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Thomas Young (scientist)
Encyclopedia
Thomas Young was an English
polymath
. He is famous for having partly deciphered Egyptian hieroglyphics (specifically the Rosetta Stone
) before Jean-François Champollion
eventually expanded on his work. He was admired by, among others, Herschel
and Einstein.
Young made notable scientific contributions to the fields of vision
, light
, solid mechanics
, energy
, physiology
, language
, musical harmony
and Egyptology
.
, Somerset
, where he was born in 1773, the eldest of ten children. At the age of fourteen Young had learned Greek
and Latin
and was acquainted with French
, Italian
, Hebrew
, German
, Chaldean
, Syriac
, Samaritan, Arabic
, Persian
, Turkish
and Amharic.
Young began to study medicine in London
in 1792, moved to Edinburgh
in 1794, and a year later went to Göttingen
, Lower Saxony
, Germany
where he obtained the degree of doctor of physics
in 1796. In 1797 he entered Emmanuel College, Cambridge
. In the same year he inherited the estate of his granduncle, Richard Brocklesby
, which made him financially independent, and in 1799 he established himself as a physician
at 48 Welbeck Street
, London (now recorded with a blue plaque
). Young published many of his first academic articles anonymously to protect his reputation as a physician.
In 1801 Young was appointed professor of natural philosophy
(mainly physics
) at the Royal Institution
. In two years he delivered 91 lectures. In 1802, he was appointed foreign secretary of the Royal Society
, of which he had been elected a fellow in 1794. He resigned his professorship in 1803, fearing that its duties would interfere with his medical practice. His lectures were published in 1807 in the Course of Lectures on Natural Philosophy and contain a number of anticipations of later theories.
In 1811 Young became physician to St. George's Hospital, and in 1814 he served on a committee appointed to consider the dangers involved in the general introduction of gas
into London. In 1816 he was secretary of a commission charged with ascertaining the precise length of the second's or seconds pendulum
(the length of a pendulum whose period is exactly 2 seconds), and in 1818 he became secretary to the Board of Longitude
and superintendent of the HM Nautical Almanac Office
.
A few years before his death he became interested in life insurance
, and in 1827 he was chosen one of the eight foreign associates of the French Academy of Sciences
. In 1828, he was elected a foreign member of the Royal Swedish Academy of Sciences
.
Thomas Young died in London on 10 May 1829, and was buried in the cemetery of St. Giles Church in Farnborough
, Kent
, England.
Later scholars and scientists have praised Young's work although they may know him only through achievements he made in their fields. His contemporary Sir John Herschel
called him a "truly original genius". Albert Einstein
praised him in the 1931 foreword to an edition of Newton
's Opticks. Other admirers include physicist Lord Rayleigh and Nobel laureate Philip Anderson
.
Thomas Young's name has been adopted as the name of the London-based Thomas Young Centre
, an alliance of academic research groups engaged in the theory and simulation of materials.
he demonstrated the idea of interference in the context of water waves. With the two-slit, or double-slit experiment
, he demonstrated interference in the context of light as a wave. In a paper entitled Experiments and Calculations Relative to Physical Optics, published in 1804, Young describes an experiment in which he placed a narrow card (approx. 1/30th in.) in a beam of light
from a single opening in a window and observed the fringes of color in the shadow and to the sides of the card. He observed that placing another card before or after the narrow strip so as to prevent light from the beam from striking one of its edges caused the fringes to disappear. This supported the contention that light is composed of wave
s. Young performed and analyzed a number of experiments, including interference of light from reflection off nearby pairs of micrometer grooves, from reflection off thin films of soap and oil, and from Newton's rings
. He also performed two important diffraction experiments using fibers and long narrow strips. In his Course of Lectures on Natural Philosophy and the Mechanical Arts (1807) he gives Grimaldi
credit for first observing the fringes in the shadow of an object placed in a beam of light. Within ten years, much of Young's work was reproduced and then extended by Fresnel. (Tony Rothman
in Everything's Relative and Other Fables from Science and Technology argues that there is no clear evidence that Young actually did the two-slit experiment. See also Newton
wave–particle duality
.)
, denoted as E, in 1807, and further described it in his Course of Lectures on Natural Philosophy and the Mechanical Arts.
However, the first use of the concept of Young's modulus in experiments was by Giordano Riccati
in 1782 – predating Young by 25 years.
Furthermore, the idea can be traced back to a paper by Leonhard Euler
published in 1727, some 80 years before Thomas Young's 1807 paper.
The Young's modulus relates the stress (pressure) in a body to its associated strain (change in length as a ratio of the original length); that is, stress = E × strain, for a uniaxially loaded specimen. Young's modulus is independent of the component under investigation; that is, it is an inherent material property (the term modulus refers to an inherent material property). Young's Modulus allowed, for the first time, prediction of the strain in a component subject to a known stress (and vice versa). Prior to Young's contribution, engineers were required to apply Hooke's F = kx relationship to identify the deformation (x) of a body subject to a known load (F), where the constant (k) is a function of both the geometry and material under consideration. Finding k required physical testing for any new component, as the F = kx relationship is a function of both geometry and material. Young's Modulus depends only on the material, not its geometry, thus allowing a revolution in engineering strategies.
itself to vision at different distances as depending on change of the curvature of the crystalline lens; in 1801 he was the first to describe astigmatism
; and in his Lectures he presented the hypothesis, afterwards developed by Hermann von Helmholtz
, that colour perception depends on the presence in the retina of three kinds of nerve fibres which respond respectively to red, green and violet light. This foreshadowed the modern understanding of color vision
, in particular the finding that the eye does indeed have three color receptors which are sensitive to different wavelength ranges.
. He also observed the constancy of the angle of contact of a liquid surface with a solid, and showed how from these two principles to deduce the phenomena of capillary action.
In 1805 Pierre-Simon Laplace
, the French philosopher, discovered the significance of meniscus radii with respect to capillary action.
In 1830 Carl Friedrich Gauss
, the German mathematician, unified the work of these two scientists to derive the Young–Laplace equation
, the formula that describes the capillary pressure difference sustained across the interface between two static fluids.
Young was the first to define the term "energy" in the modern sense.
of a liquid drop on a plane solid surface as a function of the surface free energy, the interfacial free energy and the surface tension of the liquid. Young’s equation was developed further some 60 years later by Dupré to account for thermodynamic effects, and this is known as the Young–Dupré equation.
Young devised a rule of thumb for determining a child’s drug dosage. Young’s Rule states that the child dosage is equal to the adult dosage multiplied by the child’s age in years, divided by the sum of 12 plus the child’s age.
In his Encyclopædia Britannica article "Languages", Young compared the grammar and vocabulary of 400 languages. In a separate work in 1813, he introduced the term Indo-European languages
, 165 years after the Dutch linguist and scholar Marcus Zuerius van Boxhorn
proposed the grouping to which this term refers in 1647.
Egyptian hieroglyphs
, with the help of a demotic alphabet of 29 letters built up by Johan David Åkerblad
in 1802 (14 turned out to be incorrect), but Åkerblad wrongly believed that demotic was entirely alphabetic. "Dr Young however showed that neither the alphabet of Akerblad, nor any modification of it which could be proposed, was applicable to any considerable part of the enchorial portion of the Rosetta inscription beyond the proper names." By 1814 Young had completely translated the "enchorial" (demotic
, in modern terms) text of the Rosetta Stone
(he had a list with 86 demotic words), and then studied the hieroglyphic alphabet but initially failed to recognize that the demotic and hieroglyphic texts were paraphrases and not simple translations. Some of Young's conclusions appeared in the famous article "Egypt" he wrote for the 1818 edition of the Encyclopædia Britannica.
When the French linguist Jean-François Champollion
in 1822 published a translation of the hieroglyphs and the key to the grammatical system, Young (and many others) praised his work. In 1823 Young published an Account of the Recent Discoveries in Hieroglyphic Literature and Egyptian Antiquities, in order to have his own work recognised as the basis for Champollion's system. In this he made it clear that many of his findings had been published and sent to Paris in 1816. Young had correctly found the sound value of six signs, but had not deduced the grammar of the language. Champollion was unwilling to share the credit. In the ensuing schism, strongly motivated by the political tensions of that time, the British championed Young, while the French supported Champollion. Champollion maintained that he alone had deciphered the hieroglyphs, although his understanding of the hieroglyphic grammar showed the same mistakes made by Young. However, after 1826, when Champollion was a curator in the Louvre
he did offer Young access to demotic manuscripts.
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
polymath
Polymath
A polymath is a person whose expertise spans a significant number of different subject areas. In less formal terms, a polymath may simply be someone who is very knowledgeable...
. He is famous for having partly deciphered Egyptian hieroglyphics (specifically the Rosetta Stone
Rosetta Stone
The Rosetta Stone is an ancient Egyptian granodiorite stele inscribed with a decree issued at Memphis in 196 BC on behalf of King Ptolemy V. The decree appears in three scripts: the upper text is Ancient Egyptian hieroglyphs, the middle portion Demotic script, and the lowest Ancient Greek...
) before Jean-François Champollion
Jean-François Champollion
Jean-François Champollion was a French classical scholar, philologist and orientalist, decipherer of the Egyptian hieroglyphs....
eventually expanded on his work. He was admired by, among others, Herschel
William Herschel
Sir Frederick William Herschel, KH, FRS, German: Friedrich Wilhelm Herschel was a German-born British astronomer, technical expert, and composer. Born in Hanover, Wilhelm first followed his father into the Military Band of Hanover, but emigrated to Britain at age 19...
and Einstein.
Young made notable scientific contributions to the fields of vision
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...
, light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
, solid mechanics
Solid mechanics
Solid mechanics is the branch of mechanics, physics, and mathematics that concerns the behavior of solid matter under external actions . It is part of a broader study known as continuum mechanics. One of the most common practical applications of solid mechanics is the Euler-Bernoulli beam equation...
, energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
, physiology
Physiology
Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...
, language
Language
Language may refer either to the specifically human capacity for acquiring and using complex systems of communication, or to a specific instance of such a system of complex communication...
, musical harmony
Harmony
In music, harmony is the use of simultaneous pitches , or chords. The study of harmony involves chords and their construction and chord progressions and the principles of connection that govern them. Harmony is often said to refer to the "vertical" aspect of music, as distinguished from melodic...
and Egyptology
Egyptology
Egyptology is the study of ancient Egyptian history, language, literature, religion, and art from the 5th millennium BC until the end of its native religious practices in the AD 4th century. A practitioner of the discipline is an “Egyptologist”...
.
Biography
Young belonged to a Quaker family of MilvertonMilverton, Somerset
Milverton is a village and civil parish in Somerset, England, situated in the valley of the River Tone west of Taunton in the Taunton Deane district. The village has a population of 1,385...
, Somerset
Somerset
The ceremonial and non-metropolitan county of Somerset in South West England borders Bristol and Gloucestershire to the north, Wiltshire to the east, Dorset to the south-east, and Devon to the south-west. It is partly bounded to the north and west by the Bristol Channel and the estuary of the...
, where he was born in 1773, the eldest of ten children. At the age of fourteen Young had learned Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
and Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
and was acquainted with French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...
, Italian
Italian language
Italian is a Romance language spoken mainly in Europe: Italy, Switzerland, San Marino, Vatican City, by minorities in Malta, Monaco, Croatia, Slovenia, France, Libya, Eritrea, and Somalia, and by immigrant communities in the Americas and Australia...
, Hebrew
Hebrew language
Hebrew is a Semitic language of the Afroasiatic language family. Culturally, is it considered by Jews and other religious groups as the language of the Jewish people, though other Jewish languages had originated among diaspora Jews, and the Hebrew language is also used by non-Jewish groups, such...
, German
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....
, Chaldean
Chaldean Neo-Aramaic
Chaldean Neo-Aramaic is a Northeastern Neo-Aramaic dialect. Chaldean Neo-Aramaic is spoken on the plain of Mosul in northern Iraq, as well as by the Chaldean communities worldwide. Most speakers are Chaldean Catholics....
, Syriac
Syriac language
Syriac is a dialect of Middle Aramaic that was once spoken across much of the Fertile Crescent. Having first appeared as a script in the 1st century AD after being spoken as an unwritten language for five centuries, Classical Syriac became a major literary language throughout the Middle East from...
, Samaritan, Arabic
Arabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...
, Persian
Persian language
Persian is an Iranian language within the Indo-Iranian branch of the Indo-European languages. It is primarily spoken in Iran, Afghanistan, Tajikistan and countries which historically came under Persian influence...
, Turkish
Turkish language
Turkish is a language spoken as a native language by over 83 million people worldwide, making it the most commonly spoken of the Turkic languages. Its speakers are located predominantly in Turkey and Northern Cyprus with smaller groups in Iraq, Greece, Bulgaria, the Republic of Macedonia, Kosovo,...
and Amharic.
Young began to study medicine in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
in 1792, moved to Edinburgh
Edinburgh
Edinburgh is the capital city of Scotland, the second largest city in Scotland, and the eighth most populous in the United Kingdom. The City of Edinburgh Council governs one of Scotland's 32 local government council areas. The council area includes urban Edinburgh and a rural area...
in 1794, and a year later went to Göttingen
Göttingen
Göttingen is a university town in Lower Saxony, Germany. It is the capital of the district of Göttingen. The Leine river runs through the town. In 2006 the population was 129,686.-General information:...
, Lower Saxony
Lower Saxony
Lower Saxony is a German state situated in north-western Germany and is second in area and fourth in population among the sixteen states of Germany...
, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
where he obtained the degree of doctor of physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
in 1796. In 1797 he entered Emmanuel College, Cambridge
Emmanuel College, Cambridge
Emmanuel College is a constituent college of the University of Cambridge.The college was founded in 1584 by Sir Walter Mildmay on the site of a Dominican friary...
. In the same year he inherited the estate of his granduncle, Richard Brocklesby
Richard Brocklesby
Richard Brocklesby , an English physician, was born at Minehead, Somerset.He was educated at Ballitore, in Ireland, where Edmund Burke was one of his school fellows, studied medicine at Edinburgh, and finally graduated at Leiden in 1745...
, which made him financially independent, and in 1799 he established himself as a physician
Physician
A physician is a health care provider who practices the profession of medicine, which is concerned with promoting, maintaining or restoring human health through the study, diagnosis, and treatment of disease, injury and other physical and mental impairments...
at 48 Welbeck Street
Welbeck Street
Welbeck Street is a street in the West End, central London, England. It has historically been associated with the medical profession.- Location :...
, London (now recorded with a blue plaque
Blue plaque
A blue plaque is a permanent sign installed in a public place to commemorate a link between that location and a famous person or event, serving as a historical marker....
). Young published many of his first academic articles anonymously to protect his reputation as a physician.
In 1801 Young was appointed professor of natural philosophy
Natural philosophy
Natural philosophy or the philosophy of nature , is a term applied to the study of nature and the physical universe that was dominant before the development of modern science...
(mainly physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
) at the Royal Institution
Royal Institution
The Royal Institution of Great Britain is an organization devoted to scientific education and research, based in London.-Overview:...
. In two years he delivered 91 lectures. In 1802, he was appointed foreign secretary of the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
, of which he had been elected a fellow in 1794. He resigned his professorship in 1803, fearing that its duties would interfere with his medical practice. His lectures were published in 1807 in the Course of Lectures on Natural Philosophy and contain a number of anticipations of later theories.
In 1811 Young became physician to St. George's Hospital, and in 1814 he served on a committee appointed to consider the dangers involved in the general introduction of gas
Gas lighting
Gas lighting is production of artificial light from combustion of a gaseous fuel, including hydrogen, methane, carbon monoxide, propane, butane, acetylene, ethylene, or natural gas. Before electricity became sufficiently widespread and economical to allow for general public use, gas was the most...
into London. In 1816 he was secretary of a commission charged with ascertaining the precise length of the second's or seconds pendulum
Seconds pendulum
A seconds pendulum is a pendulum whose period is precisely two seconds; one second for a swing in one direction and one second for the return swing, a frequency of 1/2 Hz....
(the length of a pendulum whose period is exactly 2 seconds), and in 1818 he became secretary to the Board of Longitude
Board of Longitude
The Board of Longitude was the popular name for the Commissioners for the Discovery of the Longitude at Sea. It was a British Government body formed in 1714 to administer a scheme of prizes intended to encourage innovators to solve the problem of finding longitude at sea.-Origins:Navigators and...
and superintendent of the HM Nautical Almanac Office
HM Nautical Almanac Office
Her Majesty's Nautical Almanac Office , now part of the United Kingdom Hydrographic Office, was established in 1832 on the site of the Royal Greenwich Observatory , where the Nautical Almanac had been published since 1767...
.
A few years before his death he became interested in life insurance
Life insurance
Life insurance is a contract between an insurance policy holder and an insurer, where the insurer promises to pay a designated beneficiary a sum of money upon the death of the insured person. Depending on the contract, other events such as terminal illness or critical illness may also trigger...
, and in 1827 he was chosen one of the eight foreign associates of the French Academy of Sciences
French Academy of Sciences
The French Academy of Sciences is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research...
. In 1828, he was elected a foreign member of the Royal Swedish Academy of Sciences
Royal Swedish Academy of Sciences
The Royal Swedish Academy of Sciences or Kungliga Vetenskapsakademien is one of the Royal Academies of Sweden. The Academy is an independent, non-governmental scientific organization which acts to promote the sciences, primarily the natural sciences and mathematics.The Academy was founded on 2...
.
Thomas Young died in London on 10 May 1829, and was buried in the cemetery of St. Giles Church in Farnborough
Farnborough, London
Farnborough is a settlement in the London Borough of Bromley. It is a suburban development located 13.4 miles southeast of Charing Cross.-History:...
, Kent
Kent
Kent is a county in southeast England, and is one of the home counties. It borders East Sussex, Surrey and Greater London and has a defined boundary with Essex in the middle of the Thames Estuary. The ceremonial county boundaries of Kent include the shire county of Kent and the unitary borough of...
, England.
Later scholars and scientists have praised Young's work although they may know him only through achievements he made in their fields. His contemporary Sir John Herschel
John Herschel
Sir John Frederick William Herschel, 1st Baronet KH, FRS ,was an English mathematician, astronomer, chemist, and experimental photographer/inventor, who in some years also did valuable botanical work...
called him a "truly original genius". Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...
praised him in the 1931 foreword to an edition of Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
's Opticks. Other admirers include physicist Lord Rayleigh and Nobel laureate Philip Anderson
Philip Anderson
Philip Anderson may refer to:* Phil Anderson , cyclist* Philip Carr Anderson, , professor of medicine* Philip W. Anderson , film editor* Philip Warren Anderson , physicist-See also:...
.
Thomas Young's name has been adopted as the name of the London-based Thomas Young Centre
Thomas Young Centre
The Thomas Young Centre is an alliance of London research groups working on the theory and simulation ofmaterials .It is named after the celebrated scientist and polymath Thomas Young , who lived and worked in London and is known in the world of science for a number of important discoveries...
, an alliance of academic research groups engaged in the theory and simulation of materials.
Wave theory of light
In Young's own judgment, of his many achievements the most important was to establish the wave theory of light. To do so, he had to overcome the century-old view, expressed in the venerable Isaac Newton's "Optics", that light is a particle. Nevertheless, in the early 19th century Young put forth a number of theoretical reasons supporting the wave theory of light, and he developed two enduring demonstrations to support this viewpoint. With the ripple tankRipple tank
In physics and engineering, a ripple tank is a shallow glass tank of water used in schools and colleges to demonstrate the basic properties of waves. It is a specialized form of a wave tank. The ripple tank is usually illuminated from above, so that the light shines through the water. Some small...
he demonstrated the idea of interference in the context of water waves. With the two-slit, or double-slit experiment
Double-slit experiment
The double-slit experiment, sometimes called Young's experiment, is a demonstration that matter and energy can display characteristics of both waves and particles...
, he demonstrated interference in the context of light as a wave. In a paper entitled Experiments and Calculations Relative to Physical Optics, published in 1804, Young describes an experiment in which he placed a narrow card (approx. 1/30th in.) in a beam of light
Light beam
A light beam or beam of light is a narrow projection of light energy radiating from a source into a beam. Sunlight is a natural example of a light beam when filtered through various mediums...
from a single opening in a window and observed the fringes of color in the shadow and to the sides of the card. He observed that placing another card before or after the narrow strip so as to prevent light from the beam from striking one of its edges caused the fringes to disappear. This supported the contention that light is composed of wave
Wave
In physics, a wave is a disturbance that travels through space and time, accompanied by the transfer of energy.Waves travel and the wave motion transfers energy from one point to another, often with no permanent displacement of the particles of the medium—that is, with little or no associated mass...
s. Young performed and analyzed a number of experiments, including interference of light from reflection off nearby pairs of micrometer grooves, from reflection off thin films of soap and oil, and from Newton's rings
Newton's rings
The phenomenon of Newton's rings, named after Isaac Newton who first studied them in 1717, is an interference pattern caused by the reflection of light between two surfaces - a spherical surface and an adjacent flat surface...
. He also performed two important diffraction experiments using fibers and long narrow strips. In his Course of Lectures on Natural Philosophy and the Mechanical Arts (1807) he gives Grimaldi
Francesco Maria Grimaldi
Francesco Maria Grimaldi was an Italian Jesuit priest, mathematician and physicist who taught at the Jesuit college in Bologna....
credit for first observing the fringes in the shadow of an object placed in a beam of light. Within ten years, much of Young's work was reproduced and then extended by Fresnel. (Tony Rothman
Tony Rothman
Tony Rothman is an American theoretical physicist, academic and writer.-Early life:Tony is the son of science fiction writer Milton A. Rothman....
in Everything's Relative and Other Fables from Science and Technology argues that there is no clear evidence that Young actually did the two-slit experiment. See also Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
wave–particle duality
Wave–particle duality
Wave–particle duality postulates that all particles exhibit both wave and particle properties. A central concept of quantum mechanics, this duality addresses the inability of classical concepts like "particle" and "wave" to fully describe the behavior of quantum-scale objects...
.)
Young's modulus
Young described the characterization of elasticity that came to be known as Young's modulusYoung's modulus
Young's modulus is a measure of the stiffness of an elastic material and is a quantity used to characterize materials. It is defined as the ratio of the uniaxial stress over the uniaxial strain in the range of stress in which Hooke's Law holds. In solid mechanics, the slope of the stress-strain...
, denoted as E, in 1807, and further described it in his Course of Lectures on Natural Philosophy and the Mechanical Arts.
However, the first use of the concept of Young's modulus in experiments was by Giordano Riccati
Giordano Riccati
Giordano Riccati or Jordan Riccati was the first experimental mechanician to study material elastic moduli as we understand them today. His 1782 paper on determining the relative Young's moduli of steel and brass using flexural vibrations predated Thomas Young's 1807 paper on the subject of moduli...
in 1782 – predating Young by 25 years.
Furthermore, the idea can be traced back to a paper by Leonhard Euler
Leonhard Euler
Leonhard Euler was a pioneering Swiss mathematician and physicist. He made important discoveries in fields as diverse as infinitesimal calculus and graph theory. He also introduced much of the modern mathematical terminology and notation, particularly for mathematical analysis, such as the notion...
published in 1727, some 80 years before Thomas Young's 1807 paper.
The Young's modulus relates the stress (pressure) in a body to its associated strain (change in length as a ratio of the original length); that is, stress = E × strain, for a uniaxially loaded specimen. Young's modulus is independent of the component under investigation; that is, it is an inherent material property (the term modulus refers to an inherent material property). Young's Modulus allowed, for the first time, prediction of the strain in a component subject to a known stress (and vice versa). Prior to Young's contribution, engineers were required to apply Hooke's F = kx relationship to identify the deformation (x) of a body subject to a known load (F), where the constant (k) is a function of both the geometry and material under consideration. Finding k required physical testing for any new component, as the F = kx relationship is a function of both geometry and material. Young's Modulus depends only on the material, not its geometry, thus allowing a revolution in engineering strategies.
Vision and colour theory
Young has also been called the founder of physiological optics. In 1793 he explained the mode in which the eye accommodatesAccommodation (eye)
Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image on an object as its distance changes....
itself to vision at different distances as depending on change of the curvature of the crystalline lens; in 1801 he was the first to describe astigmatism
Astigmatism
An optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances...
; and in his Lectures he presented the hypothesis, afterwards developed by Hermann von Helmholtz
Hermann von Helmholtz
Hermann Ludwig Ferdinand von Helmholtz was a German physician and physicist who made significant contributions to several widely varied areas of modern science...
, that colour perception depends on the presence in the retina of three kinds of nerve fibres which respond respectively to red, green and violet light. This foreshadowed the modern understanding of color vision
Color vision
Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths of the light they reflect, emit, or transmit...
, in particular the finding that the eye does indeed have three color receptors which are sensitive to different wavelength ranges.
Young–Laplace equation
In 1804, Young developed the theory of capillary phenomena on the principle of surface tensionSurface tension
Surface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects to run on the water surface...
. He also observed the constancy of the angle of contact of a liquid surface with a solid, and showed how from these two principles to deduce the phenomena of capillary action.
In 1805 Pierre-Simon Laplace
Pierre-Simon Laplace
Pierre-Simon, marquis de Laplace was a French mathematician and astronomer whose work was pivotal to the development of mathematical astronomy and statistics. He summarized and extended the work of his predecessors in his five volume Mécanique Céleste...
, the French philosopher, discovered the significance of meniscus radii with respect to capillary action.
In 1830 Carl Friedrich Gauss
Carl Friedrich Gauss
Johann Carl Friedrich Gauss was a German mathematician and scientist who contributed significantly to many fields, including number theory, statistics, analysis, differential geometry, geodesy, geophysics, electrostatics, astronomy and optics.Sometimes referred to as the Princeps mathematicorum...
, the German mathematician, unified the work of these two scientists to derive the Young–Laplace equation
Young–Laplace equation
In physics, the Young–Laplace equation is a nonlinear partial differential equation that describes the capillary pressure difference sustained across the interface between two static fluids, such as water and air, due to the phenomenon of surface tension or wall tension, although usage on the...
, the formula that describes the capillary pressure difference sustained across the interface between two static fluids.
Young was the first to define the term "energy" in the modern sense.
Young's equation and Young–Dupré equation
Young’s equation describes the contact angleContact angle
The contact angle is the angle at which a liquid/vapor interface meets a solid surface. The contact angle is specific for any given system and is determined by the interactions across the three interfaces. Most often the concept is illustrated with a small liquid droplet resting on a flat...
of a liquid drop on a plane solid surface as a function of the surface free energy, the interfacial free energy and the surface tension of the liquid. Young’s equation was developed further some 60 years later by Dupré to account for thermodynamic effects, and this is known as the Young–Dupré equation.
Medicine
In physiology Young made an important contribution to haemodynamics in the Croonian lecture for 1808 on the "Functions of the Heart and Arteries," and his medical writings included An Introduction to Medical Literature, including a System of Practical Nosology (1813) and A Practical and Historical Treatise on Consumptive Diseases (1815).Young devised a rule of thumb for determining a child’s drug dosage. Young’s Rule states that the child dosage is equal to the adult dosage multiplied by the child’s age in years, divided by the sum of 12 plus the child’s age.
Languages
In an appendix to his Göttingen dissertation (1796; "De corporis hvmani viribvs conservatricibvs. Dissertatio.") there are four pages added proposing a universal phonetic alphabet (so as 'not to leave these pages blank'; lit.: "Ne vacuae starent hae paginae, libuit e praelectione ante disputationem habenda tabellam literarum vniuersalem raptim describere"). It includes 16 "pure" vowel symbols, nasal vowels, various consonants, and examples of these, drawn primarily from French and English.In his Encyclopædia Britannica article "Languages", Young compared the grammar and vocabulary of 400 languages. In a separate work in 1813, he introduced the term Indo-European languages
Indo-European languages
The Indo-European languages are a family of several hundred related languages and dialects, including most major current languages of Europe, the Iranian plateau, and South Asia and also historically predominant in Anatolia...
, 165 years after the Dutch linguist and scholar Marcus Zuerius van Boxhorn
Marcus Zuerius van Boxhorn
Marcus Zuerius van Boxhorn was a Dutch scholar . Born in Bergen op Zoom, he was professor at the University of Leiden. He discovered the similarity among Indo-European languages, and supposed the existence of a primitive common language which he called 'Scythian'...
proposed the grouping to which this term refers in 1647.
Egyptian hieroglyphs
Young was also one of the first who tried to decipherDECIPHER
DECIPHER is a web-based resource and database of array comparative genomic hybridization data from analysis of patient DNA. It documents submicroscopic chromosome abnormalities, including microdeletions and duplications, from over 6000 patients and maps them to the human genome using the Ensembl...
Egyptian hieroglyphs
Egyptian hieroglyphs
Egyptian hieroglyphs were a formal writing system used by the ancient Egyptians that combined logographic and alphabetic elements. Egyptians used cursive hieroglyphs for religious literature on papyrus and wood...
, with the help of a demotic alphabet of 29 letters built up by Johan David Åkerblad
Johan David Åkerblad
Johan David Åkerblad was a Swedish diplomat and orientalist, a student of Silvestre de Sacy. Sacy's investigation of the Rosetta Stone did not give any result and Åkerblad took on his work in 1802 and managed to identify all proper names in the demotic text in just two months...
in 1802 (14 turned out to be incorrect), but Åkerblad wrongly believed that demotic was entirely alphabetic. "Dr Young however showed that neither the alphabet of Akerblad, nor any modification of it which could be proposed, was applicable to any considerable part of the enchorial portion of the Rosetta inscription beyond the proper names." By 1814 Young had completely translated the "enchorial" (demotic
Demotic
Demotic may refer to:*Demotic Greek, a variety of the Greek language*Demotic , a script and stage of the Egyptian language...
, in modern terms) text of the Rosetta Stone
Rosetta Stone
The Rosetta Stone is an ancient Egyptian granodiorite stele inscribed with a decree issued at Memphis in 196 BC on behalf of King Ptolemy V. The decree appears in three scripts: the upper text is Ancient Egyptian hieroglyphs, the middle portion Demotic script, and the lowest Ancient Greek...
(he had a list with 86 demotic words), and then studied the hieroglyphic alphabet but initially failed to recognize that the demotic and hieroglyphic texts were paraphrases and not simple translations. Some of Young's conclusions appeared in the famous article "Egypt" he wrote for the 1818 edition of the Encyclopædia Britannica.
When the French linguist Jean-François Champollion
Jean-François Champollion
Jean-François Champollion was a French classical scholar, philologist and orientalist, decipherer of the Egyptian hieroglyphs....
in 1822 published a translation of the hieroglyphs and the key to the grammatical system, Young (and many others) praised his work. In 1823 Young published an Account of the Recent Discoveries in Hieroglyphic Literature and Egyptian Antiquities, in order to have his own work recognised as the basis for Champollion's system. In this he made it clear that many of his findings had been published and sent to Paris in 1816. Young had correctly found the sound value of six signs, but had not deduced the grammar of the language. Champollion was unwilling to share the credit. In the ensuing schism, strongly motivated by the political tensions of that time, the British championed Young, while the French supported Champollion. Champollion maintained that he alone had deciphered the hieroglyphs, although his understanding of the hieroglyphic grammar showed the same mistakes made by Young. However, after 1826, when Champollion was a curator in the Louvre
Louvre
The Musée du Louvre – in English, the Louvre Museum or simply the Louvre – is one of the world's largest museums, the most visited art museum in the world and a historic monument. A central landmark of Paris, it is located on the Right Bank of the Seine in the 1st arrondissement...
he did offer Young access to demotic manuscripts.
Selected writings
- A Course of Lectures on Natural Philosophy and the Mechanical Arts (1807, republished 2002 by Thoemmes Press).
- Miscellaneous Works of the Late Thomas Young, M.D., F.R.S. (1855, 3 volumes, editor John Murray, republished 2003 by Thoemmes Press).
Further reading
- The link is to a pdf version of the paper.-
- Reviewed by Nicholas Shakespeare in The Telegraph, September 24, 2006.
- Reviewed by Michael Bywater in The New Statesman, November 13, 2006.
- Reviewed by Simon Singh in The Telegraph, November 26, 2006.
- Reviewed by Rosemary Hill in The Times, December 10, 2006.
- Reviewed by PD Smith in The GuardianThe GuardianThe Guardian, formerly known as The Manchester Guardian , is a British national daily newspaper in the Berliner format...
, January 20, 2007.- Discusses Young's theoretical and experimental work on interference Young's account of his hieroglyphic research. (reissued by Cambridge University PressCambridge University PressCambridge University Press is the publishing business of the University of Cambridge. Granted letters patent by Henry VIII in 1534, it is the world's oldest publishing house, and the second largest university press in the world...
, 2010. ISBN 9781108017169)
External links
- ABC Radio International program (Ockham's Razor) on Thomas Young -- available for download and streaming (as of 9 July 2006)