Martin Ohm (May 6, 1792 in

Erlangen Erlangen (; East Franconian German, East Franconian: ''Erlang'', Bavarian language, Bavarian: ''Erlanga'') is a Middle Franconian city in Bavaria, Germany. It is the seat of the administrative district Erlangen-Höchstadt (former administrative d ...

– April 1, 1872 in

Berlin Berlin ( , ) is the capital and largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's most populous city, according to population within city limits. One of Germany's sixteen constitue ...

) was a German

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

and a younger brother of

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...

Georg Ohm Georg Simon Ohm (, ; 16 March 1789 – 6 July 1854) was a German physicist and mathematician. As a school teacher, Ohm began his research with the new electrochemical cell, invented by Italian scientist Alessandro Volta. Using equipment of his o ...

Biography

He earned his doctorate in 1811 at Friedrich-Alexander-University, Erlangen-Nuremberg where his advisor was

Karl Christian von Langsdorf Karl Christian von Langsdorf, also known as Carl Christian von Langsdorff (18 May 1757 in Bad Nauheim, Nauheim – 10 June 1834 in Heidelberg), was a German mathematician, geologist, natural scientist and engineer. Life Langsdorf was the son of ...

. In 1817, he was appointed professor of mathematics and physics in the gymnasium at

Thorn Thorn(s) or The Thorn(s) may refer to: Botany * Thorns, spines, and prickles, sharp structures on plants * ''Crataegus monogyna'', or common hawthorn, a plant species Comics and literature * Rose and Thorn, the two personalities of two DC Com ...

. In 1821 he moved to Berlin, and in 1839 became a full professor in the

University of Berlin Humboldt-Universität zu Berlin (german: Humboldt-Universität zu Berlin, abbreviated HU Berlin) is a German public research university in the central borough of Mitte in Berlin. It was established by Frederick William III on the initiative o ...

. He delivered courses of lectures at the academy of architecture from 1824 to 1831, and at the schools of artillery and engineering from 1833 to 1852; and he also taught in the military school from 1826 to 1849.

Work

Ohm was the first to fully develop the theory of the

exponential Exponential may refer to any of several mathematical topics related to exponentiation, including: *Exponential function, also: **Matrix exponential, the matrix analogue to the above * Exponential decay, decrease at a rate proportional to value *Exp ...

''a''^''b'' when both ''a'' and ''b'' are

complex number In mathematics, a complex number is an element of a number system that extends the real numbers with a specific element denoted , called the imaginary unit and satisfying the equation i^= -1; every complex number can be expressed in the form ...

s in 1823. The 1835 second edition of Ohm's textbook, ''Die reine Elementar Mathematik'' was the first time that Euclid's 'extreme and mean ratio' was given the name of the "

golden section In mathematics, two quantities are in the golden ratio if their ratio is the same as the ratio of their sum to the larger of the two quantities. Expressed algebraically, for quantities a and b with a > b > 0, where the Greek letter phi ( ...

" (''goldener Schnitt''). It was via sources relying on Ohm that the psychologist

Adolf Zeising Adolf Zeising (24 September 181027 April 1876) was a German psychologist, whose main interests were mathematics and philosophy. Among his theories, Zeising claimed to have found the golden ratio expressed in the arrangement of branches along th ...

adopted and popularised the term.

Students

Ohm's students included Friedrich August, Friedrich Bachmann,

Elwin Bruno Christoffel Elwin Bruno Christoffel (; 10 November 1829 – 15 March 1900) was a German mathematician and physicist. He introduced fundamental concepts of differential geometry, opening the way for the development of tensor calculus, which would later provid ...

, Paul Bachmann, Joseph Brutkowski, Heinrich Eduard Heine,

Rudolf Lipschitz Rudolf Otto Sigismund Lipschitz (14 May 1832 – 7 October 1903) was a German mathematician who made contributions to mathematical analysis (where he gave his name to the Lipschitz continuity condition) and differential geometry, as well as numbe ...

, Leo Pochhammer,

Friedrich Prym Friedrich Emil Fritz Prym (28 September 1841, Düren – 15 December 1915, Bonn) was a German mathematician who introduced Prym varieties and Prym differentials. Prym completed his Ph.D. at the University of Berlin in 1863 with a thesis writ ...

, Wilhelm Wagner, Hermann Waldaestel, Wilhelm Wernicke, Elena Gerz, Valentien Gerz, and Johanna Gerz.

Selected publications

* ''Die reine Elementar Mathematik (Pure elementary mathematics).'' Berlin, 1825; second edition 1835. * ''Kurzes Elementar-Lehrbuch der gesammten mechanischen Wissenschaften für höhere Bürger-, technische, Gewerb- und Militär-Schule''n. Berlin, 1840. * ''Aufsätze aus dem Gebiete der höhern Mathematik'' * ''Die analytische und höhere Geometrie in ihren Elementen mit vorzüglicher Berücksichtigung der Theorie der Kegelschnitte,'' Berlin Riemann 1826 * ''Versuch eines vollkommen consequenten Systems der Mathematik''. Nürnberg, F. Korn, 1853-55. * Lehrbuch der Mechanik zugleich mit den dazu nöthigen Lehren der höhern Analysis und der höhern Geometrie 1 Mechanik des Atoms. Berlin Enslin 1836

References

{{DEFAULTSORT:Ohm, Martin 19th-century German mathematicians 1792 births 1872 deaths Humboldt University of Berlin faculty Georg Ohm