Question: What is at the end of the universe

Kristian Harder answered on 14 Nov 2013:

Same thing as at the end of a rainbow: a pot of gold, except that you’ll never get there. 😉
Well, it’s only a pot of gold in a figurative sense, because the knowledge to be gained by being able to peek beyond the end of the universe would be worth a lot more than some shabby chunks of metal!
All that said, I don’t even know whether you are talking about the end of the universe in space (aka the edge of the visible universe), or the end of the universe in time (how it will look like when the party is over).
I’ll try to answer both, even though I expect our theorists to be able to give you better answers, because we poor experimentalists can’t look as far as they can think. 🙂
What’s beyond the edge of the visible universe is difficult to tell. Probably you get more of the same for quite a while, because the universe is bigger than the part we can see. It’s “only” 13 billion years old, and thus we can only see a certain distance in each direction, because light from regions further away wouldn’t have reached us yet, even if it was sent out at the very beginning. That certain distance to which we can see is larger than 13 billion light years, though, because space has been expanding (as consequence of the Big Bang) while the light has been on its way to us. So we can look about 50 billion light years into each direction, which is a lot, but not enough to see the edge of the universe. Therefore, no idea what’s happening out there. Our own universe is of limited size (though still growing), and beyond that there may be nothing at all, or maybe other “bubbles” of similar universes from other Big Bangs nearby. We really have no idea.
The end of the universe in time is *a bit* easier to figure out. From the way all the galaxies are moving now, we can guess that they are probably going to fly further apart forever, because there does not seem to be enough matter in the universe to stop the expansion and make it all fall back due to mutual gravitational attraction. Thus, the universe will probably end up being a very dark and dull place, all stars having burned out eventually, a lot of matter sucked up by black holes, and all matter spreading out so much that space gets emptier and emptier. Right now seems a much better time to live than in that far future. 🙂