The fact that hot water freezes faster than cold has been known for many
centuries. The earliest reference to this phenomenon dates back to
Aristotle in 300 B.C. The phenomenon was later discussed in the medieval
era, as European physicists struggled to come up with a theory of heat.
But by the 20th century the phenomenon was only known as common folklore, until
it was reintroduced to the scientific community in 1969 by Mpemba, a Tanzanian
high school student. Since then, numerous experiments have confirmed the
existence of the "Mpemba effect", but have not settled on any single
explanation.
