escape velocity refers to how hard you have to throw something so it never comes back down.
the escape velocity of a black hole is faster than any speed any matter could reach (the speed of light).
is there any problem with leaving more slowly? building a staircase and walking out? a slower constant rocket? a ladder?
(ignore the problem of being dead and all if your on a black hole…)
[QUOTE=owlofcreamcheese]
is there any problem with leaving more slowly? building a staircase and walking out? a slower constant rocket? a ladder?
[QUOTE]
Escape velocity is really just about energy conservation. In order to escape the blackhole you basically need to add more energy to the system that is leaving than is available by all possible means. A ladder does not work because you won’t be able to lift it. A staircase does not work because it will collapse under its own weight. Walking will not work because you will fall down. A slower rocket will not work because you cannot gain more energy than your mass energy no matter how much you constantly accelerate.
End of story.
You’d have to be exerting more force toward a vector AWAY from the black hole than the hole was exerting on ITS vector PULLING you towards itself.
Considering that not even photons can escape that kind of pull, this would be a hell of a trick. You’d need a hellacious power source, even by stellar standards, and/or you’d have to be operating at faster-than-light speeds.
Considering that according to Einsteinian physics this would cause your mass to become infinite, I’d think that in and of itself would prove to be a bigger problem than a piddling little black hole.
Of course, there’s always hyperspace theory. But if any of that turns out to be true, you can simply leave three-dimensional space before you fall completely INTO the black hole, and then cruise away at a speed of your choosing…
Inside the event horizon the light cone tips in such a manner that the space axis becomes the time axis. So you can no more avoid the singularity than you can avoid tomorrow, and therefore in order to escape you’d have to move backward in time.
<stealing the op>
Silly question that has me curious – if I stuck my arm through the event horizon, would it chop cleanly off, or would it pull me in completely? I guess it’d have something to do with the size of black hole (accretion disk? mass?)
</stealing the op>
Assuming that you had magic powers and enabled yourself to hover just above a black hole’s horizon, yes, your arm would be ripped off. In reality, you’d be ripped completely apart atom by atom before you even got to the event horizon. This holds true for most black holes, but for supermassive black holes at the center of galaxies, their event horizons are so large that the gravitation force is spread out over a greater volume, so it might be possible to make it to the horizon without being ripped apart. Unfortunately, once you get inside you’re still doomed, and it would still take a ridiculous amount of energy to hover right outside the horizon.