I was under the impression that the Universe would expand, contract, big bang, expand, contract, etc. Apparently there are competing theories where things just fade away. Dark Energy seems to account for the theoretical change.
Anyway, here’s a video explaining the competing theories:

And of course you need a song for that:
R.E.M. – It’s the End of the World As We Know It (And I Feel Fine)http://assets.bop.fm/embed.js