Changes

== The current problem ==

== The current problem ==

[[Image:Sky wmap.jpg|100px|left]]The current problem involving a mass deficit in astronomical observations has been known since the 1930's, when astronomers first found serious differences between the masses they inferred by examining orbital speeds and the masses they inferred by measuring stellar, galactic, and other visual magnitudes. The classic gravitational equation, derived from the theory of [[gravity]] of Sir [[Isaac Newton]], gives the total dynamical mass in any system that is inside the orbit of any given body (for example, a particular star in its galaxy):

[[Image:Sky wmap.jpg|100px|left]]The current problem involving a mass deficit in astronomical observations has been known since the 1930s, when astronomers first found serious differences between the masses they inferred by examining orbital speeds and the masses they inferred by measuring stellar, galactic, and other visual magnitudes. The classic gravitational equation, derived from the theory of [[gravity]] of Sir [[Isaac Newton]], gives the total dynamical mass in any system that is inside the orbit of any given body (for example, a particular star in its galaxy):

<math>M = \frac{v^{2}R}{G}</math>

<math>M = \frac{v^{2}R}{G}</math>

The ''luminous mass'' of any galaxy or other object is the mass that corresponds to the measured light from the object.

The ''luminous mass'' of any galaxy or other object is the mass that corresponds to the measured light from the object.

[[Jan Oort]] first determined that the total mass of our [[galaxy]] was insufficient by a factor of at least two to account for the galaxy's rotational speed.<ref name=Thompson>Thompson, Tim. "[http://www.electric-cosmos.org/darkmatter.htm Missing 'Dark' Matter]." ''[http://www.electric-cosmos.org/indexOLD.htm The Electric Cosmos], n.d. Accessed July 28, 2008.</ref> The swiss astronomer Fritz Zwicky is also credited with the discovery of the discrepancy between dynamical and luminous mass, in 1933. Zwicky examined the Coma supercluster, and found that its dynamical mass exceeded the luminous mass by a factor of ten.<ref name=Silk>Silk, Joe. "[http://astro.berkeley.edu/~mwhite/darkmatter/essay.html Dark Matter]." Department of Astronomy, University of California-Berkeley, ca. 1995. Accessed July 28, 2008.</ref><ref name=Soter>Soter S and deGrasse-Tyson N, eds. "[Fritz Zwicky's Extraordinary Vision]." Excerpt from ''Cosmic Horizons: Astronomy at the Cutting Edge'', New Press, 2000. ISBN 978-1565846029 Accessed July 28, 2008.</ref><ref name=Miller>Miller CM. "[http://www.eclipse.net/~cmmiller/DM/ Cosmic Hide and Seek: the Search for the Missing Mass]." 1995. Accessed July 28, 2008.</ref>

[[Jan Oort]] first determined that the total mass of our [[galaxy]] was insufficient by a factor of at least two to account for the galaxy's rotational speed.<ref name=Thompson>Thompson, Tim. "[http://www.electric-cosmos.org/darkmatter.htm Missing 'Dark' Matter]." ''[http://www.electric-cosmos.org/indexOLD.htm The Electric Cosmos], n.d. Accessed July 28, 2008.</ref> The Swiss astronomer Fritz Zwicky is also credited with the discovery of the discrepancy between dynamical and luminous mass, in 1933. Zwicky examined the Coma supercluster, and found that its dynamical mass exceeded the luminous mass by a factor of ten.<ref name=Silk>Silk, Joe. "[http://astro.berkeley.edu/~mwhite/darkmatter/essay.html Dark Matter]." Department of Astronomy, University of California-Berkeley, ca. 1995. Accessed July 28, 2008.</ref><ref name=Soter>Soter S and deGrasse-Tyson N, eds. "[Fritz Zwicky's Extraordinary Vision]." Excerpt from ''Cosmic Horizons: Astronomy at the Cutting Edge'', New Press, 2000. ISBN 978-1565846029 Accessed July 28, 2008.</ref><ref name=Miller>Miller CM. "[http://www.eclipse.net/~cmmiller/DM/ Cosmic Hide and Seek: the Search for the Missing Mass]." 1995. Accessed July 28, 2008.</ref>

[[Image:HubbleDarkMatterRing.jpg|thumb|300px|left|Image of galactic cluster with ring of alleged dark matter around it]]Since that time, astronomers have assumed that some form of matter, which gives off no measurable radiation, is nevertheless present in various galaxies and galactic clusters that clearly spin faster than their measured luminous masses would predict.<ref name=Harvard>Authors unknown. "[http://xrtpub.harvard.edu/xray_astro/dark_matter.html Dark Matter Mystery]." ''Field Guide to X-ray Astronomy'', Chandra X-ray Center, Harvard University, Cambridge, MA, August 29, 2006. Accessed July 28, 2008.</ref> They acknowledge, however, that the notion of a new, non-luminous form of matter is difficult to accept. Yet many astronomers insist that they have observational evidence for which dark matter remains the only plausible explanation. One such communication comes from the Chandra X-ray Center, whose astronomers stated in 2006 that they had observed two galactic clusters for hundreds of hours, and that each one clearly showed a rotational speed consistent with far more mass than was visible.<ref name=Chandra>Hupp E, Roy S., and Watzke M. "[http://www.nasa.gov/home/hqnews/2006/aug/HQ_06297_CHANDRA_Dark_Matter.html NASA Finds Direct Proof of Dark Matter]." [[NASA]], press release 06-297, August 21, 2006. Accessed July 28, 2008.</ref>

[[Image:HubbleDarkMatterRing.jpg|thumb|300px|left|Image of galactic cluster with ring of alleged dark matter around it]]Since that time, astronomers have assumed that some form of matter, which gives off no measurable radiation, is nevertheless present in various galaxies and galactic clusters that clearly spin faster than their measured luminous masses would predict.<ref name=Harvard>Authors unknown. "[http://xrtpub.harvard.edu/xray_astro/dark_matter.html Dark Matter Mystery]." ''Field Guide to X-ray Astronomy'', Chandra X-ray Center, Harvard University, Cambridge, MA, August 29, 2006. Accessed July 28, 2008.</ref> They acknowledge, however, that the notion of a new, non-luminous form of matter is difficult to accept. Yet many astronomers insist that they have observational evidence for which dark matter remains the only plausible explanation. One such communication comes from the Chandra X-ray Center, whose astronomers stated in 2006 that they had observed two galactic clusters for hundreds of hours, and that each one clearly showed a rotational speed consistent with far more mass than was visible.<ref name=Chandra>Hupp E, Roy S., and Watzke M. "[http://www.nasa.gov/home/hqnews/2006/aug/HQ_06297_CHANDRA_Dark_Matter.html NASA Finds Direct Proof of Dark Matter]." [[NASA]], press release 06-297, August 21, 2006. Accessed July 28, 2008.</ref>