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Thread: Should gravitational lensing produce chromatic aberrations?

  1. #1 Should gravitational lensing produce chromatic aberrations? 
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    Title says it all.


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    Anti-Crank AlexG's Avatar
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    In optics, chromatic aberration (CA, also called achromatism or chromatic distortion) is a type of distortion in which there is a failure of a lens to focus all colors to the same convergence point.[1] It occurs because lenses have different refractive indices for different wavelengths of light (the dispersion of the lens). The refractive index decreases with increasing wavelength.[2]
    In the case of graitational lensing, there's no refractive indices. The light is following the geodesic, which is bent, but it's not passing from one medium to another, hence no refraction.

    I think.


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    Moderator Moderator Janus's Avatar
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    Quote Originally Posted by dan hunter View Post
    The paper makes no mention of chromatic aberration. Aberration can refer to one of many effects. The one dealt with in the article is monochromatic by nature.

    The difference is that with chromatic aberration, different wavelengths of light have different indices of refraction in any given medium. With monochromatic, all frequencies are effected equally.
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    Quote Originally Posted by Janus View Post
    Quote Originally Posted by dan hunter View Post
    The paper makes no mention of chromatic aberration. Aberration can refer to one of many effects. The one dealt with in the article is monochromatic by nature.

    The difference is that with chromatic aberration, different wavelengths of light have different indices of refraction in any given medium. With monochromatic, all frequencies are effected equally.
    No the paper does not mention chromatic abberation. It is talking about how the refractive index changes when the gravitational lense is moving. Alex thinks there is no refraction from the gravity but that is silly because then there would be no gravitaional lensing to observe.
    My original question was whether or not gravitational lensing should produce chromatic aberrations.
    I think maybe it should because as the strength of the gravity changes it should cause the frequency of the light passing through it to shift by different amounts.

    edit: Einstein shift?
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    Anti-Crank AlexG's Avatar
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    Alex thinks there is no refraction from the gravity but that is silly because then there would be no gravitaional lensing to observe.
    I didn't say there's no refraction, I said there's no change in the index of refraction because the medium doesn't change.Without a change in the index of refraction, all wavelengths are bent by the same amount, and so there's no chromatic aberation.
    Its the way nature is!
    If you dont like it, go somewhere else....
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