On 18 February 2016, a memorial plaque with a bust of Ernst Mach (1838 Chrlice u Brna - 1916 Haar near Munich) was unveiled on the building of the Rector’s Office of Charles University in Prague. The plaque commemorates Mach as a mathematician and physicist, but also as a philosopher and rector of the Prague University. Ernst Mach worked at the University from 1867 to 1895. Many physical variables and terms are named after him.

Ernst Mach (1838-1916), who was born in Chrlice (formerly a village near Brno, today part of Brno), was an important figure in the field of science in the second half of the 19th century. After graduating from the Piarist grammar school in Kroměříž in 1855, he continued his studies in physics and mathematics in Vienna, where he was habilitated in 1861. From 1864 onwards, he worked at important university departments - first as a professor of mathematics in Graz, then at the Physics Cabinet that later became the Institute of Physics of the Prague University. In Prague he also became dean of the Faculty of Philosophy (1872/73) and rector of the Charles-Ferdinand University (1879/80 and 1883/84). From 1895 he lectured at the University of Vienna on philosophy, to which he came through physiology and psychology.

The unveiling of the commemorative plaque as an important memorial site on the list of the so-called Historical Sites of the European Physical Society (EPS) was timed to coincide with the celebration of the centenary of Mach’s death. Celebrations were also held in Brno, where a memorial plaque can also be found on the house where he was born, which has been removed and reinstalled several times, most recently in 1988.

The bronze memorial plaque at Ovocný trh in Prague was created by sculptor Jakub Vlček. Mach’s photograph of a missile from 1888 flying at supersonic speed became the basis for the sculptural division and rendering of the plaque. The author of the accompanying brass plaque with the logos of the Czech Physical Society and Charles University in Prague in the upper right corner and the European Physical Society (EPS) logo in the left corner is graphic designer Ondřej Brom. The trilingual plaque says in Czech, English and German:

The physicist and philosopher Ernst Mach worked in this house between 1857 and 1879. It was here that he began his ground-breaking research into shock waves (Mach number) as head of the University’s Institute of Physics. His critique of Newtonian mechanics profoundly influenced Albert Einstein (Mach’s principle).

The significance of most of Mach’s work in physics is time-independent: Albert Einstein introduced the concept of Mach’s principle, which later led to the theory of relativity. To this day, the Mach wave machine or Mach pendulum is still used in physics teaching, and the aerodynamics of supersonic speeds is linked to the Mach cone, Mach angle and Mach number.

In his work he concentrated on reviewing basic physical concepts and he also tried to overcome outdated ways of looking at the process of knowledge: a new way of scientific thinking came to Prague with him. In addition to his scientific achievements, Ernst Mach was also a highly successful educator all through his career, fostering a new generation of physicists with his innovative approach. He built the so-called physics school, from which many leading Czech researchers came (A. Seydler, Č. Strouhal, Č. Dvořák).

Keywords: physics; mathematics; Ernst Mach; immanent positivism; empiriocriticism; Charles University Rector; Charles-Ferdinand University; Mach number; Mach ‘s principle; Mach wave machine; Mach pendulum; Mach cone; Mach angle; Physics Institute in Viničná; Prague

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Mlynář, J.: Slavnostní odhalení pamětní desky Ernsta Macha v Praze. Pokroky matematiky, fyziky a astronomie, Vol. 61 (2016), No. 2, 131–136. – URL: https://dml.cz/bitstream/handle/10338.dmlcz/145764/PokrokyMFA_61-2016-2_4.pdf [24. 11. 2021].

Ernst Mach’s Commemorative Plaque with Bust in Prague