Before Ice: Interfacial Ordering and the Mpemba Effect

The Mpemba effect refers to the counterintuitive observation that, under certain conditions, an initially hotter water sample may freeze more rapidly than a colder comparison sample. Although the phenomenon has often been discussed in terms of evaporation, convection, dissolved gases, and supercooling, recent work indicates that freezing cannot be understood solely as a problem of bulk cooling. In particular, current studies of ice nucleation show that free surfaces and three-phase contact lines can play an active role in determining nucleation pathways and rates, suggesting that the liquid boundary must be treated as a kinetically relevant region rather than as a passive thermal interface. Within the logic of the model, the reported results are consistent with the interpretation that initially hotter samples generate stronger boundary activation and may therefore reach a nucleation-permissive interfacial state earlier than colder samples despite their greater initial sensible heat. The study does not claim a final microscopic proof of a unique mechanism. Its contribution lies instead in providing a more rigorous and empirically testable framework through which anomalous freezing can be analysed as a problem of evolving interfacial order, wetting, and barrier-controlled nucleation.