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How dropping needles on a floor reveals the number π: Buffon's needle Toss a match onto a plank floor and ask: does it touch a crack? Do it thousands of times and the fraction that do will quietly spell out π, though no circle is… Maths3 min read4 Oct Why one day on Mercury lasts two Mercury years Mercury circles the Sun in 88 Earth days and spins once every 58.6 days. That odd pairing, three spins for every two orbits, means one sunrise to the next… Earth & Space3 min read4 Oct Why you hear bass from a speaker too small to make it: the missing fundamental Your phone speaker is far too small to produce a deep bass note, yet you still hear the bass. The trick is that pitch is not a frequency in the air. It is a… Music & Sound3 min read3 Oct How honeybees give directions by dancing in the dark A honeybee that finds good flowers can tell her sisters where they are, inside a pitch-black hive, by dancing. She runs in a straight line while shaking her… Biology5 min read2 Oct How one doctor's map traced a cholera outbreak to a single pump In 1854 most doctors blamed cholera on bad air. When it tore through Soho, killing hundreds in days, John Snow went door to door asking one question: where did… History5 min read1 Oct How a 9th-century scholar cracked secret codes by counting letters For roughly nine centuries after Julius Caesar, swapping each letter for another was a perfectly good way to keep a secret. Then, in 9th-century Baghdad, the… History5 min read30 Sep Why 23 people are enough for two to share a birthday Put 23 people in a room and there's a better-than-even chance that two of them share a birthday. That sounds wrong, because 23 is tiny next to 365. The catch… Maths4 min read29 Sep Why guitar frets get closer together as you go up the neck Guitar frets crowd together toward the body because of one fact about hearing: we hear pitch by ratio, not by difference. Each fret has to raise the note by… Music & Sound5 min read28 Sep Why some notes sound sweet together and others seem to fight Play C and E together and they sound sweet. Play C and C sharp and they buzz. The notes aren't the problem: the clash only happens when they meet. Every… Music & Sound5 min read28 Sep Chilli isn't hot: capsaicin trips the heat alarm on your tongue A chilli is exactly as warm as the room. There is no heat in it at all. The burn comes from capsaicin, a molecule that pries open TRPV1, the gate in your… Food Science5 min read28 Sep How chameleons change colour: they stretch a mirror made of crystals A chameleon doesn't change colour by mixing pigments. Under its skin sit cells packed with tiny guanine crystals, arranged in a lattice that works like a… Biology4 min read28 Sep Why everyone agrees which blob is 'bouba' and which is 'kiki' Show people a soft blob and a spiky star and ask which one is bouba and which is kiki. The words are made up, yet in the classic version of the test about 95%… Language5 min read27 Sep