Thursday, June 18, 2015

[xznzjieg] Minimum number of fixed points on the hairy ball

The Hairy Ball Theorem states that there must be at least one pole.  Mapping a sphere onto a rotation of itself yields two poles, and one might conjecture there must be at least two.  This is false: it can be done with just one, as illustrated on the current Wikipedia page.

Very roughly, take the two poles and mash them together, creating a single-point dipole.

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