MACH, Ernst

M. was born to Johann M., a teacher and landowner and his wife Josephine in Chrlicea and was baptized in the nearby Turany. The family soon moved to Untersiebenbrunn (Lower Austria), where he grew up and was first taught by his father. In 1847/48 M. entered the Benedictine grammar school in Seitenstettn. As he was not interested in theorems or old languages, his pious teacher considered him untalented which resulted in M. being later taught by his father again. For more than two years he was taught the carpentry trade so that he could later emigrate to America. His solidarity with the Austrian Socialists stems from experience he acquired carrying out various field works, while attending primary school, and out of respect for craft work. He finished sixth grade of the Kroměříž grammar school, where he also graduated. He refused religion since childhood.
In 1854 M. studied physics, philosophy and mathematics at the University of Vienna under Andreas von Ettingshausen, Josef Grailich and Josef →Petzval. He received his doctorate in physics for the thesis entitled On electrical discharge and induction (Über Induktion und elektrische Entladung) in January 1860. The following year he received his habilitation at the Vienna University of Physics. In 1861 he demonstrated the Doppler effect in acoustics. In 1864 M. took a job as professor of mathematics in Graz and was in 1866 appointed professor of physics. In 1867 he in Graz married Luisa Marussig, with whom he had four sons and one daughter. The same year he took the chair of professor of experimental physics in Prague. In 1879/80 he was the dean of the University of Prague, after he already worked as Dean of the Faculty of Arts in 1972/73.
He unsuccessfully fought to prevent the division of the University on German and Czech part and later championed the creation of the second Czech University. M. was chosen the rector for the second time in 1883, but after only half a year withdrew from his office. At the time that he spent in Prague he created his most important monographs and nearly all were published in several editions and reprints.

The name M. represents a concept to many researchers, mainly because of his research about flying projectiles between 1878 and 1889. The ratio of the speed of projectile to the speed of sound is now called the Mach number. In aviation the Mach number is commonly used to represent a speed of object, when it is travelling at the speed of sound. In 1886 M. published the first photograph of the shock waves formed by a bullet travelling faster than the speed of sound. His research is the cornerstone of the theory of relativity, developed by A. Einstein.
In 1867 he was elected a correspondent, in 1880 a full member and in 1897 the secretary of the Mathematical science department of the Academy of Sciences in Vienna. In 1895 M. was finally elected a professor at the University in the capital of Austria-Hungary monarchy. The chair of philosophy, history and theory of inductive science was specially established in his honour in Vienna. The change in his research interests, which increasingly led M. to the epistemological, philosophical and historical issues, was now visible outside as well. He was granted court councillor function in 1897. A year later he suffered a stroke, which did not cause any harm to his lively spirit, but being partially paralyzed he could not fulfil his professorial duties anymore. In 1901 he voluntarily renounced his professorship.
From 1904 onwards he carried out optical experiments with his son. In 1905 he published Knowledge and Error (Erkenntnis und Irrtum), which deals with the psychology and research logic. In the spring of 1913 he moved to his oldest son Ludwig in Haar-Vaterstetten in Munich, where he died in 1916.