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michael_nielsen's profile
michael_nielsen
michael_nielsen
michael_nielsen
@michael_nielsen

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michael_nielsen

@michael_nielsen

Searching for the numinous. Co-purveyor of https://quantum.country/ 

San Francisco, CA
michaelnielsen.org
Joined July 2008

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    1. michael_nielsen‏ @michael_nielsen 9 Aug 2017
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      During a total solar eclipse, gradually changing snake-like "shadow bands" may be seen on the ground just before & after totality:pic.twitter.com/o34H8FAMbE

      1 reply 5 retweets 16 likes
    2. michael_nielsen‏ @michael_nielsen 9 Aug 2017
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      Replying to @michael_nielsen

      The origin of the bands is still somewhat controversial. The most accepted theory seems to be Codona's (1986): http://adsabs.harvard.edu/full/1986A%26A...164..415C …

      1 reply 0 retweets 2 likes
    3. michael_nielsen‏ @michael_nielsen 9 Aug 2017
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      Replying to @michael_nielsen

      The basic idea seems to be in two parts. (1) For a point light source, low-altitude turbulence will cause refraction, and so ...

      1 reply 0 retweets 0 likes
    4. michael_nielsen‏ @michael_nielsen 9 Aug 2017
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      Replying to @michael_nielsen

      differential illumination across different parts of the ground. (2) Integrating over a crescent shape we still get that differential illmn.

      1 reply 0 retweets 0 likes
    5. michael_nielsen‏ @michael_nielsen 9 Aug 2017
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      Replying to @michael_nielsen

      Wish I had a better understanding of (a) why the scale of the bands is centimeters; (b) why integration over a crescent preserves bands, but

      2 replies 0 retweets 1 like
      michael_nielsen‏ @michael_nielsen 9 Aug 2017
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      integration over full disk does not; and (c) what sets the scale for the variation in illumination.

      8:39 PM - 9 Aug 2017
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