There are now three possible models of the universe based on the Big Bang theory. Firstly is the open Friedmann-Lemaître theory in which hyperbolically curved space is predicted to expand forever. Second is the closed Friedmann-Lemaître theory in which spherically curved space is predicted to collapse on itself. Third is the Einstein-de Sitter theory which calculates that the flat space of the universe is also destined to continually expand..
