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Can future events affect the past?

  1. Jun 24, 2015 #1
    Last edited: Jun 24, 2015
  2. jcsd
  3. Jun 24, 2015 #2

    phinds

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    This forum requires specific citations in order to discuss an experiment.
     
  4. Jun 24, 2015 #3
    Sorry,just posted a link.
     
  5. Jun 24, 2015 #4

    phinds

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    I'm out of my depth trying to explain that one but it sounds very interesting. That link is not included in the list of specifically acceptable sources for this forum and I have no idea if it's ok, but the experiment seems legit so I think it should be. We have many members who will be able to shed more light on it, I'm sure.
     
  6. Jun 24, 2015 #5
    So the team sent a particle back in time or prove retrocausality?
     
  7. Jun 24, 2015 #6

    phinds

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    No, that is not what it says. Did you read the link?
     
  8. Jun 24, 2015 #7

    e.bar.goum

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    Last edited by a moderator: May 7, 2017
  9. Jun 24, 2015 #8
    Its says they affected the past from the future.im a bit confused.or am I misreading the article.
     
    Last edited: Jun 24, 2015
  10. Jun 24, 2015 #9
    The past you refer to was undetermined (the system was in a superposition of acting as a wave and a particle at the same time). So a decision in the future caused the system to behave as a particle or wave.

    I think however that explanation is very vague and up to interpretation. May I suggest 'Quantum Enigma' page 153:
    to clarify what I mean.
     
  11. Jun 24, 2015 #10
    So an event in the future did not affect an event in the present or past in reality?
     
  12. Jun 24, 2015 #11

    Drakkith

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    I don't think there's a 100% agreed upon answer to your question.
     
  13. Jun 24, 2015 #12
    Im a bit confused,what did the experiment prove?
     
  14. Jun 24, 2015 #13

    ShayanJ

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    How much QM do you know?
    I don't think you can get an answer, if you don't know enough about QM.(Which it seems to me is the case.)
     
  15. Jun 24, 2015 #14
    I Don't know really anything about QM im just curious.
     
  16. Jun 24, 2015 #15

    ShayanJ

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    I want to bring into your attention what StevieTNZ quoted a few posts ago:
    This is what happened. This is what the experiment immediately implies and we shouldn't think further than this. This is a typical situation in QM.

    Let me see if I can give you an analogy. Imagine I tell you that I want to take you somewhere, an island or a desert. For going to the island, we should use a boat. For the desert, we should use a car.
    I don't tell you which one we're going to do. Then I close your eyes and do all things necessary to make sure you can't know we're on a boat or in a car. But after reaching there, I open your eyes and you see you're in an island and you immediately find out you were on a boat all along the way. This isn't strange because your history was there, you just didn't know it.
    But this experiment is different. There was no specific history to the atom, but after the measurement, the relevant history is created. Its not a popular view to interpret it as "future affecting past". In fact I myself don't like "future affecting the past", its just over-thinking it.
     
  17. Jun 24, 2015 #16
    So retrocausality or time travel to the past is still impossible?
     
  18. Jun 24, 2015 #17

    ShayanJ

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    I can't speak that generally. But about this experiment, yes, it doesn't mean you can affect the past or travel back in time.
     
  19. Jun 24, 2015 #18

    Drakkith

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    This sounds similar to the idea of using quantum entanglement for FTL communication. I assume the problems inherent in that area are also applicable here.
     
  20. Jun 24, 2015 #19

    ShayanJ

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    Actually I was thinking the same thing!
     
  21. Jun 24, 2015 #20

    bhobba

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    Its a subtle issue and we have interpretations where it does:
    https://en.wikipedia.org/wiki/Transactional_interpretation

    Generally you can't send information into the past - that would violate causality.

    But there are all sorts of notions about with parallel universes and what not that if true allow such problems to be circumvented.

    It also needs to be said that experiment is just a variation of the delayed choice experiment and what's going on is no mystery:
    http://quantum.phys.cmu.edu/CQT/chaps/cqt20.pdf

    Thanks
    Bill
     
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