jul 11, 1687 - Isaac Newton's Philosophiæ Naturalis Principia Mathematica, known as the Principia, is published by the Royal Society of London. In it, Newton describes his law of universal gravitation, explains the laws of mechanics, and gives a formula for the speed of sound. The writing of Principia Mathematica ushers in a tidal wave of changes in thought, significantly accelerating the scientific revolution by providing new and practical intellectual tools, and becomes the foundation of modern physics