Theorems in algebraic topology | Fixed points (mathematics) | Theorems in differential topology
The hairy ball theorem of algebraic topology (sometimes called the hedgehog theorem in Europe) states that there is no nonvanishing continuous tangent vector field on even-dimensional n-spheres. For the ordinary sphere, or 2‑sphere, if f is a continuous function that assigns a vector in R3 to every point p on a sphere such that f(p) is always tangent to the sphere at p, then there is at least one pole, a point where the field vanishes (a p such that f(p) = 0). The theorem was first proved by Henri Poincaré for the 2-sphere in 1885, and extended to higher dimensions in 1912 by Luitzen Egbertus Jan Brouwer. The theorem has been expressed colloquially as "you can't comb a hairy ball flat without creating a cowlick" or "you can't comb the hair on a coconut". (Wikipedia).
Ever tried to comb a hairy ball? Math says you failed! Trying out a new feature: English Transcript! Let me know how it works Tweet it - http://bit.ly/sKAjpS Facebook it - http://on.fb.me/ujIFvN minutephysics is now on Google+ - http://bit.ly/qzEwc6 And facebook - http://facebo
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From playlist Geometry
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You or someone you know may have struggled to get a cowlick to just stay down already, but you can take solace in the fact that these inconvenient hair tufts have a lot to teach us about the world around us. Hosted by: Michael Aranda SciShow has a spinoff podcast! It's called SciShow Tan
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From playlist Pythagorean Theorem
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