Ernst Mach

Born on 18 February 1838 in Moravia, then part of the Austrian Empire, Ernst Mach became one of the best-known scientific thinkers of his time. He taught at the University of Graz, later held a chair in Prague, and eventually became professor of the history and theory of the inductive sciences at the University of Vienna.

In physics, Mach made important contributions to optics, mechanics, and the study of shock waves. His name lives on in the Mach number, the measure comparing an object's speed with the speed of sound. He was also known for careful experiments on sensation and perception, including visual effects such as Mach bands.

Mach was just as influential as a philosopher of science. He argued that science should stay close to experience and observation, and he was deeply skeptical of ideas that could not be tested directly. That outlook made him a major figure for later thinkers interested in empiricism and the foundations of modern science.