Black hole?

[Dubbelosix]

I'll see if I can find a reference. 

4 minutes ago, interested said:

ditto how does a spinning black hole produce a charge if nothing can get out, do they have a magnetic field no

 

 

If they are diamagnetic, then they will not, no. But there some recent evidence which suggests you can order magnetic structure inside of the superconductor, which holds importance to the notion of diamagnets in physics. 

sorry, read back, I got confused, kerr black hole is the non-charge solution

There are three solutions:

 

• its mass M (it will be called a Schwarzschild black hole if it has no angular momentum and no electric charge),
• its angular momentum J (and called a Kerr black hole if it has no charge), and
• its electric charge Q (a charged black hole is called a Reissner–Nordström black hole if the angular momentum is zero or a Kerr–Newman black hole if it has both angular momentum and electric charge).

Edited November 29, 2017 by Dubbelosix

[Strange]

4 minutes ago, Dubbelosix said:

If memory serves well, the Kerr Black hole is the rotating solution of the Schwarzschild black hole (non-rotating variation) which has no charge. 

Indeed: http://www.daviddarling.info/encyclopedia/K/Kerr_black_hole.html

And Kerr-Newman for a rotating charged black hole: https://en.wikipedia.org/wiki/Kerr–Newman_metric

And then there is charged but not rotating: http://www.daviddarling.info/encyclopedia/R/Reissner-Nordstrom_black_hole.html

 

[Dubbelosix]

Sorry, made a few mistakes there, but yes, the rotation can be linked to the charge. I'll demonstrate this quickly if I can. Spin is of course related to magnetism - in fact, the rotation or angular momentum of electrons result in the magnetic force of a system. The black hole has two poles, which can emit energy in very explosive ejections. This may involve magnetic fields as well in some form we are unaware of.

 

I want to make it clear, we do not know everything about black holes at all. 

1 minute ago, Strange said:

Indeed: http://www.daviddarling.info/encyclopedia/K/Kerr_black_hole.html

And Kerr-Newman for a rotating charged black hole: https://en.wikipedia.org/wiki/Kerr–Newman_metric

And then there is charged but not rotating: http://www.daviddarling.info/encyclopedia/R/Reissner-Nordstrom_black_hole.html

 

right, but I made a mistake before, let's just be clear. 

Of course, the ejection of gas from a black hole may not be from the inside, I am unsure how these models properly treat these ejections. It seems, that gas is ejected from near the poles from the surrounding gas of matter and energy https://phys.org/news/2017-03-ejection-gasses-black-holes-due.html but according to this link, still has origin in the magnetic field. 

It''s probably wise to think these ejections have nothing then, to do with the actual dynamics inside the black hole... or as I prefer, the frozen star

And its probably also wise to think a rotating black hole has magnetic dynamics. Just as a rotating electron experieneces a magnetic field. 

[beecee]

3 hours ago, interested said:

ditto how does a spinning black hole produce a charge if nothing can get out, do they have a magnetic field no

 

A spinning BH (Kerr BH) need not have a charge, but a charged spinning BH, called a Kerr-Newman BH is rotating and charged. The charge most probably stems from interaction/s with incoming matter and the accretion disk...Like I said, nothing crosses the EH from inside to outside.

4 hours ago, interested said:

How does BB fit with GR hand in glove unless the two things are the same thing. Black holes according to relativity do not explode, BB does. 

I can't do better then to quote Strange's answer to that question....

Quote

Exactly. LeMaitre (who published Hubble's Law before Hubble) used GR to show there should be expansion and then used the redshift-distance relation to calculate the rate of expansion. Others then came up with all the other predictions that have been confirmed over and over.

 

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You have stated above that matter is continually crushed down becoming more dense particles. What I was suggesting that seems reasonable to me is that matter entering a black hole may break down into radiation if heated enough, we know two particles cant occupy the same space, whereas bosons can. If all or part of the mass inside a black hole was converted to radiation with just inertia, does it not look like a BB after the plank time with no need for the laws of physics to break down.

I have stated that further collapse is compulsory at least up to the singularity as defined by where GR is invalid, that is the quantum/Planck level. A mass approaching and/or crossing the BH's EH, is  spaghettified  and torn apart, broken down into its most basic fundamentals as it approaches the singularity by tidal gravitational effects. Whether or not a Plasma forms or any form of radiation, all matter/energy only has one path...it has no choice in the matter.

 

Quote

What I was trying to look at is the similarity between the big bang and what may be happening inside a black hole, ie the Blackhole reversing the Big Bang, by at sufficiently high temperatures converting matter back into radiation. 

The BB singularity is a singularity "OF" spacetime: A BH singularity, is a singularity "IN" spacetime

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Would a black hole that hypothetically converted it mass into radiation not fulfill the requirements to be a BB.  

No, the BB was an evolution of spacetime as we know it, from a hot dense state, from a time of t+10-43 seconds. A BH radiating away {Hawking Radiation} simply loses its EH and becomes just another arena of spacetime.

 

Quote

The Schwarzschild radius (sometimes historically referred to as the gravitational radius) is the radius of a sphere such that, if all the mass of an object were to be compressed within that sphere, the escape velocity from the surface of the sphere would equal the speed of light. What happens if the mass in the sphere is converted to radiation, ie high energy gamma rays, having only inertia and no mass. 

All paths lead to the singularity: There is no choice in the matter.

Quote

I was kind of hoping someone could explain why the mass wont just convert back to radiation at high enough pressures and temperatures, and replicate a BB. 

Matter is disassembled inside a BH via tidal gravity effects...It probably along with all matter and radiation forms a surface or conglomeration unknown to us at the quantum Planck level.

[MigL]

As far as I know static, non rotating Black Hole would be almost impossible, as any object, having even the slightest rotation ( almost all astronomical objects do ), would see that rotation amplified immensely during gravitational collapse.

Charge itself is extremely hard to retain for a collapsing body which sheds some of its mass in a ( super )nova explosion, as the EM force is 36 orders of magnitude stronger than gravity at the atomic level. It would get rid of any excess charge way before the collapse.

The only physical ( viable ) solution seems to be the rotating, non-charged Kerr solution.
But of course I could be ( and have often been ) wrong.

[beecee]

3 hours ago, MigL said:

Charge itself is extremely hard to retain for a collapsing body which sheds some of its mass in a ( super )nova explosion, as the EM force is 36 orders of magnitude stronger than gravity at the atomic level. It would get rid of any excess charge way before the collapse.

The only physical ( viable ) solution seems to be the rotating, non-charged Kerr solution.
But of course I could be ( and have often been ) wrong.

Charge I'm sure, would be negated rather quickly and I would guess so to would angular momentum, but over a far longer period. Which seems to tell me that the simple Schwarzchild solution would be the final destination of any BH. Like you I aint sure but, just offering my thoughts.

[Strange]

There is no easy way for a black hole to lose angular momentum (unless it collides with a lot of material with the opposite angular momentum). It won't just decrease over time (it is a conserved quantity, remember.)

[interested]

It was accepted earlier that the concept of infinities, singularities and everything being compressed down to the planck length are examples of mathematical  thereoms being stretched beyond reality and do not reflect the real world. 

The Schwarzchild radius of a spinning BH is 10 times less than a theoretically stationary BH at the poles, anything escaping from a spinning BH is more likely to escape at the poles in the form of gamma rays. Gamma rays are emitted from the poles of BH's

A spinning mass contracting in diameter will spin faster, on a sphere it will appear squashed like the earth. How fast can a black hole theoretically spin without flying apart? 

If the centre of a star collapses it will reduce in diameter, in a normal star what happens if the core collapses. Super novae? What would a super novae contrained by enormous gravity do inside a BH. Infinities are values that can never be reached. Infinite gravity does not exist. Would we see some gamma rays escaping the poles?

What is the difference between a big BH and a little BH mentioned before other than temperature of the event horizons, have they both been detected and known to exist or is one theoretical? 

 

[Strange]

1 minute ago, interested said:

The Schwarzchild radius of a spinning BH is 10 times less than a theoretically stationary BH at the poles, anything escaping from a spinning BH is more likely to escape at the poles in the form of gamma rays. Gamma rays are emitted from the poles of BH's

If it is a spinning black hole, then it isn't Schwarzschild. 

The radius at the poles depends on the rate of spin - I don't know where you got the "10 times less" from but it could be true for a specific mass angular momentum.

Nothing can escape from a stationary or a spinning black hole.

The jets from the poles of active black holes come from the accretion disk, not the inside of a black hole.

5 minutes ago, interested said:

How fast can a black hole theoretically spin without flying apart? 

There is an upper limit to the angular momentum (spin) of a black hole. I don't know how to calculate this (I suspect it is very complicated, but it might just be when the speed at the event horizon becomes equal to the speed of light).

But a black hole cannot fly apart.

Quote

Would we see some gamma rays escaping the poles?

No. Nothing can escape from a black hole. (You might begin to see a theme here.)

7 minutes ago, interested said:

What is the difference between a big BH and a little BH mentioned before other than temperature of the event horizons, have they both been detected and known to exist or is one theoretical? 

The radius is proportional to the mass. The temperature is inversely proportional to mass. A black hole is defined by mass, charge and angular momentum. The internal state or structure has no external effect (that is what "event horizon" means).

A number of possible black holes have been detected ranging from stellar mass (small multiples the mass of the Sun) up to supermassive (millions or billions of times larger). The black hole mergers that have been detected have been 10s of solar masses.

https://en.wikipedia.org/wiki/List_of_black_holes

 

[interested]

3 hours ago, Strange said:

If it is a spinning black hole, then it isn't Schwarzschild. 

Here is me thinking black holes were defined by mass or Swarzschild radius, Wikipedia.

3 hours ago, Strange said:

I don't know where you got the "10 times less" from but it could be true for a specific mass angular momentum.

At the moment I dont either but I did read it somewhere yesterday morning. I am going to start noting which web pages I am on so I do not lose the link.

3 hours ago, Strange said:

There is an upper limit to the angular momentum (spin) of a black hole. I don't know how to calculate this (I suspect it is very complicated, but it might just be when the speed at the event horizon becomes equal to the speed of light).

Are you sure the event horizon is spinning, space itself is turning with the Black hole spin. I thought gravity was a unidirectional force, and nothing escapes the event horizon except radiation.  

4 hours ago, Strange said:

The radius is proportional to the mass. The temperature is inversely proportional to mass. A black hole is defined by mass, charge and angular momentum. The internal state or structure has no external effect (that is what "event horizon" means).

It is the internal state of the Black hole that is intriguing, and most like a BB in reverse. 

4 hours ago, Strange said:

No. Nothing can escape from a black hole. (You might begin to see a theme here.)

So when two blackholes collide they dont lose mass or energy, in any form what so ever.

What does Ligo detect, an expansion or contraction in space as the gravitational wave goes past.

4 hours ago, Strange said:

A number of possible black holes have been detected ranging from stellar mass (small multiples the mass of the Sun) up to supermassive (millions or billions of times larger). The black hole mergers that have been detected have been 10s of solar masses.

https://en.wikipedia.org/wiki/List_of_black_holes

Thank you very much for that link, I think that question can be ticked off.

 

 

[Strange]

14 minutes ago, interested said:

Here is me thinking black holes were defined by mass or Swarzschild radius, Wikipedia

Strictly speaking the Schwarzschild radius only applies to a non-rotating black hole (and, even more strictly, only to one that has existed for eternity in an otherwise empty universe - but it is still a useful approximation).

14 minutes ago, interested said:

Are you sure the event horizon is spinning, space itself is turning with the Black hole spin.

The event horizon is not a "thing" so it doesn't really make sense to talk about it moving. But I think the limit on angular momentum is based on the nominal speed of [something at] the event horizon. But I may well be wrong about that.

14 minutes ago, interested said:

I thought gravity was a unidirectional force, and nothing escapes the event horizon except radiation.

Gravity is unidirectional (has anything here suggested it isn't?)

And nothing escapes the event horizon. Not even radiation.

14 minutes ago, interested said:

So when two blackholes collide they dont lose mass or energy, in any form what so ever.

The energy for the gravitational waves comes from the space between the black holes. I posted a link about this in another thread, recently. I'll see if I can find it again.

Here: https://www.forbes.com/sites/startswithabang/2017/11/10/ask-ethan-could-matter-escape-the-event-horizon-during-a-black-hole-merger/#6db659b76f9e

Quote

What does Ligo detect, an expansion or contraction in space as the gravitational wave goes past.

It is an alternating stretching and squashing in the directions at right angles to the direction of travel.

Edited November 30, 2017 by Strange

[interested]

Thanks again this will take some time to absorb. 

I was kind of contemplating looking at the following, but you may have covered at above.

There is an upper limit to how large supermassive black holes can grow. So-called ultramassive black holes (UMBHs), which are at least ten times the size of supermassive black holes, appear to have a theoretical upper limit of around 50 billion solar masses, as anything above this slows growth down to a crawl (the slowdown tends to start around 10 billion solar masses) and causes the unstable accretion disk surrounding the black hole to coalesce into stars that orbit it.

49 minutes ago, Strange said:

47 minutes ago, Strange said:

It is an alternating stretching and squashing in the directions at right angles to the direction of travel.

Assuming space is represented as steady state condition. Just to clarify by alternating do you mean 1) compress from steady state, 2) back to steady state, 3) stretch from steady state 4) back to steady state. Or does space remain more stretched in the direction the gravitational wave came from.

Could the squashing be thought of as a dark energy increase and the stretching as a gravitational increase? Or from the Mantra all things are quantum fluctuations, a compression of quantum fluctuations in space followed by a stretching of quantum fluctuations in space. 

 

[MigL]

IIRC, Strange is right ( again ).
I don't recall where I saw the math, I'll have to take a look, but I recall that the max angular momentum, or the max charge allowed to a BH does not result in the 'explosion of that BH, but rather, the shedding of the event horizon.
As this would leave a possible naked singularity, its probably not  physically possible.

[Strange]

1 hour ago, interested said:

Assuming space is represented as steady state condition. Just to clarify by alternating do you mean 1) compress from steady state, 2) back to steady state, 3) stretch from steady state 4) back to steady state. Or does space remain more stretched in the direction the gravitational wave came from.

The former: in the diagram, after the wave has passed, the particles would return to a circle.

1 hour ago, interested said:

Could the squashing be thought of as a dark energy increase and the stretching as a gravitational increase? Or from the Mantra all things are quantum fluctuations, a compression of quantum fluctuations in space followed by a stretching of quantum fluctuations in space. 

No. It is just a change in distance. 

If you imagine looking down on LIGO so it looks like an L and the gravitational wave is approaching it from that direction, then one arm will get longer as the other gets shorter and vice versa.

I don't know where you get your "mantra" from by GR is a classical theory so the mantra is not relevant to gravitational waves. The change in length is so small (by the time these gravitational waves reach us) that I doubt it has any significant effect on the vacuum energy (quantum fluctuations). 

[interested]

1 hour ago, Strange said:

I don't know where you get your "mantra" from by GR is a classical theory so the mantra is not relevant to gravitational waves. The change in length is so small (by the time these gravitational waves reach us) that I doubt it has any significant effect on the vacuum energy (quantum fluctuations). 

Mordred gave me the mantra so I am sticking with it, also I am quite interested in quantum gravity, which might give more insight into what goes on inside a black hole and even if it bounces, but hey ho I am still reading.

 

Edited November 30, 2017 by interested

[Mordred]

The mantra of applying the proper definitions under physics to understand the complexity behind any physics model ? If so a whole heartedly agree 

Dubbelosix raised an interesting question on if the accretion disk dynamics can reveal any details on the internal workings of a BH.

There is a research paper that raises this possibility 

http://arxiv.org/abs/1104.5499 :''Black hole Accretion Dis

Edited December 1, 2017 by Mordred

[interested]

12 hours ago, Mordred said:

The mantra of applying the proper definitions under physics to understand the complexity behind any physics model ? If so a whole heartedly agree 

Dubbelosix raised an interesting question on if the accretion disk dynamics can reveal any details on the internal workings of a BH.

There is a research paper that raises this possibility 

http://arxiv.org/abs/1104.5499 :''Black hole Accretion Dis

I am sticking with the Mantra  and will study the link, thanks.

I have been comparing black holes to big bangs, and been informed I am wrong in doing so, I suspect I am not completely wrong. But how does something get out of a blackhole?Theoretical Primordial Black holes fall into a category known as MACHOs Massive Compact Haqlo Objects. Some scientists have proposed that dark matter—the unseen stuff that is thought to comprise most of the mass of the universe—may be made of MACHOs in the form of primordial black holes. A detection of primordial black holes would bolster that idea, while a non-detection would cast doubt upon it.
Read more at: https://phys.org/news/2017-11-gravitational-black-holes.html#jCp

The MACHO theory is that a primordial Blackhole started with Dark Matter and was the source of the original Big Bang https://en.wikipedia.org/wiki/Massive_compact_halo_object   since I am interested in dark matter and the big bang and black holes and entanglement (or more simply Quantum Fluctuations). I would like to know if anyone has an opinion on Machos. 

Is a Macho a blackhole could the big bang happen from a Macho Black hole. 

 

Edited December 1, 2017 by interested

[Strange]

13 minutes ago, interested said:

But how does something get out of a blackhole?

It doesn't.

Very small black holes can evaporate. But, as far as we know, black holes like that don't exist.They could, hypothetically, have been formed in the early universe and some could still be around. People have looked for the characteristic radiation or gravitational lensing that we would expect to see and no evidence has been found.

15 minutes ago, interested said:

The MACHO theory is that a primordial Blackhole started with Dark Matter and was the source of the original Big Bang

MACHOs are one candidate for dark matter. But as with other candidates they have not been detected. They would also be insufficient by themselves, so some amount of non-baryonic dark matter would also be required.

And there is no evidence to say they are the source of the Big Bang.

12 hours ago, Mordred said:

Dubbelosix raised an interesting question on if the accretion disk dynamics can reveal any details on the internal workings of a BH.

There is a research paper that raises this possibility

Interesting paper. But it doesn't, as far as I can see, say anything about the internals (inside the event horizon).

[Mordred]

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.

Edited December 1, 2017 by Mordred

[Strange]

24 minutes 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.

Read that as it being either a BH (with an EH) or a neutron star (no EH).

Surely, if you have an event horizon, then it is a black hole, by definition?

[Mordred]

By the usual definitions yes, but there was at roughly the same time that article was published that argued that the collapse wouldn't be as extensive as the BH descriptive and that it is viable to have neutron stars with an EH.

At work atm but this article does mention some of issues involved.

https://www.google.ca/url?sa=t&source=web&rct=j&url=https://arxiv.org/pdf/gr-qc/9808035&ved=0ahUKEwjdsKPRl-nXAhWDyKQKHVPDCCIQFggrMAY&usg=AOvVaw3lw7EqGCYCoh_KQ9lOi7a2

[beecee]

6 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.

Yet GR tells us that once the Schwarzchild radius is reached, (the EH is formed) further collapse is compulsory, at least (in my opinion anyway) up to the quantum/Planck level, where GR is non applicable.

So isn't it more valid to accept a surface/conglomeration of sorts at that level?

Edited December 1, 2017 by beecee

[MigL]

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.

[beecee]

On 11/30/2017 at 7:59 PM, Strange said:

There is no easy way for a black hole to lose angular momentum (unless it collides with a lot of material with the opposite angular momentum). It won't just decrease over time (it is a conserved quantity, remember.)

OK, my reasoning was that the interaction/s with the accretion disks and magnetic field lines, as well as other matter/energy could/would act to slow down the angular momentum over time. But considering your point, and considering what I have claimed a few times re compulsory collapse once the Schwarzchild radius is reached, should the question then be asked, does centrifugal force act to keep it from collapsing all the way down to the Quantum/Planck length? Obviously according to current thinking, a ring singularity is formed. Can this ring singularity be at the Planck/quantum level?

And of course if one can calculate a trajectory upon entering a BH via the pole regions to pass through the middle of the ring singularity, one may effectively be able to do this without being torn asunder by gravitational effects, as one would be affected by gravity equally on all sides.

Edited December 1, 2017 by beecee

[Strange]

5 minutes ago, beecee said:

OK, my reasoning was that the interaction/s with the accretion disks and magnetic field lines, as well as other matter/energy could/would act to slow down the angular momentum over time.

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 ...