Karl Baedeker (scientist) Karl Baedeker (scientist) Karl Wilhelm Sali Baedeker (3 February 1877 – 6 August 1914) was a German physicist, and a professor at the University of Jena. He was the grandson of Karl Baedeker, the founder of the eponymous travel guide publishing house, and the son of Fritz Baedeker (1844 - 1925), who ran the same company from 1869 until his death in 1925 (see Baedeker). One of his scientific discoveries was that the resistivity of cuprous iodide (CuI) depended on its stoichiometry. Thin films of the material became much more conductive when exposed to iodine vapor; the effect was reversible.
Karl Friedrich Köppen Karl Friedrich Köppen Karl Friedrich Köppen (26 April 1808 – 26 April 1863) was a German teacher and political journalist. He was one of the Young Hegelians. Köppen was from a born in a pastor's family in Altmark. He studied theology at the University of Berlin from 1827 to 1831, but later turned to religio-critical Hegelianism. After his studies and military service in 1833, he taught at the secondary school Dorotheenstädtischer. In 1837, he met Karl Marx, with whom he developed a close friendship. In 1840 he became one of the most active associates of Arnold Ruge and published Hallischen