Jean Baptiste Joseph Fourier (March 21, 1768 - May 16, 1830) was a French mathematician and physicist who is best known for initiating the investigation of Fourier series and their application to problems of heat flow. The Fourier transform is also named in his honor. March 21 is the 80th day of the year in the Gregorian Calendar (81st in leap years). ... 1768 was a leap year starting on Friday (see link for calendar). ... May 16 is the 136th day of the year in the Gregorian Calendar (137th in leap years). ... 1830 was a common year starting on Friday (see link for calendar). ... A mathematician is a person whose area of study and research is mathematics. ... The word physicist should not be confused with physician, which means medical doctor. ... In mathematics, a Fourier series, named in honor of Joseph Fourier (1768-1830), is a representation of a periodic function (often taken to have period 2π — in a sense, the simplest case) as a sum of periodic functions of the form which are harmonics of ei x. ... The Fourier transform, named after Jean Baptiste Joseph Fourier, is an integral transform that re-expresses a function in terms of sinusoidal basis functions, i. ...

He was born at Auxerre in the Yonne département of France, the son of a tailor, and was educated by the Benedictines. The commissions in the scientific corps of the army were reserved for those of good birth, and being thus ineligible he accepted a military lectureship on mathematics. He took a prominent part in his own district in promoting the revolution, and was rewarded by an appointment in 1795 in the École Normale Supérieure, and subsequently by a chair at the École Polytechnique. Auxerre is a commune in the Burgundy (French Bourgogne) région of France, between Paris and Dijon. ... Yonne is a French département named after the Yonne River. ... The départements (or departments) are administrative units of France, roughly analogous to British counties and are now grouped into 22 metropolitan and four overseas régions. ... A Benedictine is a person who follows the Rule of Saint Benedict, whether belonging to the Roman Catholic Church, or to one of the Anglican or Protestant churches. ... 1795 was a common year starting on Thursday (see link for calendar). ... The quadrangle at the main ENS building on rue dUlm is known as the Cour aux Ernests – the Ernests being the goldfish in the pond. ... The cadets of Polytechnique rushed to the defense of Paris against the foreign armies in 1814. ...

Joseph Fourier

Fourier went with Napoleon on his Eastern expedition in 1798, and was made governor of Lower Egypt. Cut off from France by the English fleet, he organized the workshops on which the French army had to rely for their munitions of war. He also contributed several mathematical papers to the Egyptian Institute which Napoleon founded at Cairo, with a view of weakening English influence in the East. After the British victories and the capitulation of the French under General Menou in 1801, Fourier returned to France, and was made prefect of Isère, and it was while there that he made his experiments on the propagation of heat. He moved to Paris in 1816. In 1822 he published his Théorie analytique de la chaleur, in which he bases his reasoning on Newton's law of cooling, namely, that the flow of heat between two adjacent molecules is proportional to the extremely small difference of their temperatures. In this work he claims that any functions of a variable, whether continuous or discontinuous, can be expanded in a series of sines of multiples of the variable - this result isn't correct at all. But the fact that some discontinuous functions are the sum of infinite series was a breakthrough. The question of determining when a function is the sum of its Fourier series has been fundamental for centuries. Lagrange had given particular cases of this (false) theorem, and had implied that the method was general, but he had not pursued the subject. Dirichlet was the first to give a satisfactory demonstration of it, with some restrictive conditions. Imagge of fourier (the person) - from http://www-history. ... Imagge of fourier (the person) - from http://www-history. ... For other uses, see Napoleon (disambiguation). ... 1798 was a common year starting on Monday (see link for calendar). ... View of the modern citys skyline. ... 1801 was a common year starting on Thursday (see link for calendar). ... Isère is a département in the east of France named after the Isère River. ... 1816 was a leap year starting on Monday (see link for calendar). ... 1822 was a common year starting on Tuesday (see link for calendar). ... Heat flow along perfectly insulated wire Conduction is the transfer of heat or electric current from one substance to another by direct contact. ... In mathematics, a Fourier series, named in honor of Joseph Fourier (1768-1830), is a representation of a periodic function (often taken to have period 2π — in a sense, the simplest case) as a sum of periodic functions of the form which are harmonics of ei x. ... In mathematics, a Fourier series, named in honor of Joseph Fourier (1768-1830), is a representation of a periodic function (often taken to have period 2π — in a sense, the simplest case) as a sum of periodic functions of the form which are harmonics of ei x. ... Joseph Louis Lagrange Joseph Louis Lagrange (January 25, 1736 – April 10, 1813) was an Italian mathematician and astronomer who later lived in France and Prussia. ... Johann Peter Gustav Lejeune Dirichlet (February 13, 1805 - May 5, 1859) was a German mathematician credited with the modern formal definition of a function. ...

Fourier left an unfinished work on determinate equations which was edited by Claude Navier, and published in 1831; this contains much original matter, in particular there is a demonstration of Fourier's theorem on the position of the roots of an algebraic equation. Lagrange had shown how the roots of an algebraic equation might be separated by means of another equation whose roots were the squares of the differences of the roots of the original equation. François Budan, in 1807 and 1811, had enunciated the theorem generally known by the name of Fourier, but the demonstration was not altogether satisfactory. Fourier's proof is the same as that usually given in textbooks on the theory of equations. The final solution of the problem was given in 1829 by Jacques Charles François Sturm (1803--1855). 1831 was a common year starting on Saturday (see link for calendar). ... Joseph Louis Lagrange Joseph Louis Lagrange (January 25, 1736 – April 10, 1813) was an Italian mathematician and astronomer who later lived in France and Prussia. ... 1807 was a common year starting on Thursday (see link for calendar). ... 1811 was a common year starting on Tuesday (see link for calendar). ... 1829 was a common year starting on Thursday (see link for calendar). ... Jacques Charles François Sturm (September 29, 1803 - December 15, 1855), French mathematician, of German extraction, was born in Geneva. ... 1803 was a common year starting on Saturday (see link for calendar). ... 1855 was a common year starting on Monday (see link for calendar). ...

Fourier is also credited with the discovery in his essay in 1824 that gases in the atmosphere might increase the surface temperature of the Earth. This was the effect that would later be called the greenhouse effect. He established the concept of planetary energy balance. That planets obtain energy from number of sources that causes temperature increase. Planets also lose energy by infrared radiation (that Fourier called "chaleur obscure" or "dark heat") with the rate increasing with temperature. Therefore some temperature balance is reached. And atmosphere shifts the balance toward the higher temperatures due to consumption of radiation. Fourier recognized that Earth primarily gets energy from Sun radiation for which atmosphere is transparent and that internal Earth heat doesn't contribute much to the energy balance. However he incorrectly believed that there is a significant contribution of radiation from interplanetary space. Fourier reported on an experiment by M. de Saussure with a black box exposed to the Sun, and in which if thin glass is put on top of the box the temperature inside of the box increases [1] (http://www.wmconnolley.org.uk/sci/fourier_1827/fourier_1827.html#text). Infrared radiation was only discovered by Frederick Herschel 25 years later. Fourier understood that rate of infrared radiation increases with temperature but exact form of this dependency Stefan-Boltzmann law (fourth-power law) was only discovered 50 years later. 1824 was a leap year starting on Thursday (see link for calendar). ... The greenhouse effect, first discovered by Jean Baptiste Joseph Fourier in 1824, is the process by which an atmosphere warms a planet. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... Atmosphere may refer to: a celestial body atmosphere, e. ... See: transparency (optics) alpha compositing GIF#Transparency transparency (overhead projector) market transparency transparency (telecommunication) transparency (computing) For X11 pseudo-transparency, see pseudo-transparency. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... Stefan-Boltzmann law (also Stefans law) states that the total energy radiated per unit surface area of a black body in unit time (black-body irradiance), (or the energy flux density (radiant flux) or the emissive power), j* is directly proportional to the fourth power of its thermodynamic temperature...

He died in Paris. The Eiffel Tower has become a symbol of Paris throughout the world. ...

See also

• Fourier series
• Fourier transform
• Fourier's Law

In mathematics, a Fourier series, named in honor of Joseph Fourier (1768-1830), is a representation of a periodic function (often taken to have period 2π — in a sense, the simplest case) as a sum of periodic functions of the form which are harmonics of ei x. ... The Fourier transform, named after Jean Baptiste Joseph Fourier, is an integral transform that re-expresses a function in terms of sinusoidal basis functions, i. ... Heat flow along perfectly insulated wire Conduction is the transfer of heat or electric current from one substance to another by direct contact. ...

Reference

• Initial text from the public domain Rouse History of Mathematics
• Fourier, J.-B.J. Mémoires d l'Académie Royale des Sciences de l'Institute de France VII. 570-604 (1827) (greenhouse effect essay)

The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ... See also: wikipedia:history One of Wikipedias public domain resources! There are a series of articles transcribed by Dr. David R. Wilkins (dwilkins@maths. ...

External links

• University of St Andrews' page: http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Fourier.html
• Fourier 1827: MEMOIRE sur les temperatures du globe terrestre et des espaces planetaires (http://www.wmconnolley.org.uk/sci/fourier_1827/fourier_1827.html)