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I have read that there are different properties of black hole which are rotating like, they drag the spacetime, with them. Also I read that they have kind of 'ergosphere' along with event horizon. Also are rotating black holes inherently different from non rotating ones?

Qmechanic
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Kshitij Kumar
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    What are you actually asking though? It's not clear to me at least what kind of answer you're expecting here. – Charlie Feb 11 '21 at 17:23
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    This question is extremely broad, has many questions embedded in it, and an answer would likely amount to a whole chapter of a textbook. Suffice it to say that the rotating black hole solution is much more mathematically complex, and quite mathematically different from the non-spinning solution, but most physical black holes are expected to be spinning. The non-spinning solution is mostly studied for mathematical simplicity and comprehnsibility. – Zo the Relativist Feb 11 '21 at 17:23
  • @Charlie, ok I removed some questions, for more focused question – Kshitij Kumar Feb 11 '21 at 17:26
  • It seems to me that you mean frame-dragging – jng224 Feb 11 '21 at 17:33
  • @Jonas yes, I couldn't think right words at the moment. – Kshitij Kumar Feb 11 '21 at 17:35
  • Note that real black holes tend to spin very fast, even the huge ones. See the chart at the end of this answer: https://astronomy.stackexchange.com/a/20292/16685 – PM 2Ring Feb 11 '21 at 19:55

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Ill answer in broad terms, if you want a more mathematical answer just ignore this answer.

Basically the shape of space time is determined by the metric (a function that computes distance between points of spacetime), and the whole idea of general relativity is that energy (including mass), momentum and angular momentum (rotation) acts on this metric and transform it. A rotating black hole has a lot of mass transforming the metric around it, but also angular momentum. It just so happens that the theory of general relativity predicts for a rotating black hole a transformation of the metric such that space time seems dragged in the rotation. So no, rotating black holes are not inherently different than non-rotating ones, they just have additional terms due to angular momentumin the equations describing the action on the metric

Transforming the metric, means that light rays passing by the rotating black hole find the shortest path to take to be one where they go around the black hole many times.

One thing it could help us with, is verify predictions of general relativiti alternatives or confirm GR with even more precision.

I bring you attention to this post: What is exactly rotating in a rotating black hole?

TheStressTensor
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