Franz Serafin Exner (24 March 1849 – 15 October 1926) was an Austrian physicist.
Exner comes from one of the most important university families of the Austrian-Hungarian empire. The same Exner family includes Adolf Exner, Karl Exner, Sigmund Exner, and Marie von Frisch. Exner was the youngest of five children of parents Franz Serafin Exner and Charlotte Dusensy. His father Franz Serafin was, from 1831 to 1848, a professor for philosophy in Prague and from 1848 onwards was on the Board of Education in Vienna and an influential reformer of Austrian university education. He began his physics studies in Vienna in 1867 and attained a doctorate after an academic year in Zurich under August Kundt, also working with Wilhelm Conrad Röntgen, in the year 1871 in Vienna. The largest influence on his training was Viktor von Lang for his 1872 habilitation with a work entitled "On the Diffusion through Liquid Lamellas" ("Über die Diffusion durch Flüssigkeitslamellen"). In 1879 he took up an appointment as extraordinary professor and in 1891 he was renamed to full professor of the chemico-physical institute, 1902 to "second physical Institut", as a successor to Johann Josef Loschmidt, who had always worried about the "Exner children" as a close friend of family after the early death of his parents. When Exner was appointed 1908 as chancellor of the University of Vienna, he was at the pinnacle of his scientific activities.
Franz Serafin Exner can be described as a physicist with a strong vision, cultivating versatile and highly educated pupils. He was pioneer in numerous areas of modern physics. The early introduction of topics such as radioactivity, spectroscopy, electrochemistry (galvanic element), electricity in the atmosphere, and color theory in Austria can all be owed to Exner's doing. His most famous pupils included Marian Smoluchowski, a Viennese physicist of Polish descent, who discovered a theory independently of Albert Einstein and Friedrich Hasenöhrl for Brownian motion, and Victor Hess, whose attention for the exciting and extensive topic of atmospheric electricity and associated radioactivity was influenced by Franz Exner, together with Egon Schweidler, a pioneer in the study of the atmospheric electricity, and with Hess' discovery of "cosmic radiation" receiving the Nobel prize later, and the later Nobel prize winner Erwin Schroedinger, who began in 1911 as Exner's assistant, with "studies on the kinetics of dielectrics, melting point, pyro- and piezoelectricity" and finally Stefan Meyer. In the 1920s and 1930s most physics chairs were occupied by pupils of Exner: Josef Thuma, Brno, later full professor in Prague; Anton Lampa, Prague; Hans Benndorf, Graz; Marian Smoluchowski, Czernowitz, Krakau; Stefan Meyer, Vienna; Egon Schweidler, Innsbruck, Vienna; Eduard Haschek, extra full professor Vienna; Friedrich Hasenöhrl, Vienna; Arthur Szarvassi, Heinrich Mache, Vienna; Victor Conrad, Brünn, later USA; Felix Maria von Exner-Ewarten, Vienna; Friedrich von Lerch, Innsbruck; Karl Przibram, Vienna; Felix Ehrenhaft, Vienna; Erwin Lohr, Brünn; Wilhelm Schmidt, Vienna; Franz Aigner, Vienna; Victor Francis Hess, Graz, Innsbruck, New York; Karl Wilhelm Friedrich Kohlrausch, Graz; Ludwig Flamm, Vienna; Erwin Schrödinger, Jena, Leipzig, Zurich, Berlin, Graz, Dublin, Vienna; and Hans Thirring, Vienna.
- Franz Exner und Sigmund Exner: Die physikalischen Grundlagen der Blütenfärbungen, 1910
- W C Röntgen und F Exner: Über die Anwendung des Eiskalorimeters zur Bestimmung der Intensität der Sonnenstrahlen. Wien Ber 69: 228 (1874)
- Franz Exner: Vom Chaos zur Gegenwart, 1926 (unveröffentlicht)