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At 05:50 PM 8/31/00 -0400, Hugh Logan wrote:
... Max Born's ... assertion that the observed scattering of light by the
atmosphere was a fluctuation phenomena. He claims that if the density of air
were uniform throughout that the waves scattered by individual molecules
would annul each other and that the sky would appear black.
I hope we can all agree on that! It seems super-obvious based on everything
we know about the optics of homogenous materials.
If I interpret John's most recent message correctly, I get the impression
that scattering is not completely annulled by a homogeneous atmosphere, the
intensity going as 1/lambda^2
Eeek? That's not right. I didn't say that.
For air molecules, if you do all the geometry and all the counting, ITo summarize:
believe that you will find that in the absence of fluctuations, the
scattered voltage goes like 1/lambda (not 1/lambda^2) and the scattered
intensity goes like 1/lambda^2 (not 1/lambda^4).
When we consider fluctuations, the smaller cells fluctuate more, so the
final spectrum is somewhat hotter than 1/lambda^2 (but less hot than
1/lambda^4).
is as follows:
-- Yes, coherence _depends_ on wavelength.
-- No, you can't blithely set the coherence length _equal_ to the wavelength.
At 05:50 PM 8/31/00 -0400, Hugh Logan wrote:
Stone refers the reader to ... cautioning the reader that these
are very difficult reading.
Hmmmm. Born. Smoluchowski. Einstein. Anderson. I'm not sure this topic
should be considered low-hanging fruit. :-)