Newton — Laws of Motion & Gravitation
The Principia Mathematica and the unification of heaven and Earth
4.1 The Principia
Isaac Newton (1642–1727) published Philosophiæ Naturalis Principia Mathematica in 1687. In it he stated three laws of motion and the law of universal gravitation, showing that the same force that pulls an apple to the ground keeps the Moon in orbit.
4.2 The Three Laws of Motion
Newton's First Law (inertia), Second Law (F = ma), and Third Law (action-reaction) provided a complete framework for mechanics. Combined with his calculus, they allowed precise prediction of the motion of everything from cannonballs to comets.
4.3 Legacy
The Principia dominated physics for over two centuries. Newton's mechanics guided the design of bridges, ships, and steam engines, and successfully predicted the existence of Neptune. Only with Einstein's relativity and quantum mechanics did its limits become apparent.