Hermann von Helmholtz

Hermann von Helmholtz was a physicist, professor in physiology, mathematician, surgeon, military veteran, philosopher, inventor, and a key figure of the 19th century for perception and attention. He was born August 31, 1821 in Potsdam Germany and passed on in Berlin 1894 at the age of 73, cause of death unknown. Hermon von Helmholtz is said to have a relation through his mother’s side to William Penn, the founder of Pennsylvania (Nndb, 2011). His father was a major influence on him as a military veteran and as a teacher of philosophy in the Potsdam Gymnasium (a job that did not pay well); he naturally exposed his son to the earlier philosophers such as Immanuel Kant which would later shape Hermon von Helmholtz’s way of thinking (Encyclopedia Britannica, 2011). He came from a not-so wealthy family, as the oldest of four children. Later he joined the Prussian army as a surgeon, rather than adhering to strictly scholarly endeavors early in his life (Nndb, 2011). Further on he would end up making several huge breakthroughs and contributions to just about every field of science.

Key Findings

Helmholtz most notable contributions to the fields are his Conservation of Energy Law, the Theory of Unconscious Inference, the Young-Helmholtz Theory of Color Vision, the invention of the ophthalmoscope, the Theory of Differential and Summational Tones, and his arguments against vitalism and natural philosophy, as well as much more that can not even be relevantly mentioned.
The Theory of Unconscious Inference says that perceptions are the result of unconscious assumptions made on our environment. These assumptions are based on the likelihood principle. “The observer brings his or her own knowledge of the environment in order to infer what the object might be” (Goldstein, 2010).
Helmholtz found that nerve impulses can be measured with his invention of the myograph. He also developed the ophthalmoscope. Using his mathematical prowess, he showed there is a possibility of non-Euclidean space. ("Encyclopedia Britannica," 2011)

A theory of color vision was proposed earlier by Thomas Young (1802) and later revised by Helmholtz (1852) in what is now known as the Young-Helmholtz Theory of Color Vision. “Color vision depends on three receptor mechanisms…the pattern of activity in the three mechanisms results in the perception of a color.” (Goldstein, 2010). The three receptors would later be found out to be three different types of cones that respond to the three primary colors.
(Goldstein, 2010)

In his work with eyes, Helmholtz invented the ophthalmoscope and the opthalmometer in 1851. Physicians still use the scope to examine retinal blood vessels to check for high blood pressure and arterial disease, and the opthalmometer is a key in measuring the accommodation of the eye in different circumstances for prescription of eyeglasses ("Encyclopedia Britannica," 2011).
“He explained accurately the mechanism of the bones of the ear, and he discussed the physiological action of the cochlea on the principles of sympathetic vibration” (Nndb, 2011).
Now we have technologies such as cochlear implants that aid the deaf in hearing that would not be possible without the foundation he laid. Then there is his theory of quality of tone where he showed that quality depends on order, number and intensity of overtones or harmonics that may make a tone musical. He also came up with the fixed pitch theory of how vowels sounds are so according to resonance of the mouth (Nndb, 2011). Don’t stop there; he came up with the theory of differential and summational tones. He of course did much more with acoustics but that is for another time.

Helmholtz is criticized for a controversial claim to the Conservation of Energy Law.

“On the 23rd of July in 1847, Helmholtz gave an address, “The Conservation of Force,” at the Physical Society. “Force” [Kraft], as Helmholtz uses it, is equivalent to the modern term ‘energy’.” (Lydia, 2008).

“In 1842–1843, Robert Mayer and James Joule had formulated principles of the conservation of energy. Their work asserted the conservation of mv2, the mass of a particle times the square of its velocity. Further, Joule and Mayer argued that heat and mechanical work are interchangeable (see Kuhn 1969, Mach 1911). Helmholtz called on Joule's work (though he claimed to be unaware of Meyer's) to achieve three results.” (Lydia, 2008).

The criticism comes from the unawareness he claimed regarding Meyer’s previous work and this law should therefore be attributed to the works of many prominent scientists. Helmholtz is already known for expanding on a theory which is the Young-Helmholtz theory of color vision, though he still pushed science in a further direction, maybe he should not get 100% of the credit.

“Helmholtz acknowledged in his essay that earlier scientists, including Joule, Newton, Bernoulli, and Rumford, had arrived at various forms of the principle of energy conservation. In his history of mechanics, Ernst Mach argues that some form of Helmholtz's principle was known to “almost all eminent investigators” in history (Mach 1911, 20). In his landmark study of energy conservation, Thomas Kuhn presents the work of Joule, Mayer, and others from the 1830's, which argues that heat and work can be substituted for each other quantitatively, which is a significant component of Helmholtz's principle (Kuhn 1969, 321, see also Weber 2000, 279). Kuhn argues that the discovery of the principle of energy conservation is a case in which several scientists lay the experimental and conceptual framework for a principle together.” (Lydia, 2008).

Because of his more mathematical and physiological approach to science, he faced criticisms of his teaching.
“Before the publication of this paper Helmholtz had become unhappy with his new position in Bonn [as professor of anatomy and physiology]. Part of the problem seemed to revolve round the fact that the chair involved anatomy and complaints were made to the Minister of Education that his lectures on this topic were incompetent. Helmholtz reacted strongly to these criticisms which, he felt, were made by traditionalists who did not understand his new mechanical approach to the subject. It was a somewhat strange position for Helmholtz to be in for he had a very strong reputation as a leading world scientist. When he was offered the chair in Heidelberg in 1857, he did not accept at once however. When further sweeteners were put forward in 1858 to entice him to accept, such as the promise of setting up a new Physiology Institute, Helmholtz agreed.” (O'connor, 2001).

--Dillon B.