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Random Points on a Sphere

120 pointsby johndcookalmost 7 years ago

6 comments

unholinessalmost 7 years ago
High dimensional spheres are very counterintuitive! The volume of a n-dimensional unit sphere goes to zero as n increases, almost all the volume is contained near the surface.<p>Some interesting musings in this realm: <a href="https:&#x2F;&#x2F;marckhoury.github.io&#x2F;counterintuitive-properties-of-high-dimensional-space&#x2F;" rel="nofollow">https:&#x2F;&#x2F;marckhoury.github.io&#x2F;counterintuitive-properties-of-...</a>
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unwindalmost 7 years ago
Awesome.<p>Also it seems Greg Egan is the SF author[1] which for me makes it extra cool.<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Greg_Egan" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Greg_Egan</a>
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max_likelihoodalmost 7 years ago
Wow, mind blown. Unfortunately, even with an undergraduate degree in mathematics, I was lost after this paragraph:<p>`This made me eager to find a proof that all the even moments of the probability distribution of distances between points on the unit sphere in \mathbb{R}^d are integers when \mathbb{R}^d is an associatve normed division algebra.`<p>Nonetheless, very interesting!
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crasshopperalmost 7 years ago
Persi Diaconis <a href="https:&#x2F;&#x2F;www.ams.org&#x2F;notices&#x2F;200511&#x2F;what-is.pdf" rel="nofollow">https:&#x2F;&#x2F;www.ams.org&#x2F;notices&#x2F;200511&#x2F;what-is.pdf</a><p>Niles Johnson on Hopf&#x2F;Milnor fibrations <a href="https:&#x2F;&#x2F;nilesjohnson.net&#x2F;hopf.html" rel="nofollow">https:&#x2F;&#x2F;nilesjohnson.net&#x2F;hopf.html</a>
pathsjsalmost 7 years ago
The obvious question is actually the converse: assume all even moments of the distance are integers - does it follow that S^(n-1) is a group (hence n=1, 2 or 4)?
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ttoinoualmost 7 years ago
Wait, there are a lot of ways in computer science to choose points randomly, and points randomly with constraints (here belong to unit sphere) and that could change the result, no ?
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