Could the Visible Universe Be a Fuzzball in String Theory?

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SUMMARY

The discussion centers on the hypothesis that the visible universe, approximately 13.7 billion light-years in diameter, could be the event horizon of a fuzzball, a type of non-classical black hole in string theory. Participants reference the properties of fuzzballs, such as the supermassive black hole Sagittarius A* with a mass of 4.3 million solar masses and a mean density of 1.2 kg/m³, suggesting that the universe's density could align with that of a fuzzball. The conversation also explores the implications of cosmic expansion and the potential for smaller fuzzballs existing within the universe. Ultimately, the discussion raises questions about the observable limits of the universe and the nature of its expansion.

PREREQUISITES
  • Understanding of string theory and fuzzball concepts
  • Knowledge of black hole physics, particularly supermassive black holes
  • Familiarity with cosmological principles, including the expansion of the universe
  • Basic grasp of astrophysical measurements, such as light-years and astronomical units
NEXT STEPS
  • Research the properties and implications of fuzzballs in string theory
  • Study the characteristics of supermassive black holes, focusing on Sagittarius A*
  • Explore the concept of cosmic expansion and its relationship to black holes
  • Investigate observational evidence for the structure of the universe and its boundaries
USEFUL FOR

Astronomers, physicists, and cosmologists interested in theoretical astrophysics, particularly those exploring the intersections of black hole physics and the structure of the universe.

Jonny_trigonometry
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Could the edge of the visible universe (13.7 billion light-years, where recession velocity equals light speed), be the radius of an event horizon of a non-classical black hole such as a fuzzball?

http://en.wikipedia.org/wiki/Fuzzball_(string_theory )

"Due to the mass-density inverse-square rule, all fuzzballs need not have unimaginable densities. There are also supermassive black holes, which are found at the center of virtually all galaxies. Sagittarius A*, the black hole at the center of our Milky Way galaxy, is 4.3 million solar masses. If it is actually a fuzzball, it has a mean density that is “only” 51 times that of gold. At 3.9 billion solar masses, near the upper bounds for supermassive black holes, a fuzzball would have a radius of 77 astronomical units—about the same size as the termination shock of our solar system’s heliosphere—and a mean density equal to that of the Earth's atmosphere at sea level (1.2 kg/m3)."

From this quote, a fuzzball (non-classical black hole) can have a radius of 77au, and have a mean density of 1.2 kg/m^3? Wow, doesn't it seem that there would be no reason for strings in some regions to stay non-condensed, but instead condense into elementary particles? Further, why couldn't there be elements in regions of this space? Even further, why can't there be many smaller fuzzballs inside? Now consider my thread topic. Why not? The mean density of the visible universe could be on par with that found in a fuzzball with the radius of the visible universe.

Furthermore, consider expansion. Could the reason for expansion be due to infalling matter? Much like what we observe as black holes devour matter surrounding them, if our visible universe is the inside of a fuzzball, then if it's gaining mass, its schwartzchild radius is expanding over time.

Now consider rapid expansion in the early universe. It could have been caused by the initial beginning of the black hole universe, sucking in its immediate surroundings, undergoing rapid expansion. It has slowed down since--though it's still gaining mass--because it's pulling in more energetic matter that it wasn't able to pull in at the beginning.
 
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Why pick the visible universe limit for the radius? Wouldn't that imply we are in the center? Do you think that someone 13billion ly away will see an edge to the Universe 0.7billion ly away?

There are a lot of discussions in PF about whether the Universe is inside a BH of one kind or another.

https://www.physicsforums.com/archive/index.php/t-106841.html

I think the trick is coming up with an observation that requires the Universe to be inside a fuzzball ...
 
Simon Bridge said:
Why pick the visible universe limit for the radius? Wouldn't that imply we are in the center? Do you think that someone 13billion ly away will see an edge to the Universe 0.7billion ly away?

you are absolutely right. I didn't think of that. Kind of makes the idea seem unworkable
 

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