Think about a busy street on New York. All the people are walking the same direction. A skinny person walking through in the other direction will not cause much disturbance to everybody else walking, an obese person doing the same will cause a big disturbance. [i]More mass=more gravitational force onto other masses in the universe.[/i] When this obese person gets hungry, he becomes very angry and starts jumping up and down. If he is large enough, he ends up creating a sinkhole in the ground, which goes down so deep that if you fall into it, you die. [i]Black holes, which emerge from massive stars after they die.[/i]