Handy Talk

When We Talk About Holes

Evelyn Lamb | Scientific American | 25th December 2014

Yes of course one knows what a hole is ... Or so you might think until you read this attempt to arrive at a satisfactory mathematical definition. Holes turn out to be things that only specialists in holes can fully understand. A simple definition goes as follows: “A hole in a mathematical object is a topological structure which prevents the object from being continuously shrunk to a point” (2,300 words)

Handy Mnemonics

Kensy Cooperrider | Public Domain Review | 21st April 2022

For at least a thousand years, from the 8th to the 18th centuries, hands and fingers served as memory-palaces in miniature, using up to 92 points on the front and back of each hand as placeholders for data. Such systems enabled scholars to keep the lunar calendar on the tips of their fingers in 8th century England, musical scales in 12th century Italy, syllabaries in 13th century China (2,730 words)

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