By formulating the direct integral equation for the Gaussian scaler gravitational potential, we were able to generalize the Newtonian law of gravity. Hence the obtained integral equation is differentiated to obtain another integral equation for the gravitational force. A new indicator (Ri) is then defined. By the application of suitable fundamental solution, it was demonstrated that both Gauss and Newton gravity was equivalent only in case of having the (Ri) indicator equals to zero. This proves that our universe is topologically 3D infinite (with no external boundary). Other cases of having values for the (Ri) indicator due to nearby blackholes demonstrated that such blackholes create internal boundaries in our universe. The developed integral equations are then generalized to 4D spatial space to account for possible nearby universes. With the proposed generalized integral equations together with the help of suitable measurements, a proposal is given for computational methodology that could help in inversely locating internal boundaries of our universe or giving us a clue about places where nearby universes might be located.