"classical" physics is completely defined by three basic theories. It starts with the basic theory, F=dp/dt, p = mv, etc. (sorry, I'm blanking on what its called). The forces, E&M and gravity, are then defined by Maxwells equations and the GEM equations. You could include special relativity here but its really just a consequence of those three theories. Light and gravity waves are just massless, energyless waves in the two sets of fields (E&M and GEM). As far as I know, this classical theory is completely self-consistent, and very closely describes the world. In addition, its a very elegant theory with just two forces that are almost identical. My question is: knowing this theory does NOT accurately describe the world at large and small scales, how can you explain the symmetry between the only two forces in it? Gravity, described by GR, deviates from GEM at large scales and E&M, described by QED, deviates from maxwells equations at small scales. Photons and gravitons have both energy and mass, and the two forces act nothing alike when described with modern theories. In addition, there's the strong force and the weak interaction that deviate even further from gravity and E&M. Why does the world appear to be so simple and elegant at human scales, when its actually much more complex? Is there any kind of explanation given as to why gravity and E&M are almost identical at these scales or is it just generally thought of as a coincidence? P.S. I realize GEM is not generally thought of as classical physics, but Einstein was really ahead of his time in formulating GR. In order for newtonian gravity to be lorentz invariant, there must be a magnetic component to it. GEM comes straight from special relativity, and is necessary for a consistent classical theory.