Astronomers Spot Black Hole Spinning Near the Speed of Light

[Thaluikhain]

I'm still trying to wrap my mind around "the surface" of the black hole. It would be the event horizon, but that's not really a "surface" and I can't see how it could be spinning since it's really just a point at which light can't escape. So does that mean that the event horizon is the surface, or that past the event horizon is the singularity which is spinning at near-maximum speed.

And then I start to think of why a black hole would have to obey the speed of light limit. My brain . . .

Yeah, I noticed that too. I'm going to go with it being badly worded, or perhaps the writer rephrasing something they read somewhere else without understanding it.

Oh, wait, they say it's the event horizon that is 2 million miles across and spinning.

...

Now that I think of it, a black hole seems a likely thing to spin close to C. It has a lot of mass, but no dimensions as we'd think of them, due to being a singularity. The spin thus doesn't involve any distance. Yeah, the event horizon is a certain distance away, but that's not a tangible thing. I could spin around in my room and an imaginary point some fixed distance away where I was facing would "move" faster than light.

 

[Treblaine]

*insert "Yo mama so fat" joke here.

 

[DasDestroyer]

I'm still trying to wrap my mind around "the surface" of the black hole. It would be the event horizon but that's not really a "surface" and I can't see how it could be spinning since it's really just a point at which light can't escape. So does that mean that the event horizon is the surface, or that past the event horizon is the singularity which is spinning at near-maximum speed.

And then I start to think of why a black hole would have to obey the speed of light limit. My brain . . .

Yeah, I noticed that too. I'm going to go with it being badly worded, or perhaps the writer rephrasing something they read somewhere else without understanding it.

Oh, wait, they say it's the event horizon that is 2 million miles across and spinning.

...

Now that I think of it, a black hole seems a likely thing to spin close to C. It has a lot of mass, but no dimensions as we'd think of them, due to being a singularity. The spin thus doesn't involve any distance. Yeah, the event horizon is a certain distance away, but that's not a tangible thing. I could spin around in my room and an imaginary point some fixed distance away where I was facing would "move" faster than light.

From what I remember learning about this stuff, black holes do have dimensions, but they're infinitesimal on the scale of the universe. But the more mass a black hole has, the bigger it is. Don't take my word for it, but I've heard that a black hole with the mass of the sun would have a radius of about 1cm. But the masses of these things are so huge that it still takes a lot of energy to make them spin.

Actually, wouldn't it be harder to get something that small to rotate at the speed of light than something bigger? Think about it, since you can't move faster than light, then the outermost layer would move closest to the speed of light, but the closer you get to the center, the slower you need to move to keep up with the outer layer. But since black holes are so small, the decrease in speed wouldn't be as big as for something millions of times bigger, so the average speed of the whole thing is higher and you'll need more energy to get the thing to rotate at the speed of light.

 

[Ghostdraconi]

I'm still trying to wrap my mind around "the surface" of the black hole. It would be the event horizon but that's not really a "surface" and I can't see how it could be spinning since it's really just a point at which light can't escape. So does that mean that the event horizon is the surface, or that past the event horizon is the singularity which is spinning at near-maximum speed.

And then I start to think of why a black hole would have to obey the speed of light limit. My brain . . .

Yeah, I noticed that too. I'm going to go with it being badly worded, or perhaps the writer rephrasing something they read somewhere else without understanding it.

Oh, wait, they say it's the event horizon that is 2 million miles across and spinning.

...

Now that I think of it, a black hole seems a likely thing to spin close to C. It has a lot of mass, but no dimensions as we'd think of them, due to being a singularity. The spin thus doesn't involve any distance. Yeah, the event horizon is a certain distance away, but that's not a tangible thing. I could spin around in my room and an imaginary point some fixed distance away where I was facing would "move" faster than light.

From what I remember learning about this stuff, black holes do have dimensions, but they're infinitesimal on the scale of the universe. But the more mass a black hole has, the bigger it is. Don't take my word for it, but I've heard that a black hole with the mass of the sun would have a radius of about 1cm. But the masses of these things are so huge that it still takes a lot of energy to make them spin.

Actually, wouldn't it be harder to get something that small to rotate at the speed of light than something bigger? Think about it, since you can't move faster than light, then the outermost layer would move closest to the speed of light, but the closer you get to the center, the slower you need to move to keep up with the outer layer. But since black holes are so small, the decrease in speed wouldn't be as big as for something millions of times bigger, so the average speed of the whole thing is higher and you'll need more energy to get the thing to rotate at the speed of light.

It's basically conservation of angular momentum

From Wikipedia

The conservation of angular momentum explains the angular acceleration of an ice skater as she brings her arms and legs close to the vertical axis of rotation. By bringing part of mass of her body closer to the axis she decreases her body's moment of inertia. Because angular momentum is constant in the absence of external torques, the angular velocity (rotational speed) of the skater has to increase.
The same phenomenon results in extremely fast spin of compact stars (like white dwarfs, neutron stars and black holes) when they are formed out of much larger and slower rotating stars (indeed, decreasing the size of object 104 times results in increase of its angular velocity by the factor 108).

 

[FalloutJack]

There has been a lot of black hole related breakthroughs lately, and it just makes me think that scientists recently discovered there is no possible way of observing black holes, and have just been making stuff up since then.

And the LHC is for making cotton candy. Riiight...

OT: Let's see here... Black holes suck in light at a rate of...immeasurable. They have been proven to - aside from the fact that the entire universe is in constant motion as whole galaxies are in flux - be able to move around. Most things in the universe DO tend to rotate.

I believe it.

 

[evilneko]

Anybody else think that if we applied a drill to this situation, we would rip the "fabric" of the space-time continuum?

A cookie if you get the (vague and possibly incorrect) reference.

Mode II, go!

GYUUUIIIIIIINNNNNNN!

Teto's drills will pierce the heavens!

....what?

....wrong drill?

 

[RADIALTHRONE1]

Spoiler: snip

Anybody else think that if we applied a drill to this situation, we would rip the "fabric" of the space-time continuum?

A cookie if you get the (vague and possibly incorrect) reference.

Mode II, go!

GYUUUIIIIIIINNNNNNN!

Teto's drills will pierce the heavens!

....what?

....wrong drill?

Not what i was getting at, but close.