Not to be a pest, because this discussion is WAY over my head given how sick I am. But, Newton's "Law of Gravity" was just that - a law. But it was also superseded by Einstein's "General Theory of Relativity". Well, there's a difference between Newton's Law of Gravity, and the theory behind Gravity, is what I meant. Superseded by Einstein's Theory does illustrate the point, though...that until something comes along and proves it otherwise, it's generally accepted as true, which is how science works. Newton's Law of Gravity, which is called Newton's law of Universal Gravitation, is in short, a statement of fact meant to concisely describe an action or set of actions. Laws are generally accepted to be true and universal, and can sometimes be expressed in terms of a single mathematical equation. In this particular case it is the fact: "every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them." The difference here between law and theory, is the law describes a fact of gravity, in the above case involving mass and distance. A scientific theory of gravity would be the best explanation of why Newton's law of Universal Gravitation works, why does every object with mass attract every other object of mass. In another way: A law describes a single action, whereas a theory explains an entire group of related phenomena. Einstein's General Theory of Relativity doesn't negate Newton's law of Universal Gravitation, but instead attempts to more precisely explain the how and why gravity works the way it does; Newton's law is still as true today as when he first wrote it.