First of all, I want to say that I am totally ignorant about physics. And I do not understand the general concepts of physics at all. Now coming to the question. Suppose, you drop a green tennis ball from above. Now It usually lands on earth and stop there ( ignore the bounces for now. ) Suppose, the point at which the green ball lands is a red ball. Since the earth is made of ''a mass of balls'' ( to get the concept, I am using such metaphors ), below the red ball should be another ball, and below that another ball, and so on, till you reach the opposite point on the earth, which is, suppose, a pink ball. Now since all the balls from the red ball upto the pink ball is drawing the green ball toward them, how can this one little green ball stop just over the red ball ignoring the pull of all the balls between the red and the pink one? Shouldn't it just ''break the red ball'' and keep reaching toward the next ball and break that too? I mean, drilling through earth? I know the earth is more or less a sphere. So are the pulls from balls around the red ball preventing the green ball from drilling through earth?