Water: the weirdest liquid on the planet
by Alok Jha
Water is the only substance on Earth whose chemical formula has entered the vernacular. We all know H2O, even if we don't understand precisely what it means. But if it sounds simple, the reality is different. This common, seemingly boring substance baffles and confuses anyone who peers at it for long enough.
If you thought that was strange, how about this: hot water freezes faster than cold water. It's a peculiarity known as the Mpemba effect, after a Tanzanian high-school student named Erasto Mpemba, who found in 1963 that hot ice-cream mix froze faster than a colder mix in a classroom experiment. Though ridiculed by his teacher, Mpemba was not alone in noticing this peculiar effect of water; Aristotle, Francis Bacon and Rene Descartes have all written about it.