The year 1668 in science and technology involved some significant events.
Astronomy
Isaac Newton invents the reflecting telescope.
Biology
Francesco Redi publishes Esperienze Intorno alla Generazione degl'Insetti ("Experiments on the Generation of Insects"), disproving theories of the spontaneous generation of maggots in putrefying matter.
Mathematics
Nicholas Mercator and William Brouncker discover an infinite series for the logarithm while attempting to calculate the area under a hyperbolic segment.
Medicine
François Mauriceau publishes Traité des Maladies des Femmes Grosses et Accouchées in Paris, a key text in scientific obstetrics. John Mayow publishes a tract on respiration in Oxford, recognising "spiritus nitro-aereus" as a component of air, prefiguring the isolation of oxygen.
Publications
John Wilkins publishes An Essay towards a Real Character and a Philosophical Language proposing a universal language and a uniform system of measurement for international communication between natural philosophers.
Births
December 31 – Herman Boerhaave, Dutch physician and chemist who makes Leiden a European centre of medical knowledge (died 1738)