Asteroid hits static black hole

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Discussion Overview

The discussion revolves around the implications of an asteroid impacting a static black hole, particularly focusing on whether such an event would induce rotation in the black hole. Participants explore theoretical aspects of black hole physics, including angular momentum, the nature of singularities, and the effects of infalling mass on black hole characteristics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that an object with angular momentum relative to a non-rotating black hole would result in a black hole with that angular momentum.
  • Others argue that a Schwarzschild black hole has zero angular momentum everywhere in spacetime, suggesting that an asteroid cannot exist within this framework.
  • There is a discussion about the nature of singularities, with some noting that the non-rotating singularity is spacelike while the rotating singularity is timelike, raising questions about the transition between these states.
  • Participants mention the Penrose process as a method to extract energy from rotating black holes, indicating that mass infall can influence black hole spin.
  • Some contributions highlight that dropping mass into a Schwarzschild black hole behaves like a non-interactive scenario, where angular momentum is not created.
  • There are references to quantum effects potentially altering the characteristics of black holes, including their evaporation and the nature of their horizons.
  • Several participants express uncertainty about the physical realization of the maximally extended Kerr solution and its implications for actual black holes.

Areas of Agreement / Disagreement

Participants generally express multiple competing views regarding the effects of an asteroid on a static black hole, particularly concerning angular momentum and the nature of singularities. The discussion remains unresolved with no consensus on the implications of these interactions.

Contextual Notes

Limitations include the assumptions made regarding the nature of black holes and the simplifications involved in modeling their interactions with infalling mass. The discussion also highlights the complexity of black hole interiors and the potential need for more sophisticated models.

  • #31
timmdeeg said:
the open question is whether or not the energy conditions apply
More precisely, whether they apply under conditions of extreme gravitational collapse. As I think I mentioned, certain quantum field states can violate the energy conditions; the question is whether the conditions encountered in extreme gravitational collapse would induce a kind of phase change that would produce such states. That's likely to remain an open question for a long time since that regime is nowhere near being accessible to our experiments any time soon.
 
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  • #32
timmdeeg said:
That seems to be a quite exotic example. I'm not sure how seriously one should take that.
What you wanted to ask is whether there are more examples in nature of non-compliance with the conditions. The example I gave is within theoretical physics, as I said, and they are exact solutions of Einstein's equations.
 
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