Ernst Barthel
Ernst Philipp Barthel (17 October 1890 in Schiltigheim – 16 February 1953 in Oberkirch (Baden) was an Alsatian philosopher, mathematician and inventor. In the 1920s and 1930s he taught as a private lecturer of philosophy at the University of Cologne. From 1924 on Barthel edited the magazine "Antäus. Blätter für neues Wirklichkeitsdenken" (Antaeus. Journal for new Reality Thinking), which served as the organ of the "Gesellschaft für Lebensphilosophie" (Society for Life Philosophy) founded by him in Cologne. Barthel maintained philosophical friendships with his compatriots Albert Schweitzer and Friedrich Lienhard. Philosophy and Earth theory. The main principle of Barthel's  philosophy on the background of Christian Platonism was the "Polarity", which he understood to be the most fundamental, constitutive law in all of nature. Besides his philosophical work he also published several works on geometry, further developing a non-Euclidean (Riemannian geometry, spherical) theory of geometry, which he called "polar geometry". From this geometry he derived a new cosmology with the theory of a Great Earth, which states that the Earth is a maximal sphere in a cyclical space and its surface therefore a "total plane", the equator plane of the Cosmos. The (total) plane, as well as the straight  line and space as a whole, is flat, without curvature yet closed, running back on itself. Barthel considered this his most important theory, even "the most significant thought of the century", as he writes in his autobiography. While some of his academic colleagues stated that this theory is geometrically possible and consistent, others did not acknowledge that and resorted to "the blight of personal calumny", deriding him for allegedly "teaching that the Earth is a disk" or outright declaring him crazy, thus ruining his academic career. In November 1940 he was dismissed from the University of Cologne by the Nazi  Reich Minister Rust because of religio-metaphysical (due to his book "Der Mensch und die ewigen Hintergründe") and political (alleged Francophilia) suspicions. Ernst Barthel was a member of the National Socialist Teachers League. The Russian astronomer Leonid Andrenko considered Barthel's main thought among the most ingenious ever suggested and advocated for taking note of it and thinking about it.