Discussion Overview
The discussion revolves around the formation of the event horizon (EH) during the collapse of a star into a black hole (BH). Participants explore whether the EH first appears at zero radius or with a non-zero radius, and the implications of these scenarios on the mass captured during the collapse.
Discussion Character
- Debate/contested
- Conceptual clarification
- Technical explanation
Main Points Raised
- One participant questions whether the EH first appears at zero radius and grows outward, or if it appears with a non-zero radius, suggesting that if it appears with a non-zero radius, some stellar mass may be captured inside without crossing the EH.
- Another participant asserts that the EH is defined by the mass of the star, indicating that once the collapsing star's radius is smaller than the EH radius, it becomes a black hole.
- A different viewpoint suggests that the formation of the EH is not straightforward, as it may appear inside the collapsing star, complicating the understanding of its formation.
- One participant expresses confusion about how Hawking's holographic principle addresses the information paradox, noting that it seems to only apply to particles that have crossed the EH and does not account for mass trapped inside during the collapse.
- Another participant proposes that since the minimum mass necessary to form a black hole is the Planck mass, it is reasonable to conclude that all black holes begin with a non-zero radius, which may grow rapidly depending on the infall rate.
Areas of Agreement / Disagreement
Participants express differing views on the nature of the event horizon's formation, with no consensus reached regarding whether it first appears at zero or non-zero radius. The discussion remains unresolved with multiple competing perspectives on the implications of these scenarios.
Contextual Notes
Some participants highlight the complexity of the event horizon's formation, suggesting that additional factors such as rotation and the dynamics of stellar collapse may influence the discussion. There are also references to theoretical minimum and maximum infall rates, which remain unexplored in detail.