Space-Time Boundary Inquiry

[beecee]

1 hour ago, Itoero said:

Why does a finite universe have no boundary? I don't mean an edge where you can fall of.  

According to evidence from WMAP, the universe is flat to within small error bars, but those error bars maybe hiding the fact that the "flatness" is just the arc of a tremendously larger circle and that the universe is "closed" and finite, but just like Earth, has no real boundary, or limitation to how far one could go.  

A torus shape could I imagine also be envisaged.                                                                                            I suppose the definition of boundary is important here.  

[Strange]

2 hours ago, Itoero said:

Why does a finite universe have no boundary? 

So the usual analogy is to go to two dimensions: consider the surface of a sphere; it has a finite area but no boundary.