http://netvouz.com/tag/dark_matter?feed=rss Bookmarks tagged with "dark_matter" on Netvouz http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/ Eventually theorists came up with three sorts of explanations. Maybe it was a result of a long-discarded version of Einstein's theory of gravity, one that contained what was called a "cosmological constant." Maybe there was some strange kind of energy-fluid that filled space. Maybe there is something wrong with Einstein's theory of gravity and a new theory could include some kind of field that creates this cosmic acceleration. Theorists still don't know what the correct explanation is, but they have given the solution a name. It is called dark energy. pdboyer Sat, 06 Nov 2010 19:44:07 GMT http://chandra.harvard.edu/photo/2004/darkenergy/ A galaxy cluster is comprised on hundreds of galaxies embedded in a cloud of extremely hot gas and dark matter. Dark matter, an invisible and unknown type of material, is postulated to hold clusters together. X-ray observations have the unique ability to determine the ratio of the mass of the hot gas and the mass of the dark matter in a cluster. The observed values of the gas fraction depend on the assumed distance to the cluster. pdboyer Sat, 06 Nov 2010 19:41:34 GMT http://www.sas.upenn.edu/home/news/troddenandabbate/trodden.html Research summary of old notions of the expanding universe and newer approach to explain how galaxies can to continue moving away from each other at ever-increasing velocities. Talks about Einstein's general theory of relativity -- movement being a curvature of space/time continuum (or something like this) pdboyer Sat, 06 Nov 2010 00:14:19 GMT