Science Forums 2

[Boerseun]

This is a very common question, and a common problem encountered by teachers and students alike.

And the reason for this is that you're trying to understand the universe as being 3-dimensional (with time added), same as everything else. You're trying to shoehorn the universe into your everyday experience.

The universe is actually a hypersphere, where each and every point is the center. So there is no "border" to the universe into which it's expanding as such - although it certainly is expanding. I know it sounds like a cop-out, but it indeed seem to be the case.

Consider a point somewhere in the farthest reaches in visible space, in time almost right at the big bang. At that point, there are no stars, no galaxies, nothing. They haven't condensed yet. But if you were to look at Earth from that vantage point, you will also see a point in space where galaxies haven't condensed yet. But they must have, because you know that Earth exist - and that Earth has a visible horizon 15 billion light years in all directions, whilst from your vantage point the location of Earth is where the universe ends. And so on and so forth. If you were to instantly travel to the edge of the universe, you will find yourself in a spot that would seem to be the perfect centre of the universe, with a visible horizon of fifteen billion light years in all directions. Simply put, you will never find the edge of the universe. Doesn't matter how hard you try. The only way to reach the edge of the universe is to physically travel back in time in the exact point you are finding yourself in right now, all the way back to the Big Bang. And right between the points of Before The Big Bang and After The Big Bang, you will observe the edge of the universe.

So the question of what lies beyond the edge has very little meaning, if that edge only exist in time. Because seeing as time travel is impossible, the point is rather moot. The universe is infinite in all directions, in space. But it is clearly bound by fifteen billion years in time.