Pierre Gassendi (22.01.1592-24.10.1655) was a French philosopher and scientist. He was born in Champtercier (Provence). He was professor of theology at Digne (from 1613), of philosophy at Aix (from 1616) and of mathematics in Paris (from 1645).
His research in physics was in the fields of atomism, heat, acoustics, optics and mechanics. He promoted ancient atomism and held that everything in existence consists of atoms, which possess an inner tendency to motion, and of the void, and that space is infinite, uncreatable and indestructible.
He was one of the founders of the corpuscular theory of light. He was the first to determine the speed of sound in air. In 1641 he carried out an experiment confirming Galileo's principle of relativity.