Talk:Dark matter

I don't think the article is "too technical"

My issue is with the "housekeeping flag": that the article is "too technical" for the general audience. As an undergrad physics major this was exactly the sort of content I was looking for. A bit over my head (okay a good bit) but not too much for me to get a grasp of it, especially if I read it carefully, followed the references and did additional reading. To make the article or subject accessible to the general reader, without removing technical content, would require a book of several hundred pages. My understanding is that is not the purpose of Wikipedia (maybe WikiBooks). I don't think there is a way to do that? You cannot reduce some concepts at the edge of our understanding to something the general reader can easily grasp, without simplifying by removing information and technical content.

Perhaps what you need is a new general article that glosses over almost all of the detail, with the technical information in this article as a sub-article or series of sub-articles (but then you are starting to write a book). So basic question is where to draw the line?

- Mark 69.120.77.51 (talk) 08:36, 6 August 2012 (UTC)

The Article should at least explain, early on in the introduction and in broad, non-too-technical terms, why Dark matter is not thought to just be rogue planets, interstellar asteroids etc. (which also mostly escape detection.)--Cancun771 (talk) 13:28, 15 August 2012 (UTC)

Dark matter is very different from current theory, and vast majority may be baryonic.

"... instead of the relationship between observable light and stellar mass being universal, it varies between different types of galaxies — with some older galaxies having three times the mass suggested by the light they give off..."

"'The question of how you should turn light from a galaxy into a prediction of its mass has been hotly debated but up until now nobody has been able to kill off the idea that there's a simple and universal way to convert observed light into mass,' said Dr Cappellari. 'We now think we've done that by eliminating the 'fuzziness' in models caused by dark matter. It's exciting because it reveals how much more there is to discover about how galaxies, and the early Universe itself, evolved."

"The team's analysis means that all current models, which assumed for decades that the light we observe from a galaxy can be used to infer its stellar mass, will have to be revised. It also suggests that researchers have a new riddle to ponder: exactly how galaxies forming so early in the life of the Universe got to be massive so fast."

http://www.ox.ac.uk/media/news_releases_for_journalists/120425.html http://www.sciencedaily.com/releases/2012/05/120501211411.htm

Quoted from the same article, one is the university source, the other is a notable science website. There are dozens more available through a quick search.

Basically, they've proven that there is absolutely no predictable relationship between luminosity and mass, and they contend "dark matter" is most likely just "matter" that we can't see from Earth. — Preceding unsigned comment added by 71.60.33.136 (talk) 12:07, 19 September 2012 (UTC)

You say "they've proven that there is absolutely no predictable relationship between luminosity and mass". I don't see where that comes from - the study seems to conclude that the relationship is more complex than was previously assumed, not that there is no relationship at all. I also can't see anything in these references that supports your assertion that the study concludes that dark matter is mostly baryonic. Gandalf61 (talk) 12:52, 19 September 2012 (UTC)

I'll second Gandalf61's comment. They've adjusted the old model for estimating galaxy mass - a straight luminosity-to-mass ratio - and made a more complex model where different classes of galaxy have different luminosity-to-mass ratio. That has nothing to do with dark matter - and the vast majority of mass in all of these galaxies is still dark matter (dark matter is about 90% of galactic mass, and the updated estimates change by at most a factor of 3).

The noteworthy elements from this work were a) an improved understanding of how luminosity relates to galaxy type (obvious in hindsight; galaxies with more star formation for a given mass will have more bright but short-lived stars), and b) improved techniques for measuring the mass and mass distribution within galaxies (by measuring the velocity distributions of stars at different locations within the galaxies, if I understand correctly).

Per Gandalf61, these releases say nothing at all about the nature of dark matter and very little about its distribution, so it's puzzling that you'd cite them as support for your position. --Christopher Thomas (talk) 20:36, 19 September 2012 (UTC)

acceptance

I think it's fair to say that the theory is generally accepted, but this article lays it out like dark matter is in the same kind of "generally accepted" as relativity and evolution.

I am reading articles every now and then about some observations failing to go hand in hand with predictions in regards to dark matter. But this article reads as if dark matter theory is a fait accompli, we are just awaiting confirmation on the particle. — Preceding unsigned comment added by 217.76.196.150 (talk) 06:41, 25 October 2012 (UTC)

What is mass-energy?

"Dark matter is estimated to constitute 84% of the matter in the universe and 23% of the mass-energy."

I checked the source which this phrase links to and there is nothing about the differentiation between matter and mass-energy. Dark matter is said to constitute 23% of matter. So I think this phrase is inaccurate and needs to be fixed or else one should choose a different scientific source for it.Louigi Verona (talk) 12:17, 17 December 2012 (UTC)