Why does hot water freeze faster than cold water?
My science teacher told us that hot water freezes faster than cold water and I don't believe it. Doesn't that violate basic thermodynamics? She called it the Mpemba effect. Has this actually been proven or is it one of those 'fun facts' that isn't true? How would that even be possible?
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3 Answers
I'm a physics grad student and this is one of my favorite questions to explain. The key insight is that our everyday intuition doesn't always apply at extreme scales — very small (quantum), very large (cosmological), or very fast (relativistic).
The math looks scary but it's mostly just a precise way of saying something you can understand in plain English. Once you get the concept, the equations are just bookkeeping. Focus on the idea first, the symbols second.
This is something I struggled with until a professor explained it using an analogy that finally clicked. The real world is messy and doesn't always fit neatly into the simplified models we learn in textbooks.
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