<!-- "none" is preferred when the title is sufficiently descriptive; see WP:SDNONE -->
The year 1643 in science and technology involved some significant events.
Exploration
- January 21 – Abel Tasman discovers the Tonga archipelago.
- December 25 – Captain William Mynors of the British East India Company discovers Christmas Island.
Meteorology
- Evangelista Torricelli invents the mercury barometer.
Births
- January 4 (NS) – Isaac Newton, English physicist (died 1727)
- Jean de Fontaney, French Jesuit mathematician and astronomer (died 1710)
- Pierre Dionis, French surgeon and anatomist (died 1718)
Deaths
- April 9 – Benedetto Castelli, Italian mathematician (born 1578)
- November 3
- John Bainbridge, English astronomer (born 1582)
- Paul Guldin, Swiss mathematician and astronomer (born 1577)
- Sophia Brahe, Danish astronomer (born 1556)
- Gasparo Berti, Italian mathematician, astronomer and physicist (born c. 1600)
- Walter Warner, English scientist (born 1563)