Black Hole Spins At Almost The Speed Of Light

I read the article below, but I'm still not clear about what they mean by a BH spinning at almost the speed of light. Are they talking about the infalling mass at the event horizon or some arbitrary surface beneath the event horizon?

http://www.popsci.com/science/artic...-gargantuan-black-hole-spins-near-light-speed

 

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Yeah, it's because of the infalling matter --->http://www.slate.com/blogs/bad_astr...measure_supermassive_black_hole_rotating.html


''As the material swirls around the black hole, it emits X-rays at a very specific energy—think of it as a color. But as it orbits that color gets smeared out due to the Doppler effect. The amount of smearing indicates how fast the material is moving, and that in turn can tell astronomers how fast the black hole is spinning. This can be complicated by the presence of dense clouds of material farther out from the black hole that absorb X-rays and mess up our observations. The new data from NuSTAR allowed astronomers to show that the smearing seen is definitely due to rotation and not obscuration, unambiguously revealing the black hole's tremendous spin: just a hair below the speed of light!''

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How did they measure it ?

 

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angular rate of x-ray emissions, before quiescence?

They gathered data from: XMM-Newton and NuStar, those got x-ray telescopes on it.

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I pulled the below statement out of your posted article. Makes me wonder if this guy knows what he's talking about. Both these galaxies are very small compared to some others.

Also, I did get the impression that the matter approaching the EH at close to the speed of light was being used to measure the BH's spin. If you think about it, the spin of a BH must be coming from the mass at the core of the BH, and I think that's proof that singularities don't really exist in nature.

 

According to Einstein's solutions, singularities do exist and are even spinning in rotating black holes, so yeah.

 

Since we don't know what happens to mass on the other side of the EH, the math is not proof of anything accept the concept of a singularity. This is a far cry from reality.

What about the conservation of momentum? The rate of spin will keep increasing as the diameter of the mass decreases. At what point will the spin exceed the speed of light to maintain the conservation of momentum?

 

Huh?

 

What's the diameter of a singularity?

 

supposed to be infinite density.

 

Depends on the singularity we are talking about.

 

When pulsars were first observed, it caused quite a hullabaloo. They were neutron stars rotating several hundred times per second. At first they were viewed as evidence of ET Technology.

The explanation was simple enough. In the late stages of a star's life, the nuclear fuel gets used up & gravity crushes the star down to white dwarf or neutron star size. Conservation of angular momentum results in increasing the rotation rate.

As a star collapses to a black hole, the rotation rate becomes extreme.

I would expect that a star with a high initial rotation rate might not be able to collapse to a neutron star or black hole. Without reviewing some pertinent college courses & articles read 40-50 years ago, I have no clue about this situation & could be wrong.

 

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All I'm saying is we've observed neutron stars that have spins that are approaching light speed, so what happens if you take that same mass and reduce the diameter down to BH size? Also, in the OP article we are talking about a supermassive BH of about 2 million solar masses.

I keep hearing that the laws of physics break down on the other side of an EH. If that's true, who's to say a mass might not be able to spin faster than the speed of light? I don't really believe the laws of physics break down, but I do believe we have a lot to learn as we approach the extremes in our universe.

In any event for this spinning mass to effect the mass outside the EH and accelerate it to near light speed wouldn't it need to be spinning faster?

 

It becomes a black hole.

Is not. But even if it did, you won't be able to tell anyways 'cause no information would be able to reach you to make a measurement lol.

No. The mass outside accelerates at the cost of the rotational energy of the black holes, so actually, that infalling mass is stealing from the spin of the BH causing it to slow down!!! Nothing is free!

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Yes it would, but as it collapsed into a very much smaller diameter mass, it would still have to conserve momentum, by spinning a lot faster. If it's already close to the speed of light, where is that conservation of momentum going to come from?

A lot can be inferred by how the mass in orbit and infalling is acting.

That may be true, however the mass and rotational speed of the BH have a direct influence on how fast that accretion disk will be spinning. That the matter closest to the EH is approaching the speed of light says a lot about what's going on beneath the EH.

 

When a real world singularity is predicted by mathematics, most mainstream sicientists view it as an indication that the mathematics is not applicable to the conditions.

In the case of the predicted singularity at the center of a Black Hole, most mainstream physicists claim that some yet to be developed Quantum description of gravity is required.

BTW: Singularity conditions inside the Event Horizon need not occur until some time after the Event Horizon forms.

 

Why wouldn't fluid dynamics come into this discussion ?

I mean we're not discussing particles here people , we are talking about , trillions and trillions of plasma particles , protons and electrons , physics , which is fluidic

 

[video=youtube;GYKyt3C0oT4]http://www.youtube.com/watch?v=GYKyt3C0oT4[/video]

 

That was fun.

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I'll give it about as much credence as a BH being a wormhole.