The Fate of the Universe

Simulation of the Universe
Credit: NSO

One of the biggest questions in science is "What will happen to the Universe"?

We think that the Universe started with a Big Bang, that all the galaxies are still moving apart and the Universe expands. But what happens eventually will depend upon two things:

  • Since all the galaxies are moving apart, we might expect the Universe to expand forever and simply cool down.
  • However, gravity wants to pull things together and so is trying to slow down the expansion.

The fate of the Universe is a balance between these two. If the expansion wins, everything will expand forever. If gravity wins, the expansion will stop, and the Universe will collapse. Astronomers are trying to work out how much mass there is in the Universe to help to answer this question - the more mass, the more likely it is that gravity will win.