Before I go any further, don't think about this too hard.

The universe... what is it? Well, it's everything. But what is "everything"? There obviously can't be an infinite number of objects in the universe. So, the universe must end somewhere. But where? Why would it end in that single spot? What if it doesn't end? How would that be possible?

What if the universe is a circle? Or a sphere? Or even a donut? What's outside of it? If the universe is everything, how could there be anything outside of it? But if the universe has a shape, how could there be no outside? What would the edge look like?

People say that the universe has an age. How can that be? What was there before the universe? Even outer space is something. But the universe can't have been around forever. Everything has an age.

And what about the big bang? If the universe was compressed into the size of a ball, a marble, or even an atom, what would be outside of it? Aliens playing marbles?

My head is hurting again, so I have to stop.

The phrase that comes to mind here is finite but unbounded. That is, you can travel forever through the Universe and never reach the "edge", but it's not endless.

How could this be? Well, think of the surface of a sphere, such as the surface of the Earth. It's the same kind of thing. Except the Universe has three physical dimensions rather than the two dimensions of the surface of a sphere. So it might help to think of the Universe as the three-dimensional "surface" of a four-dimensional hypersphere. The monkey mind wasn't built to think of 4D structures, so you can only do it be analogy with the 3D sphere example, but you get the general idea.

Things really get interesting when you consider that Big Bang is kind of like a Black Hole in "reverse", and that the Universe might be the "interior" of a black hole. An event horizon such as black holes are framed by would make a nice "end" to a universe without appearing to be one. The edge is no edge.

This all opens the way for the extremely compelling idea of cosmological natural selection, as sketched out by Lee Smolin in his book The Life of the Cosmos. Highly recommended.

I hope this helps.

(heh heh)

The question "what is outside the universe?" is not an answerable question. The question itself is absurd, since the universe is space.
Everything that exists, is part of the universe. There is no outside the universe for anything to exist in.
This is similar to the question "what was there before the universe existed?". This question is equally absurd, since the universe is the combination of space/time, therefore 'before the universe' there was no time for anything to exist in.

Log in or register to write something here or to contact authors.