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Sunset Geometry (2016)

153 pointsby johndcookover 3 years ago

6 comments

darthoctopusover 3 years ago
&gt; I have never seen someone try to use Pauli matrices to solve a trigonometry problem, but it can certainly be done.<p>The Pauli matrices in this context are isomorphic to quaternions, which certainly have been used to solve geometric problems in 3 dimensions (although not necessarily by physicists), as has been discussed many many times here on HN. The property of describing spin-1&#x2F;2 particles (i.e. generating SU(2)) is precisely the same property that makes the quaternions amenable for use in reasoning about 3D rotations!
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julienchastangover 3 years ago
Somewhat related: How many of you have ever seen the green flash [0] ? I never have unfortunately even though I&#x27;ve looked for it many times.<p>[0] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Green_flash" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Green_flash</a>
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wyldfireover 3 years ago
&gt; This is 20% larger than the true value, 3960 mi<p>Whoa, that is not insignificant error. What contributes to an error of this size?
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lqetover 3 years ago
&gt; If the earth was flat, photographs of the sun setting over water would look like this:<p>I am curious: has this argument, historally, ever been used against the idea that the world is flat?
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jedimastertover 3 years ago
Sebastian Lague made a fantastic video about approximating&#x2F;simulating Rayleigh scattering in real-time (using Unity) to simulate sky color and sun sets. Really interesting stuff<p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=DxfEbulyFcY" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=DxfEbulyFcY</a>
twicover 3 years ago
Does geometric algebra provide an alternative to pseudovectors for representing things like angular velocity?<p>The fact that you have to flip the sign of pseudovectors sometimes feels like a hint that they aren&#x27;t the right representation, somehow.
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