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"Experimental nonlocal and surreal Bohmian trajectories"

  1. Feb 19, 2016 #1
    Thought people would be interested in this recently published paper:
    http://advances.sciencemag.org/content/2/2/e1501466
    It came up on my Facebook feed because I am friends with one of the authors.

    Picked up by New Scientist: https://www.newscientist.com/articl...rdness-may-hide-an-orderly-reality-after-all/

    I'm a bit suspicious, due to the use of weak measurements. Thoughts on this experiment? (The full text is available for free, from the link above.)
     
  2. jcsd
  3. Feb 20, 2016 #2

    bhobba

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    The wording of your quote tells it all. Its based on a misunderstanding of the QM formalism confusing it with interpretations. It's not exactly an uncommon thing - but its wrong. I even did that before posting a lot here and I had read quite a few books at graduate level on QM - its an easy trap to fall into. The university up the road from where I live, Griffith University, unfortunately occasionally produce papers like that,and I know they have some very good quantum people. It should have been picked up by the referees. It also needs to be said there have been quite a few papers like that discussed here.

    Thanks
    Bill
     
    Last edited: Feb 20, 2016
  4. Feb 20, 2016 #3

    Demystifier

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    The experiment confirms that QM is correct, it does not resolve the interpretation issues of QM, yet it demonstrates that Bohmian trajectories are not less measurable than the wave function.
     
  5. Feb 20, 2016 #4

    stevendaryl

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    Wait a minute...you're saying that you know that the paper is incorrect based on the quote in the original post?
     
  6. Feb 20, 2016 #5

    bhobba

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    No - I am saying the author was careless in his wording and the claim as written cant be true because its purely interpretational. Likely ignoring that it has some element of 'truth'. To be specific - 'However, when two particles are entangled, the trajectories of the first particle can depend nonlocally on the position of the second particle.' is not true in the QM formalism - in the formalism there is no properties apart from observation.

    We have had a number of papers discussed here that are like that. What they are trying to say is often interesting, but what they read into it leaves a bit to be desired.

    Thanks
    Bill
     
  7. Feb 20, 2016 #6

    stevendaryl

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    I think he's just saying that there is some notion of "trajectory" that can be associated with a quantum particle--and there certainly can be: Bohmian mechanics does (I don't understand the relationship between Bohmian trajectories and weak measurements). Of course, the claim that a particle actually moves on such a trajectory is interpretational, but you can talk about the trajectories as mathematical objects without assuming an interpretation.
     
    Last edited: Feb 21, 2016
  8. Feb 20, 2016 #7
    From the Physorg.com article on the paper: http://phys.org/news/2016-02-quantum-surrealism.html

     
  9. Feb 28, 2016 #8
    I was looking through this experiment but I don't understand what issue has been resolved. Obviously non-locality is a necessary feature of any realistic interpretation of QM, like BM. So, I don't understand what 25-year old debate has been resolved?
    Surreal behaviour spotted in photon experiment
    http://physicsworld.com/cws/article/news/2016/feb/26/surreal-behaviour-spotted-in-photon-experiment

    Experimental nonlocal and surreal Bohmian trajectories

    http://advances.sciencemag.org/content/2/2/e1501466.full-text.pdf+html
     
  10. Feb 29, 2016 #9

    Demystifier

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    Don't read what journalists say about science. Their job is to make science more interesting to lay people than it really is. Read what scientists say, in their original scientific papers.
     
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