 Likewise, B will be struck by fewer particles from the direction of A than from the opposite direction.One can say that A and B are "shadowing" each other, and the two bodies are pushed toward each other by the resulting imbalance of forces.This shadow obeys the inverse square law, because the imbalance of momentum flow over an entire spherical surface enclosing the object is independent of the size of the enclosing sphere, whereas the surface area of the sphere increases in proportion to the square of the radius.