From Pockets: "Actually, gravity is the definition of the phenomena. The phenom itself derives not so much from gravity, but from the existance of a well of force lines that curve inward towards a mass. The larger and more dense the mass, the steeper the walls of the well. Everything has a well, it's just that some are much larger and steeper than others. Of course, this is just speculation, and the concept of gravity is just as valid as saying we fall down because this place sucks."