The Mpemba Effect
A pot of boiling water and a pot of cold water go into the same freezer. Which freezes first?
1963 (observed), 1969 (published)8 min read
Tanzanian student and science communicator
Erasto Mpemba
1950
Tanzanian schoolboy who, in 1963, noticed that hot ice-cream mixture froze faster than cold mixture when placed in the same freezer. His physics teacher dismissed the observation, but when physicist Denis Osborne visited the school in 1966, Mpemba asked him about it directly. Osborne confirmed the effect experimentally and co-authored the 1969 paper introducing it to the scientific literature — with Mpemba's name first on the byline, an unusual acknowledgment for a student. The effect now bears his name.