{{short description|Danish scientist, physician and grammarian (1625–1698)}} {{Use dmy dates|date=February 2025}} {{Infobox scientist |name = Rasmus Bartholin |image =Rasmus Bartholin.jpg |image_size =150px |caption = Rasmus Bartholin |birth_date = 13 August 1625 |birth_place = Roskilde |death_date = 4 November 1698 (aged 73) |death_place = Copenhagen |residence = |citizenship = |ethnicity = |field = Physics |work_institutions = |alma_mater = |doctoral_advisor = |doctoral_students = |known_for = Double refraction of a light ray }} '''Rasmus Bartholin''' ({{IPAc-en|b|ɑr|ˈ|t|oʊ|l|ɪ|n|,_|ˈ|b|ɑr|t|əl|ɪ|n}}; Latinized: ''Erasmus Bartholinus''; 13 August 1625 – 4 November 1698) was a Danish physician and grammarian.
==Biography== Bartholin was born in Roskilde. He was the son of Caspar Bartholin the Elder (1585–1629) and Anna Fincke, daughter of the mathematician Thomas Fincke.<ref>{{cite web|url= https://runeberg.org/dbl/5/0152.html|title= Fincke, Thomas, 1561-1656 |publisher = Dansk biografisk Lexikon|access-date=1 August 2019}}</ref>
As part of his studies, he travelled in Europe for ten years. He stayed in the Netherlands, England, France and Italy. In 1647, he took a Master's degree at the University of Copenhagen. In 1654, he received a Doctoral degree at the University of Padua.
He was a professor at the University of Copenhagen, first in Geometry, later in Medicine. He was also dean of the faculty of medicine, librarian, and rector.<ref>[http://www-history.mcs.st-and.ac.uk/Biographies/Bartholin.html Erasmus Bartholin] School of Mathematics and Statistics. University of St Andrews, Scotland</ref> He wrote, in Latin, the first grammar of the Danish language, the 1657 ''De studio lingvæ danicæ''.
Rasmus Bartholin is remembered especially for his discovery (1669) of the double refraction of a light ray by Iceland spar (calcite).<ref>Erasmus Bartholin, ''Experimenta crystalli islandici disdiaclastici quibus mira & insolita refractio detegitur'' (Copenhagen ("Hafniæ"), Denmark: Daniel Paulli, 1669). English translation: ''Experiments with the double refracting Iceland crystal which led to the discovery of a marvelous and strange refraction,'' tr. by Werner Brandt. Westtown, Pa., 1959.</ref> He published an accurate description of the phenomenon, but since the physical nature of light was poorly understood at the time, he was unable to explain it.<ref>{{Cite web|url=https://www.britannica.com/biography/Erasmus-Bartholin|title=Erasmus Bartholin | Danish physician and physicist|website=Encyclopædia Britannica}}</ref> It was only after Thomas Young proposed the wave theory of light, c. 1801 that an explanation became possible.
==Personal== He was a younger brother of Thomas Bartholin (1616–1680).<ref>{{cite web|url= http://denstoredanske.dk/Dansk_Biografisk_Leksikon/Sundhed/L%C3%A6ge/Thomas_Bartholin |title= Thomas Bartholin|publisher = Dansk Biografisk Leksikon Gyldendal|author= V. Meisen |accessdate=1 August 2019}}</ref>
== References == {{reflist}}
== External links == * "De figura nivis". In Thomas Bartolin, {{google books|UYY8AAAAcAAJ|De nivis usu medico observationes variae. Accessit D. Erasmi Bartholini de figura nivis dissertatio|page=PA241}}. Copenhagen: P. Haubold, 1661 * {{MacTutor Biography|id=Bartholin|title=Erasmus Bartholin}} * [http://www.worldcat.org/identities/lccn-n93-3891 Bartholin, Erasmus 1625-1698 ] worldcat.org
{{Authority control}}
{{DEFAULTSORT:Bartholin, Rasmus}} Category:1625 births Category:1698 deaths Category:17th-century Danish medical doctors Category:17th-century Danish scientists Category:University of Copenhagen alumni Category:University of Padua alumni Category:Academic staff of the University of Copenhagen Category:Medical educators Category:Danish mathematics educators Category:People from Roskilde Category:Rectors of the University of Copenhagen Category:Bartholin family