Some astronomers think the universe will just carry on getting bigger as the galaxies speed apart. Others think that the galaxies may one day start falling back towards each other until they crash together in a Big Crunch!
The Big Crunch, as you might have guessed, is the Big Bang's opposite. All the matter expanding toward at the edges of the universe is being affected by our universe's gravity. According to this theory, gravity will eventually cause this expansion to slow to the point where it halts and begins to contract instead. The contraction will bring all of the material (planets, stars, galaxies, black holes - everything) back to the centre untill it becomes that infinitely dense singularity again, wiping out everything. And then we'd be left with the same conditions that the universe had before the Big Bang - all the matter of the universe condensed into an infinitesimal point
This is however, unlikely to happen based on current knowledge, since we've recently discovered that the universe appears to be expanding at an accelerating rate.
- Astronomers are scientists who study the stars and the planets.
