Gravity is special in that it's a vector and they begin to cancel out inside the sphere, but this is not the case for all things that follows falloffs based on distance, for example light or sound.
I haven't been able to find out what the falloff function is for sound or light for a non-point source (for example a sphere or disc). Anyone know?
@runevision I don't know for discs or anything like that (university said, that's too complicated), but isn't a sphere like a point in the sphere center but with some of the initial distance being inside the source? I'd say that's approriate.