Ernst Mach, Austrian physicist and philosopher (died 1916)

Ernst Waldfried Josef Wenzel Mach was an Austrian physicist and philosopher, who contributed to the understanding of the physics of shock waves. The ratio of the speed of a flow or object to that of sound is named the Mach number in his honour. As a philosopher of science, he was a major influence on logical positivism and American pragmatism. Through his criticism of Isaac Newton's theories of space and time, he foreshadowed Albert Einstein's theory of relativity.