 in relation to a point at infinity) makes calculations simpler, albeit at the cost of making "U" negative; for why this is physically reasonable, see below.Given this formula for "U", the total potential energy of a system of "n" bodies is found by summing, for all formula_31 pairs of two bodies, the potential energy of the system of those two bodies.Considering the system of bodies as the combined set of small particles the bodies consist of, and applying the previous on the particle level we get the negative gravitational binding energy.