The 1903 Chicago theatre fire that killed over 500 people
The Iroquois Theatre fire of December 30, 1903 killed hundreds behind locked gates and inward doors. The outrage pushed US cities to rewrite fire codes.
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Explainer.
Every explainer in the edition.
You dream for about two hours a night, and nobody knows why
Science has no single answer to why we dream. Threat rehearsal, emotional repair, memory sorting and creative search each have evidence behind them.
Why AI's water use is so hard to pin down
AI uses water mostly to cool data centre chips, but how much depends on the site, the season and the cooling design. Nobody yet agrees how to count it.
Foil is fine in an air fryer. The heating element is the risk
Aluminium foil can go in an air fryer if food weighs it down, it stays clear of the element and fan, and it leaves room for the hot air to move.
Four under-40 mathematicians took the 2026 Fields Medals
Yu Deng, John Pardon, Jacob Tsimerman and Hong Wang won the 2026 Fields Medals, a prize for work done and for the promise of more.
Maeslantkering: the Dutch barrier that shuts in half an hour
The Maeslantkering swings two doors across a 360-metre channel into Rotterdam, part of the Delta Works the Dutch built after the 1953 North Sea flood.
Doctors rarely find one cause for high blood pressure
Most high blood pressure has no single cause, say the British Heart Foundation and Cleveland Clinic. The NHS counts 140/90 as high, the United States 130/80.
Dogs eat grass, and the upset-stomach story doesn't hold up
Most dogs graze, and the settle-the-stomach story does not hold up. Dogs Trust and BBC Bitesize point to taste, low fibre and boredom, though none is proven.
Dissolved minerals crystallise into kidney stones
Kidney stones form when urine holds too much calcium, oxalate or uric acid and too little water. Fluid, salt and genes all drive that.
A comet's tail points away from the sun, whichever way it flies
Sunlight and the solar wind, not a comet's own motion, decide which way its tail streams as the comet swings past the sun.
Teachers' forecasts track exam results, and can also move them
A UK study found teacher forecasts match exam results closely, but the misses follow pupils' backgrounds. Another linked teacher training to higher scores.
How Darwin said atolls form, and what drilling found
Darwin said a reef round a sinking volcano becomes a barrier reef, then an atoll. Drilling confirmed the sinking, but two geologists now credit sea level.