Gravitational interactions become stronger with decreasing distance. Take the Newtonian gravity model, if force is proportional to 1/distance^2, as distance ap

Gravitational interactions become stronger with decreasing distance. Take the Newtonian gravity model, if force is proportional to 1/distance^2, as distance approaches zero, the force approaches infinity. You can simplify all points in a region as being one point for points that are far away, but that doesn't help with the infinite force problem with close points.