Observational analysis reveals how rapid cooling conditions influence water freezing rates, suggesting a complex interplay of molecular dynamics.
Hot water freezing faster than cold water is simply startling, and this observation is known as the Mpemba effect since its rediscovery in 1969. But we are still confused and grappling in search of the underlying experimental conditions and the microscopic physics that can confirm, experimentally and theoretically whether this effect is real or misunderstood. Here, we derive the macroscopic physics of water freezing based on Newtonian cooling. Subsequently, we invoke the effect of covalent-bonded hydrogen and oxygen atoms with polarized electrons to evaluate the temperature ( T )-dependent interaction strength between water molecules that determines the length of dynamical hydrogen bonds. After doing so, we expose the hidden Mpemba physics of superfreezing – low-density hot water (due to repulsion caused by highly polarized electrons) induce faster complete freezing compared to high-density cold water if and only if the cooling rate is sufficiently and continuously rapid. However, the question as to which water starts to freeze first (and/or reaches 0 °C first), is conditional. Along the way, we also derive the microscopic interaction potential inequality responsible for supercooling that delays freezing of cold water.
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Andrew Das Arulsamy (2025) studied this question.
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