Abstract

The name "Mpemba effect" was given to the unexpected finding that "If two systems are cooled, the water that starts hotter may freeze first". This counterintuitive finding has been later confirmed by numerous of observations. Nowadays this paradoxical statement obtained a more general form "the state that is initially more distant from its equilibrium state comes to this state earlier". Though seemingly violating the fundamental laws of physics, this effect has been experimentally demonstrated for aqueous and various other systems, up to quantum dots. It was widely discussed in the highly reputable journals, but the fundamental physical mechanism(s) underlying this effect remained elusive. Here I describe a simple mechanical system demonstrating the Mpemba effect ("the state that is initially more distant from its equilibrium state comes to this state earlier"), and show what physical mechanism causes this effect in this system.