Sir Isaac Newton is known for creating the theory of gravity. In the late 17th century, he formulated the law of universal gravitation, which describes the gravitational force between two objects based on their masses and the distance between them. His groundbreaking work in the "Principia Mathematica" laid the foundation for classical mechanics and transformed our understanding of motion and celestial bodies. Newton's theory illustrated that gravity is not just an earthly phenomenon but operates throughout the universe, influencing the orbits of planets and moons. This profound insight fundamentally changed the field of physics and remains essential to modern science.