Sir Isaac Newton is famous for his major discovery in physics, particularly the formulation of the laws of motion and universal gravitation. His seminal work, "Philosophiæ Naturalis Pricipia Mathematica," published in 1687, laid the groundwork for classical mechanics, providing a mathematical framework to describe the motion of celestial bodies and objects on Earth. Newton's laws of motion described how forces affect objects' movement and established principles that remain fundamental to physics today. His contributions have had a profound impact on science, shaping our understanding of the physical universe.