(1642–1727) English mathematician and physicist, one of the world’s greatest scientists. He went to Cambridge University in 1661 and stayed for nearly 40 years except for 1665–67, when he returned to his home at Woolsthorpe in Lincolnshire (because of the Plague), where some of his best work was done. In 1699 he was made Master of the Royal Mint. He was reluctant to publish his work and his great mathematical masterpiece, the Principia, did not appear until 1687. In it he introduced calculus and formulated Newton’s laws of motion. In 1665 he derived Newton’s law of gravitation, and in optics he produced Newton’s formula for a lens and, in 1672, his theories about light and the spectrum; these were summarized in his Opticks of 1704. Also in the late 1660s he constructed a reflecting telescope. The SI unit of force is named after him.