Hermann Ludwig Ferdinand Helmholtz (31.08.1821-8.09.1894) was a German natural scientist and a member of the Berlin Academy of Sciences (1871). He was born in Potsdam. He studied at the Military Medical Institute and at the university in Berlin. In 1842 he received his doctorate. In 1849 — 55 he was professor of physiology at the University of Königsberg, in 1855-58 at the University of Bonn and in 1858-71 at the University of Heidelberg; in 1871—88 he was professor of physics at the University of Berlin, and from 1888 president of the Physico-Technical Institute (Berlin — Charlottenburg).
His physical research was in the fields of electrodynamics, optics, heat, acoustics and hydrodynamics. In his work “On the Conservation of Force” (1847) he formulated the law of conservation of energy and gave it a mathematical basis, noting its universal character: mechanical, thermal, electrical, physiological and other processes all obey this law. He developed a thermodynamic theory of chemical processes, introducing the widely used concepts of free and bound energy.
In 1847 he pointed out the oscillatory character of the discharge of a Leyden jar, and showed in 1869 that similar oscillations arise in an induction coil connected to the plates of a capacitor; in other words, he created the oscillatory circuit, consisting of an inductance and a capacitance. In 1870 he developed the theory of electrodynamic processes in conducting irregular bodies. In 1874, within the framework of the “elastic” theory of light, he developed the theory of anomalous dispersion. In 1881 he put forward the idea of the atomic structure of electricity.
He also achieved substantial results in physiological acoustics (he discovered combination tones, put forward the resonance theory of hearing and built models of the ear) and in the physiology of vision (the theory of accommodation, the doctrine of colour vision). He developed quantitative methods of physiological research, invented a number of measuring instruments and was the first to measure the speed of propagation of nervous excitation.
In hydrodynamics he laid the foundations of the theory of the vortex motion of a liquid in 1858, and in aerodynamics Helmholtz's research on the theory of discontinuous motion was of great importance. The principle of mechanical similarity that he developed made it possible to explain a number of meteorological phenomena and the mechanism of the formation of sea waves.
In his philosophical views Helmholtz was a spontaneous materialist, but an inconsistent one. While recognising objective reality, he held at the same time that our ideas of the external world are a set of symbols, of hieroglyphs, arbitrary conventional signs having nothing in common with the objects of nature (the theory of symbols). Helmholtz's philosophical errors were criticised by F. Engels and V. I. Lenin.
A member of many academies of sciences and scientific societies, in particular of the St Petersburg Academy of Sciences (1868). The Copley Medal (1873).