In high school we learn Coulomb's law for electrostatics, and later in University find that the correct version of this equation is in field form as part of maxwell's laws where the set of these equations together are lorentz invarient. In fact in "Principles of Electrodynamics" (Dover, by Schwarz) maxwell's equations are "derived" this way by Lorentz transformation and symmetry arguments starting with the statics equation. Does anybody know a good treatment of gravity (online references preferred) that is consistent with special relativity without introducing the complexities of GR which I am not yet mathematically equipt to deal with (have no hardcore physics background, only engineering, and am studying for fun). My expectation is that one could do the same Lorentz invarient treatment for div g = \rho in gravitation as for div E = \rho in the electrodynamics book, and come up with the retarded time potential equations and other relativistically corrected versions of the newtonian GmM/r^2 "law" (probably as first order linear approximations of GR). I have a guess of what a Lorentz invarient formulation of div g = rho would look like, but figured I was reinventing the wheel. If somebody can point me in the right direction for reading I'd appreciate it.