Ernst Mach
Ernst Waldfried Josef Wenzel Mach (/ˈmɑːx/; German: [ˈɛɐ nst maχ]; February 18, 1838 – February 19, 1916) was an Austrian physicist and philosopher, noted for his contributions to physics such as the Mach number and the study of shock waves. As a philosopher of science, he was a major influence on logical positivism, American pragmatism and through his criticism of Newton, a forerunner of Einstein's relativity.