say 'force of gravity' gravity is just the observed phenomenon without that, it's like saying gravity is caused by gravity so that phenonemon of things falling or being attracted in all directions like the moon pulling up on earth. okay got it. you are saying this phenomenon is caused by density I think what you mean to type is that "it's not only the mass that affects gravity." Mass is too vague of a statement. Rather, you believe the density is the thing that creates the force Said another way, it is how much mass is allocated in a specific space determines the acting on it. So if the mass is spread out over many miles, it does not affect it as greatly as the same mass spread out over inches.