Two glasses of water: one scalding hot, the other just warm. The warm should cool first — but in the 1960s, a student from Tanzania noticed that hot ice cream freezes faster. This paradox was named the Mpemba effect. Recently, physicists found its quantum analog. Instead of temperature, here it's about disorder — entropy — and quantum "coherence" of particles. The scientists considered a group of atoms exchanging energy with light (which always flies at its constant speed), like dancers catching a shared rhythm. The more synchronized their dance, the faster the system "cools" toward equilibrium. But the real twist: the roles can be swapped. By slightly shifting the settings, the synchronized dancer starts to stumble, and the sluggish one takes the lead. The classical Mpemba effect is still unresolved, though we've seen it for half a century. And the quantum version hasn't been observed experimentally — only derived on paper. Controlling such cooling jumps could be useful for heat dissipation in microchips and quantum computers.
Ironic twist: the ordinary Mpemba effect still has no single explanation — evaporation, convection, supercooling are blamed. Yet its quantum twin can already be reversed.