Scientists now know the universe is expanding, at an ever-increasing rate. So if it's ballooning, what is it growing into? In other words, what is beyond the known universe?
Defining this "beyond the universe" would imply that the universe has an edge, and that's where things get tricky because scientists aren't certain if such a drop-off exists.
The answer depends on how one views the question.
One form of the question asks, "Could you go somewhere that you could look 'beyond' the universe," the way one might look beyond a cliff edge or look out of a window to see the outside of a building? The answer to that is "probably not.”
But, if you can’t go and look over the edge of the universe then that is surely implying that the universe has no end…Which is impossible right? There has to be an end at some point. If scientists are saying that the universe is at an ever-expanding rate than the has to be a drop off point that is just getting bigger, doesn’t there? It is surely impossible to just not have an end or an end which is expanding. This subject is very discombobulating, and I don't think that we are ever going to find out an answer to this question.
Well, our universe does have an edge — that is, if by "our universe," you mean ‘the observable universe’. The speed of light is just that — a speed — and the universe has only been around for so long (about 13.77 billion years), which means only so much of the universe has been revealed to us via the light that has been revealed to us, and what's outside our observable limit? Just more stuff like galaxies, planets, black holes and more fantastic varieties of cheese. But that we can’t see… but it is still there.
From our perspective we are at the centre of the universe and other galaxies are moving away from us (which implies that the universe is expanding).But, let’s say we were our closest neighbouring galaxy - Andromeda - we would think we were the centre of the universe and all galaxies were moving away from us. This would be the same for every other galaxy out there. To make this easier let’s pretend all galaxies are raisins in a loaf of bread that is in an oven. The loaf expands and the raisins move apart. But, the loaf of bread will burn and crumble and change into something that isn’t a loaf of bread (a burnt loaf of bread). But the universe can’t change into something else can it? So, in ‘The universe’ all galaxies have their own observable universe (mini universe) that is like a loaf of bread that we are in the middle of. We can’t see past the ‘edge’ but we know it’s there… and I guess that if the raisins never stop expanding and universe does change….well, only time will tell.
This is, of course, not proven…and I don’t think we are ever going to find a closer answer to, “If our universe has an edge?”. For all we know the universe could be getting smaller? Or our galaxies could be getting pulled out of the universe by a black hole?
So for now we should focus on what we can see in our ‘mini universe’ like stars, galaxies, super-novas and if the moon is actually made from cheese?… but that’s for a different article.