Good afternoon all, I'm going to sound like a blithering idiot in attempting to describe my question, so please forgive me. I appreciate your patience. While working on problems in the gravitation chapter in my college physics textbook, I came across a very interesting situation that I don't have the expertise to reconcile, nor can easily find a solution to on Google. It isn't with a particular problem, but rather with the concept of blending a Newtonian and relativistic concept. Take, for example, the familiar equation for computing the gravitational force between two objects: Gmm'/r^2. My question is this: Since distances between two objects are 3D vectors in "real" space, wouldn't it be more accurate to replace a one-dimensional length (like r) with something more akin to sqrt(x^2 + y^2 + z^2 + ct^2)? Thereby making the equation: Gmm'/(sqrt(x^2 + y^2 + z^2 + ct^2))^2 I get the feeling that these two concepts may be extremely distant from one another in usability like that, but I'm unfortunately unable to reach any of my professors over the summer and can't speak to someone who would actually know better. Thank you for your time. Enjoy the holiday weekend.