LOAF: Uh... You're attaching too much importance to TC's words without actually listening to what he's saying.
"The point of a spaceship is to keep vacuum out"
Is that a serious remark? Surely, it must be some sort of hard-to-read sarcasm...
While both attempt to create a habitable environment within, it must be considered that air generally moves from areas of high pressure to areas of low pressure.
A spaceship does not need to keep vacuum out, for the simple reason that as long as it keeps the air in, the vacuum automatically stays out. The problems start when there's a breach and the air moves into an area of low pressure (in this case, the vacuum outside).
And the way I see it, when TC says a submarine is designed not to implode, that implies keeping air in...
Anyway, what it all comes down to is that spaceships and submarines do indeed face different forces. I imagine that if you somehow got a submarine into space, it would explode.
