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	Dark matter - Wikipedia, the free encyclopedia
		The dark matter hypothesis aims to explain several anomalous astronomical observations, such as anomalies in the rotational speed of galaxies (the galaxy rotation problem).
		Low surface brightness dwarf galaxies are important sources of information for studying dark matter, as they have an uncommonly low ratio of visible matter to dark matter, and have few bright stars at the center which impair observations of the rotation curve of outlying stars.
		Large computer simulations of billions of dark matter particles have been used to confirm that the cold dark matter model of structure formation is consistent with the structures observed in the universe through galaxy surveys, such as the Sloan Digital Sky Survey and 2dF Galaxy Redshift Survey, as well as observations of the Lyman-alpha forest.
	en.wikipedia.org /wiki/Dark_matter (2396 words)

	Cold dark matter (Site not responding. Last check: 2007-11-07)
		Cold dark matter is a refinement of the big bang theory that contains the additional assumption most of the Universe consists of material which cannot be by its electromagnetic radiation and hence is dark while at the same time the particles making up this matter are slowly and hence are cold.
		As of 2003 cosmologists favor the cold dark matter theory a description of how the universe went a smooth initial state at early times shown by the cosmic microwave background radiation) to the lumpy distribution of galaxies and their clusters we see today — the large-scale structure of the universe.
		The predictions of hot dark matter disagree with observations of large-scale structure whereas cold dark matter paradigm is in general with the observations.
	www.freeglossary.com /Cold_dark_matter (498 words)

	Cold dark matter (Site not responding. Last check: 2007-11-07)
		Cold dark matter is a refinement of the big bang theory thatcontains the additional assumption that most of the Universe consists of materialwhich cannot be observed by its electromagneticradiation and hence is dark while at the same time the particles making up this matter are slowly moving and hence are cold.
		As of 2003, most cosmologists favor the cold dark matter theory as a description of how the universe went from a smoothinitial state at early times (as shown by the cosmic microwave background radiation), to the lumpy distribution of galaxies and their clusters wesee today — the large-scalestructure of the universe.
		The predictions of hot dark matter strongly disagree with observations oflarge-scale structure, whereas the cold dark matter paradigm is in general agreement with the observations.
	www.therfcc.org /cold-dark-matter-32300.html (413 words)

	cold dark matter (Site not responding. Last check: 2007-11-07)
		Two important discrepancies between the predictions of the cold dark matter paradigm and observations of galaxies and their clustering in space have arisen, however, creating a crisis for the cold dark matter picture.
		The missing satellites problem is that cold dark matter predicts large numbers of small dwarf galaxies about one thousandth the mass of the milky way.
		The theory makes no predictions about exactly what the cold dark matter particles are, and the one large weakness in cold dark matter is that it is unclear what the dark matter consists of.
	www.yourencyclopedia.net /Cold_dark_matter.html (476 words)

	Cold Dark Matter and Intelligent Design (Site not responding. Last check: 2007-11-07)
		The intelligent design suggests that cold dark matter could be made up of closed-string particles, which constitute the higher dimensional spirit world.
		The cold dark matter affects stellar motion in a galaxy.
		The majority of dark matter, however, is the cold dark matter which might be the spirit matter.
	www.web-books.com /GoodPost/Articles/DarkMatter.htm (593 words)

	Chandra Press Room :: Hot News for Cold Dark Matter :: June 11, 2003
		This discovery agrees with the predictions of cold dark matter models, and is contrary to other dark matter models that predict a leveling off of the amount of dark matter in the center of the cluster.
		Cold dark matter gets its name from the assumption that the dark matter particles were moving slowly when galaxies and galaxy clusters began to form.
		The hot gas in a cluster is held in the cluster primarily by the gravity of the dark matter, so the distribution of the hot gas is determined by that of the dark matter.
	chandra.harvard.edu /press/03_releases/press_061103.html (692 words)

	dark matter on Encyclopedia.com (Site not responding. Last check: 2007-11-07)
		Dark matter may consist of dust, planets, intergalactic gas formed of ordinary matter, or of MACHOs [ M assive A strophysical C ompact H alo O bjects], nonluminous bodies such as burned-out stars, fl holes, and brown dwarfs ; these are the so-called hot dark matter and would be dispersed uniformly throughout the universe.
		This suggests that the slower, cold dark matter might form the smaller clumps associated with the galaxy while the faster, hot dark matter might form the larger clumps associated with the galactic cluster.
		Unlike cold dark matter, which has mass but virtually no velocity or temperature, or hot dark matter, which has mass and is highly energetic, warm dark matter has mass and a low temperature corresponding to an extremely low velocity.
	www.encyclopedia.com /html/d1/darkmatt.asp (653 words)

	Cold dark matter - Encyclopedia.WorldSearch (Site not responding. Last check: 2007-11-07)
		As of 2004, most cosmologists favor the cold dark matter theory as a description of how the universe went from a smooth initial state at early times (as shown by the cosmic microwave background radiation), to the lumpy distribution of galaxies and their clusters we see today — the large-scale structure of the universe.
		Two important discrepancies between the predictions of the cold dark matter paradigm and observations of galaxies and their clustering in space have arisen, however, creating a potential crisis for the cold dark matter picture.
		The CDM theory makes no predictions about exactly what the cold dark matter particles are, and one large weakness in the cold dark matter theory is that it is unclear what the dark matter consists of.
	encyclopedia.worldsearch.com /cold_dark_matter.htm (452 words)

	A Cosmic Crisis?: Science News Online, Oct. 13, 2001 (Site not responding. Last check: 2007-11-07)
		Therefore, dark matter would have provided the gravitational scaffolding necessary for the first galaxies to coalesce when the universe was less than a billion years old.
		Dark matter halo of a galaxy, according to the cold-dark-matter model (left) and another dark matter halo, according to the self-interacting model (right).
		Concentrations of matter are much less dense at the cores of galaxy clusters, according to a model based on self-interacting dark matter (left) than one based on cold dark matter (right).
	www.sciencenews.org /articles/20011013/bob13.asp (2661 words)

	Dark Matter
		The nature of this dark matter, and the associated "missing mass problem", is one of the fundamental cosmological issues of modern astrophysics.
		Hot dark matter is composed of particles that have zero or near-zero mass (the neutrinos are a prime example).
		The difference between cold dark matter and hot dark matter is significant in the formation of structure, because the high velocities of hot dark matter cause it to wipe out structure on small scales.
	csep10.phys.utk.edu /astr162/lect/cosmology/darkmatter.html (890 words)

	Galaxy Building Block And Cold Dark Matter Theories (Site not responding. Last check: 2007-11-07)
		The dark matter theory tries to explain why 90 percent of the matter in the universe is invisible to telescopes.
		Astronomers theorize the existence of dark matter from the gravitational effects it exerts on the galaxies it surrounds.
		Cold dark matter could be as simple as rocks, or as exotic as cosmic particles such as neutrinos, or some other unknown particle.
	www.oarval.org /galtheory.htm (572 words)

	dark matter (Site not responding. Last check: 2007-11-07)
		Dark nebulae are visible because they block out the light from background stars and 1600 emission nebulae.
		Dark matter is thought to exist because of its gravitational effects in the universe; specifically within galaxies and clusters of galaxies.
		Dark matter may come in two principle types: the first is baryonic matter.
	www.herts.ac.uk /astro_ub/aD_ub.html (1330 words)

	Access: Shedding Light on Dark Matter
		Cold dark matter (CDM) is highly interactive gravitationally with other matter and has no relativistic speed.
		However, if most dark matter were neutrinos, matter in the universe would be quite uniformly distributed, explains Bode, and researchers know that it is not.
		Because particle velocities are lower, dark matter clumps more with its surroundings than do neutrinos but not as much as CDM particles.
	www.ncsa.uiuc.edu /News/Access/Stories/wdm/shedding2.html (281 words)

	SPACE.com -- X-ray Observations Confirm Dark Matter is Mostly Cold
		Cold dark matter is presumed to exist based on a theory holding that that dark matter particles in the early universe were moving slowly when galaxies and galaxy clusters began to form.
		This discovery agrees with predictions of cold dark matter models and is contrary to other models that predict a leveling off of the amount of dark matter in the center of the cluster.
		The observations showed the distribution of X-rays from the hot gas, which is held in the cluster primarily by the gravity of the dark matter, Lewis and colleagues explained in a statement Wednesday, so the distribution of the hot gas reveals the distribution of dark matter.
	www.space.com /scienceastronomy/dark_matter_030616.html (644 words)

	Cold Dark Matter (Site not responding. Last check: 2007-11-07)
		The dark matter theory holds that gravity amplified tiny fluctuations in the distribution of matter in the early universe to produce vast fields of galaxies.
		Another explanation for dark matter and the formation of large aggregations of galaxies is the revival of equations Einstein worked out in his theory of general relativity more than seventy years ago.
		The physical properties of the human mind compared to mind at the galactic level, as dark matter, are still unknown and not present for physical observation.
	www.soultrek.com /cdm.html (1647 words)

	Cold Dark Matter (Site not responding. Last check: 2007-11-07)
		Cold dark matter (CDM) refers to an exotic particle whose energy is low (hence cold) at the time it decouples from the ordinary (baryonic) matter.
		In a cold dark matter cosmological model of structure formation, the CDM is primarily responsible for structure formation.
		CDM cosmologies produce a Bottom-Up hierarchy of structure formation.
	www.astro.virginia.edu /~jh8h/glossary/colddark.htm (52 words)

	A Galactic Condensate
		Many predictions of the conventional cold dark matter theory agree with observations, but one of the theory's failings is its inability to accurately describe the structure of dwarf galaxies.
		With a one-dimensional computer simulation of fuzzy dark matter the team showed that the core of a typical dwarf galaxy would be less concentrated, as observations suggest they are, and that the outer edges of the galaxy would be unaffected by the new, lower mass particles.
		The fuzzy cold dark matter scenario predicts a specific relationship between the size of a dwarf galaxy's core and its density, but observations and interpretations of them are not yet precise enough for a true test.
	focus.aps.org /story/v6/st5 (714 words)

	Matterrific: Hot vs. Cold? (Site not responding. Last check: 2007-11-07)
		The temperature of dark matter is a measure of how quickly the structure particles (the particles that compose, or make up the dark matter) are moving.
		Hot refers to dark matter moving at or near the speed of light, while cold refers to dark matter particles moving much slower than that.
		If all dark matter in the early universe were cold, then galaxies would form first and later assemble into clusters.
	library.thinkquest.org /C0115023/hotcold.html (294 words)

	Accuracy of Astronomer's Predictions Challenges Accepted View of universe
		This contradicts the widely held paradigm that 90 percent of the universe is made up of unseen matter, termed cold dark matter.
		Cold dark matter is widely thought to consist of a new kind of particle rather than the protons, neutrons, and other known particles that constitute ordinary matter.
		In March, when the Boomerang results were announced, many cosmologists publicly rejoiced that the position of the first peak in the power spectrum of the microwave background indicated the universe was "flat," a key prediction of inflation, one of the central tenets of modern cosmology.
	www.spacedaily.com /news/darkmatter-00e.html (824 words)

	SPACE.com -- More Evidence that Dark Matter Rules the Universe
		"The shape and orientation of the hot gas cloud require it to be confined by an egg-shaped dark matter halo," said David Buote of the University of California, Irvine, and lead author of a report on this research in the Sept. 20 issue of The Astrophysical Journal.
		Buote and his colleagues also found that the Chandra data fit predictions of the cold dark matter theories, according to which dark matter consists of slowly moving particles, which interact with each other and "normal" matter only through gravity.
		Other forms of theorized dark matter, such as self-interacting dark matter and cold molecular dark matter, are not consistent with the observation in that they require a dark matter halo that is too round or too flat, respectively.
	www.space.com /scienceastronomy/dark_matter_021023.html (582 words)

	WMAP Cosmology 101: Matter in the Universe
		New forms of matter: particle physicists, scientists who work to understand the fundamental forces of nature and the composition of matter, have speculated that there are new forces and new types of particles.
		It is also able to determine some of the properties of the non-baryonic matter: the interactions of the non-baryonic matter with itself, its mass and its interactions with ordinary matter all affect the details of the cosmic microwave background fluctuation spectrum.
		WMAP determined that the universe is flat, from which it follows that the mean energy density in the universe is equal to the critical density (within a 2% margin of error).
	map.gsfc.nasa.gov /m_uni/uni_101matter.html (1033 words)

	CERN Courier - Hot gas reveals cold dark ma - IOP Publishing - article
		The density of dark matter appears to increase towards the centre of the cluster in agreement with cold-dark-matter predictions.
		Huge amounts of additional, invisible matter are needed for gravity to balance the pressure of the gas, which is at a temperature of more than 10 million degrees.
		It seems the distribution of hot gas is mainly determined by that of the dark matter, rather than by the distribution of visible matter in the galaxies.
	www.cerncourier.com /main/article/43/6/12 (539 words)

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