Talk:Black hole/Archive 4

message: We're going to need to cite alternate references, many of the ones in this article are permanently gone. As and when I find them, I'll edit them in, but that's relying on my memory. We also have two References sections. Or did have. I'm renaming the former to "Citations", since that's what it is. Wayne Hardman 21:51, 29 March 2006 (UTC)
thread_title:  404s in References 

message: Research done by Tiffany Marie for my powerpoint presentaion
A black hole is the escape speed that would have to be met to escape from the pull of gravity exerted upon an object. The existence of black holes in the universe is well supported by astronomical observation, particularly from studying X-ray emission from X-ray binaries and active galactic nuclei. The gravitational field is so strong that the escape velocity past its event horizon exceeds the speed of light. This implies that nothing, not even light, inside the event horizon can escape its gravity. It is, however, theorized that wormholes can let one exit a black hole.  
In 1784, John Michell realized that gravity could attract light and form "dark stars".  Michell ideas were published by Pierre Simon Laplace in first editions of an astronomy guide.  In 1795, Laplace defined the requirements for a black hole.
Einstein's general theory of relativity describes gravity as a curvature of spacetime caused by the presence of matter. If the curvature is fairly weak, Newton's laws of gravity can explain most of what is observed. For example, the regular motions of the planets. Very massive or dense objects generate much stronger gravity. The most compact objects imaginable are predicted by General Relativity to have such strong gravity that nothing, not even light, can escape their grip.
The Hubble Space Telescope (HST) is a telescope in orbit around the Earth. Its position outside the Earth‘s atmosphere allows it to take sharp optical images of very faint objects, and since its launch in 1990, it has become one of the most important telescopes in the history of astronomy. It has been responsible for many ground-breaking observations and has helped astronomers achieve a better understanding of many fundamental problems in astrophysics. Hubble's Ultra Deep Field is the deepest (most sensitive) astronomical optical image ever taken.
The Chandra X-ray Observatory is part of NASA’s fleet of “Great Observatories” along with the Hubble Space Telescope, the Spitzer Space Telescope Telescope and the now deorbited Compton Gamma Ray Observatory. Chandra allows scientists from around the world to obtain unprecedented X-ray images of exotic environments to help understand the structure and evolution of the universe. Already surpassing its ﬁve-year life, NASA's Chandra X-ray Observatory is rewriting textbooks and helping advance technology.
—Preceding unsigned comment added by 208.230.68.137 (talk • contribs)  (this machine is apparently located in Washington, PA and registered to Armstrong Cable Services, which is headquartered in Butler, PA)
:Tiffany, I don't know who you presented this "presentation" to, but your very first sentence is completely wrong.  (You defined, not quite correctly, "escape velocity", not "black hole".)  Fortunately the rest is mostly not so wrong, just very disorganized.  So were you trying to get feedback, or what? ---CH 04:24, 22 April 2006 (UTC)
thread_title: Contribution by 208.230.68.137

message: "Following the explosion, only the core of that star will remain which, if it it is massive enough (about three or four times that of the earth) its own gravity causes the core to implode and suck everything around it into this newly formed black hole."
Surely the Sun? (Ajkgordon)
:Sun, yes. This is the TOV limit. --Christopher Thomas 19:27, 4 April 2006 (UTC)
replies: text: Hang on, Ajkgordon, suck everything around it into this newly formed black hole is potentially misleading (no Newtonian limit puns, please!) since a black hole won't tug any harder than any other object with the same mass, it is just more compact, which means you can get close enough to experience (in a stellar mass hole) some rather large tidal forces. ---CH 04:08, 22 April 2006 (UTC)

text: CH notes an important point. A more accurate way of describing things would be to say that in the collapse of a star sufficiently massive, the compacted core of neutron-degenerate matter that forms during collapse quickly becomes heavier than the TOV limit, at which point it collapses, and all of the infalling matter in the collapsing star falls into the newly-forming black hole (as there is no surface left to impede its collapse). --Christopher Thomas 04:30, 24 April 2006 (UTC)
thread_title:  Mass of the earth? 

message: :::Let me break in here to point out that this talk page is not intended as a place where you can ask informational questions about black holes; see the header above for some suggestions about places where you can ask such questions. ---CH 04:59, 23 May 2006 (UTC)
replies: text: IIRC, it means that it is no longer pulling in large amounts of matter and spewing it out in jets. I've paid more attention to Linguistics than Astronomy over the past couple years though, and my beloved old Astronomy textbook is in pieces. "No longer active" doesn't say so much about the hole itself as its surroundings: there's no longer anything in the immediate vicinity that hasn't either gone into a stable orbit or been sucked in. Linguofreak 04:11, 10 April 2006 (UTC)
replies: text: Yes: it is now thought that all or almost all galaxies harbour supermassive black holes; long ago, these powered what we now see (in optical images of very far and very long ago galaxies) as quasars, in which case astronomers have long spoken of active galactic nuclei (AGNs).  Hence, we have the picture of galactic nuclei starting off very active and gradually settling down into a kind of inactive senility. ---CH 04:12, 22 April 2006 (UTC)
thread_title: non-active black holes

message: Can someone help figure out what to do with the article for Quantum Singularity? It's a mess, so I was hoping that someone here could either help at least get it started or lend an opinion as to whether it is deletable? Thanks. Madmaxmarchhare 02:47, 11 April 2006 (UTC)
replies: text: It looks like it should be drastically compacted and merged into a "list of black holes in fiction" list somewhere. I can't find any suitable merge target offhand, though. If you want to put it on AfD, go ahead, as it would likely pass. --Christopher Thomas 04:07, 11 April 2006 (UTC)
replies: text: Would it be right to just re-direct Quantum Singularity to Black Hole (disregarding what's in there already). Sorry, physics was a long time ago for me... Madmaxmarchhare 17:14, 11 April 2006 (UTC)
replies: text: There's enough activity on the page that it should probably go through a proper AfD process. See WP:AFD for directions on how to do this. For an article like this, it's a formality, but going through the process demonstrates your good intentions. --Christopher Thomas 20:41, 11 April 2006 (UTC)
replies: text: My gut feeling, actually, is that "quantum singularity" is a common enough term in fiction that it deserves its own article.  I cleaned up the article and added an intro that relates the term to real physics as far as is warranted, and moved it to Quantum singularity (fiction).  But if you still think it ought to be deleted, I won't object—Wikipedia:Proposed deletion may be the way to go, since it happens automatically after five days (without a vote) if there are no objections. -- SCZenz 22:30, 11 April 2006 (UTC)
replies: text: I generally agree that it probably deserves its own article since it appears so often in science fiction, etc. I think what you did will work as a good start and nicely blends nominal theory with the reality of its use in fiction. At this point, I'm apt to let it stand and gather. Madmaxmarchhare 23:46, 11 April 2006 (UTC)
thread_title:  Quantum Singularity 

message: i earned a c, i'm amaerican, and i can spell, in physics, and i wanna apply something.  
ok:: eventually someone might wanna figure our bigbang spot as 0,0,0. we are so obviously multidimensional that the straight, flat line, has overshadowed not solely in its dominance, yet also because of its simplicity.  ok::  mapping our visible galactic neighbors in space we can set forth  parameters of distance(time is still relative and unimportant) so that triangulations can be determined allowing a realistic picture of where we live.  in time and repetition more and more of our universal world will become visible, telling us how big our space is.  black holes are fun because they might be the keylock pieces to our space if they are massable eventhough the notion of superdense mass, mounting, and maybe stationary in our collective movement, is something.  so... a better, truer? understanding of the relation, the relativity of our space as we get to know it might allow some visions of the shape of those areas of black hole meaning traceable wormholes- that last was a bit far however, the blackhole mass could be the structure of a tube if multiple outlets could be found.  maybe superdense singularities exist
—Preceding unsigned comment added by Bigrobhollins (talk • contribs) 
:You're "amaerican" and you can spell? Anyway, you can't just ignore time and try to find "our bigbang spot as 0,0,0" because space and time are mixed up with each other. That's basic special relativity. —Keenan Pepper 07:34, 16 April 2006 (UTC)
replies: text: In the spirit of Wikipedia, I suppose we should not discourage new editors, but at the same time, it seems fair to ask that newbies avoid creating an account and posting their debut WP edit while (apparently) in a state of extreme intoxication.    Since I'm picturing Rob as a underaged drinker, one might even add a plea to avoid extreme intoxication, period, but I guess that's your business, Rob.  Or was "Rob"'s incoherent comment someone's idea of a "joke"? ---CH 03:04, 22 April 2006 (UTC)
thread_title:  3tries 

message: from Luton, England (IP registered to NTL Internet, UK) have already been reverted by Christopher Thomas, and a good thing too, but assuming good faith, I'll offer some pointers:
#Although most scientists are not entirly sure what happens within a "black hole": true, and the classic paper by Israel on black hole interiors is a good starting point; see also colliding plane wave models and their applications to this question, 
#it is widely thought that the Laws of physics do not apply: false, of course physicists expect that some theory is capable of accurately modeling black hole interiors, and indeed most physicists expect that general relativity should be perfectly capable of modeling the region not to far inside the horizon (a fringe minority dispute this, as do many cranks); however, it is widely expected that gtr should break down near putative curvature singularities in the "deep interior", where curvatures approach L-2 where L is the Planck length,
#to something with such a great mass: false; it is not the mass but the compactness of an object which determines whether or not it forms a black hole,
#and therefore time could be slowed down to a standstill: false, you are no doubt thinking of what happens just outside the event horizon of a Schwarzschild hole, but even there you are confused: of course time does not "slow to standstill" anywhere in any spacetime; rather, radio signals from a static test particle suspended (say on a long and very strong but neglible mass string) just outside the event horizon will be extremely redshifted when received by static observers far from the hole; this does not imply that time has "slowed" for the suspended particle, just that outgoing null geodesics diverge due to the spacetime curvature outside the hole (or indeed any massive object),
#or even not exist at all: half true; it seems likely that spacetime must be replaced by some underlying concept near curvature singularities,
#this means that theoretically matter could be compressed to an infinate singularity: half true; in general, gtr fails to model what happens to matter which encounters a curvature singularity, but not all singularities which (according to gtr) might be found deep inside black holes are "crushing"; the ones inside the simplest gtr models of black holes are, but the Poisson-Israel model includes the possibility that a particle falling into the interior will encounter a Cauchy horizon rather than a crushing singularity.
In the spirit of Wikipedia we should try to avoid discouraging new editors, but it seems fair to ask that newbies be very sure of their facts (and be able to cite standard textbooks or highly reputable printed math/science encyclopedias to back up their claims!) before editing articles on scientific topics.  To soften the blow, I confess that I and our Luton anon do share one characteristic: we would both benefit from a spell-checking utility!---CH 02:53, 22 April 2006 (UTC)
thread_title:  The additions by 81.102.97.175 

message: :::Let me break in here to point out that this talk page is not intended to be a place where people can ask informational questions; the top of this page now contains a pointer to some places you can try instead! ---CH 04:58, 23 May 2006 (UTC)
replies: text: I'm glad you'd like to learn more, Anonymous, but I'll suggest you look at the Wikipedia:Reference Desk for a place to put these kinds of questions.  This page is for discussion of this particular article.</br>As for your question, I think the same thing that happens when any other objects get near each other...  They will orbit each other, and one may fall into the other, adding its mass to it.  Black holes aren't really all that special, it's just that they're very compact...  Basically, they do the same thing as two suns when they get near each other, only they pull much more strongly when they get particularly close.  *shrugs*  - JC 02:58, 1 May 2006 (UTC)

text: There are some very interesting, and rather unique, phenomena that arise when black holes collide.  They are expected, for example, to produce gravitational waves. -- SCZenz 03:13, 1 May 2006 (UTC)
thread_title:  Question