I've arrived at a non-sensical solution for a pretty simple thought experiment about gravity. Please let me know where my thinking is breaking down: Assume we have a cube of even density and a point mass on center of one of the sides. There is a force of gravity between the two of GmM/r^2 where r is half the length of one of the sides (the distance to the center of gravity of the cube). Now imagine the half of the cube farthest from the point mass disappears. It vaporizes. Now the mass of the cube is M/2, but the distance to the center of gravity is r/2. This would indicate an INCREASE in the force of gravity, but this is far from intuitive. Any ideas where I'm wrong?