Franz Ernst Neumann
Encyclopedia
Franz Ernst Neumann was a German
mineralogist, physicist
and mathematician
.
, located not far from Berlin
. In 1815 he interrupted his studies at Berlin to serve as a volunteer in the Hundred Days
against Napoleon, and was wounded in the Battle of Ligny
. Subsequently he entered Berlin University as a student of theology
, but soon turned to scientific subjects. His earlier papers were mostly concerned with crystallography
, and the reputation they gained him led to his appointment as Privatdozent
at the University of Königsberg
, where in 1828 he became extraordinary, and in 1829 ordinary, professor of mineralogy
and physics
. His 1831 study on the specific heats of compounds included what is now known as Neumann's Law
: the molecular heat of a compound is equal to the sum of the atomic heats of its constituents.
Devoting himself next to optics, he produced memoirs which entitle him to a high place among the early searchers after a true dynamical theory of light. In 1832, by the aid of a particular hypothesis as to the constitution of the ether, he reached by a rigorous dynamical calculation results agreeing with those obtained by Augustin Louis Cauchy
, and succeeded in deducing laws of double refraction closely resembling those of Augustin-Jean Fresnel
. In studying double refraction, with his deduction of the elastic constants (on which the optical properties depend) Neumann employed the assumption that the symmetry of the elastic behavior of a crystal was equal to that of its form. In other words, he assumed that the magnitudes of the components of a physical property in symmetric positions are equivalent. This assumption substantially reduced the number of independent constants and greatly simplified the elastic equations. However, four decades passed before Neumann elaborated his application of symmetry in a course on elasticity in 1873. This principle was later formalized by his student Woldemar Voigt
(1850–1918) in 1885: ‘‘the symmetry of the physical phenomenon is at least as high as the crystallographic symmetry,’’ which became a fundamental postulate of crystal physics known as ‘‘Neumann’s principle’’. In 1900, Voigt attributed this principle to Neumann’s 1832 paper even though, at most, all that was present in that work was an implicit assumption that the symmetry of the phenomenon was equal to that of the crystal. Bernhard Minnigerode (1837–1896), another student of Neumann, first expressed this relation in written form in 1887 in the journal Neues Jahrb. Mineral Geol. Paleontol. (Vol. 5, p. 145).
Later, Neumann attacked the problem of giving mathematical expression to the conditions holding for a surface separating two crystalline media, and worked out from theory the laws of double refraction in strained crystalline bodies. He also made important contributions to the mathematical theory of electrodynamics, and in papers published in 1845 and 1847 established mathematically the laws of the induction of electric currents. His last publication, which appeared in 1878, was on spherical harmonics (Beitrage zur Theorie der Kugelfunctionen).
With the mathematician Carl Gustav Jacobi, he founded in 1834 the mathematisch-physikalisches seminar which operated in two sections, one for mathematics and one for mathematical physics. Not every student took both sections. In his section on mathematical physics Neumann taught mathematical methods and as well as the techniques of an exact experimental physics grounded in the type of precision measurement perfected by his astronomer colleague Friedrich Wilhelm Bessel. The objective of his seminar exercises was to perfect one's ability to practice an exact experimental physics through the control of both constant and random experimental errors. Only a few students actually produced original research in the seminar; a notable exception was Gustav Robert Kirchhoff who formulated Kirchhoff's Laws
on the basis of his seminar research. This seminar was the model for many others of the same type established after 1834, including Kirchhoff's own at Heidelberg University.
Neumann retired from his professorship in 1876, and died at Königsberg
(now Kaliningrad
, Russia
) in 1895 at the age of 96.
His children were talented. His son, Carl Gottfried Neumann (1832–1925), became in 1858 Privatdozent, and in 1863 extraordinary professor of mathematics at Halle
. He was then appointed to the ordinary chair of mathematics successively at Basel
(1863), Tübingen
(1865) and Leipzig
(1868).
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...
mineralogist, physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
and mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
.
Biography
Neumann was born in Joachimsthal, Margraviate of BrandenburgMargraviate of Brandenburg
The Margraviate of Brandenburg was a major principality of the Holy Roman Empire from 1157 to 1806. Also known as the March of Brandenburg , it played a pivotal role in the history of Germany and Central Europe....
, located not far from Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...
. In 1815 he interrupted his studies at Berlin to serve as a volunteer in the Hundred Days
Hundred Days
The Hundred Days, sometimes known as the Hundred Days of Napoleon or Napoleon's Hundred Days for specificity, marked the period between Emperor Napoleon I of France's return from exile on Elba to Paris on 20 March 1815 and the second restoration of King Louis XVIII on 8 July 1815...
against Napoleon, and was wounded in the Battle of Ligny
Battle of Ligny
The Battle of Ligny was the last victory of the military career of Napoleon I. In this battle, French troops of the Armée du Nord under Napoleon's command, defeated a Prussian army under Field Marshal Blücher, near Ligny in present-day Belgium. The bulk of the Prussian army survived, however, and...
. Subsequently he entered Berlin University as a student of theology
Theology
Theology is the systematic and rational study of religion and its influences and of the nature of religious truths, or the learned profession acquired by completing specialized training in religious studies, usually at a university or school of divinity or seminary.-Definition:Augustine of Hippo...
, but soon turned to scientific subjects. His earlier papers were mostly concerned with crystallography
Crystallography
Crystallography is the experimental science of the arrangement of atoms in solids. The word "crystallography" derives from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and grapho = write.Before the development of...
, and the reputation they gained him led to his appointment as Privatdozent
Privatdozent
Privatdozent or Private lecturer is a title conferred in some European university systems, especially in German-speaking countries, for someone who pursues an academic career and holds all formal qualifications to become a tenured university professor...
at the University of Königsberg
University of Königsberg
The University of Königsberg was the university of Königsberg in East Prussia. It was founded in 1544 as second Protestant academy by Duke Albert of Prussia, and was commonly known as the Albertina....
, where in 1828 he became extraordinary, and in 1829 ordinary, professor of mineralogy
Mineralogy
Mineralogy is the study of chemistry, crystal structure, and physical properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their utilization.-History:Early writing...
and 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...
. His 1831 study on the specific heats of compounds included what is now known as Neumann's Law
Neumann's law
Neumann's Law states that the molecular heat in compounds of analogous constitution is always the same. It is named after Franz Ernst Neumann.- References :...
: the molecular heat of a compound is equal to the sum of the atomic heats of its constituents.
Devoting himself next to optics, he produced memoirs which entitle him to a high place among the early searchers after a true dynamical theory of light. In 1832, by the aid of a particular hypothesis as to the constitution of the ether, he reached by a rigorous dynamical calculation results agreeing with those obtained by Augustin Louis Cauchy
Augustin Louis Cauchy
Baron Augustin-Louis Cauchy was a French mathematician who was an early pioneer of analysis. He started the project of formulating and proving the theorems of infinitesimal calculus in a rigorous manner, rejecting the heuristic principle of the generality of algebra exploited by earlier authors...
, and succeeded in deducing laws of double refraction closely resembling those of Augustin-Jean Fresnel
Augustin-Jean Fresnel
Augustin-Jean Fresnel , was a French engineer who contributed significantly to the establishment of the theory of wave optics. Fresnel studied the behaviour of light both theoretically and experimentally....
. In studying double refraction, with his deduction of the elastic constants (on which the optical properties depend) Neumann employed the assumption that the symmetry of the elastic behavior of a crystal was equal to that of its form. In other words, he assumed that the magnitudes of the components of a physical property in symmetric positions are equivalent. This assumption substantially reduced the number of independent constants and greatly simplified the elastic equations. However, four decades passed before Neumann elaborated his application of symmetry in a course on elasticity in 1873. This principle was later formalized by his student Woldemar Voigt
Woldemar Voigt
Woldemar Voigt was a German physicist, who taught at the Georg August University of Göttingen. Voigt eventually went on to head the Mathematical Physics Department at Göttingen and was succeeded in 1914 by Peter Debye, who took charge of the theoretical department of the Physical Institute...
(1850–1918) in 1885: ‘‘the symmetry of the physical phenomenon is at least as high as the crystallographic symmetry,’’ which became a fundamental postulate of crystal physics known as ‘‘Neumann’s principle’’. In 1900, Voigt attributed this principle to Neumann’s 1832 paper even though, at most, all that was present in that work was an implicit assumption that the symmetry of the phenomenon was equal to that of the crystal. Bernhard Minnigerode (1837–1896), another student of Neumann, first expressed this relation in written form in 1887 in the journal Neues Jahrb. Mineral Geol. Paleontol. (Vol. 5, p. 145).
Later, Neumann attacked the problem of giving mathematical expression to the conditions holding for a surface separating two crystalline media, and worked out from theory the laws of double refraction in strained crystalline bodies. He also made important contributions to the mathematical theory of electrodynamics, and in papers published in 1845 and 1847 established mathematically the laws of the induction of electric currents. His last publication, which appeared in 1878, was on spherical harmonics (Beitrage zur Theorie der Kugelfunctionen).
With the mathematician Carl Gustav Jacobi, he founded in 1834 the mathematisch-physikalisches seminar which operated in two sections, one for mathematics and one for mathematical physics. Not every student took both sections. In his section on mathematical physics Neumann taught mathematical methods and as well as the techniques of an exact experimental physics grounded in the type of precision measurement perfected by his astronomer colleague Friedrich Wilhelm Bessel. The objective of his seminar exercises was to perfect one's ability to practice an exact experimental physics through the control of both constant and random experimental errors. Only a few students actually produced original research in the seminar; a notable exception was Gustav Robert Kirchhoff who formulated Kirchhoff's Laws
Kirchhoff's laws
There are several Kirchhoff's laws, all named after Gustav Robert Kirchhoff:* Kirchhoff's circuit laws* Kirchhoff's law of thermal radiation* Kirchhoff's equations* Kirchhoff's three laws of spectroscopy* Kirchhoff's law of thermochemistry-See also:...
on the basis of his seminar research. This seminar was the model for many others of the same type established after 1834, including Kirchhoff's own at Heidelberg University.
Neumann retired from his professorship in 1876, and died at Königsberg
Königsberg
Königsberg was the capital of East Prussia from the Late Middle Ages until 1945 as well as the northernmost and easternmost German city with 286,666 inhabitants . Due to the multicultural society in and around the city, there are several local names for it...
(now Kaliningrad
Kaliningrad
Kaliningrad is a seaport and the administrative center of Kaliningrad Oblast, the Russian exclave between Poland and Lithuania on the Baltic Sea...
, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
) in 1895 at the age of 96.
His children were talented. His son, Carl Gottfried Neumann (1832–1925), became in 1858 Privatdozent, and in 1863 extraordinary professor of mathematics at Halle
Halle, Saxony-Anhalt
Halle is the largest city in the German state of Saxony-Anhalt. It is also called Halle an der Saale in order to distinguish it from the town of Halle in North Rhine-Westphalia...
. He was then appointed to the ordinary chair of mathematics successively at Basel
Basel
Basel or Basle In the national languages of Switzerland the city is also known as Bâle , Basilea and Basilea is Switzerland's third most populous city with about 166,000 inhabitants. Located where the Swiss, French and German borders meet, Basel also has suburbs in France and Germany...
(1863), Tübingen
Tübingen
Tübingen is a traditional university town in central Baden-Württemberg, Germany. It is situated south of the state capital, Stuttgart, on a ridge between the Neckar and Ammer rivers.-Geography:...
(1865) and Leipzig
Leipzig
Leipzig Leipzig has always been a trade city, situated during the time of the Holy Roman Empire at the intersection of the Via Regia and Via Imperii, two important trade routes. At one time, Leipzig was one of the major European centres of learning and culture in fields such as music and publishing...
(1868).