Discussion Overview
The discussion centers on the behavior of spin as an object collapses into a black hole, specifically whether the increase in spin continues until the object becomes a black hole and the implications of such behavior on the structure of the black hole. The conversation touches on theoretical aspects of black hole physics, including the nature of singularities and angular momentum conservation.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- Some participants propose that the increase in spin of an object collapsing into a black hole does not continue indefinitely and may stop at the moment it becomes a black hole.
- Others argue that if the spin were to continue increasing for a time before stopping, it could suggest the existence of a "hard radius" below the event horizon, although this idea has not been definitively excluded.
- One participant notes that while the frequency of spin cannot be observed, angular momentum can be observed through frame-dragging effects, which remain constant without external interactions.
- Another participant highlights the difference between the singularities in Kerr and Schwarzschild black holes, indicating that the Kerr singularity is a ring singularity and does not collapse to zero radius.
- A later reply discusses the implications of the Kerr limit, stating that if a rotating body exceeds this limit, it will not collapse into a black hole, and emphasizes that angular momentum is a conserved quantity that can change if the black hole is not isolated.
- One participant references a seminal paper discussing the internal structure of black holes, introducing the concept of mass inflation and suggesting that there may be a form of "hard radius" where infalling matter could collide before further collapse.
Areas of Agreement / Disagreement
Participants express multiple competing views regarding the behavior of spin during the collapse to a black hole, and the discussion remains unresolved with no consensus on the implications of spin behavior or the existence of a hard radius.
Contextual Notes
The discussion includes limitations related to the understanding of the interiors of spinning black holes, the dependence on specific definitions of singularities, and unresolved mathematical aspects concerning the transition from a collapsing object to a black hole.