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Why a tax lands on whoever can't walk away: tax incidence and the wedge The law decides who hands over the money for a tax, but not who ends up poorer. Put a tax on a market and two prices appear: what the buyer pays and what the… Economics5 min read9 Nov Why a roast keeps getting hotter after you take it out: carryover cooking and the heat still on its way in You pull the roast at 60 °C, and five minutes later the probe says 66 °C. Nothing is heating it, so where did the heat come from? The answer is that an oven… Food Science4 min read8 Nov Why a small push at the right beat builds a huge swing: resonance and the narrow peak Every child learns to pump a swing without a lesson: small shoves, well timed, build a huge ride, while big shoves at the wrong moment achieve nothing. That… Physics4 min read4 Nov Why nearly every species makes sons and daughters in equal numbers: Fisher's grandchildren argument Boys and girls are born in nearly equal numbers, about 105 boys for every 100 girls worldwide, even though one male could father far more children than one… Biology5 min read3 Nov How a bone tells its own age: carbon-14 and the clock that starts at death Every living thing carries a trace of carbon-14, about one atom in a trillion, topped up with every meal. At death the topping-up stops and the clock starts… History4 min read3 Nov Why a treatment can win in every group and still lose overall: Simpson's paradox Treatment B beats Treatment A overall, yet A wins for small stones and for large stones. That is Simpson's paradox, and it is real data from a kidney-stone… Maths4 min read3 Nov Why the night sky is dark: Olbers' paradox and the light that hasn't arrived yet Go outside and look between the stars: it's dark. That's strange. In an endless, unchanging universe, every line of sight would end on a star, and the whole… Earth & Space4 min read3 Nov Why a language gets grammar when nobody designs it: the iterated-learning experiment How does a language get grammar when nobody designs it? In a 2008 experiment, volunteers learned an alien language of 27 random words for pictures, saw only 14… Language4 min read2 Nov Why a CD takes 44,100 snapshots a second: Nyquist and the tone that folds back A CD stores music as 44,100 numbers a second, with nothing in between. Sample more than twice as fast as the highest pitch and the wave can be rebuilt exactly… Music & Sound4 min read2 Nov Why sorting gets slow so fast: bubble sort versus merge sort and n log n Two sorting methods can both be perfectly correct and still differ by a factor of 25,000 on a big list. Race bubble sort against merge sort on the same… Computing3 min read2 Nov Why the same circle looks smaller among big ones: the Ebbinghaus illusion and size contrast Two identical orange circles, one ringed by big circles and one by small ones, and your eyes insist they differ. That is the Ebbinghaus illusion: your visual… Mind4 min read1 Nov Why a ship rolls back upright, until the cargo goes too high: the metacentre and the righting arm A loaded ship that leans over usually rolls back upright, because the water's upward push shifts sideways and twists her straight. But raise the cargo high… Engineering4 min read1 Nov