1751-1839

Swiss Physicist

Pierre Prévost is best known for his theory of exchanges, which he articulated in 1791. Whereas scientists in his time postulated the existence of cold as a substance or phenomenon all its own, Prévost correctly stated that bodies radiate only heat. When a person's warm hand becomes cold because of touching snow, it is not because coldness passed from the snow to the hand, but because the difference in temperatures resulted in a transfer of heat from the hand to the snow. This would prove to be a crucial principle in the soon-to-emerge science of thermodynamics.

Prévost was born in Geneva—now the leading city of French-speaking Switzerland, but then an independent city-state—on March 3, 1751. His father was a Calvinist minister, and ensured that Prévost and his siblings received classical educations. As a college student, Pr...