http://deoxy.org/img/sombrerogalaxy.jpg|right22 ,, ,, ,, ,, ,, ~~~Imported from [Wikipedia:Dark_matter Wikipedia] on 2009-03-13~~~ '''The dark Videx:matter component has much more Videx:mass than the "visible" component of the Videx:universe.''' At present, the density of ordinary Videx:baryons and Videx:radiation in the universe is estimated to be equivalent to about one hydrogen Videx:atom per cubic meter of Videx:space. '''Only about 4% of the total Videx:energy density in the universe (as inferred from gravitational effects) can be seen directly.''' About 22% is thought to be composed of dark matter. The remaining 74% is thought to consist of [Media:Physics/Dark_Energy dark energy], an even Videx:stranger component, distributed diffusely in space. Some hard-to-detect baryonic matter is believed to make a contribution to dark matter but would constitute only a small portion. Determining the nature of this missing mass is one of the most important problems in modern Videx:cosmology and Videx:particle physics. '''It has been noted that the names "dark matter" and "dark energy" serve mainly as expressions of Videx:human ignorance, much like the marking of early Videx:maps with "terra incognita."''' #MAGIC Videx q="dark matter" #MAGIC SubpageIndex id=Physics/