Young T
NAME:
Young, Thomas.
ACHIEVEMENT(S): One of the outstanding personalities in the world of science, arts, and medicine in the early 19th century.
NICKNAME/ALIAS:
None.
DATE/PLACE OF BIRTH:
13th June 1773, in Milverton, Somerset, England.
DATE/PLACE/AGE AT DEATH:
10th May 1829, in London, England. Aged 55.
DISCIPLINE:
Physicist, Egyptologist.
FIELD:
Physics, egyptology
LANGUAGE:
English.
PARENTS:
Thomas Young and Sara Davis.
SIBLINGS:
Nine younger siblings.
SPOUSE:
Eliza Primrose Maxwell (1785-1859), married 1804.
CHILDREN:
None.
EDUCATION:
Schools at Bristol and Compton, Dorset, 1780-86; St. Bartholomew's Hospital, 1792-94; University of Edinburgh, 1794-96; University of Gottingen, 1796; Emmanuel College, Cambridge, 1797-1800
MAJOR WORK:
'On the Theory of Light and Colours', 1801.
LIFE AND TIMES:
By 1792 Young had mastered Hebrew, Chaldean, Syriac, Samaritan, Arabic, Persian, Turkish, Ethiopic, Greek and Latin, calculus, Newton's 'Principia' and 'Opticks', and the chemistry of Lavoisier and Joseph Black.
That year, Young began studying medicine at St. Bartholomew's Hospital, London. In 1794, he was elected to the <member of> Royal Society*, and later the same year he moved to Edinburgh to continue his medical studies.
After a tour of Germany, Young went to Emmanuel College, Cambridge, to complete his medical studies, where he became known as "Phenomenon Young". Young's early work was concerned with sense perception and the physiology of vision, a subject which, as in the work of <work related to> Berkeley*, at that time remained as much a philosophical as a physiological problem.
In 1793, while studying at St. Bartholomew's Hospital, he had dissected an ox's eye and saw that focusing at differing distances was due to a change in shape of the lens, the lens being composed of muscle fibres.
Young first reported his theory in a paper to the Royal Society of 1793, "Observations on Vision". The paper caused great controversy because almost everyone disagreed. Young temporarily abandoned his hypothesis before returning to it in 1800, when in a more detailed paper, "On the Mechanism of the Eye", he proved that the lens did change shape, and also showed that astigmatism, from which he himself suffered, was due to irregular curvature of the cornea.
Young was the first to recognize that color sensation was due not to separate mechanisms in the eye for every color, but because of structures in the retina which responded to the three colours red, green and violet. Young' s work in this field was elaborated into a complete theory of vision in the 19th century by <his work furthered by> Helmholtz* and <his work furthered by> Maxwell*, called the Young-Helmholtz three-colour theory.
In 1797, his uncle, Richard Brocklesby, had died, leaving Young his London house, library and paintings, and £10,000.
The following year, Young moved to London, where he set up a medical practice and attended the meetings of the Royal Society. Young was awarded an MB from Cambridge in 1803, and an MD five years later.
In 1898, in London, he developed an interest in the nature of light, about which there was a great controversy, as to whether it was made up of streams of particles or of waves. Young proposed that the wave theory of Christiaan Huygens gave a more convincing explanation for the phenomena of reflection, refraction and diffraction. Young assumed that light waves were propagated in a similar way to sound waves and were longitudinal vibrations with a different medium and frequency, and he proposed that different colours consist of different frequencies.
In 1801, Young announced the discovery of the principal of interference, explaining that the bright bands of fringes in effects such as Newton's rings were the result of light waves interfering so that they reinforced each other.
This was a hypothetical deduction which, over the next two years, Young proved by experiment, by passing monochromatic light through first one narrow pinhole, then through a pair of closely spaced pinholes, and finally onto a screen. He observed that the light beams spread apart and overlapped and, in the area of overlap, produced the characteristic interference fringes of alternate light and dark bands.
Young used his new wave theory of light to explain the colors of thin films, such as soap bubbles, and, relating color to wavelength, he calculated the approximate wavelengths of the seven colours recognized by Newton.
With this demonstration of the interference of light, Young convincingly proved that light consisted of waves, but his ideas were generally criticized, particularly as he had not proved that the waves were longitudinal.
The polarization of light, a discovery in 1808 by Etienne Malus, led Young to propose, in 1817, that light waves may be transverse, vibrating at right angle to the direction of travel. It had long been assumed that light vibrated longitudinally, in the direction of travel. Young’s theory explained polarization, the alignment of light waves to vibrate in the same plane.
In 1821, the French physicists <theory proved by> Fresnel* and <theory proved by> Arago* proved that light waves were entirely transverse, and established the wave nature of light, at which point Young's theory was finally accepted in Europe.
At the Royal Society, Young had met Benjamin Thompson, <hired by> Rumford*, founder of the Royal Institution, who, in 1801 appointed him professor of natural philosophy. As a lecturer at the Royal Institution, Young's first job was to prepare popular lectures on natural philosophy and the mechanical arts, which he delivered in 1802 and 1803.
Young introduced absolute measurements in elasticity by defining the modulus as the weight which would double the length of a rod of unit cross-section. Today it is usually referred to as Young's modulus, a constant in the mathematical equation describing elasticity, and equals stress divided by strain in the elastic region of the loading of a material.
In 1805, Young published his 'Essay on the Cohesion of Fluids' which contained the theory of capillary action and accounted for the angle of contact in surface-tension effects for liquids.
His contributions to medical literature concerned the function of the heart, using his earlier investigations of hydraulics, tuberculosis, classification of diseases, and the development of the clinical eriometer, an instrument for measuring the diameter of fibre particles and red blood cells.
From 1814 to 1825 Young worked on a wide range of subjects for the fourth edition of the 'Encyclopaedia Britannica', and he wrote 19 biographies of contemporary men of science.
In 1816, he was a consultant to the commission, which included the engineers <on committee with> Telford* and <on committee with> Rennie*, to assess designs for a new London Bridge.
He held several other positions, including Secretary of the Commission on Weights and Measures, Secretary of the Board of Longitude, which included <on committee with> Banks* and <on board with> Wollaston*, and was Foreign Secretary and Council Member of the Royal Society from 1804 until his death.
From 1815 onwards, Young was one of the first to interpret the writings on the Rosetta Stone, found during Napoleon's expedition, organized by <work related to> Conte*, in 1799. After studying hieroglyphic writings from other sources, Young was able to provide a nearly accurate translation of the stone within a few years, contributing greatly to deciphering the ancient Egyptian language.
In 1818, he published his work on hieroglyphics in the Encyclopedia Britannica, and established a hieroglyphic vocabulary of about 200 signs. This vocabulary greatly assisted French Egyptologist, <influenced> Champollion*, who published his own translations of the Rosetta Stone in 1822-24.
His final work was published the year after his death, as 'Enchorial Egyptian Dictionary'.
ASSESSMENT: Thomas Young established the principle of interference of light. In
proving that light travels in waves, Young discovered interference between wave patterns and founded the science of interferometry. His discoveries in vision were fundamental to an understanding of visual problems and to color reproduction, and he proposed a theory of color vision which, for the first time, suggested that the brain might not only receive information, but alsoprocessed and integrated the information it received. His interpretation of some Egyptian hieroglyphics, including the Rosetta Stone, paved the way for work on the subject.
EXTRA CONNECTIONS:
<work used by> Eiffel* used his modulus when building his tower
He was a fellow-student of <fellow-student of> Birkbeck*
His biography was written by <biography written by>George Peacock*
BIBLIOGRAPHY:
Wood, Alexander, Thomas Young, Natural Philosopher, 1773-1829, Cambridge, Cambridge University Press, 1954.