## Not just Phobos and Deimos

Space elevators, ZRVTOs and conic sections (and quite a bit more on the rest of the blog)
posted by Wolfdog on Sep 11, 2016 - 8 comments

## Loop - Pool on an elliptical table

Loop - Pool on an elliptical table. The ellipse has two significant points, called focuses, which have a remarkable geometrical property that is almost always explained using the example of an imaginary pool table. "If a pool table is the shape of an ellipse, then a ball shot from one focus will always rebound to the other focus no matter in which direction the ball is shot." That sounded interesting! Wouldnâ€™t it be fun, I thought, if I could build one of these imaginary tables? So I did.
posted by dng on Jul 26, 2015 - 22 comments

## An example of "order out of chaos"

"Draw some random points on a piece of paper and join them up to make a random polygon. Find all the midpoints and connecting them up to give a new shape, and repeat. The resulting shape will get smaller and smaller, and will tend towards an ellipse!" [code to make this in Mathematica] [a version which allows you to watch the process step by step, with 10 vertices or 100]
posted by ocherdraco on Dec 3, 2012 - 65 comments

## The crying of x^2 + xy + y^2 = 49

"Pynchon, postmodern author, is commonly said to have a non-linear narrative style. No one seems to have taken seriously the possibility, to be explored in this essay, that his narrative style might in fact be quadratic." Number theorist Michael Harris on Pynchon and conic sections.
posted by escabeche on Oct 25, 2009 - 60 comments

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