Franz Ernst Neumann

Franz Ernst Neumann (11 September 1798 – 23 May 1895) was a German mineralogist and physicist. He devised the first formulas to calculate inductance. He also formulated Neumann's law for molecular heat. In electromagnetism, he is credited for introducing the magnetic vector potential. In A Treatise on Electricity and Magnetism of 1873, James Clerk Maxwell attributes the mathematical formulation of Faraday's law of induction to Neumann.

Biography

Early life Franz Ernst Neumann was born in Joachimsthal, Margraviate of Brandenburg (near Berlin), the son of Ernst Neumann, a farmer who became a state agent. His mother was a Countess who was not allowed to marry Ernst, and Neumann did not meet her mother until he was 10 years old.

In 1845, Neumann introduced the magnetic vector potential to discuss Ampère's circuital law. In this work, expanded in 1847, he introduced the first mathematical treatment of Faraday's law of induction.

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 (Beiträge zur Theorie der Kugelfunctionen).

With the mathematician Carl Gustav Jacobi, he founded in 1834 the Mathematisch-physikalisches Seminar which operated in two sections for mathematics and for mathematical physics. Not every student took both sections. In his section on mathematical physics Neumann taught mathematical methods 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.

Children Neumann had four children with his wife Luise Florentine Hagen (born 1800): Carl Gottfried Neumann (1832–1925), Franz Ernst Christian Neumann (1834–1918), (1835-1910), and Luise Neumann (1837-1934). His son Carl, became a mathematician and physicist; his younger son, Ernst became professor of medicine in Königsberg.

Works

Beiträge zur Krystallonomie (Mittler, Berlin, 1823) Beiträge zur Theorie der Kugelfunctionen (B. G. Teubner, Leipzig, 1878)

Franz Neumanns Gesammelte werke (2 vols.) (B. C. Teubner, Leipzig, 1906–1928)