Diadem wrote:How can you be a free falling observer in a spaceship with non-zero dimensions? Different parts of the spaceship will be in different inertial frames, so for the spaceship to remain in one piece they can't all be free falling.
I started with a line the ends of which were space-like separated and then allowed each end to fall in separately. Essentially it's a ship made of jelly.
Diadem wrote:It's been a while since I did my course on black holes though. I'm a bit rusty. A sufficiently big black hole will have negligible tidal forces, so we can ignore them for our calculations. But clearly if you stick part of a spaceship through the event horizon, that part of the ship can't get back. So if you then reverse thrusters, and fly out, clearly something must happen. I'd have to think a while to remember what though.
It's late again so I can't really sketch the diagram now, but I'll have a go tomorrow and see if I can get a rough idea (although to get a sensible answer out, I think I'll need to assume the ship is actually two separate infinitely rigid bodies).
In essence, I'd need to tear it apart as starslayer said.
Not actually drawn the diagrams. Just visualised in head instead. Should be as good as sketch.
Exact behaviour will depend on the rigidity of the spaceship. For an infinitely rigid ship (by which I mean one for which the space-like separation between the two ends at a given point in time (as determined by parallel transport) is constant), the front will pull the back in no matter how strong the engines are.
For a finitely rigid but unbreakable ship, it will stretch out arbitrarily far (assuming it's made of some continuous bulk material rather than actual particles) although I think this stretching will lead to additional matter falling in as, for it to stretch, the material closer to the horizon must be moving away from it slower than the rest so, if the rest is just escaping, some of it must still fall in. Iterating this process, the ship will still get pulled in eventually, it will just take longer and will go in a lot thinner than it otherwise would.
For a more realistic ship which can be snapped, ~1/2 would escape although the less rigid the materials are, the less will escape (for the same reason the ship described above will never escape).
This question is somewhat similar to one I posed a while ago on the relativity thread about trying to break colour charge confinement by aiming a meson at an event horizon such that one quark falls in and the other doesn't (although thinking about all this black holes stuff's made me think that it won't work even neglecting quantum effects because, for it to dip in the horizon, it would have to be at c which is can't be).