The Physicist Who Made Ice Without Winter

John Leslie became one of Scotland’s leading experimental physicists through ingenious investigations of heat, radiation, moisture and cold. Born in Fife in 1766, he entered St Andrews at thirteen and later supported himself through tutoring and scientific writing. His 1804 Experimental Inquiry introduced celebrated instruments and earned the Rumford Medal. In 1810 he froze water using an air pump, producing artificial ice. This documentary follows his experiments, controversy and Edinburgh professorships.

Leslie showed that surfaces emit radiant heat differently, a principle demonstrated by the cube that still bears his name. His vacuum experiments also proved that evaporation could create enough cooling to freeze water, anticipating mechanical refrigeration. Yet his appointment at Edinburgh became entangled in accusations of religious unorthodoxy, revealing the tensions surrounding science in his era. This documentary combines inventive apparatus, public controversy and the birth of thermal physics.