When we talk about high-speed aerodynamics, which is what engineers deal with when they design aircraft that can fly at speeds greater than the speed of sound, the name Ernst Mach is often mentioned. The 19th century Austrian physicist is responsible for much of the fundamental research that allows us to understand how air behaves when it is flown through at supersonic speeds. It is because of the work of Ernst Mach that we have such terms as Mach angle, Mach wave and Mach reflection.
Mach was born in the Austrian town of Turas and spent his early years as an average student through grade school and gymnasium, but his intellectual talents became evident when he entered University of Vienna at age 17. He studied mathematics, history, philosophy and physics and earned a doctorate in physics in 1860 for his thesis on electrical discharge and induction.
In the 1870s, he turned his attention to ballistics and was able to photograph the shock waves produced when a projectile travels faster than the speed of sound. He also developed the theory of shock waves and correctly deduced that the ratio of the projectile’s speed to the speed of sound vp/vs is equal to the Mach number.
Mach went on to study many other fields of physics and made significant contributions to the theory of relativity, optics, acoustics, physical optics, history of science, mechanics, philosophy and cosmology. His writings are still taught to physics students and his thoughts on epistemology (the study of knowledge) are still discussed in philosophy classrooms.
