WHY does light bend around obstacles?

Discussion in 'General Science & Technology' started by lippylion, Dec 3, 2009.

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  1. Trippy ALEA IACTA EST Staff Member

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    Here's an example from Hubble:

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    The two bright objects that look like squares with blobs and other stuff around them are foreground galaxies. The light from these galaxies has been diffracted by the 'tube' of the Hubble Space Telescope as the light enters it.

    This is something that happens to all telescopes (IIRC google 'Diffraction limited seeing').

    Nothing to do with gravity.
    Nothing to do with the presence of some medium.

    Pure wave mechanics.

    Here, I believe, is a computer generated model of the diffraction that occurs withing the Hubble Space Telescope, whem observing a bright source:

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    Finally, here is Sirius A showing all of the same features (albeit some of them are over exposed).

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    Last edited: Jan 22, 2012
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  3. QuantumEntangled Registered Member

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    (Very first post)
    I will read every post eventually. I got to about post 10 before wanting to put this out there.

    My wife and I had observed the bending of light around objects and the first thing that came to mind is how a mass warps space around it \9no matter how much mass is involved). I always figured it was light following the direct path from the source to the eye (ie. the warped space around the object, like a finger).

    Now, back to the other posts.
     
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  5. Aqueous Id flat Earth skeptic Valued Senior Member

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    I think if you calculate that warpage of space by your mass, you will find that your proximity to the warpage reduces the angle to an imperceptible amount.

    To get a handle on this, you can consider the geometry of observing a star pass by the sun in eclipse, which entails a huge mass at a huge distance. This was Eddington's confirmation of Einstein's prediction that starlight bends around the sun, and would be visible in an eclipse:

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    The inquiry into diffraction, as explained by Trippy, is a consequence of wave mechanics. So even a water tank will demonstrate the interference resulting from a uniform wave passing through two slits:

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    If we were to measure gravitational bending in parsecs, and the diffraction bending in Angstroms, the difference in scale is 26 orders of magnitude. So the difference in scale is huge.
     
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  7. QuantumEntangled Registered Member

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    I'm definitely not arguing the wave mechanics explanation, which makes far more sense than the thought I came up with. It was an excuse to get my first post up

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    . I am actually delighted to have a better explanation to what we experienced. ATM I'm trying to get my brain to translate the effect in the 2nd pic to what we actually see.
     
  8. river

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    in space its about the atmosphere that the object gives off
     
  9. river

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    so such as the sun gives off an atmosphere , corona

    which bends the light from objects behind the sun so that then you can see what object is behind the sun ( otherwise called gravitional lensing )
     
  10. origin Trump is the best argument against a democracy. Valued Senior Member

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    Gravitational lensing has absolutely nothing to do with the atmosphere.
     
  11. Aqueous Id flat Earth skeptic Valued Senior Member

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    Here is an idea of the projected image, demonstrating the effect of adding two sinusoidal waves that vary in phase over the length of the screen:

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  12. brucep Valued Senior Member

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    QED, quantum electrodynamics. 'QED The Strange Theory of Light and Matter'. A wonderful book Feynman wrote for everybody.

    http://en.wikipedia.org/wiki/QED:_The_Strange_Theory_of_Light_and_Matter

    Prof Edwin Taylor's workbook, plus software, for studying Feynman's sum over paths method [QED]. The text would be Feynman's QED.

    http://www.eftaylor.com/quantum.html

    It's fun, informative, and free for download. It answers all your questions for the quantum domain of applicability.
     
  13. QuantumEntangled Registered Member

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    Okay, this may be off topic, but here is the effect I'm talking about:

    Hold any two objects with rounded edges very close together, but not touching (I use the tips of my fingers). When they get close enough both edges appear to be pulled toward each other and meet as one. In reality the two edges aren't actually being pulled toward each other and the effect is purely visual.
     
  14. wlminex Banned Banned

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    so . . .maybe . . . the sun's corona acts as a 'refracting' medium to light passing (from behind the sun) thru the corona??
     
  15. wlminex Banned Banned

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    Query: So . . . are the 'patterns' ('projected 'bands') of the same wavelength and frequency as the original, impinging source waves . . .??
     
  16. QuantumEntangled Registered Member

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    I doubt it would be. Each wave has a certain amount of energy. When the waves come in contact with the slits the slits take some of that energy away from the waves. So, I would say no, the resulting waves would be diminished.
     
  17. Aqueous Id flat Earth skeptic Valued Senior Member

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    Wavelength is just the reciprocal of frequency, so consider them one thing. There is some other geometry to consider. To get it straight from the horse's mouth, I went back to the era of the Louisiana Purchase to extract this definition straight from the horse's mouth, none other than the inimitable Thomas Young:

    So the distance between the slits changes the "beat frequency" and the projection of the spherical composite onto the planar surface introduces a nonlinearity. Here's another perspective, but don't stare at it too long if you have to operate a motor vehicle or any machinery:

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  18. river

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    yes
     
  19. wlminex Banned Banned

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    . . . so . . . taking this 'coronal refraction' phenomenon a bit further (beyond the current gravitational lensing interpretation) . . . perhaps 'simple' refraction due to density gradients (of coronas, or what not) around the sun, stars, galaxies, etc. is a simpler explanation than gravitational lensing?? . . . just wait 'till the SM and AE enthusiasts read this one!!
     
  20. river

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    the simplicity or the possibility of greater complexity matters not

    what matters is what is really happening
     
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