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You cannot orbit a black hole immediately outside the event horizon. The smallest distance at which a circular orbit is possible is called the photon sphere be
by splat 13y ago
You cannot orbit a black hole immediately outside the event horizon. The smallest distance at which a circular orbit is possible is called the photon sphere because you must be moving at the speed of light to maintain a circular orbit. The photon sphere is at 1.5 Schwarzschild radii.
- tehwalrus 13y agoAh, apologies, so this would be impossible with a living thing. If we substitute for a machine? Could you, perhaps, build a strong enough spaceship to dip in close enough to dangle something passed the horizon, and then accelerate away again? I don't suppose you'd be able to measure anything from the resulting object, even if you could get it back... Even if you couldn't, I still find it implausible that even large objects would travel across the even horizon effectively instantaneously.
- splat 13y agoIf you dangle something into the event horizon it will be lost forever. Large objects in free fall wouldn't travel across the event horizon instantaneously. It's just that by the time a signal from the front of the object reached the back, the back of the object would have already crossed the event horizon.
- tehwalrus 13y agoYou forgot that the object is supposed to be attached to very powerful rockets, so not in free-fall, and presumably made of some advanced material that can withstand the acceleration forces. Additionally, you still haven't addressed the issue of atoms, covalently bonded, either side of the horizon (and not in free fall downwards, but being pulled from a rocket above so as to be slower than that.)
- nikbackm 13y agoUnless the rockets can match or exceed the speed of light, does it matter since only photons can maintain a circular orbit that close the event horizon as was already stated? (PS: I think that advanced material you're referring to is also known as Unobtainium :)
- JanezStupar 13y agoAs a layman I think that if your rocket were to lower a rope towards the event horizon, the rope after it passed through - would start acting like an anchor. You cannot get it out, anymore - you can follow it or let go. The same would go for your legs. Event horizon is an abstract limit at which not even light can escape. __not even light__. I guess that the point of no escape for your rocket, no matter how powerful it was, was far, far more. What happens if a contemporary earth rocket would go into orbit around Jupiter? At some level it couldn't get away with its engines. That would be the point of no return. Nothing inherently bad happens, except there is no way to go but down.
- splat 13y agoThe part of the rope within the event horizon would not act like an anchor. It would just immediately rip apart from the rope outside of the event horizon.
- splat 13y agoIf a rod is held above the event horizon and then slowly lowered down into the event horizon, any part of it that passes through the event horizon will rip apart from the rest of the rod. It doesn't matter what the rod is made of. It's impossible for any bonds to maintain themselves on either side of the event horizon unless they are in free-fall (or close to it).
- bcbrown 13y agoI think you've reached the point where analogies break down, and you'd have to do the math and physics to resolve your objection. http://xkcd.com/895/ http://xkcd.com/895/
- gnaritas 13y agoNeither human nor machine can travel at the speed of light, so no you couldn't substitute a machine.