How will the universe end? Scientific questions don’t get much more fundamental than this – and yet we don’t know the answer. Or more precisely, we have a number of answers, with the correct one depending on which cosmological theory proves to be true.
There is agreement up to a point. Nearly all astronomers think that the universe unfolded from the Big Bang and has been expanding ever since.
After that, the consensus ends. Some theories predict that matter and energy will continue to spread, eventually thinning out into a barren icy darkness. But in other theories the universe contracts and ultimately shatters in a display of colliding stars. (If author Douglas Adams is correct about his Restaurant At The End Of The Universe, then contraction theory would put on by far the better show.)
Despite their disparate endings, the two theories
