.
We may now contrast the various types of space-time curvature produced by matter and electromagnetic energy. By writing the gravitational equations in a slightly different though equivalent way, we obtain, in the interior of matter,
whence
Thus, in the interior of matter, none of the curvatures need vanish, and hence no limitation is imposed on the curvature of space-time.
In regions where there are electromagnetic fields but no matter, we have
whence
