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Archive 1 |
Peanut gallery here. Stationary BH needs to be explained/defined. What does it mean? -- non- orbiting? No discussion or references to non-stationary bh? Why not? embedded in flat space time? What? —Preceding unsigned comment added by 69.40.245.3 ( talk) 22:58, 23 August 2008 (UTC)
I think you misread it. The outer one moves in, the inner moves out. The move toward each other.
The section "Two event horizons" is contradicting itself. As the spin increases, do they move father away from each other or towards each other? Also, it should probably state what the spin speed is where the even horizons merge, because clearly one of the two needs to change its direction at some critical spin speed. — Timwi 11:19, 21 Feb 2005 (UTC)
What I want to be explained is a transition of "Cauchy horizon". *That one* seems to be more like a "real" second horizon. As I understand it now, outer horizon is a lot like Schwarzschild hole's horizon (+ some rotation), but "Cauchy horizon" sits inside and it is basically a radius at which rotation is so strong that it actually allows you to STOP FALLING and enter an funny "orbit" where as you fly, you do not only return to the same place (just like the satellite of Earth) but to the same TIME too.
Can someone improve the picture in the article (one with ergospere and event horizon) and add Cauchy horizon? How big is it? Is it spherical or oblate or what? 89.103.91.47 ( talk) 15:47, 29 June 2008 (UTC)
Which event horizon is the ergosphere located outside of? тəzєті 18:07, May 14, 2005 (UTC)
I have read in other sources that the outer event horizon remains stationary while the inner one moves out. Which on is it?
This article needs to be expanded quite a bit. Some questions that I as a layman with no real physics background do not understand:
The image in particular is bugging me a lot - it's wholly unclear what is being displayed, I can't make sense of the labels (particularly "Our Universe" etc.), and there is no explanation of what it shows. -- Schnee ( cheeks clone) 21:05, 18 August 2005 (UTC)
I don't think there are two event horizons, scince a Kerr Black Hole spins it has an ergosphere or ergoregion. Once an object is at the ergosphere it can't remain at rest whithout falling into the black hole.-- Alex Arnold 16:51, 20 February 2006 (UTC)
If I've understood correctly, the static limit (which surrounds the ergosphere) is sometimes referred to as the "outer event horizon". I could be wrong, but if I'm not, I can't see how it is an event horizon according to definition. lotheac 21:57, 24 March 2006 (UTC)
I don't have a professional understanding of physics as I don't have a degree to back me up, but what I've derived rom this article and background knowledge is this:
I am not sure of my speculations, but it is what I have derived from the article through a tad of research (equally unclear) and too much thinking for one day. If I am completely wrong, someone who knows what is completely right should define that in the article to avoid further confusion. C3PO the Dragon Slayer 00:49, 5 November 2006 (UTC)
if a massive donet shaped disk would rotate. Then from a distance it's centre could still have a mass of a blackhole. While in theory the disk mass would not have to be at a collapsing state. The ring can grow in mass and in size without a need of a colapse. And mass in centre me teared appart, while some mass will be jetsioned out like plume. It could have also have properties like magnetism (as seen in a MEC). Such theoretical rings of dense mass how are they called, and is there research in this direction as an alternative to blackholes ?
Since these are Kerr blackholes is there any particular reason the Penrose process is given before explaining who Kerr and Newman are? Sophia 12:46, 5 September 2006 (UTC)
Gunnar Nordström was a Finn with a Swedish name, and thus his name had the letter ö, which is used in Finnish and Swedish. Ø is incorrect, because this particular letter is used only in Danish and Norwegian. 195.16.202.19 10:26, 30 November 2006 (UTC)
Apparently a few people don't understand what an event horizon is, in the context of a black hole. It's the surface at which, and within which, light cannot escape to future null infinity. It is conceptually nonsensical to talk about more than one per object, just as it's conceptually nonsensical to talk about two people of different heights that are both "the tallest person in the world". By definition, there can only be one such surface surrounding any given object. If there were an "inner" one of some sort, it would fail the criteria, and be a non-horizon of any fucking sort.
I think it's time this shit got deleted, instead of provoking more confused brow-furrowing from the peanut gallery, to be answered by people who took physics classes off the side of a fucking Crackerjack box.
-- 76.209.50.222 08:58, 20 February 2007 (UTC)
I can't explain it. But I'm pretty sure I saw it on a legitamate scientific website. Might have been NASA's... I don't really have a stance here. Just mentioning it Kaloo ( talk) 19:44, 14 May 2008 (UTC)
The "Two Horizons" section doesn't make sense. It also contradicts the previous section which implies that there is a maximum rotation rate of a BH. Also, the maximum rotation rate needs to be discussed directly. If I recall, it essentially means that the equator at the event horizon cannot move faster than light. There is a maximum % of energy that can be in the rotation vs the mass. — Długosz
Unless I get feedback, I'm going to make some changes soon (Say by 3 November 2007). I'm not sure when and why this was split from Kerr metric, but I'll respect the decision. I believe most of this page should be moved back to the Kerr page. It is generally believed that there should be an enormous class of not explicitely known rotating black hole solutions which are neither Kerr or Kerr-Newman. The ergosphere and Penrose process should be moved to the Kerr page (with a link from the Kerr-Newman page), since it's not clear that a general rotating black hole will have such structures, whereas Kerr and Kerr-Newman do. The "two event horizons" section is a mess here and clearly (and correctly!) explained on the Kerr page, so it should be cut. The Kerr and Kerr-Newman section should stay. "Kerr black holes as wormholes" should be cleaned and then moved to the Kerr page. The "see Also" and "references" look OK, but Wald's book and the one by Hawking and Ellis should probably be added. Any suggestions before I do this? 91.37.231.178 22:44, 29 October 2007 (UTC)
The article doesn't mention frames of reference at all. If you are rotating at the same speed (angular velocity) as a black hole wouldn't you 'see' a non-rotating blackhole? —Preceding unsigned comment added by 77.99.150.12 ( talk) 07:56, 9 December 2008 (UTC)
It seems like this article should be deleted. It doesn't have any properly sourced information that isn't contained in any of the other black hole related articles (especially the "black hole" article, "Kerr metric" article, and "Kerr–Newman metric" article). It is also very poorly written... it doesn't seem to have been given any attention by somebody who has actually taken General Relativity in university. —Preceding unsigned comment added by 74.14.156.248 ( talk) 04:54, 29 April 2011 (UTC)
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 |
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 |
Peanut gallery here. Stationary BH needs to be explained/defined. What does it mean? -- non- orbiting? No discussion or references to non-stationary bh? Why not? embedded in flat space time? What? —Preceding unsigned comment added by 69.40.245.3 ( talk) 22:58, 23 August 2008 (UTC)
I think you misread it. The outer one moves in, the inner moves out. The move toward each other.
The section "Two event horizons" is contradicting itself. As the spin increases, do they move father away from each other or towards each other? Also, it should probably state what the spin speed is where the even horizons merge, because clearly one of the two needs to change its direction at some critical spin speed. — Timwi 11:19, 21 Feb 2005 (UTC)
What I want to be explained is a transition of "Cauchy horizon". *That one* seems to be more like a "real" second horizon. As I understand it now, outer horizon is a lot like Schwarzschild hole's horizon (+ some rotation), but "Cauchy horizon" sits inside and it is basically a radius at which rotation is so strong that it actually allows you to STOP FALLING and enter an funny "orbit" where as you fly, you do not only return to the same place (just like the satellite of Earth) but to the same TIME too.
Can someone improve the picture in the article (one with ergospere and event horizon) and add Cauchy horizon? How big is it? Is it spherical or oblate or what? 89.103.91.47 ( talk) 15:47, 29 June 2008 (UTC)
Which event horizon is the ergosphere located outside of? тəzєті 18:07, May 14, 2005 (UTC)
I have read in other sources that the outer event horizon remains stationary while the inner one moves out. Which on is it?
This article needs to be expanded quite a bit. Some questions that I as a layman with no real physics background do not understand:
The image in particular is bugging me a lot - it's wholly unclear what is being displayed, I can't make sense of the labels (particularly "Our Universe" etc.), and there is no explanation of what it shows. -- Schnee ( cheeks clone) 21:05, 18 August 2005 (UTC)
I don't think there are two event horizons, scince a Kerr Black Hole spins it has an ergosphere or ergoregion. Once an object is at the ergosphere it can't remain at rest whithout falling into the black hole.-- Alex Arnold 16:51, 20 February 2006 (UTC)
If I've understood correctly, the static limit (which surrounds the ergosphere) is sometimes referred to as the "outer event horizon". I could be wrong, but if I'm not, I can't see how it is an event horizon according to definition. lotheac 21:57, 24 March 2006 (UTC)
I don't have a professional understanding of physics as I don't have a degree to back me up, but what I've derived rom this article and background knowledge is this:
I am not sure of my speculations, but it is what I have derived from the article through a tad of research (equally unclear) and too much thinking for one day. If I am completely wrong, someone who knows what is completely right should define that in the article to avoid further confusion. C3PO the Dragon Slayer 00:49, 5 November 2006 (UTC)
if a massive donet shaped disk would rotate. Then from a distance it's centre could still have a mass of a blackhole. While in theory the disk mass would not have to be at a collapsing state. The ring can grow in mass and in size without a need of a colapse. And mass in centre me teared appart, while some mass will be jetsioned out like plume. It could have also have properties like magnetism (as seen in a MEC). Such theoretical rings of dense mass how are they called, and is there research in this direction as an alternative to blackholes ?
Since these are Kerr blackholes is there any particular reason the Penrose process is given before explaining who Kerr and Newman are? Sophia 12:46, 5 September 2006 (UTC)
Gunnar Nordström was a Finn with a Swedish name, and thus his name had the letter ö, which is used in Finnish and Swedish. Ø is incorrect, because this particular letter is used only in Danish and Norwegian. 195.16.202.19 10:26, 30 November 2006 (UTC)
Apparently a few people don't understand what an event horizon is, in the context of a black hole. It's the surface at which, and within which, light cannot escape to future null infinity. It is conceptually nonsensical to talk about more than one per object, just as it's conceptually nonsensical to talk about two people of different heights that are both "the tallest person in the world". By definition, there can only be one such surface surrounding any given object. If there were an "inner" one of some sort, it would fail the criteria, and be a non-horizon of any fucking sort.
I think it's time this shit got deleted, instead of provoking more confused brow-furrowing from the peanut gallery, to be answered by people who took physics classes off the side of a fucking Crackerjack box.
-- 76.209.50.222 08:58, 20 February 2007 (UTC)
I can't explain it. But I'm pretty sure I saw it on a legitamate scientific website. Might have been NASA's... I don't really have a stance here. Just mentioning it Kaloo ( talk) 19:44, 14 May 2008 (UTC)
The "Two Horizons" section doesn't make sense. It also contradicts the previous section which implies that there is a maximum rotation rate of a BH. Also, the maximum rotation rate needs to be discussed directly. If I recall, it essentially means that the equator at the event horizon cannot move faster than light. There is a maximum % of energy that can be in the rotation vs the mass. — Długosz
Unless I get feedback, I'm going to make some changes soon (Say by 3 November 2007). I'm not sure when and why this was split from Kerr metric, but I'll respect the decision. I believe most of this page should be moved back to the Kerr page. It is generally believed that there should be an enormous class of not explicitely known rotating black hole solutions which are neither Kerr or Kerr-Newman. The ergosphere and Penrose process should be moved to the Kerr page (with a link from the Kerr-Newman page), since it's not clear that a general rotating black hole will have such structures, whereas Kerr and Kerr-Newman do. The "two event horizons" section is a mess here and clearly (and correctly!) explained on the Kerr page, so it should be cut. The Kerr and Kerr-Newman section should stay. "Kerr black holes as wormholes" should be cleaned and then moved to the Kerr page. The "see Also" and "references" look OK, but Wald's book and the one by Hawking and Ellis should probably be added. Any suggestions before I do this? 91.37.231.178 22:44, 29 October 2007 (UTC)
The article doesn't mention frames of reference at all. If you are rotating at the same speed (angular velocity) as a black hole wouldn't you 'see' a non-rotating blackhole? —Preceding unsigned comment added by 77.99.150.12 ( talk) 07:56, 9 December 2008 (UTC)
It seems like this article should be deleted. It doesn't have any properly sourced information that isn't contained in any of the other black hole related articles (especially the "black hole" article, "Kerr metric" article, and "Kerr–Newman metric" article). It is also very poorly written... it doesn't seem to have been given any attention by somebody who has actually taken General Relativity in university. —Preceding unsigned comment added by 74.14.156.248 ( talk) 04:54, 29 April 2011 (UTC)
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 |