HELMHOLTZ, HERMANN VON (1821–1894)

One of the most versatile scientists who ever lived, Hermann von Helmholtz was born in Potsdam, Germany, in 1821, the son of a "Gymnasium" (high school) teacher. From an early age he wanted to be a physicist, but his family could not afford the money required for his education. Instead, his father persuaded him to take up medicine, since his son's education as a physician would be subsidized by the state on the condition that he serve as a doctor in the Prussian army after he received his degree. Helmholtz attended the Institute for Medicine and Surgery in Berlin from 1838 to 1842 and fulfilled his obligation as an army surgeon from 1843 to 1848. His real interest, however, was always research; even in the army barracks he set up a small laboratory for research in physiology and physics.

On July 23, 1847, Helmholtz presented a paper on the conservation of energy at a meeting of the Berlin Physical Society. It was a talk at a reasonably high level of mathematical sophistication intended to convince physicists that energy was always conserved in any physical process. Although it was rejected by J. C. Poggendorf, the editor of the Annalen der Physik, as being too long and too mathematical for his readers, it eventually appeared in pamphlet form and was soon recognized as one of the most important papers in nineteenth-century science. This bold and path-breaking paper, written when he was only twenty-six, was Helmholtz's first and most fundamental statement of the conservation-of-energy principle. It came at a critical moment in the history of science when scientists and philosophers were waging a battle over whether conservation of energy was a truly universal principle. In his 1847 paper Helmholtz had shown convincingly that it was.

Helmholtz stated that his only purpose in his 1847 paper was to provide a careful investigation and arrangement of accepted facts about energy conservation for the benefit of both the physicists and the physiologists who attended his lecture. He never claimed priority for himself in this discovery, but later conceded that honor to J. R. Mayer and James Joule. When Helmholtz delivered this paper, however, he knew little about Joule's research, which was going on at about the same time, and nothing at all about Robert Mayer's 1842 paper, which had appeared in a journal not normally read by many scientists.

Some years later, in 1861, when Helmholtz was much involved in physiology, he realized that he had discussed physiology in only two paragraphs of his 1847 paper, and so supplemented it by a fuller consideration of energy transformations in organic systems. This he included in a talk before the Royal Society of London on April 12, 1861. Here he generously referred to the important contributions of Sadi Carnot, Mayer and Joule in establishing the principle of conservation of energy on a firm foundation.

On the basis of this work and other research, in 1849 Helmholtz was appointed professor of physiology at the University of Koönigsberg. There he devoted himself to the physiology of the eye, first explaining the mechanism of lens accommodation. In 1851 his invention of the ophthalmoscope, still the basic instrument used by eye doctors to peer at the retina of the eye, immediately made Helmholtz famous. In 1852 he also became the first experimentalist to measure the speed of nerve impulses in the human body.

Helmholtz did important research on another sense organ, the ear, and explained how it was able to detect differences in pitch. He showed how the quality of a sound depended on the number, nature and relative intensities of the harmonics present in the sound.

On the basis of his studies on the eye and ear, in 1858 Helmholtz was appointed Professor of Anatomy in Heidelberg. His thirteen years in Heidelberg gave him the opportunity to work closely with other gifted scientists including physicist Gustav Kirchhoff and chemist Robert Bunsen, in what was then called "an era of brilliance such as has seldom existed for any university and will not readily be seen again." In 1871 Helmholtz abandoned anatomy and physiology in favor of physics. He accepted the most prestigious chair of physics in Germany at the University of Berlin and spent the rest of his life there.

As he grew older, Helmholtz became more and more interested in the mathematical side of physics and made noteworthy theoretical contributions to classical mechanics, fluid mechanics, thermodynamics and electrodynamics. He devoted the last decade of his life to an attempt to unify all of physics under one fundamental principle, the principle of least action. This attempt, while evidence of Helmholtz's philosphical bent, was no more successful than was Albert Einstein's later quest for a unified field theory. Helmholtz died in 1894 as the result of a fall suffered on board ship while on his way back to Germany from the United States, after representing Germany at the Electrical Congress in Chicago in August, 1893.

It is difficult to exaggerate the influence Helmholtz had on nineteenth-century science, not only in Germany but throughout the world. It was during his lifetime that Germany gained its preeminence in science, which it was not to lose until World War II. His own research contributions, together with the impetus he gave to talented students by his teaching, research guidance, and popular lectures, had much to do with the scientific renaissance that Germany experienced during his lifetime.

Helmholtz was a sensitive and sickly man all his life, plagued by severe migraine headaches and fainting spells. He sought relief from his pain in music and the other arts, and in mountain climbing in the Alps. It is intriguing to imagine what he might have accomplished had he been in good health for all his seventy-three years. On the occasion of Helmholtz's death, Lord Kelvin stated: "In the historical record of science the name of Helmholtz stands unique in grandeur, as a master and leader in mathematics, and in biology, and in physics." Many scientists felt that Kelvin had short-changed Helmholtz by this statement; Medicine, physiology, chemistry, and philosophy certainly deserved to be added to the list of fields Helmholtz had mastered during his long and productive scientific career.

Joseph F. Mulligan

BIBLIOGRAPHY

Cahan, D., ed. (1993). Hermann von Helmholtz and the Foundations of Nineteenth-Century Science. Berkeley, California: University of California Press.

Cahan, D., ed. (1995). Science and Culture. Popular and Philosophical Essays of Hermann von Helmholtz. Chicago: University of Chicago Press.

Helmholtz, H. v. (1847). "The Conservation of Force: A Physical Memoir." In Selected Writings of Hermann von Helmholtz (1971), ed. R. Kahl, pp. 3–55. Middletown, CT: Wesleyan University Press.

Helmholtz, H. v. (1861). "The Application of the Law of Conservation of Force to Organic Nature." In Selected Writings of Hermann von Helmholtz (1971), ed. R. Kahl, pp. 109–121. Middletown, CT: Wesleyan University Press.

Kahl, R., ed. (1971). Selected Writings of Hermann von Helmholtz. Middletown, CT: Wesleyan University Press.

Koenigsberger, L. (1965). Hermann von Helmholtz (One-volume condensation of three-volume 1902 German edition), tr. Frances A. Welby. New York: Dover Publications.

Mulligan, J. F. (1989). "Hermann von Helmholtz and His Students." American Journal of Physics 57:68–74.

Turner, R. S. (1972). "Helmholtz, Hermann von." In Dictionary of Scientific Biography, ed. Charles Coulston Gillispie, Vol. 6, pp. 241–253. New York: Scribner.