Ernst Mach

Mach, Ernst (1838–1916), Austrian physicist and philosopher. His name is commemorated in the Mach number, used as a measure of the speed of bodies in terms of the speed of sound. His greatest influence was in philosophy; he rejected from science all concepts that could not be validated by experience. This approach helped inform the logical positivism of the Vienna Circle—a prominent group of intellectuals in Vienna at that time.

See also: Philosophy; Physics.