That weird thing where hot water freezes faster than cold water? It turns out that’s a fundamental rule for almost everything in the universe.
arXiv · March 13, 2026 · 2603.11707
Why it matters
Long considered a controversial quirk of freezing water, physicists have proven that this 'head-start' effect exists in nearly any many-body system. It happens because systems starting further from equilibrium can take a physical 'shortcut' through their energy states that closer systems cannot access.
From the abstract
The Mpemba effect, in which a system initially farther from equilibrium relaxes faster than a closer one, is often associated with nonlinear or far-from-equilibrium dynamics. We show that this effect can arise entirely within the linear-response regime of many-body systems. In reciprocal systems, a uniform Mpemba effect emerges for three or more degrees of freedom via spectral separation of fast and slow modes. Breaking reciprocity renders the relaxation operator non-normal, enabling a strict co