"closed universe." YourDictionary, n.d. Web. 11 November 2018. <https://www.yourdictionary.com/closed-universe>.
closed universe. (n.d.). Retrieved November 11th, 2018, from https://www.yourdictionary.com/closed-universe
A model of the universe in which the curvature of space is roughly spherical, entailing that the universe has finite size. An object moving in a straight line in a closed universe would eventually return to its starting point. According to most current cosmological theories, the universe is closed if it is sufficiently dense, and therefore possesses enough gravitational force to stop or reverse the expansion started by the big bang (resulting in what is called the big crunch).