That's of course not the point of the thought experiment. Just the mass-energy and "realness" of the spaceship after it leaves causal contact with Earth is eno

That's of course not the point of the thought experiment. Just the mass-energy and "realness" of the spaceship after it leaves causal contact with Earth is enough. Consider the statement: "Once any object gets far enough away from me that our future light cones do not intersect, it ceases to exist." And compare with the statement: "Once any configuration gets so far away from my configuration in configuration space that I can't experimentally detect it, it ceases to exist via waveform collapse." The Copenhagen Interpretation is claiming something akin to the second statement, but that seems to me to be logically isomorphic to the first statement, of which our intuitions are much better at grasping the problems.