Ernst Waldfried Josef Wenzel Mach was a Czech physicist and philosopher, who contributed to the physics of shock waves. The ratio of the speed of a flow or object to that of sound is named the Mach number in his honour. As a philosopher of science, he was a major influence on logical positivism and American pragmatism. Through his criticism of Isaac Newton's theories of space and time, he foreshadowed Albert Einstein's theory of relativity.
Ernst Mach
Self-Portrait by Ernst Mach (1886) featured in "Analysis of Sensations", also known as "view from the left eye"
Ernst Mach's historic 1887 photograph (shadowgraph) of a bow shockwave around a supersonic bullet
Ernst Mach in 1905
The Mach number, often only Mach, is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound.
It is named after the Czech physicist and philosopher Ernst Mach.
An F/A-18 Hornet creating a vapor cone at transonic speed just before reaching the speed of sound