Discussion Overview
The discussion revolves around the mechanisms by which black holes absorb matter, exploring theoretical implications of General Relativity and the nature of event horizons. Participants examine the conditions under which black holes can form and grow, as well as the complexities of time dilation and the behavior of matter near black holes.
Discussion Character
- Debate/contested
- Technical explanation
- Mathematical reasoning
Main Points Raised
- Some participants assert that according to General Relativity, time does not pass on a black hole, leading to the conclusion that a critical mass may never be reached for a black hole to form.
- Others challenge this view, arguing that while time slows down as one approaches a black hole, infalling objects can cross the event horizon in finite time according to their own clocks.
- A participant introduces the concept of a "null surface" and explains its implications for understanding event horizons, noting that they are not conventional "places."
- Another participant describes a hypothetical scenario involving a black hole surrounded by a shell of dust, suggesting that this model allows for the formation of a larger black hole as the shell collapses.
- Concerns are raised about the assumptions made regarding the behavior of light and the event horizon during the collapse of the shell, suggesting that the Schwarzschild solution may not adequately describe the situation.
- Some participants note that different coordinate systems in General Relativity, such as Lemaitre coordinates, can provide alternative perspectives on black hole formation.
- There is a discussion about the implications of the event horizon expanding during the process of matter falling into the black hole, which complicates the notion of external time and the Schwarzschild chart.
- One participant highlights a contradiction in the original post's reasoning regarding the growth of the black hole and the crossing of the event horizon.
Areas of Agreement / Disagreement
Participants express multiple competing views regarding the nature of black hole absorption and the implications of General Relativity. There is no consensus on the correctness of the various models and interpretations presented.
Contextual Notes
Limitations include the dependence on specific coordinate systems and the complexities of curved spacetime, which may lead to misunderstandings in intuitive reasoning about black holes.