Ernst Mach (18.02.1838-19.02.1916) was an Austrian physicist and idealist philosopher. He was born in Turas (now Tuřany, Czechoslovakia). He graduated from the University of Vienna (1860), where he was a Privatdozent. In 1864 —67 he was professor at the university in Graz, in 1867—95 at the German university in Prague and in 1895 — 1901 at the University of Vienna.
His research in physics was in the field of mechanics, acoustics and optics. Using photography he established the distribution of air density in the neighbourhood of a projectile flying at supersonic speed, and he studied a number of acoustic processes unknown before him. He obtained photographs of shock waves in the supersonic flow of a gas around bodies. He established that certain characteristics of a flow depend on the ratio of the speed of the flow to the speed of sound (on the Mach number). He is also known for the Mach cone, the Mach angle and Mach's principle. In his “Mechanics” (1883) he sought to give the laws of mechanics a form in which they would not depend on the uniform rectilinear motion of the reference frame or on its rotation. Rejecting Newton's absolute space, time and motion, he was the first to attempt to construct a mechanics starting from the proposition that the motions of bodies can be determined only in relation to other bodies. Mach's principle played an important heuristic part in A. Einstein's construction of general relativity.
He studied the processes of hearing and vision, in particular the mechanism of action of the vestibular apparatus.
In philosophy he is the founder of the idealist doctrine of Machism. He denied the kinetic theory of gases and atomistic teaching, and the reality of atoms and molecules. L. Boltzmann argued sharply against him on this question. Mach's idealist views were sharply criticised by V. I. Lenin in his work “Materialism and Empiriocriticism”.