A number of theories have been proposed regarding the ultimate fate of the universe. Some, like the Big Crunch and the Big Rip, suggest the universe will come to an end, while others conclude that it will exist for an infinite period of time. Most cosmologists agree that the universe’s average density, the rate at which it expands, and the physical properties of the mass and energy in the universe will determine its ultimate fate. What is the difference between an open universe and a closed one? Discuss
Source: The Free Dictionary