Ernst Waldfried Josef Wenzel Mach born on 18 February 1838 was a physicist and philosopher noted for his contributions to physics such as study of shock waves. The ratio of one's speed to that of sound is named the Mach number in his honour. Through his criticism of Newton's theories of space and time, he foreshadowed Einstein's theory of relativity.
Up to the age of 14, Mach received his education at home from his parents. In 1855 he became a student at the University of Vienna where he studied physics and for one semester medical physiology, receiving his doctorate in physics in 1860. His early work focused on the Doppler effect in optics and acoustics.
In 1864 he took a job as Professor of Mathematics at the University of Graz and in 1867, he took the chair of Experimental Physics at the Charles University, Prague, where he stayed for 28 years before returning to Vienna. Mach's main contribution to physics involved his description and photographs of spark shock-waves and then ballistic shock-waves. He described how when a bullet or shell moved faster than the speed of sound, it created a compression of air in front of it.
In 1887 Mach and physicist-photographer Peter Salcher presented a paper on this subject correctly describing the sound effects observed during the supersonic motion of a projectile.
In March 1901 Mach retired from the University of Vienna. He passed away on 19 February 1916 only one day after his 78th birthday.