Sir Isaac Newton is the famous physicist known for the law of universal gravitation. This law states that every mass attracts every other mass in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Newton's work in the 17th century laid the foundations for classical mechanics and has had a profound influence on the fields of physics, astronomy, and engineering. His seminal work, "Mathematical Principles of Natural Philosophy," introduced concepts that are still used to understand motion and forces today.