Physicists have developed a new theoretical framework which unifies a wide array of seemingly unrelated “Mpemba effects”: counterintuitive cases where systems driven further from equilibrium relax faster than those closer to it. Reporting their results in Physical Review X, researchers led by John Goold at Trinity College Dublin show that both classical and quantum versions of the effect can be understood using the same underlying logic—resolving a long-standing conceptual puzzle.
In 1963, 13-year-old Tanzanian student Erasto Mpemba noticed that when he placed an ice cream mixture in the freezer while it was still hot, it froze faster than the other, initially cooler mixtures in the freezer. His observation was later confirmed in 1969 through a study involving Mpemba, together with physicist Denis Osborne.
Since then, effects analogous to the Mpemba effect have been observed in transitions ranging from crystallizing polymers to transitions in magnetic materials. Yet despite close experimental scrutiny, the mechanisms underlying the effect remained elusive.









