Figure 21-4: The Gravitational Curvature of Spacetime According to Einstein’s general theory of relativity, spacetime becomes curved near a massive object. To help you visualize the curvature of four-dimensional spacetime, this figure shows the curvature of a two-dimensional space around a massive object. The curvature of spacetime has been measured directly around Earth, where Earth was the massive object in the center (location 1), and a satellite called Gravity Probe B was orbiting at location 3.