electric field is written as q/4*pi*r²*e0. i guess that 1/4*pi*r² stands for the decrement of flux density, with area of sphere (then it looks like force = "flux per unit area"). i need clarification about the constant epsilon 0. i'm not asking definitions such as "it's electrical permitivity of space". what's the physical meaning of it? also, if the inverse square law can be generalized for all forces in universe using the description based on sphere, why are we writing GmM/r² and not mM/4*pi*r².g0, where g0 stands for a constant such as "gravitical permitivity of space"?