Quote:
Originally Posted by Eratosthenes
How is a finite torus model of the Universe, bounded?
Unboundedness implies there is "no end" (or no edge)
The surface of a sphere is a finite but unbounded 2D surface. It is unbounded because it does not have an 'edge'. Traveling along the surface goes on forever. You will pass over your starting point over and over again.
One model of the universe is a 'finite but unbounded' 4-dimensional space-time geometry
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Yes you are correct the surface of a torus is unbounded but a 3-torus is a closed manifold and therefore forms a bounded metric space ie. a finite Universe.
Steven