in two different places at once."

    Mathematically wave function is single valued function of its arguments.
     
  6. Nov 25, 2006 #5

    selfAdjoint

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    And mathematically, the wave function's target space is not spacetime. So this is irrelevant.
     
  7. Nov 25, 2006 #6
  8. Nov 25, 2006 #7

    vanesch

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  9. Nov 25, 2006 #8
    New Scientist is the Weekly World News of the science community. Even if the article is an actual science story, they probably word it completely incorrectly.
     
  10. Nov 26, 2006 #9
    Thanks for the responces. I enjoyed the movie but it is hard on a film like that to discern what is genuine science from what is psuedo science, especiallly when many (but not all) of the presenters appear to be genuine respectable physicists
     
  11. Nov 27, 2006 #10

    DrChinese

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    I saw the movie too. Yes, that is why that movie is considered to be "bad"... it mixes fact and fiction and does have a few respected folks in it as well.

    Example of pure BS in the movie: the idea that a person can arrange the pattern of molecules in a container of water with their mind. 'Nuff said.
     
  12. Nov 27, 2006 #11

    HallsofIvy

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  13. Nov 27, 2006 #12
    Maybe we will not "see a particle being in two places at the same time", but enough experiments have been carried out to infer that, in between 2 looks, a particle is certainly in "different places", "different states", "in a superposition of places or states", or whatever you want to call it.
    The quantum zeno effect ("the pot that never boils") is a good example.

    However in principle it would seem that we should never be able to actually see a particle in 2 places at the same time, since by definition in QM, the very act of "seeing" (or our interacting with the particle) is what destroys its simultaneity.

    Probably these experiments refer still to "infering" (maybe in a much more evident or doubtless way that we have done so far, but still infering anyway), rather than actually "seing".
     
  14. Nov 27, 2006 #13
    I don't remember exactly, in the movie they talked about bose-einstein condensate.

    Where in a supercooled rubidium gas, you have one atom appearing in 5000 places at the same time.

    Could be wrong, haven't seen it in long time.
     
  15. Nov 27, 2006 #14
    In a bec, all particles are in the same state (well, all the condensate particles), and as such the states are indistinguishable. However they never measure the position, only the momentum, which since it is the lowest momentum state (zero momentum), the position is highly delocalised. One never measures properties of particles though (i.e. individual particles), only states.
     
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