Also: "Why is space flat?" > "Space is flat because of the Cosmological Principle, which states that the universe is homogeneous and isotropic. This means tha

Also: "Why is space flat?" > "Space is flat because of the Cosmological Principle, which states that the universe is homogeneous and isotropic. This means that it is the same in all directions and on all scales, so it appears to be flat. The Cosmological Principle is supported by observations of the Cosmic Microwave Background Radiation, which is the most distant light that can be detected." "Why is space curved?" > "Space is curved because of the presence of matter and energy. According to Einstein's theory of general relativity, gravity is not a force, but rather a consequence of the curvature of space and time caused by the presence of mass and energy. This curvature of space causes objects to move along curved paths, which explains why the planets move in elliptical orbits around the sun."