Young-Helmholtz theory

Young-Helmholtz theory
Young-Helm·holtz theory 'yəŋ-'helm-.hōlts- n a theory in color vision: the eye has three separate elements each of which is stimulated by a different primary color
Young Thomas (1773-1829)
British physician, physicist, and Egyptologist. Young is remembered for his efforts to win broad acceptance for the undulatory theory of light. His research led him to the discovery of accommodation, the means by which the lens of the eye changes shape to focus on objects at differing distances, and to the discovery in 1801 of the cause of astigmatism. He also studied the problem of color perception and proposed that the eye does not have or need a separate mechanism for every individual color but only for three: blue, green, and red. Young's modulus was first defined by him in a lecture on passive strength and friction that appeared in print in 1807. Young is equally famous for being one of the first to translate Egyptian hieroglyphics. He began studying the Rosetta Stone in 1814, and after obtaining additional hieroglyphic writings from other sources, he produced a nearly accurate translation within a few years. His work was a major contribution to the deciphering of the ancient Egyptian language.
Helmholtz Hermann Ludwig Ferdinand von (1821-1894)
German physicist and physiologist. Helmholtz made fundamental contributions to physiology, optics, electrodynamics, and meteorology. He is best known for his statement of the conservation of energy, which he presented in 1847. He invented the ophthalmoscope in 1851, and he determined the mechanisms of focusing in the eye and of the motion of the eyeballs to give single vision. In 1852 he revived the theory of color vision that Young had first postulated in 1801-only to refute it. In 1858 he reversed his position, amending Young's original theory and becoming its foremost advocate. He also examined the structure and function of the organs and bones of the ear and developed the theory that harmonics are determinants of musical tone.

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the doctrine that color vision depends on three sets of retinal fibers, corresponding to the colors red, green, and violet.

Medical dictionary. 2011.

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  • Young–Helmholtz theory — The Young–Helmholtz theory (proposed in the 19th century by Thomas Young and Hermann von Helmholtz) is a theory of trichromatic color vision – the manner in which the photoreceptors in the eyes of humans and other primates work to enable color… …   Wikipedia

  • young-helmholtz theory — ˈyəŋˈhel]mˌhōlts, ˈheu̇] noun Usage: usually capitalized Y&H Etymology: Thomas Young died 1829 English physician and physicist and Hermann L. F. von Helmholtz died 1894 German physicist : a theory in color vision: the eye has three separate… …   Useful english dictionary

  • theory — A reasoned explanation of known facts or phenomena that serves as a basis of investigation by which to seek the truth. SEE ALSO: hypothesis, postulate. [G. theoria, a beholding, speculation, t., fr. theoros, a beholder] adsorption t. of narcosis… …   Medical dictionary

  • Young, Thomas — born June 13, 1773, Milverton, Somerset, Eng. died May 10, 1829, London English physicist. Trained as a physician, he practiced medicine at St. George s Hospital (from 1811 until his death) but spent much of his time on scientific research. He… …   Universalium

  • Helmholtz — Hermann L.F. von, German physician, physicist, and physiologist, 1821–1894. See H. axis ligament, H. energy, H. theory of accommodation, H. theory of color vision, H. theory of hearing, H. Gibbs theory, Gibbs H. equation, Young H. theory of color …   Medical dictionary

  • Young — William John, 20th century Australian biochemist. See Harden Y. ester. Thomas, English physician and physicist, 1773–1829. See Y. modulus, Y. rule, Y. Helmholtz theory of color vision. Hugh H., U.S. urologist, 1870–1945. See Y. prostatic tractor …   Medical dictionary

  • Hermann von Helmholtz — Infobox Scientist name = Hermann von Helmholtz |225px image width = 225px caption = Hermann Ludwig Ferdinand von Helmholtz birth date = birth date|1821|8|31|mf=y birth place = Potsdam, Kingdom of Prussia residence = Germany nationality = German… …   Wikipedia

  • Thomas Young (scientist) — Infobox Scientist name = Thomas Young box width = image width = 240px caption = birth date = birth date|df=yes|1773|06|13 birth place = Milverton, Somerset, England death date = death date and age|df=yes|1829|05|10|1773|06|13 death place = London …   Wikipedia

  • Young —   [jʌȖ],    1) Andrew, amerikanischer Politiker, * New Orleans (La.) 12. 3. 1932; kongregationistischer Geistlicher, engagierte sich als Afroamerikaner in der Bürgerrechtsbewegung, in der er den gemäßigten Flügel repräsentierte, besonders für die …   Universal-Lexikon

  • Helmholtz, Hermann von — ▪ German scientist and philosopher Introduction original name  Hermann Ludwig Ferdinand Helmholtz  born Aug. 31, 1821, Potsdam, Prussia [Germany] died Sept. 8, 1894, Charlottenburg, Berlin, Ger.  German scientist and philosopher who made… …   Universalium

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