Talk:Galaxy rotation curve/Archive 1

message: Does the physics community consider the solution proposed below (paper by Cooperstock & Tieu) as a promising one to the galaxy rotation problem? I had read about this, but was surprised this entry made no substantive discussion of this recent proposal. I am not a physicist so I am hoping some kind but knowledgeable soul will give us some perspective on this work. 
"General Relativity Resolves Galactic Rotation Without Exotic Dark Matter"
F. I. Cooperstock & S. Tieu
Submitted to the Astrophysical Journal, 23 pages, 7 figures, 4 tables
http://arxiv.org/abs/astro-ph/0507619
::I just glanced through the work, and as far as general relativity theory, I am somewhat mystified myself, though I am fairly certain that this article only refers to the General Relativity of Ricci and/or Schwartszchild (sp?)  Not the General Relativity of the FLRW metric.  The fact that it refers to a gravitational body generating the gravity rather than an overall "shape" or scale factor of space is what makes me think so.
JDoolin 00:59, 22 August 2006 (UTC)
thread_title:  General Relativity Resolves this Problem? (A Question from the Unwashed Masses :-) 

message: "scientists simply assumed that the rotation curve was flat because of the presence of a large amount of matter outside the galaxies"
Are you sure this is correct? How can the presence of matter outside a galaxy affect rotation speeds with?. I thought dark matter was postulated to exist within a galaxy but not all concentrated at the centre as Newtionian models suppose. However I am not confident enough that I am correct to make the change to the page without further research. Watch this space! Theresa knott
:You're right, I'm trying a different wording: "a large amount of matter surrounding the visible part" - At18 21:46 Apr 28, 2003 (UTC)
It would be nice to post the modeled mass distribution in the galaxy that produces the A velocity curve - e.g., don't you need an assumed mass distribution to generate that curve? And wouldn't different assumed mass distributions generate different velocity curves.  Is there a mass distribution that it is reasonable or obvious to use to generate the expected velocity curve?
This page is a complete mess. I'm taking a hose to it. -- Decumanus 18:20, 12 Feb 2004 (UTC)
thread_title:  (a previous untitled discussion) 

message: The page was a disaster. I have cleaned it up. 67.172.158.8 17:23, 24 Dec 2004 (UTC)
thread_title: Cleaned up

message: One thing that I have never seen is an explanation of the galactic rotation curve that also explicitly takes into account the theory that the spiral arms are not in fact coherent but are a construct of the elliptical orbits of the stars that make them up, as explained by :Image:Spiral galaxy arms diagram.png. The implication of this is that a star in a spiral arm is near the aphelion end of the ellipse, and so is going more slowly than a star on a circular orbit at that distance would be. If the ellipses themselves are turning and giving the illusion of the spiral arms rotating evenly, then the discrepancy could disappear. It seems unlikely that this has been overlooked, but I'd be interested to see a discusson that includes this aspect.  — PhilHibbs | talk 18:41, 23 Feb 2005 (UTC)
thread_title: Elliptical orbits

message: The vertical axis of the graph really should be "Speed". I know that "Velocity" sounds more scientific, but velocity is a vector and that's not being represented on the graph, but only the magnitude, and the magnitude component of velocity is "speed". -- Ch'marr 15:29, 10 October 2005 (UTC)
thread_title:  Velocity vs Speed 

message: I'd like two citations please:
#For the general relativity theory on the Galaxy rotation problem
#That there is more than one non-standard cosmologies (the text says "various non-standard cosmologies ) theory on the Galaxy rotation problem
--Iantresman 09:16, 6 April 2006 (UTC)
thread_title: Citations required

message: The article Rotation curve is largely redundant with this article. Except that Rotation curve is clearly POVed. The only  (mostly irrelevant) paper referenced was added by the author, and phrasing such as "there is large amounts of dark matter residing in contrived places" is straight from said paper. Suggest that we delete that article (But I don't know how) and merge any salvageable material into this article. (Or vice versa). Nonsuch 21:39, 11 April 2006 (UTC)
replies: text: I think it would make better sense to merge both articles, and call it "Galaxy rotation curve" which both explains (a) what it is (b) notes the relevence to dark matter (c) notes the "problems" (d) notes other theories. If and when the Galaxy rotation problem is "solved", then there won't be a need for this article, whereas Galaxy Rotation curve will remain. --Iantresman 22:07, 11 April 2006 (UTC)
replies: text:  Seems reasonable. A quick google fight shows that "Galaxy rotation curves" is far more popular than "Galaxy rotation problem". Nonsuch 22:15, 11 April 2006 (UTC)
thread_title:  Actual Improvements