Preliminary Black Hole FAQ

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Saiph

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Allright, since that monster of a BH FAQ is lost in the archives, lets get another up and going.<br /><br />List you questions here, and I'll work them into the next reference thread. <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>
 
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Saiph

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Okay, I'm adding one that's come up:<br /><br />Polar Jets, how do they work in the case of a BH? <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>
 
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jjkeighe

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What would happen if you were to have a rotating star at the point of imergence of a black hole and you could solidify that state in time?
 
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Saiph

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I don't quite understand the question.<br /><br />You've got a rotating star about to...what?<br /><br />Solidify the state? I...don't see what you mean by that. <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>
 
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Saiph

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What, you guys don't have any questions about BH's? <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>
 
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Saiph

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I'm just going to resurrect my old BH basics post. <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>
 
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Saiph

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sweet, now I just need to pay attention, hope I understand it, and integrate it into the BH faq. that entropy section someone submitted (who was that! GAH!) I didn't really understand as well as I'd like. <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>
 
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alokmohan

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There may be theories that blackholes dont exist.Because for every theory we have opposite.Can you confirm?Is there definite proof of existence of black hole?
 
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nissasa

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What do you think about all singularities being the same mass while all BH's have different masses?
 
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jschaef5

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You should explain the whole hawkings radiation concept. I've never fully understood how it works. <div class="Discussion_UserSignature"> </div>
 
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Saiph

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short answers until I get time to write the whole thing:<br /><br />Alokmohan: There is very little definete proof in science. BH's do have enough proof that we can state that no other thing we know of, or have thought of (within the framework of modern theory) fits the bill. Not only that but BH's do a good job explaining what's going on. that's about as much as you can ask for.<br /><br />Nissasa: Your question has to do, i think, with the concept of a naked singularity. At least, to answer entirely. I'll have to check up on that, it's gotten a bit vague for me over time.<br /><br />But, in the case of a BH, no the singularity and BH created by it are the same thing. Or I don't quite understand your question.<br /><br />qazws: I think a singularity is a very very dense state of matter and energy. I personally think it has dimensions, even if it is just in the wave sense.<br /><br /><br /><br />jsheaf5: I'd love to, I'll include it, but in short: it has to do with virtual particles. Normally they occur in pairs, they pop into being, then smack into eachother and dissappear. However, a BH can pry them apart, keeping them from ever colliding. So it lends energy to the system, and one goes free, essentially create/radiated by the BH (it escapes). <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>
 
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alokmohan

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Blackholesare of two types,stellar and massive.Stellar black holes can be upto 30 times mass of sun.Massive black hole may as heavy as one billion sun.Right?
 
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qzzq

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Hi Saiph,<br /><br />I read there are spinning black holes. So are there stationary ones as well? What causes the difference? <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>
 
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Saiph

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Well, I wouldn't say they're two types. They are generally refered to and grouped into two categories by size, stellar and massive (or supermassive). The only real difference is scale, and which phenomena they tend to be associated with (though those are mostly scale differences as well). <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>
 
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Saiph

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missed this one:<br /><br />Those would be Kerr black holes. All "real" black holes are believed to be spinning, basically due to the conservation of angular momentum makinig it nearly impossible for something that size <i>not</i> to spin.<br /><br />Black holes spin for the same reasons stars and planets spin.<br /><br />The two consequences: <br /><br />The singularity is better described as a disk wiith a small hole in the center (so a very flattened ring).<br /><br />If the BH is charged as well (by charged particles following in) with a net charge, you can extract energy out of it like a giant Dynamo. <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>
 
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Saiph

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right, though the Quasar and AGN phenomena are merely really big versions of a BH syphoning material of a nearby star. Supermassive BH's tend to swallow the star, instead of nibble. <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>
 
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nikshliker

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saiph: u say that these parrticles r popping to existence or r u saying that they r just a made up quantity that we use to make sense of the black hole. and if it's made up how can we be sure or PROVE that this theory is correct.
 
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nikshliker

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as the BH sucks in more mass would the angular speed begin to increase or does it stay constant. If it increases then what is stoping it from eventually sucking in enough mass to make the angular speed spectacular. could it ever reach c? <br /><br />----again------<br />when talking about hawking radiation r we using quantum mechanics or still using relatavistic thinking? another question....those virtual particles; r they imaginary or is it an actual bit of mass that pops into existence. Will we ever really know the physics of a BH or r we just guessing things to fit the readings we have recieved from our equipment. some of these ideas seem absurd. <br /><br />:::If possible, send me links to where i can look at some of these proofs.
 
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Saiph

Guest
alokmohan: I do believe they are of similar origins, that of stardeath.<br /><br />nikshliker: The links are easy to come by, just plug in a lot of the more technical terrms I use (like hawking radiation, virtual particles, etc) into google. <br /><br />We are using quantum mechanics (which isn't entirely divorced from relativity btw). The current theory states that the virtual particles really do pop in and out of existence, there are, IIRC, several indirect proofs of this occurance and it's commonly used to explain things other than BH evaporation. I actually think virtual particles were thought up before they were applied to BH's.<br /><br />BTW, this radiation has never been observed comming from a BH (Way to faint) so it's purely theoretical at this point.<br /><br />We do understand BH physics pretty well, it's just a few details that keep nipping at our heals. Important details, sure, but that doesn't invalidate the whole picture. Its sort of like have a sculpture of a person, but you're not quite done with the face. You have a good idea of whats going on, but you don't really <i>know</i> who the person is entirely.<br /><br /><br />qazws: I am, to be best of my ability, explaining the current theories, so what I say better fit. Also, just sayiing nothing is there doesn't really make much sense. The stuff that goes in <i>is somewhere</i> and it can't leave. <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>
 
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nikshliker

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saiph: where did u become so intelligent in the field of BH. What schooling have u had and what do u do to be able to keep up with this changing topic. It would be nice to know <br /> thnx
 
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Saiph

Guest
actually, the topic doesn't change very much. Most of what I tell you was hammered out several decades ago. So keeping up with it isn't to hard. I just have a nice head start. They were a hobby of mine back in highschool. I read a few books, (one I recommend is by Kip Thorne...black holes and warped space-time IIRC).<br /><br />So I'm just more familiar with the material than most. Throw into the loop that I'm very scientifically minded, and I actually understand it, conceptually, though not mathematically. Enough so to explain some of the finer points, and talk about (though certainly not resolve) some others.<br /><br />My schooling, I'm a senior astronomy major at a state university. I'm a Research assistant (undergrad of course) for a professor working on Quasar Variability. I'm also a teachers assistant for the astronomy department (have been since I was a freshman).<br /><br />So while I'm not an Authority or Expert as far as BH's concerned, i know a decent bit and hope to share that with others who are now as confused as I used to be. Also, the discussions help clear up things in my mind, and make me find new references and explainations (which I guess keeps me somewhat current).<br /><br />That's probably a bit longer than you expected, but you asked. <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>
 
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nikshliker

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sry for posting a lot but i have a lot of questions that continue to pop in my mind. What is the ultimate fate of a black hole? is there an end? ive read books that talk about "white holes" that would expell matter rather than pull it. if these "white holes" r even true (i dont think they r) how would they be connected to BHs?<br />-------------------<br />if you were to place something in orbit around a BH directly on the event horizon could it theoretically be possible to approach the speed of light? during this rotation around the BH would u be appearing to move ahead in time or behind in time with respect to a stationary observer? <br />--------------------<br />I have also read that if you have a pair of particles, such as those virtual particles, affecting one of them affects the other. by analyzing the escaping particle could u look into the BH and tell characteristics about that particle in the BH?
 
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Saiph

Guest
white holes are also valid solutions to GR equations, same as BH's. They are theoretically possible, but have never been observed. They're basically not expected (like tachyons). <br /><br />One idea was that BH's can "lead" to a white hole, via a wormhole.<br /><br /><br />To orbit at the Event Horizons (EV) you'd have to go teh speed of light. Time for that object, would appear to be frozen, it wouldn't pass. Your best bet for getting somewhere close to that speed (using a BH), is to fall into a bh from really, really far away.<br /><br /><br />I don't think that the particle inside (once inside) can effect the one outside. Hawking has said he may have figured something out, and is giving a talk about it (to his peers) right about now IIRC. It hasn't reallly filtered down to the public yet though (obviously). <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>
 
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