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{| class="messagebox standard-talk"
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| '''IMPORTANT''': This is '''[[WP:NOT|not]]''' the place to discuss what you think black holes are. This page is for discussing the article, which is about black holes as described by [[general relativity]], and about what has been presented in peer-reviewed scientific literature about them. See [[Wikipedia:No original research]] and [[Wikipedia:Talk page guidelines]]. If you wish to discuss or debate the ''validity'' of this model, or propose alternate models, please do so at one of the forum links provided below (not here).
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== Edit request from 117.242.0.183, 24 August 2010 ==

{{tld|editsemiprotected}}
<!-- Begin request -->
refer Dr.Stephen Hawkings books and videos for more correct information

<!-- End request -->
[[Special:Contributions/117.242.0.183|117.242.0.183]] ([[User talk:117.242.0.183|talk]]) 13:31, 24 August 2010 (UTC)

{{ESp|n}} PLease be more specific about the content you would like to add to the article. Thanks, [[User:Celestra|Celestra]] ([[User talk:Celestra|talk]]) 13:56, 24 August 2010 (UTC)

== Edit request from GregoryCJohnson, 1 September 2010 ==

{{tlx|editsemiprotected}}
<!-- Begin request -->
Besides being arbitrary and capricious, in the context of physics this is immaterial and outside the discussion. (Alternately, it is inflammatory and/or discouraging, but let's be positive):
"However, the term itself has been subject of [[Black hole naming controversies|racial controversy]] for some."

In context, this merits a footnote. Kindly make it so.

<!-- End request -->
[[User:GregoryCJohnson|GregoryCJohnson]] ([[User talk:GregoryCJohnson|talk]]) 04:56, 1 September 2010 (UTC)

:Done. That should have been reverted as soon as it was added. --[[User:Christopher Thomas|Christopher Thomas]] ([[User talk:Christopher Thomas|talk]]) 06:01, 1 September 2010 (UTC)
:{{done}} Just marking to remove request from category. --<b>[[User:Stickee|Stickee]] <small>[[User_talk:Stickee|(talk)]]</small></b> 06:46, 1 September 2010 (UTC)

== Calculating the pressure and density profile in a black hole ==

{{hat}}
When a star above several solar masses collapses, the neutrons in the core disintegrate into radiation and some quark matter. As the collapse continues and temperature rises further virtually all matter converts to radiation. If the radiation is contained in the system, the pressure of the radiation is P = Dc<sup>2</sup> , where D is the equivalent mass density of the energy. The contained radiation, which has mass, also acts like a compressed gas.

With the terminology D(c) for the radiation density at the core, and D(r) the radiation density at radius r, and using the expected density profile of D(r) = D(c) (1 - r<sup>2</sup>/R<sup>2</sup>), the following equation should give the core pressure P(c) in a dark energy star. For math principles see: http://answers.yahoo.com/question/index?qid=20100213141613AAkCtWi .

P(c) = (15/16)GM<sup>2</sup>/(πR<sup>4</sup>)

''(Added by 172.162.147.96 on 01:29, 15 September 2010 (UTC).)''

This formula may not be correct because it assumes a density profile of 1/r<sup>2</sup>, but P(c) would still be proportional to M<sup>2</sup>/R<sup>4</sup> for other density profiles.

''(End of added content.)''

Its easy to understand why the structure is stable and doesn’t collapse. Gravity varies as 1/R<sup>2</sup>. The support mechanism is pressure, which is proportional to density, and varies as 1/R<sup>3</sup>. Note the ratio of mass/r is essentially constant if the density profile is 1/r<sup>2</sup> .

Because M is proportional to R ( R = 2GM/c<sup>2</sup> ), an interesting result is a more massive star (black hole) has lower internal pressure.

The logical conclusion is a black hole, or dark energy star, consists of intense radiation, with perhaps a thin atmosphere of quark type matter just below the Schwarzchild radius. A magnetic field could exist within the structure.

I realize some prefer to believe all this mass and energy converges to a point. [[Special:Contributions/172.163.116.82|172.163.116.82]] ([[User talk:172.163.116.82|talk]]) 01:51, 13 September 2010 (UTC) BG Sep 12, 2010

:First, this article is supposed to reflect material published in academic literature, not on answers.yahoo.com, so you'll need a source matching [[WP:RS]] if you want any of it changed. Second, this article is supposed to give explanations space in proportion to the fraction of the scientific community that considers those explanations either plausible or otherwise-noteworthy, per [[WP:UNDUE]] and [[WP:NPOV]]. For scientific topics, this is usually evaluated by the number of independent groups writing papers about a given topic, and for individual papers, the number of citations of it by unrelated groups' papers.

:Third, the argument for volume approaching zero does not require conversion of matter. The TOV limit exists for the same reason the Chandrasekhar limit does: relativistic effects cause the radius of a ball of neutron-degenerate matter to approach zero at some finite mass, rather than at infinite mass. A similar limit exists no matter what form of matter you assume the star is made of. Fourth, the argument for matter compressed within an event horizon collapsing to a black hole holds no matter how high you assume pressure is. See [[Penrose–Hawking singularity theorems]] for details.

:Fifthly, you are mistaken about one of your assumptions. Gravity does '''not''' vary as 1/r^2 in relativistic stars like black holes. That equation only applies in the weak-field limit, when you're working with something that looks like Newtonian gravity.

:I hope this adequately addresses your post. --[[User:Christopher Thomas|Christopher Thomas]] ([[User talk:Christopher Thomas|talk]]) 02:36, 13 September 2010 (UTC)

OK, but if gravity doesn't vary as 1/r<sup>2</sup>, shouldn't the article explain that in Physical Properties? After all the article is about a gravitational object. Presently the article says "there is no observable difference between the gravitational field of such a black hole and that of any other spherical object of the same mass." [[Special:Contributions/172.130.21.182|172.130.21.182]] ([[User talk:172.130.21.182|talk]]) 22:00, 13 September 2010 (UTC) BG
:The gravitational field of any other spherical object of the same mass also does not vary with 1/r<sup>2</sup>. At large distances (compared to the Schwarzschild radius) the corrections are very minor and negligible. At shorter distance they become relevant and the description of the gravitational field by a Newtonian potential breaks down, and more complicated mathematical machinery is needed to describe it (the Newtonian potential is essentially replaced by a 16-component rank 2 tensor). That the gravitational field as described by general relativity is different than the one from Newtonian gravity should come as no surprise as the theories are different. This currently is somewhat implicit in the article. I'll have a look if this can be made more explicit. [[User:TimothyRias|TimothyRias]] ([[User talk:TimothyRias|talk]]) 08:15, 14 September 2010 (UTC)

: I think that is interesting, and could be mentioned in the article with a link to the page/section with the relevant physics and math. [[User:Jehochman|Jehochman]] <sup>[[User talk:Jehochman|Talk]]</sup> 09:23, 14 September 2010 (UTC)

Thanks. I wasn't aware of relativistic gravitational factors, but it makes sense. Could relativistic effects on gravity and pressure cancel? A conventional gas pressure model should still work so long as the force of gravity varies less extremely than 1/r<sup>3</sup>. And the factor of (15/16) could be off by -50% to +100 % depending on the density profile. I think a profile of almost constant density could make the formulas converge better, but I can't justify that. Could the "temperature" of space within the Schwarzchild radius be constant? [[Special:Contributions/172.162.199.222|172.162.199.222]] ([[User talk:172.162.199.222|talk]]) 21:29, 15 September 2010 (UTC)BG

:Just as a point of order, per the big green banner near the top of this page, this really isn't a good place for general questions about how black holes work. The physics form (linked in that banner) would probably be the best place to get into an extended discussion of this. --[[User:Christopher Thomas|Christopher Thomas]] ([[User talk:Christopher Thomas|talk]]) 21:45, 15 September 2010 (UTC)

I know we are breaking or stretching the rules. But it looks like some good will come out of this already - soon the article might explain how gravity can be expected to work within the Schwarzchild radius for both a point mass and possibly a distributed mass. This section will surely be deleted in the future anyway. Critics who speak out usually help resolve a situation; most are silent. [[Special:Contributions/172.130.98.130|172.130.98.130]] ([[User talk:172.130.98.130|talk]]) 01:21, 16 September 2010 (UTC) BG

:The problem is that the vast majority of this thread ''hasn't'' been about how to improve the article - it's been about explaining where a misconception has occurred in your own model of black holes. As with your February thread, that is not what this page is for. I'll usually answer questions when people ask them, as it's often faster than steering people towards external references and occasionally it does point out a deficiency in the article, but you've been proposing your own models here for quite a while now, and Wikipedia was not intended to be used as a sounding-board for your own work.

:If you have ''specific'' questions about ''article content'', or ''specific'' suggestions about how the article should be improved, please make them. If you have an interesting new idea about how black holes might work, please bring them to a forum that is better suited for that purpose (you'll get better answers and longer discussions there). --[[User:Christopher Thomas|Christopher Thomas]] ([[User talk:Christopher Thomas|talk]]) 02:09, 16 September 2010 (UTC)

:The proper way to do the calculation you tried to do is discussed in [[Tolman–Oppenheimer–Volkoff equation]]. The results of that calculation are currently (IMHO) adequately treated in this article.[[User:TimothyRias|TimothyRias]] ([[User talk:TimothyRias|talk]]) 08:56, 16 September 2010 (UTC)

Those equations look like a gold mine! I will try to digest them this weekend.[[Special:Contributions/172.162.165.106|172.162.165.106]] ([[User talk:172.162.165.106|talk]]) 21:55, 16 September 2010 (UTC)BG

:This is exactly the same type of situation I described above, as well as in the February thread, so I'm puzzled that you are treating this as something new.

:A ball of [[degenerate matter]] (electron-degenerate, neutron-degenerate, or any other kind), shrinks when you add mass. At all times, there is a balance between gravitational pressure (lowering gravitational potential energy when the ball compresses) and degeneracy pressure (lowering particle energies when the ball expands to give them longer wavelengths). When treated only with non-relativistic mechanics, the ball approaches zero size as its mass approaches infinity. When treated with relativistic mechanics, it turns out to approach zero size as its mass approaches some finite value (the [[Chandrasekhar limit]] for electron-degenerate matter, and the [[TOV limit]] for neutron-degenerate matter). A ball of highly-relativistic degenerate matter is made mostly of particles that look a lot like photons as far as mass and wavelength are concerned (as most of the mass of any given particle is relativistic mass, not rest mass). Expanding the ball (making wavelengths longer) changes the energy by a different amount than for non-relativistic matter, with the net effect of lowering the degeneracy pressure (eventually to the point where it can't support the object against gravity).

:The key difference between a ball of relativistic degenerate matter and a ball of photons is that the exclusion principle prevents any two particles in the ball of degenerate matter from having the same energy and momentum (and quantum spin and yadda yadda). You don't get a thermal distribution of energies. In fact, by some arguments, it's at a very low temperature even though kinetic energy of individual components is very high (it's a highly ordered structure, close to its ground state in terms of particle configuration). --[[User:Christopher Thomas|Christopher Thomas]] ([[User talk:Christopher Thomas|talk]]) 03:17, 17 September 2010 (UTC)

You and Tim understand ten times more details about black holes than I ever will, but I think there is a simple radiation support mechanism for black holes that has somehow been overlooked, mainly P = Dc<sup>2</sup>. This equation provides conceivable support pressures that only need to be perhaps an order of magnitude or so higher than in a large neutron star. I don’t have the skill to solve the complicated Tolman–Oppenheimer–Volkoff equations, but think a logical density profile exists that is consistant with these equations, R = 2GM/c<sup>2</sup> , and P = Dc<sup>2</sup>. Please leave this section posted for at least several days to see if there are any other inputs, then I don’t mind if its deleted if you think it has little merit. Thanks for your input and patience. [[Special:Contributions/172.129.144.117|172.129.144.117]] ([[User talk:172.129.144.117|talk]]) 20:32, 18 September 2010 (UTC) BG
:Since this thread is in no way about improving the article, but an IP being arrogant enough to think the has found something that has been overlooked for almost a century consisting of some of the greatest minds to walk this planet, it is time to close and archive it.[[User:TimothyRias|TimothyRias]] ([[User talk:TimothyRias|talk]]) 22:00, 18 September 2010 (UTC)
{{hab}}

I don’t know why you aren’t more civil; maybe you are insecure about a point singularity, or are constantly being questioned by others who doubt a point singularity. No big deal, you’ve taken the time to respond, which I appreciate. I thought the best thing to do was to back away politely because you and Chris are just not receptive to the idea of a distributed mass of radiation inside the Schwarzchild radius. This is certainly your right and I do value your input. Yes, the WWII generation were incredible mental giants but they did not have access to the relatively recent information that matter essentially converts to radiation at extremely high temperatures. I am not alone in thinking Hawkins’ book was a shallow dissapointment, explained little, and glossed over the singularity concept, but this is just opinion. I think Chris is in error when applying degeneracy pressure concepts IF matter has already converted to radiation, and I think the Tolman–Oppenheimer–Volkoff equation wouldn’t apply to distributed radiation within the Schwarzchild radius either. Again, thanks for your time and I won’t bother you fusspots (not nearly as bad as arrogant!) any more. <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/172.130.2.80|172.130.2.80]] ([[User talk:172.130.2.80|talk]]) 15:19, 23 September 2010 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot--> You might as well archive this reply as well.[[Special:Contributions/172.130.2.80|172.130.2.80]] ([[User talk:172.130.2.80|talk]]) 15:23, 23 September 2010 (UTC)BG

:We have been incredibly civil, considering the fact that you have consistently ignored the fact that WP talk pages are NOT for discussing the subject of the article, but for discussing improvements to the article. Please read [[WP:TALK]] to understand why your behaviour on this talk page is unacceptable.[[User:TimothyRias|TimothyRias]] ([[User talk:TimothyRias|talk]]) 16:32, 23 September 2010 (UTC)

:To repeat something that was told to you in February: If you feel that the scientific community is wrong about something, the '''first''' thing you should do is ''learn why they think they're right''. Even if you aren't in a position to take a course on relativity, you can easily pick up [[Gravitation (book)|the MTW textbook]] from your local library. If you still need something explained to you, or if you think that there is an error in the textbook (''after'' reading it and understanding its arguments and mathematics), I suggest asking at sci.physics.research or one of the other places linked in the big green banner up top, underneath the big warning sign about this not being the place to post personal theories.

:Arguing without making an effort to understand our counterarguments shows disrespect to all of us. Arguing that the scientific community is making grave errors without first trying to understand what exactly it is you're claiming to poke holes in shows poorly-placed priorities. And ignoring repeated statements that this is not a good venue for this sort of discussion shows disrespect for Wikipedia's rules. That last bit is usually not a good idea. --[[User:Christopher Thomas|Christopher Thomas]] ([[User talk:Christopher Thomas|talk]]) 17:44, 23 September 2010 (UTC)

== Edit request from Xronon, 13 September 2010 ==

{{tlf|editsemiprotected}}
<!-- Begin request -->
REASON: The indispensable role of Charles Misner and the major contribution of Martin Kruskal are omitted. The importance of Eddington-Finkelstein coordinates is overstated compared to Birkhoff's Theorem.

REPLACE THE PARAGRAPH

===Golden age===
{{See also|Golden age of general relativity}}
In 1958, [[David Finkelstein]] introduced the concept of the [[event horizon]] by presenting [[Eddington–Finkelstein coordinates]], which enabled him to show that "The Schwarzschild surface {{nowrap begin}}''r'' = 2''m''{{nowrap end}} [in [[geometrized units]], i.e. 2''Gm''/''c''<sup>2</sup>] is not a singularity, but that it acts as a perfect unidirectional membrane: causal influences can cross it in only one direction".<ref>{{cite journal
|last=Finkelstein |first=David
|title=Past-Future Asymmetry of the Gravitational Field of a Point Particle
|journal=Phys. Rev.
|year=1958
|volume=110
|pages=965–967
|doi=10.1103/PhysRev.110.965
|ref=harv
}}</ref> This did not strictly contradict Oppenheimer's results, but extended them to include the point of view of infalling observers.

BY THE PARAGRAPH

===Golden age===
{{See also|Golden age of general relativity}}

An event horizon, a persistent boundary that signals could cross in only one sense,
came to attention in 1958 when [[David Finkelstein]] and [[Charles Misner]]
found one in the basic [[topological soliton]] of the gravitational field, the {\em gravitational kink}.
<ref>
Finkelstein, D. and Misner, C.W.
'"Some new conservation laws."
' ' Annals of Physics ' ' 6:230--243, 1959.
</ref>
Guided by this example, Finkelstein found that "the Schwarzschild surface r = 2m [in geometrized units, i.e. 2Gm/c2] is not a singularity, but that it acts as a perfect unidirectional membrane: causal influences can cross it in only one direction";
and that the apparent singularity resulted from forcing a static description on a non-static event horizon.
<ref>
Finkelstein, David. "Past-future asymmetry of the gravitational field of
a point particle." ' ' Physical Review ' ' 110:965, 1958
</ref>
A still greater manifold with two event horizons,
one inwardly directed and the other outwardly,
had already been found and mapped by [[Martin Kruskal]],
who was later persuaded to publish it.
<ref> Kruskal, Martin D.
"Maximal Extension of Schwarzschild Metric."
' ' Physical Review ' ' 119:1743, 1960.
</ref>
It was also found by [[George Szekeres]].
Schwarzschild, Finkelstein, and Kruskal mapped,
respectively, three successively larger parts of the same gravitational black hole:
its wholly static outer husk, an inward extension that is not static but persists without change, resembling a stationary vortex in this respect, and a doubling that is wholly dynamical, beginning and ending in singularities. These discoveries did not strictly contradict Oppenheimer's results, but extended them to include the point of view of infalling observers.

IF THIS CHANGE SPOILS THE BALANCE OF THE ARTICLE:

Delete the sentence in the proposal
"Schwarzschild, Finkelstein, and Kruskal mapped,... in singularities,"

<!-- End request -->
[[User:Xronon|Xronon]] ([[User talk:Xronon|talk]]) 18:43, 13 September 2010 (UTC)
:{{EP|d}} Thanks for the valid and referenced information! --[[User:Wolfnix|<span style="color:Navy">Wolfnix</span>]] • [[User talk:Wolfnix|<span style="color:Purple">Talk</span>]] • 17:41, 14 September 2010 (UTC) <span style="border:1px solid #ffa500;background:#ffce7b;"><small>If you reply here, please leave me a {{[[Template:Talkback|Talkback]]}} or {{[[Template:wb|Whisper Back]]}} message on [[User talk:Wolfnix|my talk page]].</small></span>

== Edit request , 1st October 2010 ==

{{tld|editsemiprotected}}
<!-- Begin request -->
The Article begins badly 'According to the general theory of relativity' - I don't think that the general theory states anything at all about black holes - yes, they fit in with it. I'd remove that phrase and, if referring to the GTR at all, put it much later in the paragraph and avoid the word 'according to' - maybe 'in agreement with' or something. <!-- End request -->

:I agree that that phrase is awkward, and probably unnecessary. I've removed it for now. The whole lead can use some tweaking though.[[User:TimothyRias|TimothyRias]] ([[User talk:TimothyRias|talk]]) 12:19, 1 October 2010 (UTC)

::This was added many years ago due to many, many talk page threads and text-additions about proposed objects that looked like black holes but that could be escaped. The response usually given was that this article was about black holes ''as described by general relativity'', making such additions off-topic. Nowadays we'd probably cite [[WP:UNDUE]], but I still think the "as described by GR" bit is useful to have somewhere.

::Black holes are indeed a prediction derived from general relativity. the [[Penrose-Hawking singularity theorems]] provide a proof that formation is inevitable past a certain density for any given volume, and special relativity provides a justification for the speed of light being an upper bound on velocity and rules for addition of velocity. Otherwise you could escape from, say, a Newtonian "dark star" by either having a velocity greater than that of light or by using a rocket with a delta-v greater than C (even though your travel speed at any given time is less than C). --[[User:Christopher Thomas|Christopher Thomas]] ([[User talk:Christopher Thomas|talk]]) 18:18, 1 October 2010 (UTC)

Revision as of 03:03, 15 October 2010

hey guys

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