Final answer:
According to Einstein's general theory of relativity, space and time are intertwined, creating a four-dimensional universe. Masses curve space-time, which results in the force of gravity. This curvature affects how matter and light move through the universe, demonstrating the active role of space-time.
Step-by-step explanation:
Complete the passage to describe one of the features of Einstein's general theory of relativity. According to Einstein, space and time are intertwined and are parts of a whole universe that has four dimensions. Masses in the universe curves space-time, and the resulting shape of space-time causes gravity.
Figure 1.4 of Einstein's theory of relativity describes space and time as an interweaved mesh. Large objects, such as a planet, distort space, causing objects to fall toward the planet because of gravity. These massive objects also distort time, causing it to proceed at a slower rate near the surface of the Earth compared with the area outside of the distorted region of space-time. As such, American physicist John Wheeler succinctly put it: "Matter tells spacetime how to curve; spacetime tells matter how to move." The consequences of this amazing insight mean that space-time is not just a backdrop for the universe's actions but plays an active role in the motion of matter and energy.
Furthermore, the general theory of relativity brought to light that only in the absence of mass and energy is space considered flat. The presence of either distorts space-time and this curvature is what is perceived as gravity. This interaction is vital in understanding celestial motions and phenomena like black holes, where the space-time fabric is so warped that not even light can escape from it, creating an event horizon. Consequently, we can appreciate the intricate linkages between mass, space, and time in pinpointing events in the universe.