Despite sounding like the most egregious contradiction in physics, hot water appears to freeze faster than cold water under certain circumstances. The phenomenon can be traced back to Aristotle himself, but after centuries of experiments demonstrating this phenomenon, no one’s been able to explain it. Now physicists are pointing to strange properties of hydrogen bonds as the solution to one of the oldest mysteries in physics – but others are claiming the so-called Mpemba effect doesn’t even exist at all.
“The analysis … leads us to propose a molecular explanation for the Mpemba effect. In warm water, the weaker H-bonds with predominantly electrostatic contributions are broken, and smaller water clusters with … strong H-bonding arrangements exist that accelerate the nucleation process that leads to the hexagonal lattice of solid ice.
Therefore, water freezes faster than cold water in which the transformation from a randomly-arranged water clusters costs time and energy.”