Black hole?

[beecee]

2 minutes ago, Strange said:

Interesting idea. I doubt there is a simple answer to that. My feeling is that the accretion disk is likely to be rotating in the same direction as the BH. But these things are complicated so ...

Yeah good point.In that case it may actually act to increase angular momentum. Complicated?  That is certainly an understatement!

Yet getting into this complicated scenario, could/should the angular momentum of the BH, act to prevent total compulsory collapse to the quantum/Planck level?

[interested]

8 hours ago, Strange said:

It doesn't.

Hawking radiation theoretical maybe but it gets out. 

8 hours ago, Mordred said:

See section 12.2 BH vs Neutron Star section, which explores the possibility that a BH is a Neutron star with an EH as opposed to a pointlike singularity of a BH.

Two things occur to me that I find interesting, that were not discussed in either of the links you posted and I think are relevant to black holes, or if they were discussed I missed it.

1) What is the shape of the black hole, is it a round or flattened spheroid? is it a hollow spheroid, donut or tubular? singularities and infinities do not exist. A Black hole must have shape even if you cant see it.

2) In the accretion disc the mechanism for the generation of the charge is not discussed, the disc is hot, and most likely a plasma any matter in it is ionized. Do the charges separate out heavier charges towards the event horizon, lighter charges on the outer rim. Is this what causes the plasma emitted from the BH to appear as plasma streams at the poles, due to the magnetic fields caused by moving charges.

A separate thought

The actual mechanism that causes gravity is quantum fluctuations, it is not an equation. These quantum fluctuations have not been directly detected as yet and may never be. They are either absorbed by matter, or radiated, strange stated that hot matter was heavier, does this mean that hotter material absorbs more quantum fluctuations or emits more. Is there a limit to absorption or emission of virtual particles gravitons etc. Could the surface area or density of a black hole have a maximum absorption or emission rate.

Another thought ligo detected a oscillation in quantum fluctuations in space a expansion and contraction or wave, could we surf a gravitational wave. 

1 hour ago, beecee said:

Yeah good point.In that case it may actually act to increase angular momentum. Complicated?  That is certainly an understatement!

Yet getting into this complicated scenario, could/should the angular momentum of the BH, act to prevent total compulsory collapse to the quantum/Planck level?

edit Complicated because a lot of it is just theories, and might be smoke and mirrors.

Is a compulsory collapse to the quantum plank level realistic.

How many quantum fluctuations can you get into that space. I understand only one fermion can occupy a space at once are you saying all the matter in a black hole becomes bosons ie radiation and therefore can. 

Edited December 1, 2017 by interested

[beecee]

6 minutes ago, interested said:

Hawking radiation theoretical maybe but it gets out. 

Theoretical or otherwise, Hawking Radiation does not involve anything "crossing" the EH from inside to outside.

9 minutes ago, interested said:

Is a compulsory collapse to the quantum plank level realistic.

For a Schwarzchild metric BH, it certainly is, and is what is entailed by GR.

[Strange]

14 minutes ago, interested said:

Hawking radiation theoretical maybe but it gets out. 

It is created at the event horizon.

14 minutes ago, interested said:

1) What is the shape of the black hole, is it a round or flattened spheroid?

Round if not rotating. Flattened if rotating.

15 minutes ago, interested said:

is it a hollow spheroid, donut or tubular?

It is basically spherical. But the space-time around a rotating black hole is complicated.

 

[Mordred]

3 hours ago, MigL said:

Haven't read the article you posted Mordred, but I would agree with Strange and Beecee.

What mechanism would stop the further collapse once neutron degeneracy  fails ?
And if neutron degeneracy doesn't fail, there is no need for an event horizon.

There arguments not mine so wish I could answer that one. Never looked too deep into the topic. The subject came up on another forum just prior to my joining this one that I became familiar with the argument. Though I can certainly see what I can dig up on the topic thats more recent.

Found the original paper, 

http://www.sciencedirect.com/science/article/pii/S0370269314006686

In essence the backreaction of Hawking radiation prevents further collapse and the reason we see a singularity is based on time dilation.

(keep in mind I don't particularly buy into this idea myself

Edited December 1, 2017 by Mordred

[interested]

18 hours ago, Mordred said:

 

http://www.sciencedirect.com/science/article/pii/S0370269314006686

In essence the backreaction of Hawking radiation prevents further collapse and the reason we see a singularity is based on time dilation.

(keep in mind I don't particularly buy into this idea myself

Shy kids get nowt, if no one else is going to ask this question I will.

What do you not buy into ref Hawking radiation. Everything or just a little.

[Mordred]

I don't buy the backreaction as being sufficient to prevent the collapse.

Edited December 2, 2017 by Mordred

[interested]

Does the collapse of a black hole have to be a singularity at the plank level.

2 Fermions cant occupy the same space, does all the matter turn into Bosons inside a BH. Is the singularity stationery inside a black hole, how does a boson move at light speed inside a BH if it is in a stationery singularity. 

Can a black hole collapse into something other than a singularity, a hollow sphere perhaps or other shape.

 

[Strange]

Maybe. In fact, almost certainly. But we don’t yet have any theory that explains why collapse will stop, or what will happen instead. 

[Dubbelosix]

1 hour ago, Strange said:

Maybe. In fact, almost certainly. But we don’t yet have any theory that explains why collapse will stop, or what will happen instead. 

This isn't exactly true there are a number of models which present theories which stop full collapse to singularities. They have been the focus of investigation for a long time now. 

One such model is the Planck star, in which quantum gravitational corrections act like a negative pressure capable of even being the final stage of a collapse. 

On 01/12/2017 at 8:16 PM, beecee said:

Yeah good point.In that case it may actually act to increase angular momentum. Complicated?  That is certainly an understatement!

Yet getting into this complicated scenario, could/should the angular momentum of the BH, act to prevent total compulsory collapse to the quantum/Planck level?

Possible.

One such treatment states that the angular momentum actually varies in size. If the angular momentum increases as size decreases there are centrifugal forces to take into consideration.There may need to be additional factors, but the centrifugal force (the apparent force you feel in a spinning frame) has been suggested by Michio Kaku as a proposed mechanism for keeping wormholes open. 

[interested]

15 hours ago, Dubbelosix said:

This isn't exactly true there are a number of models which present theories which stop full collapse to singularities. They have been the focus of investigation for a long time now. 

One such model is the Planck star, in which quantum gravitational corrections act like a negative pressure capable of even being the final stage of a collapse. 

Possible.

One such treatment states that the angular momentum actually varies in size. If the angular momentum increases as size decreases there are centrifugal forces to take into consideration.There may need to be additional factors, but the centrifugal force (the apparent force you feel in a spinning frame) has been suggested by Michio Kaku as a proposed mechanism for keeping wormholes open. 

Yes even I know it is not true. I already posted something on various theoretical exotic stars previously on this thread, https://en.m.wikipedia.org/wiki/Exotic_star#Boson_stars The boson star is the one that interested me for various reasons, but I am aware of the Plank star also. Something else was on the white hole theory https://en.wikipedia.org/wiki/White_hole which may all be completely theoretical and not at all related to BH's. There is also a view that space is not three dimensional and all points in space may be entangled to a certain degree, allowing energy to escape through a fourth dimension in a BH. What is the chances that something in an entangled more than 3 dimensional world with massive amounts of energy could be teleported out of a BH? https://en.wikipedia.org/wiki/Quantum_teleportation 

Clearly the whole field of black holes, is a whole lot more interesting than other holes, although white holes might be connected by black holes via worm holes. Or maybe black holes lose whole or part of their energy through entanglement to the whole of space. If one could develop a whole new theory in a hole or holes of multiple types, then a whole theory of holes could be developed and fixed in whole lot of peoples heads in a whole new way like the big bang where wholly nothing can get out of black hole via any hole in space, not even theoretically according to some. On the whole where all matter comes from in the universe is the holy of holys in a whole new wholesome sort of way, and it is wholesome and interesting too   

Edited December 3, 2017 by interested

[interested]

So what we got so far inside a black hole:- a singularity, a possible hollow interior with the shell supported by radiation, or wormholes to other worlds or dimensions. 

Wormholes out of black hole. Possible extra dimensions allowing an escape route from the BH. 

Heres a thread with info escaping a black hole https://www.wired.com/story/information-escape-wormholes/
Almost everyone believes in unitarity, which means information must escape black holes—but how? In the last five years, some theorists, most notably Joseph Polchinski of the University of California, Santa Barbara, have argued that black holes are empty shells with no interiors at all—that Ellie Arroway, upon hitting a black hole’s event horizon, would fizzle on a “firewall” and radiate out again. 

It has been repeatedly stated on this thread "Nothing gets out of a black hole" What is this Nothing that gets out of black holes. Are the people theorizing about it actual scientists or crackpots. How does Nothing get out of a Black hole? 

(I asked a question earlier on ref the graviton emission or absorption I think I have the answer. Within a black hole if absolutely nothing gets out ie a graviton, virtual particles, or quantum fluctuations, then the cause of gravity must flow into the event horizon in the same way any other quantum fluctuation does, gravity is therefore caused by the absorbtion of quantum fluctuations, possibly gravitons or virtual particles, from space. These quantum fluctuations in space must also drive the expansion of space, ie as detected from ligo a gravitational compression and stretching of space. ) 

Another question: if quantum fluctuations absorbed by matter are the cause of gravity, could the end product inside a black hole be just quantum fluctuations that either disappear out of a worm hole ie extra dimension reappearing in space somewhere else, causing the expansion of space? Answers of course not, dont know, maybe.  

[Strange]

4 minutes ago, interested said:

It has been repeatedly stated on this thread "Nothing gets out of a black hole" What is this Nothing that gets out of black holes. Are the people theorizing about it actual scientists or crackpots. How does Nothing get out of a Black hole? 

OK. So the only standard, accepted by all scientists, description of black holes we have is that specified by GR. Because that is based on a theory backed by mountains of evidence. In that model, nothing can escape. 

However, there are alls sorts of speculative/hypothetical/theoretical ideas out there about how quantum theory might change this. In some of these there are mechanisms for matter to leave a black hole. But there is no evidence for any of these ideas yet. 

If you are happy to just accept an idea because it is appealing even though there is no evidence, then go for it!

8 minutes ago, interested said:

Another question: if quantum fluctuations absorbed by matter are the cause of gravity

They aren't. It is caused by the geometry of space-time.

[interested]

22 hours ago, Strange said:

OK. So the only standard, accepted by all scientists, description of black holes we have is that specified by GR. Because that is based on a theory backed by mountains of evidence. In that model, nothing can escape. 

However, there are alls sorts of speculative/hypothetical/theoretical ideas out there about how quantum theory might change this. In some of these there are mechanisms for matter to leave a black hole. But there is no evidence for any of these ideas yet. 

If you are happy to just accept an idea because it is appealing even though there is no evidence, then go for it!

They aren't. It is caused by the geometry of space-time.

The bouncy universe or loop quantum gravity allows black holes to evolve into big bangs https://phys.org/news/2013-05-theorists-loop-quantum-gravity-theory.html#nRlv this idea sounds plausible. There is no evidence what is happening inside a black hole and most likely never will be unless one explodes violently releasing energy, in the form of radiation.

Initially I am happy to accept an idea if it sounds plausible, for instance the core of a black hole being supported by radiation, to me sounds plausible, a black hole losing energy through Hawking radiation is plausible, a BH teleporting energy out of its core by another dimension or wormhole to other parts of the universe sounds plausible, (I thought teleportation was star trek until Swansont mentioned it on the entanglement thread I started). Parallel universes do not sound plausible, whereas extra dimensions do and for me explain entanglement of particles.  

From my Mantra All things are quantum fluctuations, space time is quantum fluctuations of different types. Galaxies are all accelerating away from each other due to more quantum fluctuations(space) coming into existence than are absorbed by mass. The apparent curvature of space by mass, could equally be represented by the absorption of quantum fluctuations(space) by mass, which could be the cause of gravity and space time curvature. The problem of time between quantum gravity and space time could just be a different way of looking at the problem. https://en.wikipedia.org/wiki/Problem_of_time  The casimir effect suggests gravity is due to quantum fluctuations being reduced between the plates https://en.wikipedia.org/wiki/Casimir_effect . 

Space is space time and fixed empty dimensions for some, I prefer to think of it at the moment as supported by quantum fluctuations, which possibly are only virtual particles but could equally be mathematically described as gravitons. What would happen to a theoretical graviton inside a black hole? I guess it would be absorbed like a virtual particle.

I could always be wrong, but I am still interested and currently think I am barking up the right tree, but may change my mind next week.

Edited December 4, 2017 by interested

[Strange]

On 04/12/2017 at 6:23 PM, interested said:

The bouncy universe or loop quantum gravity allows black holes to evolve into big bangs https://phys.org/news/2013-05-theorists-loop-quantum-gravity-theory.html#nRlv 

It doesn't say that at all.

 

You might be interested in this, a VR trip into a black hole: https://www.quantamagazine.org/plunge-into-a-virtual-reality-black-hole-20171204/

[interested]

4 hours ago, Strange said:

It doesn't say that at all.

 

You might be interested in this, a VR trip into a black hole: https://www.quantamagazine.org/plunge-into-a-virtual-reality-black-hole-20171204/

Ive seen it but thanks, I like repeats, and the links are good too.

[Mordred]

I often attempt to model inside a BH. Relativity can allow for it with the right observer. I still get nonsense answers for the singularity conditions. Its been years since my last attempt. There is definetely boundaries where no metric can cross and still make sense.

Edited December 5, 2017 by Mordred

[interested]

On 05/12/2017 at 10:17 PM, Mordred said:

I often attempt to model inside a BH. Relativity can allow for it with the right observer. I still get nonsense answers for the singularity conditions. Its been years since my last attempt. There is definetely boundaries where no metric can cross and still make sense.

When the maths fail, does not help a little to fall back on speculation as to what might be happening inside a blackhole in terms of temperature, using known physics.

If you take all the matter in the univere and start squashing it down, it will become hotter than the conditions predicted at the start of the big bang.

Edit

I know you dont agree with the concept of radiation supporting the interior of a blackhole, preventing the collapse, but what would happen if most of the interior was turned into radiation. Would gravity still work the same, if there was no mass in the blackhole but just radiation with inertia.

Are photons attracted to each other by gravity, or do they converge with each other because of waves interactions.  

Edited December 9, 2017 by interested

[Mordred]

The two temperatures have a point where they reach where the math breaks down to giving rise to nonsense answers. There is a theoretical upper bound to temperature.

Planck temperature, which connects to the minimal Planck length via its wavelength.

https://en.m.wikipedia.org/wiki/Planck_temperature

[Strange]

1 hour ago, interested said:

I know you dont agree with the concept of radiation supporting the interior of a blackhole, preventing the collapse, but what would happen if most of the interior was turned into radiation. Would gravity still work the same, if there was no mass in the blackhole but just radiation with inertia.

I don't know why you think radiation would behave any differently. It is still constrained to travel through space and time. The centre of the black hole is in the future, and even radiation cannot travel backwards through time. There're literally no paths for anything to ravel along that do not lead to the centre of the black hole.

The gravitational effect of mass and energy are the same. Mass is represented in the Einstein field equations by the energy term.

[interested]

2 hours ago, Mordred said:

The two temperatures have a point where they reach where the math breaks down to giving rise to nonsense answers. There is a theoretical upper bound to temperature.

Planck temperature, which connects to the minimal Planck length via its wavelength.

https://en.m.wikipedia.org/wiki/Planck_temperature

I did not know about the theoretical max temperature 1.417×10³² kelvin, thank you for that, it is a new number in my collection. 

This still does not answer the question, during the theoretical Plank epoch of the big bang these temperatures were attained. In what way does a very hot black hole full of radiation not resemble the conditions of the big bang.

1 hour ago, Strange said:

I don't know why you think radiation would behave any differently. It is still constrained to travel through space and time. The centre of the black hole is in the future, and even radiation cannot travel backwards through time. There're literally no paths for anything to ravel along that do not lead to the centre of the black hole.

The gravitational effect of mass and energy are the same. Mass is represented in the Einstein field equations by the energy term.

Can you give an example of an experiment showing that light can be constrained by light. 

Light has energy which is represented as inertia in the Einstein field equations. If the inertia of photons is supporting the core of a black hole as theorized by Hawking what happens when all the core mass is converted to inertia. 

There are a number of theoretical exotic stars the Planck star was mentioned earlier not by me. https://en.wikipedia.org/wiki/Exotic_star I was more interested in the Boson star, both have a repulsive self supporting action and in fact would expand if not constrained by mass. 

[Strange]

2 minutes ago, interested said:

In what way does a very hot black hole full of radiation not resemble the conditions of the big bang.

Almost no ways. As matter fans to the centre of a black hole it will become compressed and therefore hot. It may form a quark-gluon plasma. But there are a couple of important differences from the Big Bang.

In the early universe, the entire universe was completely full of a hot, dense plasma. The (mathematical) singularity was in the past.

In a black hole, the hot, dense plasma is concentrated at one point in space. The (mathematical) singularity is in the future.

5 minutes ago, interested said:

Can you give an example of an experiment showing that light can be constrained by light.

I have no idea what that means.

5 minutes ago, interested said:

Light has energy which is represented as inertia in the Einstein field equations.

Energy is represented by energy in the stress energy tensor used the EFE. Inertia is one form, or definition of, mass. It doesn't appear in the EFE.

 

[interested]

4 minutes ago, Strange said:

Almost no ways. As matter fans to the centre of a black hole it will become compressed and therefore hot. It may form a quark-gluon plasma. But there are a couple of important differences from the Big Bang.

In the early universe, the entire universe was completely full of a hot, dense plasma. The (mathematical) singularity was in the past.

In a black hole, the hot, dense plasma is concentrated at one point in space. The (mathematical) singularity is in the future.

I have no idea what that means.

Energy is represented by energy in the stress energy tensor used the EFE. Inertia is one form, or definition of, mass. It doesn't appear in the EFE.

 

Yes it will form a quark gluon plasma and it will get hot. A black hole is full of hot dense plasma, if you keep compressing it, quarks will break down to radiation. 

The entire universe from the Big Bang filled a singularity, ie it was not a very big universe.

I agree it happened in the past in real time. But as you say the maths breaks down so claiming the singularity exists in the future is based on what, a broken mathematical theory.

I speculated that light iniside a black hole can not be constrained by light alone. You clearly disagree. I asked Can you give an example of an experiment showing that light can be constrained by light, as it would have to be in a theoretical boson sun at the centre of a black hole.

I have no idea what your last sentence is meant to mean. Are you saying that light has mass, If so you are wrong. It has energy and inertia, not mass.

[Strange]

9 minutes ago, interested said:

The entire universe from the Big Bang filled a singularity, ie it was not a very big universe.

I think you may be missing the point. There is an important distinction between a black hole and the early universe. A black hole exists within the universe. It is surrounded by (relatively empty) space. Things will fall in the gravitational field of the black hole. The early universe was entirely full of plasma. There was no concentration of mass.

These are physically very different and very different in the effects they have on spacetime.

1 hour ago, interested said:

I agree it happened in the past in real time.

Again, not the point I was making. When you fall through the event horizon, the centre of the black hole is no longer a point in space that you are moving towards. It is a time in your future. Similarly, the (notional) singularity in the big bang model is not a point in space, it is a time in your past.

1 hour ago, interested said:

But as you say the maths breaks down so claiming the singularity exists in the future is based on what, a broken mathematical theory.

The existence of a mathematical singularity may mean that the theory doesn't apply at that point, but that is irrelevant. The centre of the black hole is a time in the future of any material in the black hole. The event horizon is no longer a location in space but a time in your past. 

So it doesn't matter if you turn into light, that light cannot go into the past so it cannot approach or leave the event horizon. It can only go forward in time towards the centre of the black hole.

If you were to fire the engines of your spaceship to try and slow your fall, you would just get to the centre faster.

1 hour ago, interested said:

I speculated that light iniside a black hole can not be constrained by light alone. You clearly disagree.

I don't know what you mean by "constrained by light alone". The curvature of space-time in and around the black hole is defined by the mass-energy in the black hole. It doesn't matter if that is in the form of matter or photons or anything else. Light will be constrained to move along geodesics in space-time. These all go towards towards the centre. There is no other direction for light, or anything else, to go.

Stuff is not held in the black hole by the force gravity. It is because there is no direction that is "out".

1 hour ago, interested said:

I have no idea what your last sentence is meant to mean. Are you saying that light has mass, If so you are wrong. It has energy and inertia, not mass.

Light has energy and momentum (not inertia, momentum).

Let's try a few alternative ways of putting it:

• Energy and mass are equivalent.
• If all the mass in the black hole turned into light it would make no difference to the black hole.
• The gravitational effect of mass is defined (in the equations of GR) in terms of the equivalent energy.
• Mass does not appear in the equations, energy does.
• So if the mass turns into light, the energy will have the same effect as the mass did.

Does that help?

[Mordred]

The key fundamental difference between the two which Strange is pointing out is how the two singularity conditions may or may not behave under the sheer conpression due to gravity itself.

Keep in mind the observable universe singularaty of our Universe past only represents the lightcone of our Observable universe, the distribution of shared causality differs significantly than the mass distribution of a BH singularity. We have absolutely no means of testing either limit, it is well beyond any capability we have. Either from any form of observation or lab test. These are theoretical limits based upon a huge body of evidence of numerous incredibly accurate mathematical models.

It also forms a primary aspect on the quantzation of gravity itself. 

We can speculate on this till the cows come, we have absolutely no means of validation.

The other aspect is the irreversible aspects of entropy. Some processes are considered irreversible.

Here is a question even I don't know the answer to.

Is the electroweak symmetry break via the Higg's field reversible? Trust me I've looked for that answer for several years now and still cannot answer that question.

Is there any involvement of the Higgs field inside the EH of a BH. (absolutely no clue) can't answer that one either.

Edited December 9, 2017 by Mordred