The year 1723 in science and technology involved some significant events.

Geophysics

• George Graham discovers diurnal variation in Earth's magnetic field.^[1][2]
• Antoine de Jussieu publishes De l'Origine et des usages de la Pierre de Foudre on the origins of fossils, prehistoric stone tools and meteorites.^[3]

Optics

• Giacomo F. Maraldi makes the first observation of the Arago spot, unrecognized at this time.^[4]

Births

• January 5 – Nicole-Reine Lepaute, French astronomer (died 1788)
• January 31 – Petronella Johanna de Timmerman, Dutch scientist (died 1786)
• February 17 – Tobias Mayer, German cartographer, astronomer and physicist (died 1762)
• April 30 – Mathurin Jacques Brisson, French zoologist (died 1806)
• November 12 – Saverio Manetti, Italian natural historian (died 1785)

Deaths

• August 26 – Anton van Leeuwenhoek, Dutch pioneer of the microscope (born 1632)