Eilhard Ernst Gustav Wiedemann (1 August 1852, in Berlin – 7 January 1928, in Erlangen) was a German physicist and historian of science. He was the son of physicist Gustav Heinrich Wiedemann (1826–1899), and an older brother to Egyptologist Alfred Wiedemann (1856–1936).
He studied physics at the Universities of Heidelberg and Leipzig, obtaining his doctorate in 1872 with the thesis "Über die elliptische Polarisation und ihre Beziehung zu den Oberflächenfarben der Körper (On the elliptical polarization of light and its relation to surface color). From 1878 to 1886, he was an associate professor of physics at Leipzig, afterwards relocating to the University of Erlangen as a full professor (1886–1926).[1]
In addition to his duties as a physicist, he was a prolific author of works involving "history of science" themes, in particular, science as it pertained to Arab traditions.[2]