Another way to think about the universe is to think of yourself as an ant on the outside of a balloon.
Now the hard part of this idea is that you have to imagine that you, the ant, don't know anything about up or down--only go and stop, left and right, frontwards and backwards. That's hard to imagine because we're 3 dimensional beasts, and you--your antlieness--are a 2D beastie.
You can wander around on the balloon and never find an edge, never see the horizon. And if you ask, what does "up" mean, it's meaningless. Does that help?
Because we know what up means.
Do you know what a 12 dimensional space looks like? What THAT means?
Me too not. But that's the current best guess for M-theory, string theory, or whatever the hell they call it these days.