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Why Latin p became English f: Grimm's law and the sound-shift chain Latin says pes, English says foot. Latin tres, English three. Latin cornu, English horn. The swap is not random: when the Germanic languages split off, their… Language5 min read16 Oct Why a piano can never be perfectly in tune: twelve fifths overshoot seven octaves Climb twelve perfect fifths and you should land back on your starting note, seven octaves up. You don't: you overshoot by 23.46 cents, nearly a quarter of a… Music & Sound4 min read16 Oct How to find one name among a billion in 30 looks: binary search Pick a number from 1 to 1,000,000 and you can find it in at most 20 yes-or-no questions. The trick is binary search: look in the middle of a sorted list, throw… Computing4 min read15 Oct Why you forget most of it in days: Ebbinghaus's forgetting curve In the 1880s Hermann Ebbinghaus learned lists of nonsense syllables, tested himself after delays from 20 minutes to 31 days, and drew the first forgetting… Mind4 min read15 Oct Why steel beams are shaped like an I: the same steel, 25 times stiffer Put a beam across a gap and it sags: the top edge is squeezed, the bottom stretched, and the steel in the middle does almost nothing. That is why girders are… Engineering4 min read15 Oct Why mild preferences can build a segregated town: Schelling's chequerboard Nobody in this town wants it split into blue and orange districts. Each household only asks that a few of its neighbours look like it. Yet run the rule and the… Economics4 min read15 Oct Why a wet steak won't brown: boiling water caps the surface at 100 °C Put a wet steak in a hot pan and it goes grey and steams. Pat it dry and it forms a dark, savoury crust. The pan is equally hot both times. The difference is a… Food Science4 min read14 Oct Why a boat's wake is always a 39° V: Kelvin's wedge Behind every boat spreads a V of ripples, and it is always about 39° wide, whether the boat crawls or speeds. Lord Kelvin worked out why in 1887: only waves… Physics4 min read14 Oct Why a gene can vanish by pure luck: genetic drift Two versions of a gene start at 50% each. Neither is better, yet in a small population one will vanish by pure chance and the other will take over. This is… Biology5 min read14 Oct How a beam with no date gets one: tree rings and crossdating A beam from a ruined house has no date on it, but its rings do. Trees from the same region share the same wide and thin years, so a pattern of ring widths can… History5 min read14 Oct Why random bounces pile up into a bell curve: the Galton board Every ball in a Galton board makes the same blind choice at each peg: left or right, a coin flip. Yet drop enough of them and the pile always grows into the… Maths4 min read13 Oct Why a cannonball fired hard enough never lands: Newton's cannon and the orbit Fire a cannonball horizontally from a mountaintop and it lands some distance away. Fire it harder and it lands farther. Fire it hard enough and the Earth's… Earth & Space4 min read13 Oct