Not necessarily. There are theories that the universe will collapse back to cause another big bang. However there are also theories that entropy will simply end

Not necessarily. There are theories that the universe will collapse back to cause another big bang. However there are also theories that entropy will simply end up distributing all usable energy equally over all space, resulting in a universe that still exists where however nothing can happen anymore. The latter is a very drawn out kind of end, but in no way apocalyptic, as nothing is destroyed. See: http://en.wikipedia.org/wiki/Heat_death_of_the_universe http://en.wikipedia.org/wiki/Heat_death_of_the_universe