Bummel

I wonder, is scattering mostly the result of light getting refracted multiple times in non-(perfectly)homogeneous materials? It seems to be a bit more complicated for Rayleigh and Mie scattering, but do these effects have any (significant) relevance for scattering effects in f.i. wax, textiles or opaque materials in general? (for atmospheric effects they clearly have, without any doubt)

And what about absorbtion? What kind of interaction between light and matters leads to wavelength dependend absorbtion? Also, does the light change its wavelength or is it more the way that photons with a certain wavelength are "sorted out"? (what now that I think of doesn't really make sense, where should they go? )

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Just watched this video about how the sun appears dimmer when viewed from a large distance: http://www.youtube.com/watch?v=cztocbHiiqQ

It was stated that this effect was due to decreasing intensity over distance. I took the following guess about why this happens:

"Intensity (power per solid angle) is decreasing following the inverse square law, that's right. But what ideal receptors measure is not intensity, but radiance, which is power per solid angle per area. Due to this, ideally a light source should appear with a certain brightness independend of the observation distance. I would guess that this rule breaks down for really large distances because there are too few protons left to ensure that the receptor continuously gets hit by those."

What do you think?