We could never return back in a straight line. In terms of explanation, if you go straight on a flat universe there's a "point" where you would reach the end, which would make you to turn back and change the path making therefore a small curvature in your path. "Unless the Universe repeated on a scale that was less than about 15 billion light years in diameter today, we'd have no way to ever return to our original starting point by traveling in a straight line"

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Con: I don’t agree. The universe is constantly expanding so we would never reach the point where we would have to go back because the universe expands faster than us so we could never reach to the end.

Shape and size of the universe

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Cons

I don’t agree. The universe is constantly expanding so we would never reach the point where we would have to go back because the universe expands faster than us so we could never reach to the end.

Selected claim, opposing its parent

Con claim 1, children below

I don’t agree. The universe is constantly expanding so we would never reach the point where we would have to go back because the universe expands faster than us so we could never reach to the end.