Yucheng Wang

Everything tends toward equilibrium: tea cools, a pendulum swings to rest. The measure of this movement is entropy — growing disorder. But sometimes hot water freezes before warm. The Mpemba effect isn't just a curiosity: it shows up in the quantum world too. Scientists have devised a way to control this paradox.

In 1958, Philip Anderson showed that strong disorder can stop a wave. Since then, physicists have discovered that between complete stoppage and free travel there are intermediate regimes. A particle can not only stand still or fly, but also jitter in place, pulse, or combine several types of motion at once.