Talk:Gravastar/Archive 2

Archive 1

Archive 2

Categorization

I have removed the category links for "Black holes" and the redundent "Stellar mass black holes". Gravastars are not black holes. Instead I have placed this article under "general relativity". I also removed the "Cosmology" category link: I cannot see why a proposed stellar phenomenon relates to cosmology. (I may add "stellar phenomena" as a catergory now.) --EMS | Talk 16:10, 27 July 2005 (UTC)

Merge Gravastar and Dark Energy Star

see also Talk:Dark energy star

'Gravastar' vs 'Dark Energy Star'

Having read both entries and several linked pages, I am still unclear as to the distinction. Are these simply alternative names for a single concept? If so, would it not be advisable to merge them into a single entry?

Someone please perform the merge ASAP - JustinWick 03:58, 20 January 2006 (UTC)

'Gravastar' vs 'Dark Energy Star'

Please do NOT merge! AFAIK Gravastar is einstein-bose condensate. However Gravastar article is wrong - not all matter can form einstein-bose condensate. Some form fermion condensates. The catch with Gravastar is that *gravitons* form einstein-bose condensate cuz they have spin 2. On the contrary, this new buzz may or may not involve quantum condensates (they talk about superfluids), but only on the star surface. And bigger difference is, there's nothing about gravtions in this new one.

unsigned vote

I dissagree, the two pages shoule be kept seperate

Above vote by 20:37, 15 March 2006 User:Eevo

New dark energy star theory

This makes for an excellent read... New Scientist Article. From my reading of that the dark energy star is a completely different beast to the gravastar or dark star which some people seem to equate it with - it should end any confusion. --LiamE 10:13, 10 March 2006 (UTC)

Having said that a read a bit deeper it the article is rather similar to a gravastar as descibed in its article. Can someone please clarify the differences between the theories please. --LiamE 10:35, 10 March 2006 (UTC)

I read the articles and Gravastar and Dark Energy Star and Dark Star. At first they all seemed completely different - now they are starting to sound so similar that the Dark Energy Star appears like a refinement on the idea of a Gravastar. As far as I can tell, the heart of the Gravastar / Dark Energy Star articles is the idea that there are no event horizons, singularities, or regions of negative time-dilation - because of locally observable quantum effects at the Schwarzschild radius (in contradiction to classical General Relativity which suggests no locally observable effects at the horizon in the case of large masses). The Gravastar paper focuses on the geometry of space time that arises if a quantum shell forms close to the Schwarzschild radius and concludes that the shell is stable, there are no horizons, or singularities - it speculates somewhat tangentially and vaguely on both the nature of the quantum shell and observable differences between a Gravastar and a classical General Relativity Black Hole. The dark energy star paper makes passing reference to the Gravastar paper and its space-time geometry and stability (treating no negative time dilation, no horizons, no singularities, and stability as givens) and instead focuses on the behavior of infalling matter as it approaches the shell from outside. In particular, it predicts observably accelerated proton decay at the shell. — Preceding unsigned comment added by 64.42.233.61 (talk) 15:54, 23 August 2006

Revision

I don't mean to step on any toes, but I've made some revisions which will hopefully clarify issues and treat the idea in a more neutral and consistent tone. I don't believe that gravastars are a particularly interesting idea, but I think they should at least be described accurately in the wikipedia, presenting the claims of their creators in a fair light.

I'd like to clarify the difference between a gravastar and a dark energy star. Dark energy is a completely hypothetical form of energy which may exist in the Universe presently, and could explain certain problems in cosmology. In fact, it is thought that dark energy may account for roughly 70% of the mass-energy content of the Universe. This energy could find itself condensed in a region of space, and collapse to form a "star". Of course, there would be no reason for it to stop collapsing, since it presumably has almost no interactions, so a "dark energy star" should just be a black hole which formed out of dark energy somehow.

On the other hand, a gravastar (also completely hypothetical) would be composed of a very unusual form of matter which would be extremely rare in the Universe, except in the vicinity of a gravastar. Indeed, the primary mechanism for the formation of that form of matter would be the collapse nearly to what would be a regular black hole.

We know very little about either dark energy, or gravastar matter, but there is no reason to expect that they are related. It is possible that dark matter and/or dark energy and/or gravastar matter are related, but they are beyond present understanding of science.

As for the New Scientist article, I think the only issue it presents is that Chapline (somewhat arbitrarily) dubs part of this gravastar solution "dark energy". Calling a gravastar a "dark energy star" reeks of trying to put his name on a totally different idea. This is liable to be very confusing, but it might become standard usage among that tiny fraction of astrophysicists who give any credence to . Since they are essentially (though not exactly) the same idea, I think the dark energy page should just contain a brief explanation---maybe a clearer version of the mess I seem to be leaving on this page---of what a dark matter star should be, and what Chapline has dubbed it, along with a prominent link to this page.

Basically, the problem with dark energy, dark matter, and gravastars is that there is no good theoretical understanding of why or how they exist. On the other hand, there are at least observation clues which indicate that dark energy and dark matter do exist, whatever they're made of.

[I can give a first-hand account of that Gravity Meeting mentioned in the article. Note that the meeting does not have rigorous academic standards. I'm slightly surprised that New Scientist would treat Chapline's claims so seriously. I'm all for questioning accepted notions. I'm not all for rejecting accepted notions for no other reason than the fact that their accepted. Nor am I for accepting ideas just because I came up with them. Chapline does not seem to believe the same. Chapline's objections to more commonly accepted physics seem to be based on misunderstandings of it, or discomfort with a more-or-less random subset of ideas it contains. Chapline's proposed alternatives don't really explain much, either. (Pawel Mazur was also present, creating a ruckus along the same lines.) All in good fun, but no science resulted.]

P.S. I won't make any comment about the correct classification of this article, but "Stellar mass black holes" is not redundant in the presence of "Black holes". "Stellar mass black holes" are black holes which have roughly the same mass as an ordinary star, as opposed to tiny black holes, or supermassive black holes. --MOBle 07:12, 11 July 2006 (UTC)

More scientific explanation

I found the previous description of a Gravastar unsatisfactory, as it appeared very biased and written by someone who didn't fully understand the physics behind it and was convinced it was false. I tried to word it in a neutral way, so as to leave judgement to the reader.

I also deleted one of the "Problems with the theory" because it was very opinionated. --MaizeAndBlue86 (talk) 03:45, 27 February 2008 (UTC)

The citations to the "dynamic stability" section do not support that section. The section asserts that gravastars fail as a theory because they are dynamically unstable. The citations following those claims are to popular-press accounts of claims by proponents of gravastar theory, which do not assert that gravastars are dynamically unstable. 38.107.64.54 (talk) 20:08, 11 November 2009 (UTC)

Added a citation to the "dynamic stability" section regarding the stability of rotating gravastars. The support for the added remarks is near and through the conclusion of the paper. (stairs123). — Preceding unsigned comment added by Stairs123 (talk • contribs) 00:28, 12 April 2011 (UTC)

Citation Needed Tag and Plagerism

I noticed a citation needed tag in the Dynamic Stability section, however only a few words past it there is a citation. I looked at it, and the sentence cited is a word for word copy of page 98 from "The Cosmic Compendium: Black Holes". That being said, the tag at the end of the sentence is the source cited in the book itself for the same line. I'm pretty new to this, and I am not sure how to procede; should I edit to remove the plagerism and remove the citation needed tag, or should the sentence be removed entirely? Thanks and cheers. Blablabliam (talk) 16:03, 14 February 2017 (UTC)

@Blablabliam: Thanks for letting us know about this. I don't have access to the book, so I'll take your word for it. I will remove the sentence and notify the contributor; the procedure is outlined here. Did you check the remaining sentences in that paragraph against that source? RockMagnetist(talk) 18:57, 15 February 2017 (UTC)

Actually, on closer inspection, it appears that the plagiarism goes the other way, since this passage was written in 2011 and modified in 2014, while the book was published in 2015. The book is self-published, it appears, and may be a compendium of articles taken from Wikipedia. So I'm going to leave the passage alone. RockMagnetist(talk) 19:04, 15 February 2017 (UTC)

@RockMagnetist: I appreciate you taking a look at that. Blablabliam (talk) 05:51, 17 February 2017 (UTC)

Revamp

I am currently working on gravastar research and believe I can clear up some of the confusion. I will be making some fairly heavy edits over the coming days. Phipbel (talk) 20:28, 21 December 2017 (UTC)