A German scientist who conducted breakthrough research on the nervous system.
Hermann Ludwig Ferdinand Helmholtz, more commonly known as Hermann von Helmholtz, is one of the few scientists to master two disciplines: medicine and physics. He conducted breakthrough research on the nervous system, as well as the functions of the eye and ear. In physics, he is recognized (along with two other scientists) as the author of the concept of conservation of energy.
Helmholtz entered the Royal Friedrich Wilhelm Institute in Berlin in 1898, receiving his medical degree four years later. Upon graduation, he was immediately assigned to military duty, practicing as a surgeon for the Prussian army. After several years of active duty, he was discharged, free to pursue a career in academia. In 1848, he secured a position as lecturer at the Berlin Academy of Arts. Just a year later he was offered a professorship teaching physiology at the University of Konigsberg. Over the next 22 years, he moved to the universities at Bonn and Heidelberg, and it was during this time that he conducted his major works in the field of medicine.
Helmholtz studied the human eye, a task that was all the more difficult for the lack of precise medical equipment. In order to better understand the function of the eye he invented the ophthalmoscope, a device used to observe the retina. Invented in 1851, the ophthalmoscope, in a slightly modified form, is still used by modern eye specialists. Helmholtz also designed a device used to measure the curvature of the eye called an ophthalmometer. Using these devices, he advanced the theory of three-color vision first proposed by Thomas Young (1773–1829). This theory, now called the Young-Helmholtz theory, helps ophthalmologists to understand the nature of color blindness and other afflictions.
Intrigued by the inner workings of the sense organs, Helmholtz went on to study the ear. Being an expert pianist, he was particularly interested in the way the ear distinguishes pitch and tone. He suggested that the inner ear is structured in such a way as to cause resonations at certain frequencies. This allows the ear to discern similar tones, overtones, and timbres, such as an identical note played by two different instruments.
In 1852, Helmholtz conducted what was probably his most important work as a physician—the measurement of the speed of a nerve impulse. It had been assumed that such a measurement could never be obtained, since the speed was far too great for instruments to record. Some physicians even used this belief as proof that living organisms are powered by an innate vital force rather than energy. Helmholtz disproved this assumption by stimulating a frog's nerve first near a muscle and then farther away. When the stimulus was farther from the muscle, it contracted just a little more slowly. After a few simple calculations, Helmholtz announced the impulse velocity within the nervous system to be about one-tenth the speed of sound.
After completing much of the work on sensory physiology that had interested him, Helmholtz found himself bored with medicine. In 1868, he decided to return to his first love—physical science. However, it was not until 1870 that he was offered the physics chair at the University of Berlin and only after it had been turned down by Gustav Kirchhoff (1824–1887). By that time, Helmholtz had already completed his groundbreaking research on energetics.
The concept of conservation of energy was introduced by Julius Mayer (1814–1878) in 1842, but Helmholtz was unaware of Mayer's work. Helmholtz conducted his own research on energy, basing his theories upon his previous experience with muscles. It could be observed that animal heat was generated by muscle action, as well as chemical reactions within a working muscle. Helmholtz believed that this energy is derived from food and that food gets its energy from the Sun. He proposed that energy cannot be created spontaneously; and it does not vanish; it is either used or released as heat. Helmholtz is often considered the true originator of the concept of the conservation of energy.
Helmholtz had been a sickly child. Even throughout his adult life, he was plagued by migraine headaches and dizzy spells. In 1894, shortly after a lecture tour of the United States, he fainted and fell, suffering a concussion. He never completely recovered, dying of complications several months later in Germany, on September 8, 1894, at the age of 73.
See also Hearing .
Meulders, Michel. Helmholtz: From Enlightenment to Neuroscience. Cambridge, MA: MIT Press, 2010.
Schiemann, Gregor. Hermann von Helmholtz's Mechanism: The Loss of Certainty: A Study on the Transition from Classical to Modern Philosophy of Nature. Dordrecht: Springer, 2009.
Steege, Benjamin. Helmholtz and the Modern Listener. New York: Cambridge University Press, 2012.
Cahan, David. “Helmholtz and the British Scientific Elite: From Force Conservation to Energy Conservation.” Notes and Records of the Royal Society 66, no. 1 (2011): 55–69.
De Kock, Liesbet. “Voluntarism in Early Psychology: The case of Hermann von Helmholtz.” History of Psychology 17, no. 2 (2014): 105–28.
Hui, A. E. “Instruments of Music, Instruments of Science: Hermann von Helmholtz's Musical Practices, His Classicism, and His Beethoven Sonata.” Annals of Science 68, no. 2 (2011): 149–77.
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