the closed universe
if our universe has a high enough mass, expansion will eventually stop . gravitational attraction between matter will then pull it all closer together , just as the earths greavity pulls objects closer to the centre to the centre of the earth.
eventually all matter superheated and atoms would disintegrate in a reversal of the big bang. black holes would suck in more and more matter until a final big crunch packed everything into a single black hole. then there would be another big bang and the cycle would start again.
