The shape of the universe affects what the final fate of the universe will be. The universe is currently expanding, and if the geometry of the universe is closed, then the expansion would most likely slow gradually, then eventually stop, reverse into a contraction, and result in a “Big Crunch” in which the universe ends as a super-tiny, superhot point, much as Big Bang in reverse. If the geometry of the universe is flat or open, then the universe will most likely expand forever.