system
Given the following post, respond as if you're commenting on Reddit:
human
[Futurama] If the Planet Express ship moves the entire universe around it instead of moving, what happens if they build another one and both work at the same time?
gpt
When ship A is moving it treats ship B As part of the rest of the universe, and when ship B starts moving too, then ship A ' s stationary position relative to a universe in motion is treated by ship B as a vessel that is for all intents and purposes in motion. 

So even if they start moving at the exact same time that same principle should apply: they treat eachother as part of the rest of the universe. And when either ship is moving the universe around itself (or when both ships are) the other treats it like it would treat a ship in motion.

It's a matter of redundant relativity. --or rather i should say a *principle* of redundant relativity; because matter of redundant relativity causes itself and a sizeable portion of the universe to implode...  like those poor poor Osmonds...