Talk:Dark matter

Dark matter has been observed: See follows these links for the news story.

http://home.slac.stanford.edu/pressreleases/2006/20060821.htm

http://www.sciencenews.org/articles/20060826/fob1.asp

Hello David E. Volk,

Not convinced. It has not been directly observed--no surprises there. They presume its existence because it does clear up some problems and they insist that they have the gravitational lensing effect that also supports their theory.

The dark matter is supposed to interact gravitationally but why are the two types separating as they pass through the mass of another galaxy? Why doesn't the dark matter interact? It is supposed to be quite dense in comparison with the luminous matter.

See NASA Finds Direct Proof of Dark Matter. "The hot gas in this collision was slowed by a drag force, similar to air resistance. In contrast, the dark matter was not slowed by the impact, because it does not interact directly with itself or the gas except through gravity. This produced the separation of the dark and normal matter seen in the data. If hot gas was the most massive component in the clusters, as proposed by alternative gravity theories, such a separation would not have been seen. Instead, dark matter is required."

So it did not interact with the baryonic matter but it has mass, why do they say that? They are missing something crucial. --Thomas Simmons 06:53, 12 January 2008 (CST)

Hello Thomas, Neither one of us needs to be convinced (neutrality issue) to report it in the encyclopedia. The news stories I suggested point to some of the latest data, and observation of dark matter. Many physicists I know believe in dark matter, but are more dubious of dark energy. Clearly there is still something we do not know, but we should report the most up to date thoughts on the subject. David E. Volk 08:25, 12 January 2008 (CST)

Hi David,

Yea, I get the gist of the message now. The fact is, it has not been observed, that much is obvious. We have a massive collection of mass that supposedly holds entire galaxies together such that they are like flies caught in amber. Then the whole thing gets ripped apart as it passes through another galaxy? The dark matter in one rips off the baryonic matter in the oncoming galaxy and the oncoming galaxy's dark matter does the same to its counterpart? There are people out here calling this proof--which it ain't. Ned Wright likes to tell people that science never proves anything. Einstein said something along those lines as well. On the other hand this series of events involving the Chandra X-ray demands a mention. I will get on it, today hopefully. I'd like to get another take on it though, someone who has played it down and put a little perspective on it if I can. Then put the two points in there together. They are excited though. The results are pretty extraordinary. I'd be jumping up and down if it were me.--Thomas Simmons 17:13, 12 January 2008 (CST)

Two recent news sources on the existence of Dark Matter

• First: A yahoo news summary here.
• Second: a link from ESA here. Here's the original ESA story link here.

The observations make a proposal about the existence of an antimatter cloud that could potentially supercede the existence for theoretical explanations of dark matter.

I haven't read the entire thing (as it's a little bit out of my scope) but I thought I'd at least bring it to someone's attention to see if it's relevant. --Robert W King 12:43, 16 January 2008 (CST)

More news on "Dark Energy".

• http://www.eurekalert.org/pub_releases/2008-01/e-nlo012808.php
• http://blog.wired.com/wiredscience/2008/01/is-dark-energy.html
• And the current issue of Nature has the paper published.

--Robert W King 14:11, 30 January 2008 (CST)

Capitolisation etc. and Strunk & White

Hi,

Ro changed a 'It' to an 'it' after a colon. Strunk and White ("Elements of style" basically says that a capitol will follow a colon if the expanding sentence is itself an independent clause or complete sentence.

Here "Dark matter (DM) is aptly labeled: it is theoretical matter that can not be directly studied and observed by current technologies because it neither emits nor absorbs light or heat and appears to interact with other matter only gravitationally."

The clause preceding the sentence is a complete sentence and the one following is also a complete sentence, ergo, it should begin with a capitols letter. APA Publication Manual advises us to always capitalize an independent clause following a colon. Chicago Manual of style is flexible but consistency is paramount if at all possible.--Thomas Simmons 19:10, 2 April 2008 (CDT)

I normally use the style Ro is using. I don't capitalize after the ":" unless that that latter part is intended to be a separate, free-standing sentence: the fact that it is grammatically a complete sentence is not what is paramount. J. Noel Chiappa 21:16, 2 April 2008 (CDT)