# Möbius, August Ferdinand

### colours strip mathematics astronomy

[moe byus] (1790–1868) German mathematician and astronomer: inventor of barycentric calculus and of the Möbius strip.

Möbius studied law at the University of Leipzig, before abandoning it in favour of mathematics and astronomy. In 1816 he was appointed professor of astronomy at Leipzig, and in 1848 became director of its observatory.

Although in mathematics Möbius developed barycentric calculus, which simplifies a number of geometric and mechanical problems, he is better known for his work on topology. In this field he invented, to illustrate the idea of a one-sided surface, the Möbius strip. This can be formed by taking a strip of paper, rotating one end through 180° and connecting the ends together. Möbius’s description of it was only discovered in his papers after his death. Möbius is also remembered for posing the ‘four-colour problem’ in a lecture in 1840: what is the least number of colours needed in a plane map to distinguish political regions, given that each boundary must separate two differently-coloured regions? No such map requiring five colours has been found, despite attempts, and in 1976 a computer-based proof was offered showing that four colours will always suffice.

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