How does the general theory of relativity relate to spacetime?

   After the special theory of relativity came the general theory of relativity, in which physicist Albert Einstein connected the curvature of spacetime with gravity. Einstein argued that gravity is not a force (like magnetism), as was previously thought, but is the result of curved spacetime. He wrote that the reason large objects (such as the Sun) draw smaller objects (such as the planets) toward them is that large objects curve spacetime while smaller objects become trapped in those curves. To envision this, imagine the Sun curving spacetime into the shape of a shallow bowl. The planets are drawn into orbit around the Sun like small balls rolling around the sides of the bowl. This describes how gravity is simply the changed motion of an object due to curved spacetime.