WikiVisually
The entire wiki reimagined as a visual magazine with video discovery · Watch your interests come alive
WikiVisually
The entire wiki reimagined as a visual magazine with video discovery · Watch your interests come alive
Nature The World Movies USA Top Art Fine & Rare History Ivy & Inquiry
Hairy ball theorem
Videos
The hairy ball theorem of algebraic topology states that there is no non-vanishing continuous tangent vector field on even-dimensional n-spheres. For the ordinary sphere, or 2‑sphere, if f is a contin
A continuous tangent vector field on a 2-sphere with only one pole, in this case a dipole field with index 2. See also an animated version of this gra
A continuous tangent vector field on a 2-sphere with only one pole, in this case a dipole field with index 2. See also an animated version of this graphic.
A hair whorl
A hair whorl
Cowlick
Videos
A cowlick is a section of human hair that stands straight up or lies at an angle at odds with the style in which the rest of an individual's hair is worn.
Hairy ball theorem
…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". Every zero of a vector field has a (non-zero) "index", and it can be shown that the sum of all of the indices…
A child with a double crown
A child with a double crown