University of Canberra Erasto Bartholomeo Mpemba[1] (1950–2023)[note 1] was a Tanzanian game warden who, as a schoolboy, discovered the eponymously named Mpemba effect, a paradoxical phenomenon in which hot water freezes faster than cold water under certain conditions; this effect had been observed previously by Aristotle, Francis Bacon, and René Descartes.

[11][5] Due to lack of time, he skipped the cooling phase when preparing the ice cream and immediately put it into the freezer; unexpectedly, his milk mixture froze faster than that of his classmates.

[3] A few years later, the head of Mpemba's school invited British physicist Denis Osborne (1932–2014) from the University of Dar es Salaam to give a guest lecture on his work.

[12] At the end of the presentation, Mpemba asked the question that had been bothering him for so long: “If you take two beakers with equal volumes of water, one at 35°C and the other at 100°C, and put them into a refrigerator, the one that started at 100°C freezes first.

[3][12] In 1969, during Mpemba's studies at the College of African Wildlife Management near Moshi, a paper that he and Osborne had written on the phenomenon was published.