https://en.wikipedia.org/wiki/Big_Crunch A hypothetical scenario for the ultimate fate of the universe. The expansion of the universe reverses, the scale factor become negative. The universe collapses in onto itself
https://en.wikipedia.org/wiki/Big_Crunch A hypothetical scenario for the ultimate fate of the universe. The expansion of the universe reverses, the scale factor become negative. The universe collapses in onto itself