Carl Gottfried Neumann (7.05.1832-27.03.1925) was a German mathematician and theoretical physicist and a corresponding member of the Berlin Academy of Sciences (1893). He was the son of F. Neumann. He was born in Königsberg, where he graduated from the university (1855). In 1858-63 he worked at the University of Halle, and he was professor at the University of Basel in 1863 —65, at the University of Tübingen in 1865-68 and at the University of Leipzig in 1868-1911.
His physical research was on mathematical physics, electrodynamics, mechanics and hydrodynamics. He developed potential theory. He put forward (1870) the idea of an inertial frame of reference. He predicted the phenomenon of thermal diffusion (1872). In 1875 he carried out a mathematical analysis of the differential relations of thermodynamics (introducing a difference in the notation of total differentials and infinitesimal quantities).