User talk:Mpatel/sandbox/Black hole

Improvement

• Need to make lead better - too much detail in places and not everything is covered generally.

• Improve style, grammar, tone etc.

MP ^{(talk•contribs)} 20:23, 22 December 2008 (UTC)

Need other information

The article is lacking mention of the relation of black holes to white holes and wormholes. MP ^{(talk•contribs)} 19:49, 23 December 2008 (UTC)

I'm not sure that a detailed treatment of this is needed in the black hole article. As small mention of the subject might be needed somewhere, but it might be enough to just have them in the "see also" section. The white hole and wormhole articles should then explain the relation with black holes. (TimothyRias (talk) 12:54, 6 January 2009 (UTC))

Major issues/points with article

• Should spacetime or space be mentioned in the opening sentence ?

• The event horizon terminology ('point', 'area') should be made consistent.

MP ^{(talk•contribs)} 10:33, 24 December 2008 (UTC)

• The "evidence and detection" section reads as a loose almost random collection of ideas that have to do with the evidence for the existence of black holes. The section does really comprehensively cover the subject, while it is overly detailed in some aspects. ::Obviously, a comprehensive treatment of the subject would become too long for this article. The best way to deal with this probably is to have other article(s) cover the subject of evidence comprehensively and treat it summary style in the black hole article.

I have however not really found a satisfactory way of doing this yet. One option I have thought about is the following: Since the techniques used for investigating stellar black holes and supermassive black holes are quite different it might actual be best to have those article treat the evidence for each class and then just highlighting the main points here. (TimothyRias (talk) 12:51, 6 January 2009 (UTC))

• The "journey into a black hole section" contains a lot of information that would be of interest to many readers, but the setup of the article makes it inherently unencyclopedic.(TimothyRias (talk) 12:51, 6 January 2009 (UTC))

Good article criteria

I have placed the good article criteria here for ease of reference.

• 1. Well-written:
  • (a) the prose is clear and the spelling and grammar are correct; and
  • (b) it complies with the manual of style guidelines for lead sections, layout, jargon, words to avoid, fiction, and list incorporation.

• 2. Factually accurate and verifiable:
  • (a) it provides references to all sources of information, and at minimum contains a section dedicated to the attribution of those sources in accordance with the guide to layout;
  • (b) at minimum, it provides in-line citations from reliable sources for direct quotations, statistics, published opinion, counter-intuitive or controversial statements that are challenged or likely to be challenged, and contentious material relating to living persons; and
  • (c) it contains no original research.

• 3. Broad in its coverage:
  • (a) it addresses the main aspects of the topic; and
  • (b) it stays focused on the topic without going into unnecessary detail (see summary style).

• 4. Neutral: it represents viewpoints fairly and without bias.

• 5. Stable: it does not change significantly from day-to-day because of an ongoing edit war or content dispute.

• 6. Illustrated, if possible, by images:
  • (a) images are tagged with their copyright status, and valid fair use rationales are provided for non-free content; and
  • (b) images are relevant to the topic, and have suitable captions.

Discussing GA criteria for this sandbox article

Well-written

1(b)

• I've made a first attempt at rewriting the lead. Of course, it's by no means perfect, and I'd like to improve it. I would like to mention in the article (possibly in the lead ?) a few things about the merger of black holes and what string theory has to say about black holes. Thoughts on these issues? MP ^{(talk•contribs)} 21:26, 11 January 2009 (UTC)

Factually accurate and verifiable

2(a)

• In the history section, although there are links and refs., it might be worth having an actual link to Laplace's book Exposition du système du Monde (I couldn't find one, though), or at least to list the book in the references section. MP ^{(talk•contribs)} 13:00, 28 December 2008 (UTC)

Although there is this at wikisource. MP ^{(talk•contribs)} 13:25, 28 December 2008 (UTC)

2(b)

• Apparently, rotating charged black holes were discovered by Teukolsky and Shapiro, Newman just extending Kerr's ideas of the Kerr metric. These facts need to be checked and references provided. MP ^{(talk•contribs)} 20:15, 11 January 2009 (UTC)

Broad in its coverage

3(a)

• I think the article needs to include a discussion of white holes and wormholes, as they are related to black holes (albeit only theoretically). MP ^{(talk•contribs)} 12:31, 28 December 2008 (UTC)

TimothyRias has suggested that these be mentioned briefly. I agree. I've taken out the section on this topic and intend to incorporate the white hole/wormhole stuff somewhere in the article; possibly in the quantum mechanics discussions, or perhaps in a new section entitled Speculative Ideas (or something of that ilk), as there are a lot of (unverified, of course) hypotheses made about black holes. MP ^{(talk•contribs)} 21:12, 11 January 2009 (UTC)

• Mention some aspects of string theory that generalise black holes, such as black brane and black string ? MP ^{(talk•contribs)} 16:57, 28 December 2008 (UTC)

• Mention mergers of black holes somewhere ? MP ^{(talk•contribs)} 21:22, 11 January 2009 (UTC)

3(b)

• The Journey into a black hole section does not, I agree, fit in well with the ethos of the encyclopedia. It is also, even after trimming down, still very long. I would like to shorten it (and possibly rename it) or incorporate it somewhere else into the article (Features section perhaps ?). MP ^{(talk•contribs)} 21:32, 11 January 2009 (UTC)

The Journey section has been merged into the Features section. MP ^{(talk•contribs)} 19:30, 18 January 2009 (UTC)

Illustrated

6(b)

• The sections Characterisation, Formation and Hawking Radiation have no images. Perhaps these sections could do with an image/diagram here and there. MP ^{(talk•contribs)} 21:17, 11 January 2009 (UTC)

Comments by TR

Hi, first of all I would like to applaud you for undertaking the effort to try to improve this article. If have been struggling with it since spring last year, to the point that I basically gave up. I will gladly help out anyway I can. I will note my concerns with the article with yours above. Hopefully, we can finally get this article back to GA! (TimothyRias (talk) 12:35, 6 January 2009 (UTC))

Hi and thanks. The suggestions you made above - for example, a brief mention of white holes and wormholes - seem reasonable to me. When I saw the state the black hole article was in, I felt I just had to try and improve it. Hopefully, every 2-3 days, I'll have a stab at clearing up a section (or at least a major part thereof). I will also note down any problems or queries I have in this talk page. Comments on these updates would be highly appreciated. As we both know, this sandbox article still has a long way to go... I appreciate the support :) MP ^{(talk•contribs)} 22:05, 8 January 2009 (UTC)

Journey into a black hole section

If we are going to integrate the information from this section to other parts of the article what parts are worth saving and where should they go? My thoughts would be:

• Spaghettification/tidal forces. The amount of information in the current section can probably be trimmed down to just a few sentences which can be incorporated in the "singularity" subsection of the "features" section.
• gravitational red-shift/time dilation. This can be treated in the "event horizon" subsection of the features section. The article should be clear on the following points:
  • For an outside observer it takes infinitely long for an object to reach the event horizon.
  • For an object moving into a black hole it only takes a finite amount of time to reach the singularity.
  • Any objects falling into a black hole disappear before reach the horizon due to gravitation red-shift.

• Other stuff in the section is already repeated elsewhere in the article. Or it is trivia that can be omitted (such as the piece of information that the free-falling trajectory towards the singularity is the one with the largest proper time)

(TimothyRias (talk) 11:08, 12 January 2009 (UTC))

Agreed. I've merged the Journey section into the Features section. MP ^{(talk•contribs)} 19:30, 18 January 2009 (UTC)

Nice job. I did a bit copy editting and streamlining to the event horizon section. I also added {{fact}}-tags to all statements in that section that should get a reference at some point. Don't take it the wrong way, I generally agree with the statements, but to pass GAR the article needs to be suitably referenced. Moreover, a well-reference article tends to be less prone to erosion from well intended edits. I'll try to provide so refs for these tags. (TimothyRias (talk) 14:49, 19 January 2009 (UTC))

Suggestions for the evidence section

This has been the section been troubling me for some time. Here some of my ideas of what it should at least cover.

1. Accretion. Due to restructuring elsewhere in the article no longer contains a description of what accretion is. The evidence section probably should briefly explain the phenomenon. It should at least cover the following points:

• accretion is one of the most efficient energy conversion processes known. It can produce up to 50% of the rest mass of the infalling material in radiation. Compare that fusion produces only a few tenths of a percent of the rest mass of the fuel in energy. This makes accretion a likely candidate for any observed high-energy process in the universe.
• accretion disks can occure on all compact objects, and thus the pressence of an accretion disk is not actual evidence for a BH.
• (maybe) mention that the ADAF model for accretion during quiescence of black holes can be interpretted as direct evidence of an event horizon. (I know this was a popular claim in the late 90's, I'm still searching for a reliable review from the Chandra/XMM-Newton age to give a more actual status of this hypthesis.)
• Variations in emitted signal constrain region from which energy is emitted.

(more to come) (TimothyRias (talk) 11:36, 13 January 2009 (UTC))

Pictures

Here are some links to NASA Apod pictures of black holes we might use. Most pictures are created by NASA and thus in the public domain, however this needs to be checked for each picture if we decide to use them since some are contribute from outside NASA.

• [1] HST visible light picture of AGN.
• [2] Center of our galaxy.
• [3]
• [4] and [5] Center of our galaxy, again.
• [6] simulation of accretion disk.

(TimothyRias (talk) 15:38, 19 January 2009 (UTC))