The Austrian physicist and philosopher, Ernst Mach, whose work in physics and in philosophy had a great influence on 20th-century thought, was born on February 18, 1838, at Turas in Moravia and educated in Vienna. He was professor of physics at Graz from 1864 to 1867 and at Prague from 1867 to 1895, and professor of inductive philosophy at Vienna from 1895 to 1901. He was made a member of the Austrian House of Peers in 1901 and died at Munich on February 19, 1916.
Mach was a thorough-going positivist and took the view, which most scientists now share, that no statement is admissible in natural science unless it is empirically verifiable. His criteria of verifiability were, however, exceptionally rigorous: they led him not only to reject such metaphysical conceptions as that of the ether and that of absolute space and time but also to oppose the introduction of atoms and molecules into physical theory. Nevertheless, it was his criticism along these lines of Sir Isaac Newton's system that made the way clear for Albert Einstein's Theory of Relativity. As a positivist, he regarded scientific laws as purely descriptive; and he held that the choice between alternative hypotheses covering the same facts was to be made on the grounds of economy.
Mach's name is associated with Mach Number, which expresses the speed of matter relative to the local speed of sound.