There was a topic long time ago (like 2.5 years) where someone asked how we knew whether there was a 4th spatial dimension and I answered something like "because we know the universe is finite but has no boundary (i.e. space is like the surface of the Earth but +height)" and jinydu answered that current models explained the universe in 3 spatial dimensions while it is finite...
I guess I'm wondering what the current consensus thinks of the shape of the universe and its relationship with the 4th spatial dimension.