Science a GoGo's Home Page Forums General Discussion Physics Forum More Problems with Dark Matter

Is there really such a thing as Dark Matter?

Dark Matter is invisible, and has never been observed. Yet it is believed to exist, because the 'Gavitational Maths' that we use to account for the reason that rotating Galaxies are held together, predict that about 25% of the Universe is composed of dark matter, as opposed to only 5% which is the more common (to us) visible matter.

Questions about Dark Matter's very existence will now have to be re-examined, since NASA's Chandra X-ray observatory and optical telescopes revealed a core, of Dark matter, but the bright optical Galaxies seem to have flown away from the core.

The whole theoretical basis of Dark Matters existence, is that although invisible...It still possesses gravitational attraction.

However, when the Chandra data of the galaxy cluster system known as Abell 520 was mapped along with the optical data from the Canada-France-Hawaii Telescope and Subaru Telescope atop Mauna Kea, HI, a puzzling picture emerged. A dark matter core was found, which also contained hot gas but no bright galaxies.

http://www.nasa.gov/mission_pages/chandra/news/07-090.html

Scientists all over the world are getting concerned over conflicting questions raised by dark matter.

http://www.shanghaidaily.com/sp/article/2007/200708/20070818/article_327696.htm

I have included a previous discussion we have had in this forum. An answer which seems too simplistic to be true?

http://www.scienceagogo.com/forum/ubbthr...age=2#Post21054

Yet either way, the truth will change Physics as we know it today.

I still always mix up dark matter, dark energy, and whatever else there is (or is not?). I was reading a book (Alpha and Omega) and throughout the book he talks about such, but are they the same? Or different?

Could someone clarify?

I'll have to come back. Short of time. But this is interesting. Haven't had time to get click the links yet.

Tim, very briefly. Dark Matter is proposed to account for observations regarding gravtational lensing and galaxy rotation, and is said to comprise something like 90% of all the matter in the universe.

Dark energy is proposed as a force that accounts for accelerating expansion of space.

Oops. Error, Tim. The figures for mass/energy in the universe are currently estimated to be 4% 'normal' matter, 23% dark matter (as mentioned by Mike), and the other 73% being accounted for by dark energy. That's saying that if all the normal matter, together with the much greater mass of dark matter, could be converted to energy, it would result in only 27% of all existing energy!

I found this site very useful. Check the side bar contents, especially the FAQ:
http://cdms.berkeley.edu/Education/DMpages/essays/ingredients.shtml