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- Is the universe finite or infinite? 6 answers
If you could build a spaceship and keep travelling in one direction, what would finally happen? One answer is that you would never ever reach the end. But this sounds purely platonic space and comes into conflict with the big bang theory (or the very first big bang, if you claim there have been many big bangs). That is, space was created in the big bang and is expanding and there is no space outside that realm.
So what happens if the spaceship doesn't continue travelling forever? This brings us to the second possible answer: the spaceship would eventually stop travelling farther, change its direction and may return.
To me, both of these answers are equally scary and unconvincing and contradicting. What would be the ultimate fate of the spaceship considering the big bang as the origin of space?
The attempt here is to also make a distinction between the space produced by the big bang and the dimensions outside the universe or whatever existed before the big bang, and come up with an answer as less contradictory as possible.
Let us, only for the sake of discussion, imagine a virtual spaceship that can overtake the accelerating expansion of the universe and let it travel in a particular direction. When it reaches the edges of the universe, if that is not very inconvenient, it would surpass the universe itself, in case it doesn't go in circle.
Even though this particular thought experiment wouldn't be fundamentally different than the expansion of the universe itself, it may help understand a bit about beyond the universe. Now if the spaceship continues travelling alone outwards, would it be extending the space itself in that particular direction?