ok, like this. a line is defined by a series of points (1-dimensional objects), right? and a cube is defined (well, its boundaries, etc) by a series of 2-dimensional shapes, right? Well, a hypercube is defined by 3-dimensional objects in the same way -- its boundaries are described by 3-dimensional "points." There's no way to describe what this would look like, really, we don't have any point of reference. But anyway, the universe is similar -- time and space are the same thing, a description of the motion of objects in four dimensions. If you jump into the air, you're moving up, then down, but also "forward" through space-time... which is not really "forward" at all, since if you had an outside perspective (as in, outside time), you could take a look at the whole sequence forward or backward, like looking at a fly trapped in amber. Only amber with... playback? It's hard to describe.