- Johann Heinrich Lambert
Infobox_Scientist

name = Johann Heinrich Lambert

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caption = Johann Heinrich Lambert (1728-1777)

birth_date =26 August ,1728

birth_place =Mülhausen ,Alsace ,France

death_date =25 September ,1777

death_place =Berlin ,Prussia

residence =Germany

nationality = German

field =Mathematician ,physicist andastronomer

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known_for = Irrationality of π

Lambert-Beer-Bouguer Law

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religion =Huguenot

footnotes =**Johann Heinrich Lambert**(August 26 ,1728 –September 25 1777 ), was a Swissmathematician ,physicist andastronomer .He was born in Mülhausen (now

Mulhouse ,Alsace ,France ). His father was a poortailor , so Johann had to struggle to gain an education. He first worked as a clerk in an ironworks, then gained a position in anewspaper office. The editor recommended him as a private tutor to a family, which gave him access to a good library and provided enough leisure time in which to explore it. In 1759 he moved toAugsburg , then in 1763 he dwelled inBerlin . In the final decade of his life he gained the sponsorship of Frederick II ofPrussia , and passed the rest of his life in reasonable comfort. He died inBerlin ,Prussia (todayGermany ).Lambert studied

light intensity and was the first to introducehyperbolic function s intotrigonometry . Also, he made conjectures regardingnon-Euclidean space. Lambert is credited with the first proof that π is irrational in 1761cite web

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title =Lambert Azimuthal Equal Area

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publisher = manifold.net

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url =http://www.manifold.net/doc/7x/lambert_azimuthal_equal_area.htm

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accessdate = 2007-03-30 ] and of severalmap projection s in 1772 such as theLambert cylindrical equal-area projection cite web

last =Mulcahy

first =Karen

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title =Cylindrical Projections

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publisher =City University of New York

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url =http://www.geo.hunter.cuny.edu/mp/cylind.html

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accessdate = 2007-03-30 ] cite web| last =Lambert| first =Johann Heinrich| authorlink =| coauthors =| title =Anmerkungen und Zusätze zur Entwerfung der Land- und Himmelscharten. Von J. H. Lambert (1772.) Hrsg. von A. Wangerin. Mit 21 Textfiguren. | work =| publisher =W. Engelmann, reprint 1894| date =1772| url =http://name.umdl.umich.edu/ABR2581.0001.001 |format =xml| doi =| accessdate =2007-04-10 ] . Lambert also devised theorems regardingconic sections that made the calculation of theorbit s ofcomet s simpler. The first practicalhygrometer andphotometer were invented by Lambert. In 1760, he published a book on light reflection inLatin , in which the wordalbedo was introduced. In 1761, he hypothesized that the stars near thesun were part of a group which travelled together through theMilky Way , and that there were many such groupings (star system s) throughout thegalaxy . The former was later confirmed by SirWilliam Herschel . Lambert wrote a classic work on perspective and also contributed togeometrical optics .In his "New Organon", Lambert studied the rules for distinguishing subjective from objective

appearance s. This involved him with thescience ofoptics . TheLambert-Beer law describes the way in which light is absorbed. In his "Cosmological Letters on the Arrangement of the Universe ", he coined the word "phenomenology." This signified the study of the way that objects appear to thehuman mind .Lambert also developed a theory of the generation of the

universe that was similar to thenebular hypothesis thatImmanuel Kant had recently published.Lambert had read Kant's "The Only Possible Argument in Support of a Demonstration of the Existence of God ". In it, Kant had briefly summarized his theory of the origin of the planets from a gassy cloud. Kant's purpose was to illustrateGod 's wisdom and purposiveness and in this way to support hisexistence . Originally, Kant had published an extended version of thistheory in his "Universal Natural History and Theory of the Heavens". Lambert was struck by the account that he read in Kant's summary and began a correspondence with thephilosopher regarding this theory. Shortly afterward, Lambert published his own version of thenebular hypothesis of the origin of thesolar system .Lambert devised a formula for the relationship between the angles and the area of

hyperbolic triangle s. These are triangles drawn on a concave surface, as on asaddle , instead of the usual flat Euclidean surface. Lambert showed that the angles cannot add up toπ (radians ), or 180°. The amount of shortfall, called defect, is proportional to the area. The larger the triangle's area, the smaller the sum of the angles and hence the larger the defect CΔ = π — (α + β + γ). That is, the area of a hyperbolic triangle (multiplied by a constant C) is equal to π (in radians), or 180°, minus the sum of the angles α, β, and γ. Here C denotes, in the present sense, the negative of thecurvature of the surface (taking the negative is necessary as the curvature of a saddle surface is defined to be negative in the first place). As the triangle gets larger or smaller, the angles change in a way that forbids the existence of similar hyperbolic triangles, as only triangles that have the same angles will have the same area. Hence, instead of expressing the area of the triangle in terms of the lengths of its sides, as in Euclid's geometry, the area of Lambert's hyperbolic triangle can be expressed in terms of its angles.**Notes****References***"A Short Account of the History of Mathematics", W. W. Rouse Ball, 1908.

*"Asimov's Biographical Encyclopedia of Science and Technology",Isaac Asimov , Doubleday & Co., Inc., 1972, ISBN 0-385-17771-2.**See also***

Beer-Lambert law (Lambert-Beer law, Beer-Lambert-Bouguer law)

*lambert (unit)

*Lambert quadrilateral

*Lambert's cosine law

*Lambertian reflectance

*Lambert cylindrical equal-area projection

*Lambert series , of importance in number theory.

*Lambert's trinomial equation

*Lambert's W function

* π**External links***MacTutor Biography|id=Lambert

* [*http://www.maths.tcd.ie/pub/HistMath/People/Lambert/RouseBall/RB_Lambert.html Entry from "A Short Account of the History of Mathematics"*] .

* [*http://www.britannica.com/eb/article-9046942/Johann-Heinrich-Lambert Britannica*]

* [*http://www.nndb.com/people/654/000096366/ NNDB*]

* [*http://www.maths.tcd.ie/pub/HistMath/People/Lambert/RouseBall/RB_Lambert.html Rouse Ball*]

* [*http://num-scd-ulp.u-strasbg.fr:8080/view/authors/Lambert,_Jean-Henri.html fascimiles of publications at*]Université Louis Pasteur Persondata

NAME= Lambert, Johann Heinrich

ALTERNATIVE NAMES=

SHORT DESCRIPTION= GermanMathematician ,physicist andastronomer

DATE OF BIRTH=26 August ,1728

PLACE OF BIRTH=Mülhausen ,Alsace ,France

DATE OF DEATH=25 September ,1777

PLACE OF DEATH=Berlin ,Prussia

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