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Life changing "Two Slit Experiment" .help please

  1. Dec 26, 2014 #1
    A couple of days ago i stumble across the two slit vid on youtube and entanglement.

    before this day i thought quantum physics was just some kind time travel mumbo jumbo ..... Im sure you get my level of noobieness from this :)

    ok questions if you would be so kind :)
    ( don't forget the noobieness ).

    1: does the proton wave collapse through subconscious observation or mechanic photon detectors?

    2: does the quantum entanglement of the photon being in 2 places at the same time mean that the photon can be in all places .... All the time ?

    3:does the two slit experiment mean we know light is a wave but when observed it isn't ? And is this called duality ( two realitys ) ?


    thank you :)



    Ps........ I struggled answering the e=mc² question when i signed up for this site lol........that's how noobie i am :)
     
  2. jcsd
  3. Dec 26, 2014 #2

    DrChinese

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    Welcome to PhysicsForums, mainliner!

    1. I know you mean photon rather than proton. Wave collapse is independent of consciousness as far as anyone knows. It occurs upon irreversible measurement or observation. So in the case you describe, when the photon detector "clicks".

    2. Quantum particles are not in 2 places at the same time. But they have a chance of being in 2 different places. This is quite different.

    3. The 2 slit experiment demonstrates several important quantum issues, including what I said in 2 above. No only can a particle have a chance of being in different places, it has a chance of taking different paths. The effect of these different paths causes interference between them, and that can be seen in the 2 slit experiment.

    I don't think the wave vs particle analogy is all that great. But in the extreme cases, you could say that a photon sometimes acts as a wave, sometimes as a particle.

    And it doesn't have anything to do with it being observed so much as its path being known.
     
  4. Dec 26, 2014 #3
    Hello there

    this is all new to me , it just interests me :)

    now i understand the observation bit , how does the other wave collapse when they do that entanglement test 100 miles apart Through just electronic detectors ?


    Ps.... Photon proton bad spelling lol
     
  5. Dec 26, 2014 #4

    DrChinese

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    The principle is a function of the formalism (which is mathematical in nature) of Quantum Mechanics. But no one exactly knows the underlying mechanism. So what I can say comes down to this: a) distance does not matter; b) the order of the measurements (i.e. which one is first) does not matter. And when I say "does not matter", I mean there is no evidence that it does based on the statistical predictions of QM.
     
  6. Dec 26, 2014 #5
    So in reality the photons have two realitys .....one quantum and one classical laws of physics?
     
  7. Dec 26, 2014 #6
    i looked your home page :)

    the cartoons are an easy way for explanations lol
    that's my level of QM :)
     
  8. Dec 26, 2014 #7

    DrChinese

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    There is a lot of debate about that. A lot depends on definitions. The word "reality" can a great many things in quantum physics. Most physicists think there is only a quantum world, but that it appears to behave classically in many situations.
     
  9. Dec 26, 2014 #8

    DrChinese

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    Glad they were of use! :-)
     
  10. Dec 26, 2014 #9
    can we only observe one at a time? ..... That's if there is two :)
     
  11. Dec 26, 2014 #10

    phinds

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    It's not a matter of their being one or two, there are both simultaneously but what you observe depends on what you measure. The two-slit experiment at the macro level examines, and shows evidence of, both particle behavior and wave behavior. At the micro level it shows evidence of them one at at time (waves through the slit, particles on hitting the screen).
     
  12. Dec 26, 2014 #11
    What exactly is it all about ?..... Quantum tunnling, entanglement, all this light phenomena etc etc and electromagnetic energy......why are the classic laws of physics all different and ....erm...well ..... Spooky.

    being some one who believes in god and lucid dreams ....... This all seems to make sense in my non classically mind :).......why is this?
     
  13. Dec 26, 2014 #12

    phinds

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    It is about reality. Physics is the process of discovering and describing the characteristics of reality.
     
  14. Dec 26, 2014 #13
    is the characteristics of reality not how i know it , or the same but also different?
    ....after watching the two slit experiment
     
  15. Dec 26, 2014 #14

    phinds

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    I have no idea what you mean by "how I know it" since I am not you. How you "know" it is subjective and not likely to be helpful.

    Things in cosmology (the very large) and Quantum Mechanics (the very small) are WAY outside of human's evolutionary experience and not anything that there was any survival value in knowing (because it was all unknowable for all but the tiniest portion of human evolution) so "common sense" and "intuition" are often not only not helpful in those arenas, they are downright counter-productive.
     
  16. Dec 26, 2014 #15
    "how i know it" ..... In a schoolboy physics class like for example , gravity and solids etc.

    completely the opposite of "QUANTUM ENTANGLEMENT" thingy .

    its all different....why?
     
  17. Dec 26, 2014 #16
    And keep your post simple :) trust my first post ....... IM a noooooobie beyond belief :)

    thank u
     
  18. Dec 26, 2014 #17

    bhobba

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  19. Dec 26, 2014 #18
    Last edited by a moderator: May 7, 2017
  20. Dec 26, 2014 #19
    I do constant reading and watching youtube videos on the internet :)
    i just thought id get my info from the horses mouth as we say in England .

    its just a puzzle to me im not quite sure what to make of it , the fact that i know about quantum entanglement is enough.

    so light is a particle and a wave ..... And that's the true reality of physics?....
     
  21. Dec 26, 2014 #20

    bhobba

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    It's neither, nor both - it quantum stuff - see our FAQ:
    https://www.physicsforums.com/threads/is-light-a-wave-or-a-particle.511178/

    It would be better to say its an excitation of a quantum field - but unless you know the technicalities of such a statement, while correct, its rather meaningless.

    Thanks
    Bill
     
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