1644 in science

	… 1634; 1635; 1636; 1637; 1638; 1639; 1640; ; 1641; 1642; 1643; 1644; 1645; 1646; 1647; ; 1648; 1649; 1650; 1651; 1652; 1653; 1654 …;
	Art; Archaeology; Architecture; Literature; Music; Philosophy; Science; +...

The year 1644 AD in science and technology involved several significant events in mathematics, technology, and medicine.

Mathematics

Jan Baptist van Helmont publishes Dageraad ofte Nieuwe Opkomst der Geneeskunst ("Daybreak, or the New Rise of Medicine").^[3]

25 September – Ole Rømer, Danish astronomer who makes the first quantitative measurements of the speed of light (died 1710)^[4]

^ Sandifer, C. Edward (2007). How Euler Did It. MAA. p. 205. ISBN 9780883855638.
^ Lehr, André (1991). The Art of the Carillon in the Low Countries. Tielt, Belgium: Lannoo. ISBN 90-209-1917-2.
^ ^a ^b "Jan Baptista van Helmont - Belgian scientist". Encyclopedia Britannica. Retrieved 3 April 2018.
^ "Ole Rømer - Danish astronomer". Encyclopedia Britannica. Retrieved 3 April 2018.
^ Vaquero, J. M.; Vázquez, M. (2009). The Sun Recorded Through History. Springer Science & Business Media. p. 236. ISBN 9780387927909.