Whose laws govern motion and gravity?

Sir Isaac Newton published his masterwork, the Principia, in 1687, setting out three laws of motion and the law of universal gravitation. His first law describes inertia, the second links force to mass and acceleration (F = ma), and the third states that every action has an equal and opposite reaction. His law of gravitation explained that every mass attracts every other mass, accounting for both falling apples and orbiting planets with a single principle. Newton also made huge contributions to optics and co-invented calculus. His framework dominated physics for over two centuries, until Einstein’s relativity refined it for extreme speeds and gravity.