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Why a healthy bank can still collapse: Diamond and Dybvig's bank run A bank keeps only a slice of your deposit as cash and lends the rest for years, so it quietly bets that almost nobody asks for their money at once. Diamond and… Economics4 min read29 Oct Why honey never spoils: it isn't the sugar, it's the missing water Honey is rich, sweet and nutritious, so why don't bacteria and moulds move in? Because microbes need free water, and honey's sugar holds almost all of it… Food Science4 min read29 Oct Why a small ball on a big ball shoots up nine times higher: the two-step bounce Drop a tennis ball on top of a basketball and the small ball can fly far above the height it fell from. Nothing is cheating: it is a two-step bounce. The floor… Physics4 min read28 Oct Why a nerve spike is always the same size: the all-or-nothing action potential Every nerve signal in your body is the same size. A feather touch and a hammer blow send identical electrical spikes, so how does the brain tell them apart?… Biology4 min read28 Oct How two royal names in rings cracked hieroglyphs: Ptolemy, Cleopatra and the Rosetta Stone In 1799 a slab was dug up near Rosetta carrying one decree in three scripts, and nobody could read two of them. The first foothold was tiny: royal names sealed… History4 min read28 Oct Why sunflower seeds never leave gaps: the golden angle and the Fibonacci spirals Sunflower seeds are not placed in spirals on purpose. Each new seed turns a fixed angle from the last, and only one angle, about 137.5 degrees, leaves no bare… Maths4 min read28 Oct Why there are two high tides a day: the Moon pulls the near sea harder and the far sea softer The sea rises twice a day, not once, and the second high tide happens on the side of the Earth facing away from the Moon. Why? The Moon pulls the near ocean a… Earth & Space4 min read27 Oct Why Russians have two blues: how a colour word can speed up your eyes Russian has two basic words for blue, goluboy (light) and siniy (dark), and in a 2007 experiment Russian speakers were about 124 milliseconds faster at telling… Language4 min read27 Oct Why two steady rhythms can fight and still groove: the hidden grid of 3 against 2 Tap a steady beat with one hand and three evenly spaced taps in the same time with the other, and you get a 3:2 polyrhythm: two perfectly regular clocks that… Music & Sound4 min read27 Oct Why eight yes/no answers can draw a fractal, make noise or compute: elementary cellular automata Take a row of lit and dark squares and repeat one tiny rule to make the next row: look at a square and its two neighbours, then decide if it is lit. There are… Computing3 min read27 Oct Why still rocks creep upward after you stare at a waterfall: the motion aftereffect Stare at a waterfall, then look at the rocks beside it, and they seem to crawl upward. They go nowhere, yet they move. This is the motion aftereffect, noticed… Mind3 min read26 Oct Why a dam is fat at the bottom: water's push grows with depth squared, its tipping with depth cubed A dam is fat at the bottom and slim at the top because water pressure grows with depth, so the push grows with depth squared and the tipping effect with depth… Engineering5 min read26 Oct