[guest45734]

The inflationary universe is but one of many theories ref the beginnings of the universe. Nikodem Popolawski a theoretical physicist, has theorized we could live inside a black hole and that ER bridges and other universes might exist.  https://en.wikipedia.org/wiki/Nikodem_Popławski.

Understanding exactly what space is and how gravity works at the quantum level is key to knowing what goes on inside a Black hole. Popalawski does not adhere to Hoyles ideas of matter constantly coming into existence or the inflationary universe.

Popalawski theorizes big bounces are the source of matter in the universe, he is a prolific worker https://arxiv.org/a/poplawski_n_1.html the paper of interest here is this https://arxiv.org/pdf/1801.08076.pdf

[evan_au]

The super massive black hole thought to be at the center of the milky way should have an average mass density about the same as water on Earth.

All of that is wrong. Where did you get that idea from?

A back-of-the-envelope calculation suggests:
- Mass of the Milky Way's supermassive black hole: 8.2x10³⁶ kg
- Schwarzchild radius: 1.2x10¹⁰m
- Density: 4600 tonnes/cubic meter

This is a lot higher than Earth's density of 5 tonnes/cubic meter, or water at 1 tonne/cubic meter.

the average density of a SMBH (defined as the mass of the black hole divided by the volume within its Schwarzschild radius) can be less than the density of water in the case of some SMBHs. This is because the Schwarzschild radius is directly proportional to mass, while density is inversely proportional to the volume.

- It's just that the one at the center of our galaxy is only around 4 million times the mass of the Sun.
- The M87 galaxy is estimated to have a black hole about 6 billion times the mass of the Sun

[Bill S]

......to an outside observer of our universe time does not exist, it only exists in our reference frame.

Now, there's an interesting comment.

To some extent, I agree, but in your view, if there were observers outside our Universe, how could they do any observing if time didn't exist?

[Bill S]

The light of the infalling object is snuffed out in microseconds, by being red-shifted into oblivion.

So, the idea that an outside observer would continue to see objects, indefinitely, at the event horizon is not right?

How long might it take for the light to be red-shifted beyond microwave radiation? 

[PmbPhy]

......to an outside observer of our universe time does not exist, it only exists in our reference frame.

Now, there's an interesting comment.

To some extent, I agree, but in your view, if there were observers outside our Universe, how could they do any observing if time didn't exist?

He's totally wrong. To be an observer one must observe. That's something that occurs in time.

There's the concept of parallel universes and in those universes there's no reason to assume there's no time. In fact if those universes have the same property as ours then time does indeed exist for them.

[Halc]

A black hole can be made up of very normal matter, it depends on the size of the black hole. The super massive black hole thought to be at the center of the milky way should have an average mass density about the same as water on Earth.

All of that is wrong. Where did you get that idea from?

It cannot be made of normal matter.  That part is wrong.  Normal matter of that mass cannot support its own weight, and breaks down even before the black hole forms.
The density part can be as low as (or much lower than) water.  I'm getting conflicting figures for the average density (total mass/volume inside the Schwarzschild radius) of our galactic black hole that both higher and lower than water.

[Halc]

......to an outside observer of our universe time does not exist, it only exists in our reference frame.

[PmbPhy is] totally wrong. To be an observer one must observe. That's something that occurs in time.

There's the concept of parallel universes and in those universes there's no reason to assume there's no time. In fact if those universes have the same property as ours then time does indeed exist for them.

I have to agree with dead cat here.  A human inside a large black hole is an observer (inside a small one, he's a smear), and effectively exits the universe when crossing the event horizon.  If he's looking backwards, he sees the stars wink out in a rush of red-shift and from that point on, he cannot see anything from the outside.  Sure, light still falls in, but it cannot reach our observer, who very much is still observing and exists in a time, even if that time is now bent in a different direction.

From the perspective of the rest of the universe, the falling observer never left it.  Glued on the surface of the black hole, yes: Not by slowing of velocity, but just not entering it yet as the event of him crossing over is in the future of the current moment of the distant observer, in the frame of that distant observer.  Such is the weirdness of bent space it seems.

[PmbPhy]

......to an outside observer of our universe time does not exist, it only exists in our reference frame.

[PmbPhy is] totally wrong. To be an observer one must observe. That's something that occurs in time.

There's the concept of parallel universes and in those universes there's no reason to assume there's no time. In fact if those universes have the same property as ours then time does indeed exist for them.

I have to agree with dead cat here.  A human inside a large black hole is an observer (inside a small one, he's a smear), and effectively exits the universe when crossing the event horizon.  If he's looking backwards, he sees the stars wink out in a rush of red-shift and from that point on, he cannot see anything from the outside.  Sure, light still falls in, but it cannot reach our observer, who very much is still observing and exists in a time, even if that time is now bent in a different direction.

From the perspective of the rest of the universe, the falling observer never left it.  Glued on the surface of the black hole, yes: Not by slowing of velocity, but just not entering it yet as the event of him crossing over is in the future of the current moment of the distant observer, in the frame of that distant observer.  Such is the weirdness of bent space it seems.

He said "to an outside observer of our universe time does not exist". I didn't realize he was talking about the inside of a black hole. One doesn't call that a universe. It should say "our portion of the universe" or something so people like me don't get confused. Lol.  And its wrong to claim that time doesn't exist because it does. Outside observers simply have no access to it and they also can't see inside the black hole to verify their claim is true or not.

Messy stuff.

RE - "Not by slowing of velocity..." - That's wrong. All objects slow down and are redshifted to the extent they can't be seen. Even light slows down in a gravitational field and so too for photons moving towards the black hole.

[geordief]

Even light slows down in a gravitational field and so too for photons moving towards the black hole.

Does it slow down in a continuous way ?(ie if the gravitation increases it slows down more and more until the gravItational force is equal to that of a black hole and its speed is zero: do more powerful black holes make its velocity reverse?)

At what stage do photons (=em waves?) cease to exist in a BH?

[Bill S]

  What is observed and what is happening is all relative, to an outside observer of our universe time does not exist, it only exists in our reference frame.

I, too, interpreted this as meaning outside our Universe, rather than inside a BH.  Only Dead-cat can tell us what the intended meaning was.

A human inside a large black hole is an observer (inside a small one, he's a smear), and effectively exits the universe when crossing the event horizon.

I’m going to sidestep the question of what constitutes an observer.

However, I cannot agree that an observer exits the Universe “when crossing the event horizon”.  The BH is in the Universe, so, surely, its contents are also in the Universe.

One might subscribe to the view that a BH “singularity” is a gate (or bridge) to another universe; but even if that were the case, the observer would have to pass through that gate to exit the Universe, so would, arguably, no longer be in the BH.

[guest45734]

Even light slows down in a gravitational field and so too for photons moving towards the black hole.

Does it slow down in a continuous way ?(ie if the gravitation increases it slows down more and more until the gravItational force is equal to that of a black hole and its speed is zero: do more powerful black holes make its velocity reverse?) 

At what stage do photons (=em waves?) cease to exist in a BH?

Light speed is a universal constant it does not vary or slow. A photon loses energy escaping a gravitational field. A photon ceases to exist when the frequency is 0 ie E = hf 

[guest46746]

Is a BH empty? If it rotates, the answer needs to be no. Mass is required for rotation. So, does a BH illuminate? No, illumination requires photonic energy. So, if a BH is not void of mass and it doesnot illuminate, it must be composed of subatomic particles that arenot congealed in a structure. This would emmulate the condition directly after the big bang, where subatomic particle mass was abundant but due to the highly energetic environment formation of structure was impeded. Imagine an environment where massless and near massless particles are compressed into a quantum state of sharing the same space/time local, 2D. Now return to the big bang, where the this primordial soup of subatomic particle stewed until a time where a cooling transpired and the congealing took place by way of gravity. Under the auspicious of this cooling, a shrinking transpired, this shrinking initiated a motion, a movement. As there was no impediment to the "initial motion" it went into a free fall of rotation. The ensuing accumulation of free fall rotation velocity produced a chiralty gravititaional effect. This gravitational effect acted as a large tumbler, allowing the subatomic particles to engage and disengage in an infinite number of ways. Eventually, subatomic particles coupled into a Light/EM combination. This coupling, producing a light singularity became the predominant structure to emerge from the dark period.   

So, a BH rotates, it is comprised of subatomic particles that are locked in a quantum state of compressed engagement. This state is where quantum has multiple subatomic particles compressed into and sharing a single local of time/space. The closest analogy to visualize this quantum state is to imagine a 2D environment surround by a 3D environment. The BH surrounded by a Galaxy,  Does this preclude a BH as a different dimension? No. So, how does this relate to the Big Bang? Think of the BH has a localized version model the big bang. The black hole, is a singularity, it is comprised of unattached subatomic particles, It requires a catalyst to release it's potential. The Hawkings theory leaves open the possibilty of a strong gravitional field creating a particle and an antiparticle pair at the event hole horizon. If the anti-particle were to be separated into the BH from it's particle counterpart prior to annilation, it is possible that the anti-particle could be the catalyst for a BH gamma ray burst. lol

What is constantly being demonstrated in nature, is that property attributes of a child systems are legacies of a parent system. Although the model of the Big Bang and a Black Hole may differ in regards to their individual catalyst,
and their respective releases of energy, their results are comparative as to generative abilities.  lol

[Halc]

He said "to an outside observer of our universe time does not exist". I didn't realize he was talking about the inside of a black hole. One doesn't call that a universe.

Well, I called the outside of it a universe, and our observer severs all connection with that.  We on the outside and him on the inside can exchange no information.  That sounds like separate worlds at least, albeit not separate universes.

It should say "our portion of the universe" or something so people like me don't get confused. Lol.  And its wrong to claim that time doesn't exist because it does.

I said "who very much is still observing and exists in a time", so I'm not sure who claimed time not existing there.  A different dimension is time, but there is still the 3 spatial and 1 time dimension to it all.

RE - "Not by slowing of velocity..." - That's wrong. All objects slow down and are redshifted to the extent they can't be seen. Even light slows down in a gravitational field and so too for photons moving towards the black hole.

Intuitions are funny here, but you're right I think.  I unrealistically envision fast things approaching light speed and they never hit c but they don't slow down either.  But he event horizon is super-bent space and the rules there are different.  Yes, at the singularity, things stop in our external reference. Hawking was worried about preservation of information when things fall irretrievably into a black hole, but all the information pasting to the surface is not lost information.

[evan_au]

(A Black Hole) cannot be made of normal matter.  That part is wrong.  Normal matter of that mass cannot support its own weight, and breaks down even before the black hole forms.

I think it is just a matter of grammatical tense here.
- We see mechanisms that form black holes from normal matter when a star implodes and/or explodes.
- However, once this matter approaches the singularity, normal matter should be torn apart - it's not clear what the components would be (eg would they be outside the Standard Model?)
- And once it reaches the singularity, normal matter should be mashed together - it's not clear what the result would be
- But really, we can't say much about what happens inside the event horizon of a black hole

Is a BH empty? If it rotates, the answer needs to be no.

We expect that most black holes will form with the angular momentum of their parent star, accretion disk or galaxy.
It is theoretically possible for a black hole to have near-zero angular momentum:
- If there was a merger of two black holes with opposite and equal angular momentum.
- Or transiently, if the black hole was tearing off the atmosphere of a nearby star which was orbiting in the opposite direction to the direction of black hole rotation.
- But I expect that most black holes would have considerable angular momentum

The black hole, is a singularity, it is comprised of unattached subatomic particles

A black hole singularity in general relativity is where all of the particles end up at a single point; all paths entering the event horizon end up at the singularity.

Some theories of Quantum Gravity may allow some quantum fuzziness about the "single point".

But Quantum Gravity is not yet sufficiently mature to assert that "it must be composed of subatomic particles that are not congealed in a structure".

a chiralty gravitational effect

Gravitational waves are polarized.

Once 3 gravitational wave observatories were online, it was possible to detect the polarization of gravitational waves.

The first one was: https://en.wikipedia.org/wiki/GW170814

But I don't understand  "a chiralty gravitational effect".

[guest46746]

But I don't understand  "a chiralty gravitational effect".

Chirality gravitational effect, is an innate effect that is completely random and permanently imbued at the moment of it's initiation. Gravity was the first fundamental force. At the first rotation of the Light singularity, a left handed chirality for it's particle nature was established. . If the EM/Light singularity had rotated to the right our Universe would have been a righthanded chirality Universe. The nature of electromagnetism is that once the direction of force has been established only a a stronger force can reverse it's direction. We live in a fermion Universe where fermion particles spin to the left and anti-particles spin to the right. The overwhelming nature of our Universe consist of fermion particles. This was determined at the foundation and was a completely random event. lol

[guest46746]

A BH is the proof of Light at rest = 0. A BH has a "below the well" energy of -0. It exists has a 1D and 2D structure and therefore not restricted from possessing a -0 "below the well" energy. It acts as a gravitational monopole singularity. It does not have a time/space 3D structure, therefore it is a null location, it is a dormant singularity incapable of activity without a catalyst. It has not the plasticity of gravitational or light waves. It is monolithic in purpose, collect and converse Light. The BH is a centralize quantum structure with a 1D singularity gravitational point. As a quantum structure it cannot contain 3D fermion mass particles which are under the standard physics limitation of two particles cannot share the same space/time location. It can however, contain 2D low mass and massless particles that have no such space/time restrictions. Although dormant, a catalyst can promote a BH release of gamma rays energy. The trigger mechanism for this release is most likely an external catalyst that activates the 2D particles into active light photons which causes an cascading avalanche of energy out of the BH. This expulsion of energy ignites the stores of frozen Light at the Event Horizon, resulting in a Gamma ray burst. lol   

[PmbPhy]

A BH is the proof of Light at rest = 0.

What does the "= 0" mean? Light can never be a rest, even near a BH.

[Halc]

I think it is just a matter of grammatical tense here.
- We see mechanisms that form black holes from normal matter when a star implodes and/or explodes.
- However, once this matter approaches the singularity, normal matter should be torn apart - it's not clear what the components would be (eg would they be outside the Standard Model?)
- And once it reaches the singularity, normal matter should be mashed together - it's not clear what the result would be
- But really, we can't say much about what happens inside the event horizon of a black hole

Agree to all of that.  The contents are the same stuff as on the outside, but not likely in any form we've seen.
Even neutron stars are pretty much beyond empirical testing, leaving only the energy bursts to paint a picture of the structure within.

[guest46746]

What does the "= 0" mean? Light can never be a rest, even near a BH.

Light at a BH is not traveling at the speed of light! It is not traveling at all, as it cannot escape the BH gravitational attraction. At rest it has 0 mass energy! lol

[evan_au]

Although dormant, a catalyst can promote a BH release of gamma rays energy.

By "a catalyst", do you mean a neutron star that passes close enough to be disrupted by the black hole?
- I expect that would cause quite a burst of gamma rays

But the gamma rays come from the neutron star, which is outside the black hole's event horizon, not from within the black hole itself.

And the definition of a catalyst is that it is not disrupted by the reaction that it catalyzes. Definitely not the case here!

Or are you referring to the hypothesis that the singularity at the center of a black hole could be the origin of a separate Big Bang, in a universe contained within the black hole? In that case, the gamma rays would not be emitted outside the event horizon in our universe, but into the new universe within the black hole.
See: https://en.wikipedia.org/wiki/Black_hole_cosmology

I know that evidence about Black Holes is hard to obtain at this point in time, but please provide some evidence for your theories.