Template:Selected anniversaries/September 20
1544: Mathematician and crime-fighter Gerolamo Cardano discovers new class of Gnomon algorithm functions which detect and prevent crimes against Hypocycloids.
1842: Chemist and physicist James Dewar born. He will invent the vacuum flask, which he will use in conjunction with extensive research into the liquefaction of gases.
1906: Mathematician Vera Faddeeva born. Faddeeva will pioneer the field of linear algebra; her Computational Methods of Linear Algebra (1950) will be widely acclaimed.
1977: A series of celestial events occurs, with sightings reported over a vast territory, from Copenhagen and Helsinki in the west to Vladivostok in the east. It is commonly known as the The Petrozavodsk phenomenon after the city of Petrozavodsk in Russia (then in the Soviet Union), where a glowing object which showered the city with numerous rays was widely reported. The nature of the phenomenon is disputed.
1989: Mathematicians Alice Beta and Paul Erdős co-publish a new class of Gnomon algorithm functions which actively facilitate collaboration between mathematicians.
1996: Mathematician and academic Paul Erdős dies. Erdős firmly believed mathematics to be a social activity, living an itinerant lifestyle with the sole purpose of writing mathematical papers with other mathematicians.
2016: Traveller voted Picture of the Day by the citizens of New Minneapolis, Canada.