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November 4, 2007

Duality is nature’s way of saying it is inherently confused.

srikanth @ 10:11 am, GMT +0000 ( 1194171063 ) Play

This question was sent in by Arjun. Thanks a lot, saar

(And for all the rest of you, we demand that you to get off your lazy backsides and send in guest questions to , so that we can just post those and get back onto our lazy backsides)

This image below shows a strange phenomenon. It is an image of the shadow of an object, but there seem to be bands of light in the shadow!


What is this, and why is it significant?

And just in case you’re under the smart-alecky impression that this phenomenon is not significant, here’s a clue. A clue to get the clue: why is their logo so weird?

Cracked (in whole or in part) by: 2ndratequizzer , sidsen , iamniks , prasanth and VikraM.

Answer:That is the picture of what is called Arago’s Spot. This phenomenon “proved” the wave-particle duality of light. In essence, it was predicted that if light was only particle, there cannot be any brightness in the circular objects shadow, and if it had a dual nature, there would be brightness in the shadow of the object due to diffraction. Further, Poisson hypothesized that the exact center would have a bright spot since all the waves would interfere constructively.

The New World’s mission (linked in the clue) plans to push a telescope into space to look for other planets with life by blocking out their sun with a giant occluding disk. But, if the disk were to be circular, the arago’s spot in the center would destroy the darkness. Hence the occluding disk has to be a “starshade” with that peculiar lotus-like pattern to ensure that the spot doesn’t obstruct the telescope’s view of the planets its looking at.

All insults to be directed at Arjun :-)

16 Responses to “Duality is nature’s way of saying it is inherently confused.”

  1. MGS

    newton's rings?

  2. Thats the airy pattern caused by diffraction. The shadow is of a small circular object.

    it is significant because it is diffraction that limits the resolving power of telescopes etc. among many many many other things !

  3. sidsen

    arago's spot

  4. shivathilak

    the bands of light are because of constructive interference of the light diffracted around the object whose shadow we are seeing. this is significant cause it is proof of the wave nature of light… why u gave the new world clue… i have no clue… maybe im missing something here…

  5. iamniks

     "INTERFERENCE"…it supports wave nature of light.. it has many advantages…one of them ,as the logo shows which i think is  specially designed occulting disc which is used to view planets outside our solar system by blocking the light from other stars.

  6. shreyas

    are these newton's rings??caused due to constructive and destructive interference.

  7. alephnull

    It looks like the interference rings we have all used in Physics lab to measure the wavelength of monochromatic light.

    The applications are numerous, including blocking out the light of a star.

  8. prasanth

    Arago Spot

    1)historical part it played in the Wave theory of light
    2)The New worlds mission, a proposal to directly image extrasolar planets, relies on Arago's spot to isolate the reflected light of a planet from the sun it orbits.

  9. vijayaraghavan


  10. sidsen

    o sorry just noticed you had asked for significance too. well amongst other things this is conclusive evidence of the wave theory of light.

  11. VikraM

    This is the diffraction pattern of a single photon….. (Airy discs?) It upholds the wave-particle duality, as a single photon cannot pass through both of the 2 slits simultaneously, thereby necessitating wave nature….

    the logo is a starshade, which enables destructive interference to "block" a star's light, and lets us see planets etc…

  12. Tathagata Chatterjee

    Atmospheric airy pattern ( with an airy disc in the middle, named by George Airy), caused by diffraction of light.
    Tathagata Chatterjee

  13. piezocake

    Evidence of anti-matter, seems like.

  14. Shakeel

    Diffraction,bends light around curves and causes image to distort.

  15. Poornima

    Newton's rings showing inteference phenomenon

  16. BiGFooT

    I guess ur talking about Diffraction here, the bright bands in the shadow are due to the constructive interference of the light waves that have undergone diffraction around the edges of the  object.
    The New Worlds logo (interesting project,that one) is a "Starshade" , a sunflower-shaped "occulter" that aims to make the light waves diffracting around its petal-shaped edges go out-of-phase & cancel each other.
    Net Effect: They get Kodak Moments of planetary proportions

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