What’s after space? – Pip, age four, North Yorkshire, England
When we look up at a clear night sky, we see space: a vast, seemingly limitless expanse that contains everything we know exists.
To find out what’s out in space, a good place to start is figuring out where space — our universe — ends. The problem is, we don’t know where space ends, or even whether space ends at all.
The farthest we can see into space, using all the technology we have today, is 46 billion light years. The volume of space that we can see is called observable universe. We don’t know what’s out there. Maybe there are more galaxies, stars, and space. Maybe it’s the edge of the universe.
Some people think that the universe is infinite – meaning the universe goes on forever, in all directions. In this case, there is nothing else after space, because space is everything.
However, if the universe did have an edge, it would probably be very difficult for us to know where it ends.
Think about our home on planet Earth, for example. We know that Earth does not go on indefinitely: Earth will end and space will begin. But if you walk, looking for the ends of the Earth, you will never get there even if you walk forever. This is because the Earth is a ball. To know that the Earth has an edge, and where it is, we need to know its shape.
By understanding the shape of the universe, we can know where its edges are. Astronomers are studying the universe right now, looking for clues that can tell us more about the shape of the universe.
Understanding the universe
We know what the Earth looks like because we can photograph it from space – and several astronauts have gone to space to see it. Maybe we can also see the end of the universe, if we know where to look.
However, there is another problem. The universe is expanding – and at that speed getting faster. The distance between us and other galaxies continues to increase. The farther the distance, the longer it takes for light from distant galaxies to reach us.
At some point, these galaxies will be so far away that their light will not reach us at all. The night sky will be completely dark, and we will have little, if any, chance of seeing stars. This expansion of the universe could mean that the edge – and whatever lies beyond it – will also get further away from us.
Even though we don’t know where the end of our universe is, scientists still spend a lot of time thinking about what lies beyond.
It is possible that there is not just one universe, and that outside our universe there are other universes. We might live in just one small part of multiverse.
Universes can overlap or merge.
Perhaps our universe exists in its own domain distinct from other universes, separated from them by a vast expanse of nothingness. Or maybe there are parallel universes that are close together, or even overlap. This means there are no real “edges” at all, but universes that blend into each other.
The true nature of the universe may be beyond our current ability to visualize or understand. Understanding the shape of the universe can help us to know whether the universe lasts forever or has an end. What happened after that could be an even bigger mystery.
Rahma Sekar Andini from Malang State University translated this article from English