Big Crunch, Big Rip or Big Freeze?
The Big Rip hypothesizes that the rapid increase in the universe’s expansion powered by dark energy will eventually create greater forces than gravity. This would essentially rip apart all matter in the universe such as the sun, the Earth and even black holes!
The Big Crunch hypothesizes that if the rate of expansion of the universe ever slows, then gravity could dominate and, instead of expanding, the universe could start to shrink, causing it to collapse in on itself… crunch!
The Big Freeze, or sometimes confusingly called the ‘Heat Death’, hypothesizes that if the universe keeps expanding the energy within it will be spread out more and more, leading to a reduction in average temperature and over time the universe will become very, very cold.