There's a baby crying next to you, and it's extremely annoying. You hate it. It's a cute baby, but come on, you're trying to sleep on the train. Luckily, maths (and tech that uses it) can wipe the baby out.
The noise-cancelling headphones you use to shield yourself from babies, traffic, annoying spouses, and other sonic nuisances, are all powered by a single mathematical formula, Wired explains: the Fourier Transform. Sounds are waves. The Fourier Transform analyses a given wave, and produces the equivalent of its audio opposite. When that's played, the two more or less cancel out, muffling your audio environs. Think of it as bizarro Superman punching Superman in the face. [Wired]