Almost-universe-sized black hole

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Discussion Overview

The discussion explores a speculative model regarding the nature of black holes and cosmic expansion, questioning whether acceleration in the universe could be attributed to an attraction to a massive black hole rather than an outward expansion. The scope includes theoretical implications for cosmology and the behavior of galaxies in relation to this model.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that if a black hole expanded to encompass a significant portion of the universe, it could create an illusion of accelerating expansion as galaxies are drawn toward it.
  • Others argue that this model would contradict the observed Hubble law, which states that galaxy velocities are proportional to their distances from us.
  • There is a suggestion that if the black hole were sufficiently distant, it might be difficult to measure deviations from the expected cosmic structure, potentially allowing for a perception of being at the center of the universe.
  • One participant raises a question about the cosmic microwave background, pondering if it could be related to material falling into the black hole, although they acknowledge this idea is speculative.
  • Another participant emphasizes that the proposed model conflicts with the cosmological principle, which suggests a homogeneous universe.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the proposed model, particularly regarding its compatibility with established cosmological principles and observations. The discussion remains unresolved, with multiple competing perspectives on the nature of cosmic expansion and black holes.

Contextual Notes

Limitations include the speculative nature of the proposed model, potential contradictions with established cosmological observations, and the challenge of measuring cosmic distances accurately in relation to the black hole's influence.

Meatbot
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What if acceleration is really an attraction to something surrounding us?

What would happen if a black hole gained size over the history of the universe until it comprised a huge percentage of the universe? And what if that universe was curved so that as the black hole expanded, it began to approach itself on the other side, like drawing larger and larger circles on a ball? What would the observer in the remaining part of the universe see as this black hole closed up? Wouldn't it look like accelerating expansion as the galaxies are pulled toward the monster black hole all around them with greater and greater force? Does this model have any correlation with anything in the real world or am I a crackpot? Has anyone looked at this?

Basically the idea is: What if expansion is really being attracted to something which surrounds us instead of being propelled outward from within?
 
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Meatbot said:
Basically the idea is: What if expansion is really being attracted to something which surrounds us instead of being propelled outward from within?
Then the velocities of galaxies would not be proportional to the distance, contradicting the observed Hubble law (or perhaps we would have a privileged role of being in the center of the universe).
And of course, there would be no cosmic microwave background.

But this belongs to the Cosmology subforum.
 
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Demystifier said:
Then the velocities of galaxies would not be proportional to the distance, contradicting the observed Hubble law (or perhaps we would have a privileged role of being in the center of the universe).
And of course, there would be no cosmic microwave background.

But this belongs to the Cosmology subforum.

What if it was so far away that even if you weren't exactly in the center you wouldn't be able to get enough accuracy on your measurements to tell the difference?

Cosmic background is a big problem, though. I didn't think of that. Any way that the cosmic background could be closer to us than the event horizon of this black hole? What if it's actually the material falling into it? It's a stretch I know.

Sorry about posting to the wrong subforum.
 
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Meatbot said:
What if it was so far away that even if you weren't exactly in the center you wouldn't be able to get enough accuracy on your measurements to tell the difference?
But that means we're pretty much in the centre of the universe (since your black hole is on the same scale as the size of the universe). This does not agree with the cosmological principle.

Sorry about posting to the wrong subforum.

Yes, this is cosmology and thus, if appropriate to any forum, would belong there.
 

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