Main Question or Discussion Point
I am confused about the modified theories of gravity. We all know there is the Schwarzchild solution for GR. The solution can give right prediction for the solar-system experiments, such as Light deflection, perihelion shift of the Mercury and gravitational time delay. Whether all kinds of modified theories of gravity should have the same Schwarzchild solution, otherwise they will be ruled out by the solar-system experiments. I know some modified theories of gravity don't have the Schwarzchild-like solution for spherically symmetric vaccum spacetime.