Black Hole Spins At Almost The Speed Of Light

[pywakit]

For what it's worth Lady E ...

In case you didn't catch my tone, I was not disturbed or offended by any characterizations you made.

Compared to some your comments were quite benign.

As a non-degreed (and woefully ignorant) amateur, I fully expect my most definitely non-mainstream views to elicit impatient, if not rather harsh responses.

It's not my place to welcome you to the fold, but welcome nonetheless. I look forward to crossing swords again.

 

[brucep]

Good find, however the example the author was working with was a small solar sized BH. I can believe the polar jets might shed angular momentum as matter is accreted by the central object, and that might work to prevent a rotational speed greater than the speed of light.

But I still have a problem with a supermassive BH of about 2 million solar masses with a rated spin very close to the speed of light being slowed down enough to be noticed, because of the polar jets. There is just to much mass and not enough energy being shed. But I do agree there must be something that causes the angular momentum to be conserved without the spin exceeding the speed of light.

I do remember something about mass increasing as it approaches the speed of light, and that it would become infinite at the speed of light. Not enough energy in the universe to make that happen. Just can't see how that might apply to this problem.

The rotation parameter [a], of the rotating black hole is associated with the angular momentum [particle motion of angular momentum J and mass M] in this way.

a=J/M

Project F for rotating black holes, Exploring Black Holes Taylor and Wheeler.
http://www.eftaylor.com/pub/SpinNEW.pdf

When you look at the metric you'll notice [a] is either factored or summed to the mass. For an example we can use the famous black hole x-1 in Cygnus. J for x-1 is .75. The .75 represents the particle angular momentum at .75c. The mass of x-1 is 1.75 times it's mass if is was non rotating and spherical. So if you get to the end of the project there is a summation of the Penrose Process. A proposal for mining the energy associated with [a]. When J goes to 0 the rotating black hole goes to a non rotating spherical symmetric Schwarzschild BH.

BTW mass is an invariant. What can increase without bound is momentum. J for a maximal rotating black hole is 1. It goes to 1 as a limit since the particle motion for objects with invariant mass has to <c.

 

[KilljoyKlown]

The rotation parameter [a], of the rotating black hole is associated with the angular momentum [particle motion of angular momentum J and mass M] in this way.

a=J/M

Project F for rotating black holes, Exploring Black Holes Taylor and Wheeler.
http://www.eftaylor.com/pub/SpinNEW.pdf

When you look at the metric you'll notice [a] is either factored or summed to the mass. For an example we can use the famous black hole x-1 in Cygnus. J for x-1 is .75. The .75 represents the particle angular momentum at .75c. The mass of x-1 is 1.75 times it's mass if is was non rotating and spherical. So if you get to the end of the project there is a summation of the Penrose Process. A proposal for mining the energy associated with [a]. When J goes to 0 the rotating black hole goes to a non rotating spherical symmetric Schwarzschild BH.

BTW mass is an invariant. What can increase without bound is momentum. J for a maximal rotating black hole is 1. It goes to 1 as a limit since the particle motion for objects with invariant mass has to <c.

Thanks for the article. It was a bit long and technical for my poor ADD condition. But I can say I don't believe a "non rotating spherical symmetric Schwarzschild BH" is something that exists in nature. It's just another interesting mathematical concept that has no real analog in nature. But then I think they sort of said that in the article.

 

[brucep]

Thanks for the article. It was a bit long and technical for my poor ADD condition. But I can say I don't believe a "non rotating spherical symmetric Schwarzschild BH" is something that exists in nature. It's just another interesting mathematical concept that has no real analog in nature. But then I think they sort of said that in the article.

I agree that Schwarzschild Black Holes most likely don't exist in nature. That's part of what Chandrasekhar was saying in the introduction to the Project. The reason we have a spherically symmetric non rotating solution is it was the first solution and Schwarzschid idealized the solution parameters to be non rotating and spherically symmetric. Getting that solutions was such meaningful work. Einstein thought any solution to the EFE would be awhile coming. Not a few months after publishing the EFE. If you could realize the Penrose Process you could build a spherically symmetric non rotating black hole beginning with a Kerr hole. This is real esoteric physics but fun. You can learn lots of black hole physics just by reading the project.

 

[Lady Elizabeth]

For what it's worth Lady E ...

In case you didn't catch my tone, I was not disturbed or offended by any characterizations you made.

Compared to some your comments were quite benign.

As a non-degreed (and woefully ignorant) amateur, I fully expect my most definitely non-mainstream views to elicit impatient, if not rather harsh responses.

It's not my place to welcome you to the fold, but welcome nonetheless. I look forward to crossing swords again.

Yeah, to avoid a totally instant ban I've needed to relinquish 99% of my vocab', that aside, you're infinitely smarter/sane than those I battle @ physforums; although, this doesn't really say much.

 

[pywakit]

Yeah, to avoid a totally instant ban I've needed to relinquish 99% of my vocab', that aside, you're infinitely smarter/sane than those I battle @ physforums; although, this doesn't really say much.

Lol. The Lord ... errm ... Lady giveth and the Lady taketh away.

 

[pywakit]

Speaking of Hawking radiation (not especially germane to the OP, but I am going to talk about it anyway) mainstream's ongoing stance on this (as it pertains to the theorized decaying universe) appears to border on the irrational.

Before I say anything else, I must once again provide this disclaimer: I'm not a mathematician. I'm not a physicist. I rely on publicly available information ... with the exception of information I have been provided through email exchanges (generally brief, often condescending) I have had over the last few years with actual academicians, including a few prominent ones.

Such as Neil DeGrasse Tyson. If the following (from early 2009) is inaccurate, blame him. Lol.

According to Tyson, a non-feeding 50 million sol black hole would take 10^100 years to evaporate. Give or take. This figure was apparently worked out by Hawking 30+ years ago.

When I asked Tyson how long it would take for a 50 billion sol black hole to evaporate, he didn't know, other than to say the evaporation process slows as the mass increases according to some inverse formula ... but that it wasn't relevant since there was no evidence of 50 billion sol black holes, and mainstream theorists were quite certain none could exist. Those theories were of course based on generally accepted (and seemingly well-supported by observations) theories relating to the hierarchical formation of galaxies and black holes. Which in turn were well-supported by pretty much everything we had come to accept relating to the standard model of cosmology and the evolution of matter. Simply put, theorists were certain black holes could not have grown that large this early in the universe.

This was 'corroborated' in an email to me from Nicholas Suntzeff (High~z Super Nova team) a couple years ago, by the way. I had suggested to him that black holes could have existed from the start, immediately following the Big Bang, rather than having evolved just through the hierarchical process. That it was possible we could discover black holes weighing not just a few billions of solar masses but ones in the trillions. While he did concede the possibility of theorists being incorrect and black holes might have existed very early in the universe, he said those even in the tens of billions of sols would be extremely rare ... if there were any at all. I asked him how he could be so sure, and he said "Because we have already looked. If there were any that big, we would know."

Hmm. 10 out of 18 observed galaxies appear to have black holes in the tens of billions of solar masses. I wonder if he remembers our conversation.

I guess it's time to mention that 10^100 years is just a bit longer than the projected life-span of the universe. Meaning ... when all the lights have gone out for good. Going from memory here, but I think that is estimated to be 10^45 years, more or less.

So ... the theorists were wrong about black holes forming only through the heirarchical process. Tyson was wrong. Suntzeff was wrong.

Well, they were wrong about something else. And this is what really seems to border on the irrational. Whether or not a black hole is visibly feeding, barring magic, they will never stop feeding on the CMBR. Worse, the more massive the black hole, the more CMBR it accretes. And the slower it evaporates.

How is a black hole going to 'fade away' if it is constantly accreting mass at a far greater rate than it would evaporate ... if they even do evaporate? Is there a known mechanism that prevents black holes from accreting CMBR?

It only gets worse ...

To my understanding, it has been established that space itself has an energy content. Further, that black holes 'eat' space. I could concede that at some point a black hole could 'clean out' all the available CMBR, but could it run out of space to eat?

As I have said, I'm no physicist. But this just doesn't make any sense to me.

 

[KilljoyKlown]

pywakit

I think the OP for this thread has about run it's course, so I don't mind a little side tracking as BH's are always one of my favorite topics. You've touched on some ideas I've had for a long time now. They have discovered at least 2 BH's over the billion solar mass size that were in existence within the first billion years after the big bang. The following article questions the standard big bang model of our universe, but in my opinion they don't take it far enough. I think the BB that started our universe took place in a much larger structure in which very large BH's already existed. When you think about it once BH's come into existence they are pretty indestructible and I don't think a little thing like a BB would disturb them very much, other than to ad a great deal of mass for them to chew on as they flare into active quasars. But I don't have a lot of support for those ideas, and our cosmic observations haven't been able to show any direct evidence yet. However we do have a great deal of circumstantial evidence that lends itself to more than one interpretation. I could be wrong, but I like to push the limits on new ideas popular or not.

http://www.nasa.gov/centers/marshall/news/news/releases/2004/04-283.html

 

[Farsight]

...To my understanding, it has been established that space itself has an energy content. Further, that black holes 'eat' space. I could concede that at some point a black hole could 'clean out' all the available CMBR, but could it run out of space to eat? As I have said, I'm no physicist. But this just doesn't make any sense to me.

That's because it's garbage. Black holes don't eat space at all. That comes from the "waterfall analogy", which is misleading. It's equivalent to the sky is falling in. A gravitational field is described as curved spacetime, and depicted via the bowling ball analogy. The bowling ball curves the rubber sheet, but it isn't gobbling it up like some Pacman. I should distinguish beyween space and spacetime I suppose. Look around and you can find papers like Inhomogeneous Vacuum: An Alternative Interpretation of Curved Spacetime. Check out Einstein's Leyden Address and you can see him saying "the recognition of the fact that 'empty space' in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials gμν)". Curved spacetime is synonymous with inhomogeneous space. Light moves through space over time, and curves. So we say spacetime is curved. It doesn't matter whether you say spacetime is curved or space is inhomogeneous, all a gravitational field does is alter the motion of light and matter through space over time. It doesn't suck space in.

...I think the BB that started our universe took place in a much larger structure in which very large BH's already existed...

If you like to push the limits, you should explore the original "frozen star" black hole interpretation which treats the Schwarzschild singularity as something more than a mere artefact. Then imagine the early universe was something like one big frozen-star black hole with no space around it. Then something happened and it started expanding. I don't know what. But if it was like a frozen star, everything inside was frozen. So the initial expansion looks like it was rapid. Then ask yourself this: what if some bits didn't expand? What if whatever the thing was that caused the expansion, had holes in it.