Helmholtz, Hermann Ludwig Ferdinand von

Born Aug. 31, 1821, in Potsdam; died Sept. 8, 1894, in Berlin. German physicist, mathematician, physiologist, and psychologist.

Helmholtz studied at the Military Institute of Medicine in Berlin. Beginning in 1843 he was a military physician in Potsdam. He was a professor of physiology at the universities of Konigsberg (from 1849), Bonn (from 1855), and Heidelberg (from 1858). In 1871 he became a professor of physics at the University of Berlin, and in 1888 he was appointed director of the physicotechnical institute in Berlin.

In 1847, Helmholtz presented for the first time a mathematical basis for the law of the conservation of energy in the paper On the Conservation of Force. Having analyzed most of the physical phenomena known at that time, he demonstrated the universality of this law, including the fact that processes occurring in living organisms are also subject to the law of the conservation of energy. This was the strongest argument against the concept of a special “vital force,” which supposedly governed organisms. Helmholtz demonstrated for the first time the applicability of the principle of least action to thermal, electromagnetic, and optical phenomena and discovered the relationship of this principle to the second law of thermodynamics. In 1882 he formulated the second law of thermodynamics in a form permitting its application to the study of chemical processes and introduced the concept of free energy and combined energy. Helmholtz laid the foundations of the theory of vortex motion in liquids (1858). His studies of discontinuous motion (1868) were of great importance to the development of aerodynamics. The principle of mechanical similarity formulated by him made it possible to explain a number of meteorological phenomena as well as the kinetics and behavior of sea waves. In 1873 he presented a discussion of some theoretical problems of guided air flight.

The works of Helmholtz in electromagnetism, optics, and acoustics are mostly related to his physiological studies. He discovered the phenomenon of the oscillating nature of the discharge of the Leyden jar, a fact of great importance for the development of electromagnetic theory. Helmholtz attempted to determine the velocity of propagation of electromagnetic disturbances, but he did not succeed. At his suggestion, H. Hertz conducted experiments with electromagnetic waves. Helmholtz developed the theory of anomalous dispersion (1874). In 1881 he advanced the idea of the atomic nature of electricity. In the field of acoustics, he discovered the combination tones, constructed models of the ear, which made studies of the action of sound waves on the hearing organ possible, developed the theory of this interaction, formulated the science of the auditory function of the organ of Corti, and solved the so-called problem of the organ pipe. He also developed the physical and physiological theory of music sound perception.

Helmholtz’ studies in physiology include investigations of the nervous and muscular systems. He discovered and measured heat generation in the muscle (1845-47) and studied the process of muscular contraction (1850-54). He determined for the first time (1850) the rate of propagation of excitation in nerves and determined the induction period in reflexes (1854). Helmholtz performed the basic studies in the physiology of vision. In 1853 he proposed the accommodation theory. Between 1859 and 1866 he developed the theory of color vision. He constructed a number of measuring instruments (ophthalmoscope, Helmholtz’s pendulum, and others) and also developed quantitative methods for physiological studies.

Helmholtz’ studies in geometry are also of interest. He suggested that all the geometric postulates have an experimental origin and that the shape of space could be determined experimentally. In discussing space, however, he paid tribute to Kantianism by admitting that the a priori nature of space is a mode of contemplation.

V. I. Lenin pointed out that Helmholtz’ philosophical position is characterized by inconsistency. “Helmholtz was an inconsistent Kantian … now deriving human sensations from external objects acting on our sense organs and now declaring sensation to be only symbols, that is, certain arbitrary signs divorced from the ‘entirely different’ world of the things signified” (Poln. sobr. soch., 5th ed., vol. 18, p. 246). Helmholtz formed these views under the influence of J. Müller, the founder of physiological idealism.