Everything is centered around the ship. The ship isn't moving, the universe does.
All external models are, as @north valve said one mesh. So nothing is actually simulated in detail on the other end.
If you enter your shuttle\yacht, you will 'teleport' (not a in-game teleport) to a shuttle that is in-game simulated while your actual ship is unloaded and shown as one big mesh/model without detail-simulation. Also, when visiting a planet, there will be a very short transition period between the galaxy and the planet. (I think, like Empyrion does)
In multiplayer, I'm not 100% sure how it'll be done technically, but the same goes as before, but with different viewpoints. So your ship #1 will view Ship #2 as one big mesh. The opponent sees it the other way around. If you shoot, the damage is calculated on the receiving end because only that side will know the details of all simulated parts. The number of ships in MP will depend on how big the ships are, aka how many the simulated parts they have. So for example 2 big ships OR 1 big ship and 3 shuttles OR 6 shuttles.
Other interesting info about this:
Multiple ships:
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Do note:
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