Inside black hole

Jul 13, 2022
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What are the chances of our Universe being inside a giant black hole? What's your argument in denial or support of this statement?

'There being multitude of black holes in the observable Universe don't prove otherwise'.
 
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Catastrophe

"There never was a good war, or a bad peace."
We have a semantic problem here.

What are the chances of our Universe being inside a giant black hole? What's your argument in denial or support of this statement?
Since the Universe is defined as "everything there is", it cannot be inside anything. We know nothing about the Universe in toto. Science can only address the observable universe, which is variable according to the location of the observer. Of course, all observers we know about are in one general location.

We can only ask whether our observable universe is in a black hole, which, itself is part of the Universe. This cannot be answered, as it is beyond the scope of our observing capability. Based on our observable universe, this seems unlikely for the reason given in post #2.

If, as a flight of unscientific fancy, one imagines our observable universe going into a reversal, contracting phase, then one might suggest that it might be in a black hole. This is just as much a waste of time and effort as to ask whether any continent north of the north pole can be painted purple within 10 nanoseconds. It is a totally meaningless.

Cat :)
 
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Nov 19, 2021
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Definitions I gleaned from reading:
- Universe: All existing matter and space as a whole
- Observable Universe: All signals since end of inflationary epoch (10^-33s)
- Visible Universe: Signals emitted since recombination (ie: 3°K CMB)

And, yes, the univere cannot be "inside" anything as that "thing" would be part of the universe.
The universe could, however, be a giant black hole as some theorists maintain.
I don't think it is, since galaxies are acellerating away from each other, as measured at large distances, not flowing towards a central singularity.
 
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Catastrophe

"There never was a good war, or a bad peace."
Nov 19, 2021
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Yes, scientists denote the "visual universe" as that which we can see, beginning with the 3°K remnant of the radiation emitted during recombination.

They refer also to the "observable universe" which goes back farther in time to the end of inflation.
 

Catastrophe

"There never was a good war, or a bad peace."
Bill, it is possible to dig around and find definitions, but, as Korzybski said,
the map is not the territory
.
For the purposes of this discussion, I only want to point out that there is a difference between the totality, and what we are able to abstract of it.

Cat :) :) :)
 
Apr 24, 2022
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The observable universe exists inside a black hole created by the total mass present in the observable universe.

1.Black hole cosmology
If we find the size at which the mass distribution with the average mass density of the present universe forms a black hole.

R=2GM/c^2
R_UB=(3c^2/8πGρ)^(1/2)=14.3Gly

The above expression means that if the present universe has a critical mass density ρ_c(the order of 5~6 hydrogen atoms per 1/m^3) value and the size is approximately R_UB=14.3Gly or more, this region becomes a black hole.

Currently, we estimate that the size of the observable universe is larger than 14.3 Gly, and the entire universe is estimated to be larger than the observable universe 46.5Gly, so our observable universe inevitably exists inside a huge black hole called the universe.

Black hole cosmology holds true if the following four things are true.
1)Finite Universe

We do not yet know whether the universe is finite or infinite. However, in my personal opinion, infinity is a mathematical notion, and there seems to be no infinite in physical reality. Even flat space-time does not guarantee an infinite universe (infinite mass-energy distribution). Since the age of the universe is finite and the propagation velocity of the field is also finite, the mass distribution is considered to be finite. Therefore, if we exclude the infinite universe, we face the problems 2)~4).

2)Schwarzschild's radius equation R=2GM/c^2

3)Observed average density

4)The observable universe 46.5Gly, the entire universe much larger than the observable universe.


The Black Hole Cosmology is the inevitable conclusion of the above 4 items. 2) is an equation that has been verified in two different theoretical systems (Newtonian mechanics and general relativity), 3) and 4) is on a very solid foundation, and even if 3) and 4) have some errors, the entire universe is estimated to be much larger than the observable universe. Even if the average density is lower than the current observation, the much larger entire universe inevitably renders the universe a black hole. This is because when the universe becomes R times larger, the density required to become a black hole decreases by 1/R^2.

2.Weaknesses of the Black Hole Cosmology
1) In a black hole, all matter is compressed into a singularity, so there is no space for humans to live. There is no almost flat space-time that could contain the observable universe inside a black hole.

2) In the black hole, singularity exist in the future, and in the universe, singularity exist in the past. Black hole and the universe are opposites.

3) The universe is expanding. Inside a black hole, all matter must contract at a singularity. The two models show opposite phenomena. It is difficult to explain the expansion of the universe inside a black hole.

Problems such as strong tidal force enough to disintegrate people, the movement of all matter in the direction of the singularity, and the expanding universe have been pointed out as fatal weaknesses of the Black Hole Cosmology. If our universe was a black hole, all galaxies should have collapsed into a singularity or exhibit motion in the direction of the singularity, but the real universe does not exhibit such motion characteristics. Therefore, the Black Hole Cosmology was judged to be inconsistent with the current observations, and the Black Hole Cosmology did not become a mainstream cosmological model.

A singularity exists inside a black hole, and all matter falls to the singularity and is destroyed.

In other words, if we were inside a black hole now, it would have collapsed due to gravity as a singularity, so we would not have been able to form the current structure of the galaxy or the solar system, and we could not exist.

Although this objection(Weaknesses) appears to be clear and well-grounded, in fact, this objection also has its own weaknesses.

1) The proposed weakness does not break the argument 2)~4) of the Black Hole Cosmology. Whatever the weakness , if 1) ~ 4) does not collapse, the Black Hole Cosmology is very likely to hold.

2) Most physicists and astronomers believe that the singularity problem will be solved either using quantum mechanics or in some unknown way, so there will be no singularity.
In other words, in the process of solving the singularity problem, there is a possibility that the singularity problem of the Black Hole Cosmology will also be solved.

3) Since the singularity exists in the Schwarzschild solution, the Schwarzschild solution must be changed for the singularity problem to disappear. That is, among the elements constituting the Black Hole Cosmology, the 2)Schwarzschild radius equation is affected.
For the singularity to disappear, there must be a repulsive force inside the black hole. Due to this repulsive force, an uncompressed region inevitably exists inside the black hole.

The remaining problem is, "Could an incompressible region be larger than the observable universe?"

Solutions to the problems of Black Hole Cosmology
Fatal weakness: 1)
In a black hole, all matter is compressed into a singularity, so there is no space for humans to live. There is no almost flat space-time that could contain the observable universe inside a black hole

1. Gravitational self-energy
~~~
U_gs=-(3/5)GM^2/R

In the generality of cases, the value of gravitational self-energy is small enough to be negligible, compared to mass energy mc^2. So generally, there was no need to consider gravitational self-energy. However the smaller R becomes, the higher the absolute value of U_gs. For this reason, we can see that U_gs is likely to offset the mass energy in a certain radius.

Thus, looking for the size in which gravitational self-energy becomes equal to rest mass energy by comparing both,

This equation means that if mass M is uniformly distributed within the radius R_gs, gravitational self-energy for such an object equals mass energy in size. So, in case of such an object, (positive) mass energy and (negative) gravitational self-energy can be completely offset while total energy is zero. Since total energy of such an object is 0, gravity exercised on another object outside is also 0.

Comparing R_gs with R_S, the radius of Schwarzschild black hole,


This means that there exists the point where negative gravitational self-energy becomes equal to positive mass energy within the radius of black hole, and that, supposing a uniform distribution, the value exists at the point 0.3R_S, about 30% level of the black hole radius.
~~~


Fig.x. Internal structure of the black hole. a)Existing model b)New model. If, over time, the black hole stabilizes,the black hole does not have a singularity in the center, but it has a zero (total) energy zone.

2. Inside a sufficiently large black hole, there is enough space for intelligent life to exist
A black hole has no singularity, has a Zero Energy Zone with a total energy of zero, and this region is very large, reaching 15% ~ 30% of the radius of the black hole. It suggests an internal structure of a black hole that is completely different from the existing model. Inside the huge black hole, there is an area where intelligent life can live.


For example, if the masses are distributed approximately 46.5Gly with the average density of the current universe, the size of the black hole created by this mass distribution will be 491.6Gly, and the size of the Zero Energy Zone will be approximately 73.7Gly ~147.5Gly. In other words, there is no strong tidal force and a region with almost flat space-time that can form a stable galaxy structure is much larger than the observable range of 46.5 Gly. The entire universe is estimated to be much larger than the observable universe, so it may not be at all unusual for us to observe only the Zero Energy Zone (nearly flat space-time).

Fatal weakness: 2) In the black hole, singularity exist in the future, and in the universe, singularity exist in the past. Black hole and the universe are opposites
~~~

Fatal weakness: 3) The problem of cosmic expansion inside a black hole. The universe is expanding. It is difficult to explain the distance between galaxies inside a black hole
~~~

#Problems and Solutions of Black Hole Cosmology
https://www.researchgate.net/publication/359192496
 
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That is a very interesting write-up.

However, it seems to still have some assumptions about space and time that might not be true. Our Big Bang Theory postulates that space itself is infinitely expandable and contractible, and can change "dimensions" faster than the speed of light. So, the real question is "How do we know what is expansion and contraction by observations, if we and things around us are all expanding or contracting together? And, what if the expansions and contractions are not uniform everywhere?

So, thinking about measuring everything collapsing into a single point while we are doing it seems much more problematic to me than what I typically see written.

If we were/are inside a black hole, thinking first about just the radial direction, things closer to the center would be accelerating toward it faster than us, and things farther away from it than us would appear to be getting farther behind. So, that could look like 'expansion" to us.

Now, think about the other directions besides along our own radial line into the center (not necessarily a singularity, BTW). If space itself is becoming smaller in the radial direction from everywhere, then so are the things that we perceive to measure it by observations. All of the write-ups I have read seem to falter in that regard, seeming to just assume that things will look like they are traveling through space, rather than thinking about how they would look when traveling with space, and maybe even shrinking along with space, as we assume happened in reverse with the Big Bang.

Putting it another way, if space and time are both being changed together along all radial lines toward some huge attractor for all that we observe, would we really be able to tell that by observations from a single point over a tiny amount of time (in the cosmological scale of time)? If so, how?

The other issue about falling into a black hole is whether those doing it see time "going backwards" But, if that direction of time is all we know about, to us it is "forward", right? How would we know what "backwards" is or even looks like? I guess we could try to use entropy, and suppose that things would look like order increases when going backwards. But, that would look like things like energy are attractive forces rather than dissipative forces. And I guess that gravity would look like a dissipative rather than an attractive force. If that is all we ever experienced, then wouldn't we think that those were the laws of nature, just like we now think that gravity is an attractive force? We really don't know how gravity works - we just know that our equations fit our very limited observations.

Conceptualizing cosmological things with a human mind is limiting because our minds have developed to rationalize what we observe into useable expectations for the situations that directly affect us. So, when we try to imagine things that have not affected us in perceivable ways during our evolution, we are really stretching our cognitive abilities. We can intuitively conceive of particles that can fly though emptiness and waves that can transmit energy through materials with mass, but we are already stumbling when trying to deal with experiments that make the same things look like particle sometimes and waves through massless "fields" other times. We really have no intuitive idea how waves propagate through "nothings" that have no mass or other physical properties. Then, finding that light appears to travel at the same speed no matter how it is observed really gets us out of our intuitive understanding of space and time.

We can deduce some equations to quantify our observations, but many of those equations are difficult or impossible for us to solve without making assumptions. And, extrapolations of those equations that are made by using "simplifying" assumptions gets us right back into stumbling around with our intuitive biases on what things "should" be like. That is what I think I am seeing in how people are writing about how things would look to us if we are inside a black hole's event horizon and falling toward it center. Some people are conceptualizing that it would look like an expanding universe, and others are thinking it would have to look different from what we see.

Neither side has convinced me that they have it figured out properly, yet.
 
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