A Question Concerning Blackholes

[Saiph]

GR says, that a spinning black hole creates a phenomena called "frame dragging" where the spacetime is actually twisted around the black hole, and dragged in a circle around it.<br /><br />This has some odd consequences to the observed orbit of an object around the black hole. First note that the object will always go the same way through space (law of inertia). Lets say it starts going in clockwise. Now, the hole is rotating counter-clockwise, and dragging space in that direction.<br /><br />The object approaches clockwise, but the space begins to move slowly in the counterclockwise direction (increasing in pace as it gets closer to the event horizon). Eventually it's just like walking on a treadmill going to fast...the object will keep going that way, but spacetime will drag it around the opposite direction as seen by an outside observer.<br /><br />However, these effects are minor until you get really close to the event horizon. Further out, newtons laws of motion (i.e. standard orbital mechanics) work just fine. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[nexium]

Since all stars likely rotate and thus have angular momentum, should we expect all black holes to rotate = spin? Neil

 

[rfoshaug]

I have two questions about spinning black holes.<br /><br />Firstly, isn't a black hole a point with no size (singularity)? If a planet spins we can see that because it's surface features change position in relation to its center (ie. they move round and round). How can a black hole spin if it's just a point?<br /><br /><br />And secondly, the reason we know a black hole is spinning is because it affects material entering the black hole, isnt'it? But shouldn't gases and material accelerate straight towards the black hole regardless of spin? Shouldn't the acceleration be exactly in the direction of the black hole at all times? How can spin affect this?<br /><br /><br />Or have i misunderstood the entire concept of how astronomers decide a black hole is spinning? <div class="Discussion_UserSignature"> <p><font color="#ff9900">----------------------------------</font></p><p><font color="#ff9900">My minds have many opinions</font></p> </div>

 

[harmonicaman]

<i>"Firstly, isn't a black hole a point with no size (singularity)?"</i><br /><br />Not a singularity, but a very small area! It is theorized that if something the mass of Earth was inside of a black hole, it would end up the size of a basketball - the matter <b>does not</b> shrink down to the area of a point! <br /><br />This compaction is likely due to the fact that atoms are comprized of mostly open space (and "Vibrations") and the extreme gravity of the BH compacts the atoms very tightly together in a way that we do not fully understand (the laws of physics must be different inside of a BH). <br /><br />Note that even under this extreme gravity and packed tighly together, the mass in a BH still maintains its fundamental ability to bend time and space; the gravitation influence of the mass does not change even though it is compressed within the BH!<br /><br /><i>"And secondly, the reason we know a black hole is spinning is because it affects material entering the black hole, isnt'it? But shouldn't gases and material accelerate straight towards the black hole regardless of spin? Shouldn't the acceleration be exactly in the direction of the black hole at all times?"</i><br /><br />I agree with Eddie; one reason we suspect BHs are spinning, and spinning <i>very rapidly,</i> is due to the Law of the Conservation of Angular Momentum. When a rotating stellar mass collapses into a small area (a BH) it will spin faster and faster - just like a spinning ice skater spins faster when they pull their arms in.<br /><br />For this reason, it is thought that BHs are really shaped more like Frisbees (or a torus?) rather than spheres.<br /><br />Note that I'm sure there are exceptions out there and BHs without appreciable spin likely exist. I think we'll find that BHs will exhibit different characteristics depending not only on their size, but also on their rate of spin.<br /><br />Note that nothing in the universe can travel in a straight line because space itself is curved. Material des

 

[neutron_star69]

wait now, so could black holes be moving so fast we just dont realize due to them moving so fast?

 

[rhinorulz]

first they will conect to form a time warp. for info see the link for warp holes.

 

[rhinorulz]

we know of at least one. the center of the gelecy is one

 

[nojocujo]

Saiph<br /><br />To quote:<br /><br />GR says, that a spinning black hole creates a phenomena called "frame dragging" where the spacetime is actually twisted around the black hole, and dragged in a circle around it. <br /><br />This has some odd consequences to the observed orbit of an object around the black hole. First note that the object will always go the same way through space (law of inertia). Lets say it starts going in clockwise. Now, the hole is rotating counter-clockwise, and dragging space in that direction. <br /><br />The object approaches clockwise, but the space begins to move slowly in the counterclockwise direction (increasing in pace as it gets closer to the event horizon). Eventually it's just like walking on a treadmill going to fast...the object will keep going that way, but spacetime will drag it around the opposite direction as seen by an outside observer. <br /><br />However, these effects are minor until you get really close to the event horizon. Further out, newtons laws of motion (i.e. standard orbital mechanics) work just fine. <br /><br />Question?<br />To what extent will the inspiral be diminished by the reverse rotation to the spin of the BH?<br /><br />I don't like the inspiral model since it can be so much more cataclysmic with a direct hit and the inspiral produces a short duration GRB and Gravitational Waves that will be hard to detect since the gravitational potential has basically merged long before the actual merger take place. A direct merger should produce a implosive/explosive gravitational wave and several rebounds as the merged gravitationalpotentials become one. I also like the idea that the initial wave and the rebound waves may actually cancel the schwartzchild radius briefly allowing the inital GRB of the merger and several subsequent spike in the long GRB to occur.<br />Whew sorry I got off subject a bit!

 

[kmarinas86]

The objects are dark, they be black.<br />They are like holes, cuz they be taking in.<br />They are small, but very, very dense, and very heavy.<br /><br />Is it a singularity? No. A black hole? Yes.

 

[kmarinas86]

<font color="yellow">A BH *is* a Singularity. Black Hole is merely a popularized word *for* a Singularity.</font><br /><br />That's what I don't like.<br /><br />Cause saying that black holes don't exist is like saying that dark objects in space with high density don't exist <- a wrong belief.<br /><br />So what I am supposed to call it then?<br /><br />Cygnus X-1 is proof of a dark object with high density, but it is not proof of a singularity.

 

[yevaud]

Doubleplusungood, K. That's wrong.<br /><br />"Black Hole" is merely the popularized word *for* a Singularity. They're one and the same thing. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[kmarinas86]

<font color="yellow">"Black Hole" is merely the popularized word *for* a Singularity. They're one and the same thing.</font><br /><br />As I said. That's what I don't like. Because the evidence for dark objects with higher density than neutron stars is there. It's just that I believe the existence of a singuarity hasn't been proven.<br /><br />They're Massive Compact Halo objects that's for sure.<br /><br />http://en.wikipedia.org/wiki/Massive_compact_halo_object

 

[yevaud]

We do have observations of their effects on other stellar bodies, energetic output from infalling material, polar jets - all predicted.<br /><br />I don't believe anything short of a Singularity could do such. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[neutron_star69]

how do you know what a sinularity is capable of?

 

[siriusmre]

That's a good question, neutron_star69. How DOES he know?<br /><br /><font color="yellow">"We do have observations of their effects on other stellar bodies, energetic output from infalling material, polar jets..."</font><br /><br />We certainly do see those motions and energetic characteristics, but it is POSTULATED that some impossibly massive object is at the heart of these phenomena ONLY because astronomers are currently ideologically incapable of envisioning anything other than clumps of isolated mass in space under the puny influence of gravity. As a result, their objects are fantastically massive and/or take tens of billions of years to form.<br /><br /><font color="yellow">"...all predicted. "</font><br /><br />Predicted? Really? Maybe it's because now that we have seen things like polar jets, the "black hole" hypothesis "predicts" them. When this postulation was fresh out of the box, did it predict polar jets? How DO those jets remain so confined over such distances, BTW?<br /><br /><font color="yellow">"I don't believe anything short of a Singularity could do such."</font><br /><br />Well, I guess that's it, isn't it? Belief. You "don't believe anything short of a singularity could do" what we see probably because, frankly, you don't know any better. Modern astrophysics really only has one tool to try to explain the universe: gravity. What if we had another way to interpret the data? A way that is EQUALLY supported by the facts? Obviously, gravity does not tell the whole story. <div class="Discussion_UserSignature"> </div>

 

[nexium]

We may eventually find a vastly different set of theories that make nuetron stars and black holes very improbable. Unless SiriusMrE or someone else can present that new set of theories, I see little logic in rejecting the present main stream theory just because it has some possible problems such as complexity. Neil

 

[yevaud]

More than happy to debate this and that with you. However...<br /><br />Belief?<br /><br />No, I was taught this is a degree program by people who themselves were taught it, and so on.<br /><br />"Standing on the shoulders of Giants," as the saying goes.<br /><br />These things have been analyzed, theorized, calculated, observed, for decades. And that should all be pitched out the window because a few people - who can't adequately even explain *why* their hypothesis should prevail - have "issues?"<br /><br />We have all been presented with the "Electric Universe" idea before. This isn't new to us. And all who brought it here share one thing in common...<br /><br />...none of them could explain why they're right and current science is wrong.<br /><br />So, Ahhhh.....no. Not belief.<br /><br />Science. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>