# Could the unobservable universe have curvature (be spherical)?

What prevents the unobservable universe from being a continuously enlarging sphere due to the inflating bubble universes? Our observable universe being close to flat could support such a scenario?

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Nothing. Philosophically many people prefer some sort of mediocrity principle which say that what we experience is roughly similar to what is the case everywhere else. But by definition what is unobservable is beyond the (current) scope of testable hypotheses and hence beyond the realm of science. So no scientific statement can assert anything about the "unobservable universe". –  Willie Wong Apr 10 '12 at 10:56

Having said that, you ask an interesting question and I'm not sure how the large scale geometry of a post inflation patch relates to to the geometry of the parent "multiverse". I don't think the post inflation patch "pinches off" from the multiverse, so I don't think it can have the topology of a sphere. That restricts it to the topology of a flat universe, though if it's big enough even a very small deviation from $\Omega$ = 1 will be significant.