Alex McColgan

Amazingly, according to scientists, all of these are possible, but which one is correct comes down to the nature of that unseen world all around us.

I'm Alex McColgan and you're watching Astrum.

Join me today as we continue our series exploring the unseen world of 4D space and discuss possible answers to the question, what is the shape of the universe itself?

But first, let's begin by talking about infinity.

You are likely already familiar with infinity.

In maths, it is the concept of a number so large it cannot possibly be beaten.

Of course, no such number exists.

For any number you can name, I could come up with a number that is at least one larger than it.

But in a way, that's sort of the point.

In infinity, there is always another number.

And when it comes to our universe, we have so far discovered no edges.

There may always be another star or planet.

An infinite universe is a little mind boggling for us.

We live in a very finite world, with edges and endings, so the idea that there might be literally infinite more planets out there is a little bewildering.

However, as we develop more and more powerful telescopes, and push back the darkness further and further at the edges of what we can observe in our universe, all we are finding is that even the darkest patches of the night sky are turning out to be brimming with stars.

So, increasingly, an infinite universe might be something we are forced to contemplate.

But that is not to say that just because the universe is infinite, there are not a finite number of things in it.

That may sound a little counter-intuitive, but let me show you what I mean.

Believe it or not, there are different kinds of infinity when it comes to our universe.

Three possible scenarios could be true – a flat universe, a spherical one, or a hyperbolic universe.