See main: Mpemba effectIn 1961 (age 7) (Ѻ) or 1963 (age 9) (Ѻ), Mpemba, while making ice cream, noted the phenomenon — also commented on by Aristotle, Roger Bacon, Francis Bacon, and Rene Descartes — that “warm-freezes-faster”, meaning that if he heated his water (or cream) before freezing, he could make ice cream faster. Mpemba told his teachers about this, who at the time, supposedly, laughed at him.
“If you take two similar containers with equal volumes of water, one at 95°F and the other at 212°F and put them into a freezer, the one that started at 212°F freezes first. Why?”In 1969, Osborn co-authored with Mpemba this experimental phenomena, which thereafter became dubbed the Mpemba effect, i.e. the hot-begets-cold-quicker phenomenon, that lays question to Newton's law of cooling, one of the supposed big seven paradoxes of thermodynamics. 
|Erasto Mpemba (left) and Denis Osborne (right) in London (2013). |