What is "dark matter"

n. (context astronomy English) Particles of matter that cannot be detected by their radiation but whose presence is inferred from gravitational effects.

n. (cosmology) a hypothetical form of matter that is believed to make up 90 percent of the matter in the universe; it is invisible (does not absorb or emit light) and does not collide with atomic particles but exerts gravitational force

Dark matter is an unidentified type of matter comprising approximately 27% of the mass and energy in the observable universe that is not accounted for by dark energy, baryonic matter (ordinary matter), and neutrinos. The name refers to the fact that it does not emit or interact with electromagnetic radiation, such as light, and is thus invisible to the entire electromagnetic spectrum. Although dark matter has not been directly observed, its existence and properties are inferred from its gravitational effects such as the motions of visible matter, gravitational lensing, its influence on the universe's large-scale structure, and its effects in the cosmic microwave background. Dark matter is transparent to electromagnetic radiation and/or is so dense and small that it fails to absorb or emit enough radiation to be detectable with current imaging technology.

Estimates of masses for galaxies and larger structures via dynamical and general relativistic means are much greater than those based on the mass of the visible "luminous" matter.

The standard model of cosmology indicates that the total mass–energy of the universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy. Thus, dark matter constitutes 84.5% of total mass, while dark energy plus dark matter constitute 95.1% of total mass–energy content. The great majority of ordinary matter in the universe is also unseen, since visible stars and gas inside galaxies and clusters account for less than 10% of the ordinary matter contribution to the mass-energy density of the universe.

The dark matter hypothesis plays a central role in current modeling of cosmic structure formation and galaxy formation and evolution and on explanations of the anisotropies observed in the cosmic microwave background (CMB). All these lines of evidence suggest that galaxies, clusters of galaxies, and the universe as a whole contain far more matter than that which is observable via electromagnetic signals.

The most widely accepted hypothesis on the form for dark matter is that it is composed of weakly interacting massive particles (WIMPs) that interact only through gravity and the weak force.

Although the existence of dark matter is generally accepted by most of the astronomical community, a minority of astronomers argue for various modifications of the standard laws of general relativity, such as MOND, TeVeS, and conformal gravity that attempt to account for the observations without invoking additional matter.

Many experiments to detect proposed dark matter particles through non-gravitational means are under way.

Dark matter is matter that is undetectable by its emitted radiation, but whose presence can be inferred from gravitational effects. It is subdivided into different types of dark matter:

• Cold dark matter
• Warm dark matter
• Hot dark matter
• Mixed dark matter

Dark Matter(s) or Darkmatter may also refer to:

Dark Matter is the title of a 1990 science fiction novel by Garfield Reeves-Stevens. It involves mystery, horror, and physics, and was first published by Doubleday in September 1990.

Dark Matter is the first feature film by opera director Chen Shi-zheng, starring Liu Ye, Aidan Quinn and Meryl Streep. It won the Alfred P. Sloan Prize at the 2007 Sundance Film Festival.

Liu Ye plays a young scientist whose rising star must confront the dark forces of politics, ego, and cultural insensitivity. The film is based on the University of Iowa shooting.

Dark Matter is a studio album by the British neo-progressive band IQ, released in 2004. It is the last with founding member Martin Orford as he had left the band and music industry by 2009.

Dark Matter is an anthology series of science fiction, fantasy, and horror stories and essays produced by people of African descent. The editor of the series is Sheree Thomas. The first book in the series, Dark Matter: A Century of Speculative Fiction from the African Diaspora (2000), won the 2001 World Fantasy Award for Best Anthology. The second book in the Dark Matter series, Dark Matter: Reading the Bones (2004), won the World Fantasy Award for Best Anthology in 2005. A forthcoming third book in the series is tentatively named Dark Matter: Africa Rising.

Dark Matter is a speculative fiction novel from Michelle Paver. Part horror, part ghost story, it was published in the UK on October 21, 2010.

Dark Matter is the second studio album by guitarist Brett Garsed, released independently on 29 June 2011. It was first made available as a digital download on iTunes and CD Baby, followed by a CD release on Garsed's official website.

Dark Matter is a 2007 novel by the German writer Juli Zeh. It was published as In Free Fall in the United States. It tells the story of a physics professor who is told he has to kill a man in order to get his kidnapped son back, and a detective, Schilf, who steps in to solve the case. As of December 2011, a German film adaptation directed by Claudia Lehmann was in post-production.

Dark Matter is a comic book series created by writers Joseph Mallozzi and Paul Mullie. The science fiction story follows six individuals who wake up in a spacecraft with no memory of their past. The concept was originally intended for a television series, but was published through Dark Horse Comics with art by Garry Brown. On October 15, 2014, Syfy announced they had picked up a 13-episode first season of a Dark Matter TV series, which premiered on June 12, 2015.

Dark Matter is a Canadian science fiction series created by Joseph Mallozzi and Paul Mullie, based on their comic book of the same name and developed by Prodigy Pictures in association with Space channel. An order for 13 episodes was placed for the first season of the series, which premiered on June 12, 2015. The series was renewed for a 13-episode second season in September 2015, which premiered on July 1, 2016.

Dark Matter is an indie metroidvania/ survival horror video game developed by Interwave Studios and published by Iceberg Interactive for the Windows, Linux and iOS in 2013.

Dark Matter is the fourth studio album from American metalcore band The Word Alive. It was released on March 18, 2016 through Fearless Records. The album's lead single, Trapped, was released on January 8.