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Dentin comments on Questions for shminux - Less Wrong
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Leaving aside the question of space-time curvature at various places near/around the rod, there is an obvious answer:
If an event horizon forms around some part of the rod, say near one of the ends, that part of the rod is no longer connected to the remainder, and the rod now exists entirely outside of the black hole.
As for whether or not a black hole is symmetric, the answer (in the real universe) is almost certainly no. There's no requirement for symmetry in regard to event horizons (assuming that by 'symmetric', you mean 'spherical'.)
-dentin
It is NOT a black hole at all in one direction, it is in the other.
The same for pragmatist. THAT was the question.
And that was my point: you can't have that scenario. If you have an event horizon, it's closed. There is no 'other direction'.
-dentin
Surprisingly, in 3 spatial dimensions there are very few possible stationary configurations, and they are all quite symmetric, as I mentioned in my other reply. Once you consider extra dimensions, however, the space of possible stationary black hole configurations gets pretty large in a hurry.
I was primarily referring to rotation, which pretty much all 'real' black holes would have, where as I understand it the event horizon is distorted from spherical. I can't really think of any other configurations like that, but I don't know relativity that well either.
-dentin
I suppose we use the term "spherical" in different ways. I mean it in the topological sense, to say "shaped like a ball, or a cube or a pear", as opposed to something with holes, like a donut. I guess you take it to mean "a perfect sphere", where it looks exactly the same from all directions (has spherical symmetry). In that sense, yes, there are just two kinds of stationary of black holes, the Schwarzschild one (non-rotating) and the Kerr one (rotating). There are no other kinds in 3D. However, in 4D there are also toroidal black holes, string-like and some irregularly shaped ones, too.