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How accurate is this video? Double Slit experiment

  1. Apr 24, 2012 #1
    Today, my teacher showed us a video in class (AP physics B) as part of our quantum physics unit.



    I'm really skeptical about the video, and I wanted to seek the opinion of people who are actually knowledgable in this field. Is there anything wrong with the information provided (conceptually, historically, etc.)?

    Thanks!
     
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Apr 26, 2012 #2

    Fredrik

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    It's pretty accurate, but it has one big flaw. It describes particle detection as "just looking", which suggests that it's a passive process that doesn't disturb the particle, and just "finds out" where the particle already is. This is very misleading, for two reasons:

    1. Detection is an interaction between the particle and the detector that significantly changes the state of the particle. It's nothing like "just looking" in your apartment to find your pants.

    2. QM doesn't say that particles are always localized at some specific position. In fact, it suggests that they're not. So it's pretty naive to think that "position" is even an attribute of the particle before detection.

    By the way, the Dr Quantum video on the double-slit experiment was made for the movie "What the #$*! do we know!?". This is one of the worst pieces of pseudo-scientific new age garbage that you can find. This Dr Quantum video is the only part of it that isn't completely absurd. It describes the results of single-slit and double-slit experiments accurately enough, but is misleading in the explanation of what's actually happening.

    The frustrating truth is that we don't really know what's actually happening to the individual particles in the double-slit experiment. QM tells us how to predict results of experiments, but there are many ways to interpret QM as a description of something that's "actually happening", and we don't even know if any of them is essentially correct.

    I have no idea what "AP physics B" means. That just tells me that you're American. Not because I recognize it as American, but because experience tells me that only Americans assume that these things don't need to be explained.
     
    Last edited: Apr 26, 2012
  4. Apr 26, 2012 #3

    Demystifier

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    Fredrik, your explanation is OK, but the best part was:
    :rofl:
    Thank you for saying it! I always wanted to make a similar remark, but was afraid to. (By the way, I never asked you where are you from?)
     
  5. Apr 26, 2012 #4

    jtbell

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    It's not just us (which not to say that it's appropriate). I've seen many people refer to "A levels" and "GCSE" without further qualification. And then there are threads like this:

    MSC in IIT (JAM)

    :tongue:
     
  6. Apr 26, 2012 #5

    Fredrik

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    Glad I could provide some entertainment. :smile: I'm from Sweden.
     
  7. Apr 26, 2012 #6

    DrChinese

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    I forget... is Sweden closer to Holland or the Netherlands?




    (must be an American) :smile:
     
  8. Apr 26, 2012 #7

    Fredrik

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    Hah, I'm not falling for your trick question. The Netherlands is the fictional place where Tinker Bell and Peter Pan live.
     
  9. Apr 27, 2012 #8

    Demystifier

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    No, a true American would write:

    I 4 get ... is Sw closer 2 Hl or Nt?
     
  10. Apr 27, 2012 #9
    AP Physics B, for those wondering, is an Advanced Placement course, i.e. a nationally standardized high school course for advanced students designed to cover the material that would usually be covered in a college course, so that when they go to college they will be able to place out of those courses. Specifically, AP Physics B tries to mimic the non-calculus based one-semester introductory/survey course in physics that non-physics students would take in the beginning of college. This is to be distinguished from AP Physics C, which tries to mimic the calculus-based introductions to classical mechanics and classical electromagnetism that students majoring typically take in the beginning of college. And no, there is no AP Physics A.
     
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