Talk:Dark energy star
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[edit] Dark star
- merge into dark star
This discussion is at talk:Dark star#Dark-energy star
[edit] Currency of the term
Does anyone other than Dr. Chapeline use this term? --Wtshymanski 05:19, 8 Apr 2005 (UTC)
It seems like the article is describing what is commonly called a White Hole MikeMorley 15:43, 13 July 2005 (UTC)
The latest Analog Science Fiction Science Fact pulper has an article on it. 67.68.67.165 03:50, 5 August 2005 (UTC)
[edit] Points needing fine-tuning
I've put a link to this article on Wikipedia:Pages needing attention/Physics, to reflect the "needs attention" template on the article itself. Hopefully this will bring in more editors to contribute.
[edit] From PNA/Physics
- Dark energy star - Needs to be overhauled by a physicist familiar with the models involved. As-is, several points in the description are inaccurate (noted in the article's talk page). The model has been published in reputable journals, if I'm remembering which one this is correctly. Still fringe science, for now. --Christopher Thomas 01:23, 21 Jun 2005 (UTC)
[edit] Back to talk page
Points that I find odd in the current write-up:
- The description of how GR treats black holes isn't quite accurate. Infalling objects appear stationary only to distant observers, and this effect is definitely only an appearance. What actually happens depends on how you choose to measure time in the vicinity of the hole, but the infalling object measures itself to have passed through the horizon very shortly after starting to fall, and any form of measurement the distant observer could try would fail to interact with the infalling object despite an image of it being present (you can't bounce a radar pulse off the image, for instance; it's just an image formed by light that took a long time to escape from the point where it was emitted).
- The description of an object "bouncing" after passing through the horizon seems odd, as if there's actually a horizon, it implies a causal disconnection between the regions outside and inside. If I recall correctly, the papers about this type of object described the resulting structure as having a region of very high density outside of where the horizon would be, but no event horizon. However, I'd be more comfortable if an astrophysicist could read the publications and adjust the write-up accordingly (I'm not one).
- More detail on the "stranger effects" due to quantum fluctuations is needed. Most people know about Hawking radiation, but it should be mentioned. I also recall mentions of a fuzziness in the exact location of the event horizon, and of certain situations causing infalling objects to encounter large amounts of matter produced by interactions between the black hole and virtual particles (I'd want to look these up again before claiming they accurately represent mainstream views, though).
- Clarification - I recall references to encountering large amounts of matter _inside_ the horizon, in the vicinity of the Cauchy horizon (as distinct from plowing through Hawking radiation of great intensity when you approach the event horizon from the outside). --Christopher Thomas 06:32, 21 Jun 2005 (UTC)
An excellent start, but could use more fine-tuning.--Christopher Thomas 01:37, 21 Jun 2005 (UTC)
[edit] 'Gravastar' vs 'Dark Energy Star'
- see also Talk:Gravastar
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 the two entries?
- Please refer to discussion here for this; and to ask any further questions. - RoyBoy 800 21:50, 21 August 2005 (UTC)
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- There is no useful content pertaining to the distinction between gravastars and dark energy stars on that page. Most of the thread you participated in discusses "dark stars", which are the Newtonian equivalent of black holes. Discussion of the proposed merge should either be here, or at Talk:Gravastar. --Christopher Thomas 22:22, 11 January 2006 (UTC)
"Chapline theorized that a phase transition in the phase of space occurs at the event horizon"- whats a phase of space (or am I reading this incorrectly)?
"As there is no singularity to evaporate, Hawking radiation may not exist in this model of black holes." - A singularity is not required for Hawking radiation. All that is needed is a horizon. eg: see http://arxiv.org/abs/hep-th/0106111. However, I'm not sure there is a horizon. My understanding is that collapse of matter halts before the outer surface of the matter falls over the horizon radius (certainly true for a gravastar, I'm now reading to see if a gravastar is a dark star - I'm pretty sure they aren't since they have been invented by different authors). Therefore one would not have Hawking radiation.
Don't merge. But the articles need major rebuilding: both are very ambiguous on the differences. Steve Max 16:10, 13 April 2006 (UTC)
- I got the impression that an observer outside the horizon could tell the difference between a dark energy star and a black hole but that a gravastar appears identical to a black hole outside the horizon. Namely, normal matter falling into a dark energy star would decay into dark energy before crossing the horizon. Protons would also first decay into observable positrons and photons. These quantum/dark energy effects would be observable even if the object were very massive and lacked the extreme tidal forces needed to be even noticeable in a system modelled on General Relativity alone (where an event horizon is not significant to a local observer). A gravastar seems to differ from a black hole only on the inside - where no singularity forms because of some sort of phase transition on space-time. So to sum up the differences: space changes inside the horizon of a gravastar, matter changes outside the horizon of a dark energy star.
A dark energy star is an alternative explaination to black holes in which instead of entering the star, matter is converted into dark energy. A gravastar however is a different explaination in which matter enters the star but, unlike a black hole, space keeps the matter from collapsing into a singularity. Instead the matter is compressed to a high density in the center of the star. In a black hole matter collapses into a singularity in the center of the black hole. —The preceding unsigned comment was added by 66.213.78.130 (talk • contribs) on 19:13, 24 May 2006.
[edit] Revised introduction
Hi all, hypothetical speculations for possible compact objects which could avoid invoking the black hole concept which troubles so many (including some astronomers) is a legitimate topic, since this is genuine if controversial topic in the research literature. However, please try to make it clear in the first paragraph when a speculation is regarded as dubious by the majority of physicists, as is the case with gravastars. IOW, please make every attempt to keep discussion of both black holes, neutron stars, and possible other kinds of compact objects as fair and accurate as possible with regard to current scientific status. I don't want to get into Chapline et al. right now (but see recent discussion in sci.physics.research), but I took the time to try to slighly modify the introduction to better suggest the speculative status of gravastars. Even editors who feel that black holes are equally speculative should not suggest that they are not the mainstream explanation for observed black hole candidates (in fact, very few would even be as careful as I am to sometimes refer to black hole candidates rather than simply black holes). ---CH (talk) 10:35, 3 October 2005 (UTC)
[edit] 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)
