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B Why adding more polarized filters results in more light passing?

  1. May 17, 2018 at 2:41 PM #1
    I was watching this video ...



    And basically the video show how adding in middle angle polarized filters it makes more light to pass.

    Then comments about quantics and blah blah blah.



    Why cientifics thinks lot weird and how was discard the following line of a more natural thinking:

    My thinking:

    "Why?, why to scratch the head thinking weird anti-natural like this, "erroneous" thinking. Why they didn't simply think that passing light by a filter it can shift the polarization angle of the light itself, so, inserting a middle filter it shift a bit the light polarization angle, which result in more light be able to pass the final filter. But If you set a 90º filter to the light that comes perfectly perpendicular, the light just crashes and can't pass. But if inserting more filters in middle angles, it is like guiding a car which driver are sleep, if the car found a dead end street or 90º instant turn, it will crash, but if the car gets a curve little a little the edge of the road will make the car to turn totally and pass it safe, when more in middle steps more safe.


    Why not? How this thinking was discarded? or not taken in account at all?"
     
  2. jcsd
  3. May 17, 2018 at 3:18 PM #2

    Nugatory

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    What you are describing is a kinda-sorta-OK math-free description of how quantum mechanics describes this phenomenon. The problem is that before the discovery of quantum mechanics we had no theory that explained how light and polarizing filters could behave that way - everything that we knew about electromagnetic radiation (which was a lot) said that adding a filter had to further reduce the amount of light passing through.
     
  4. May 17, 2018 at 3:38 PM #3

    sophiecentaur

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    If a linear polariser passes the component of the E field that's aligned with the x axis then following it with a polariser that's aligned with the y axis will pass nothing.
    However, if you follow the first polariser with a polariser aligned at 45°, it will pass a wave with 1/√2 E field strength. Following these two with a polariser on the y axis will pass 1/√2 of what comes out of the second polariser so the overall effect is that 1/2 is passed.
    This works every day with radio waves and it spoils the polarisation isolation between a HP transmitter and a VP receiver when a diagonal wire or grid intervenes.
    That explanation of the phenomenon is a wave based one and it works. If it turns out to be a surprise that the photon based explanation is extra complicated then so be it but that video makes a very over simplified statement at the beginning when it claims that a polariser "selects photons" with a particular polarisation (and implies that it rejects all others). If it were as simple as that would let through a vanishingly small number of photons - which is clearly not true. It is never surprising when an over simplified approach to QM produces dodgy results.
     
  5. May 17, 2018 at 4:09 PM #4

    phinds

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    @flyguille, I would extend Sophiecentaur's comment to say that it is surprising (to me anyway) when pop-sci presentations actually get something RIGHT. I always assume they have it wrong in some way because over many years of watching a LOT of pro-sci TV shows and reading pop-sci books, that has been my experience. This applies to all areas of science but is particularly something to watch out for with Quantum Mechanics and also with Cosmology.
     
  6. May 17, 2018 at 4:14 PM #5

    FactChecker

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    It was addressed. The part of the video about filtering entangled photons separated by a distance was to address that. Only one is filtered, yet the effects show up in the other. They are separated too far for any filter effect to travel at the speed of light.
     
  7. May 17, 2018 at 4:33 PM #6
    why distance matters?, I agree photons is a mistery which they didn't decides what exactly it is so theorems are it is a particle and a wave at the same time. (that is what I understand)

    So, we can imagine it like a flock of birds acting as one , but individually they are particles, but in conjuntion form waves. That is what I have in mind.

    So, I wonder how with so many doubts in the middle, they discard more normal natural thinking,

    And then prove it!.
     
  8. May 17, 2018 at 4:43 PM #7

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    You say it is more natural, but what mechanism do you propose that could transmit the filter effect faster than the speed of light to the other location? In trying to answer that, the "natural" explanation becomes a can of worms.
     
  9. May 17, 2018 at 6:22 PM #8

    sophiecentaur

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    Any analogy that has been grabbed randomly out of the air is likely to lead you to very wrong conclusions. You need to be far more rigorous.
     
  10. May 18, 2018 at 9:20 AM #9
    faster than light? I never said something about "Faster than light", what I mean, the photons can be altered by each filter shifting its polarization, so the effect travels with the photon which was altered.

    But, anyway, I will study more about what scientifics know "what photons really is", but I fear It is just a lot of theories, nothing proven, because how to see that? only can be observed the effects of the object in study, and measurement machines are done of atoms, and also the exact sub atomic model is in discussion, so, how to have realiable data out of two "in progress" models.

    But I will study, and remove a bit of my own ignorance.
     
  11. May 18, 2018 at 9:44 AM #10

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    No. The video does. The distance and short time between the filtering of one light beam and the effects on the other light beam are what make it such a challenging test of what you are calling the "natural" explanation.
     
  12. May 18, 2018 at 10:10 AM #11
    "Other"?, no, the same beam, I don't like that video, I thinks the video is wrong, so that is the reason why I am discussing it and wondered why too much trouble was made.
     
  13. May 18, 2018 at 3:13 PM #12

    FactChecker

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    It doesn't matter how many simple experiments you can explain with a simple, "natural", theory. If someone can come up with another experiment, no matter how complicated, that your theory fails at, then your theory is no good. So you should stop thinking about your example and pay close attention to what the video is saying.

    Instead of saying vaguely that the video is too complicated and wrong, you should watch it carefully and say exactly which step is wrong. The fact that very expert people believe it should give you pause.
     
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