How can a black hole be infinitely small?

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Discussion Overview

The discussion revolves around the concept of black holes, particularly the idea of them being "infinitely small" and how their gravity operates. Participants explore the implications of black holes in the context of gravity, event horizons, and the intersection of general relativity and quantum theory.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions how a black hole can be infinitely small and still have gravity that holds it together, drawing an analogy to being at the center of the Earth where gravitational forces cancel out.
  • Another participant asserts that applying Newtonian physics to black holes is inappropriate, as their behavior cannot be accurately described within that framework.
  • There is a challenge regarding the notion of black holes being "infinitely small," with a clarification that black holes are defined by their event horizons, and what occurs inside them remains an open question in current theory.
  • Some participants emphasize that the event horizon is not a physical boundary but rather a null surface with specific significance in the context of black holes.
  • Concerns are raised about the concept of a singularity arising from applying general relativity without considering quantum theory, suggesting that this leads to contradictions and that the true nature of black holes is still uncertain.

Areas of Agreement / Disagreement

Participants express differing views on the nature of black holes, particularly regarding their size and the implications of their event horizons. The discussion remains unresolved, with multiple competing perspectives presented.

Contextual Notes

There are limitations in the discussion regarding the definitions of black holes and the assumptions made about their properties. The relationship between general relativity and quantum theory is also highlighted as a source of ongoing debate.

Aaron380
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Hi everyone. First post here!

It's an odd thought and relax I'm expecting to be wrong but the more I think about this the more interested I get.. Let's say you're chilling in the centre of earth, you feel no (little) pull because the gravity of Earth cancels out in all directions.

If a black hole is infinitely small how does it's own gravity hold it in because there is no direction that the matter would be being pulled as its in the centre of itself?
 
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You are trying to apply Newtonian physics to a black hole, which is a situation which is far from being possible to describe in the Newtonian limit. It is simply not describable in those terms.
 
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Aaron380 said:
Hi everyone. First post here!

It's an odd thought and relax I'm expecting to be wrong but the more I think about this the more interested I get.. Let's say you're chilling in the centre of earth, you feel no (little) pull because the gravity of Earth cancels out in all directions.

If a black hole is infinitely small how does it's own gravity hold it in because there is no direction that the matter would be being pulled as its in the centre of itself?
Where did you get the idea that black holes are "infinitely small"? From the outside, black holes are defined by their event horizons. What happens inside is an open question of current theory.
 
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mathman said:
Where did you get the idea that black holes are "infinitely small"? From the outside, black holes are defined by their event horizons. What happens inside is an open question of current theory.

Yeah I don't actually like that idea but it does appear to be the most common theory in research. The event horizon is not a physical border, simply a specific area of space with special meaning.
 
Aaron380 said:
The event horizon is not a physical border, simply a specific area of space with special meaning.
Be careful here! The event horizon is not a spatial surface, it is a null surface.
 
Aaron380 said:
Yeah I don't actually like that idea but it does appear to be the most common theory in research. The event horizon is not a physical border, simply a specific area of space with special meaning.
The idea of a "singularity" results from applying General Relativity without taking into account quantum theory. Applying both leads to contradictions, so what is really going on is an open question.
 

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