“dark matter”的概念、定义、翻译、参考文献-科学参考

dark matter

Physics

See missing mass.

http://cdms.berkeley.edu/ The home page of the Cryogenic Dark Matter Search Experiment

Astronomy

Material whose presence can be inferred from its effects on the motions of stars and galaxies, but which cannot be seen directly because it emits little or no radiation; also known as missing mass. Evidence for dark matter in spiral galaxies is provided by their rotation curves. The existence of dark matter in rich clusters of galaxies can be deduced from the motions of the member galaxies (see Virial Theorem), and also by their gravitational lensing of background galaxies. Additional evidence for the existence of dark matter comes from observations of distant supernovae and of the cosmic microwave background. According to precise measurements by the Planck satellite, dark matter comprises 26.8% of the Universe. Models of how elements such as helium were formed during the first few minutes after the Big Bang imply that only about 20% of the dark matter can consist of so-called baryonic matter, the protons and neutrons that make up stars, galaxies, and our everyday world. The composition of the remaining 80% is unknown, although various possibilities, including hypothetical particles such as axions and photinos, have been suggested. See also Cold Dark Matter; Hot Dark Matter; Macho; Non-Baryonic Matter; Wimp

Space Exploration

The theoretical matter that, according to certain modern theories of cosmology, is thought to make up over 90% of the mass of the universe but so far remains undetected. Measurements of the mass of galaxies using modern theories showed large discrepancies in the expected values, which led scientists to the conclusion that a theoretical substance that cannot be seen had to account for a significant proportion of the universe. Dark matter, if shown to exist, would account for many currently unexplained gravitational effects in the movement of galaxies.
Theories of the composition of dark matter include unknown atomic particles (cold dark matter) or fast-moving neutrinos (hot dark matter) or a combination of both. Other theories postulate that massively dense objects such as black holes form the majority of the ‘missing’ mass in the universe.
In 1993, astronomers identified part of the dark matter in the form of stray planets and brown dwarfs, and, possibly, stars that have failed to ignite. These objects are known as massive astrophysical compact halo objects (MACHOs) and may make up approximately half of the dark matter in the Milky Way's halo.
In July 2003, the first detailed map of the dark matter distribution in a galaxy cluster was reported. An international team of astronomers studied galaxy cluster CL0024+1654, one of the largest structures in the known universe, using the Hubble Space Telescope. The cluster is mainly composed of dark matter that is only detectable by analysing the gravitational interaction between objects. The researchers targeted 39 regions of the cluster and were able to show gravitational warping, known as weak gravitational lensing, of images of galaxies beyond the cluster, caused by the presence of dark matter. The astronomers used their accumulated data to create the first dark matter map of a galaxy cluster.

单词	dark matter
释义	dark matter Physics See missing mass. http://cdms.berkeley.edu/ The home page of the Cryogenic Dark Matter Search Experiment Astronomy Material whose presence can be inferred from its effects on the motions of stars and galaxies, but which cannot be seen directly because it emits little or no radiation; also known as missing mass. Evidence for dark matter in spiral galaxies is provided by their rotation curves. The existence of dark matter in rich clusters of galaxies can be deduced from the motions of the member galaxies (see Virial Theorem), and also by their gravitational lensing of background galaxies. Additional evidence for the existence of dark matter comes from observations of distant supernovae and of the cosmic microwave background. According to precise measurements by the Planck satellite, dark matter comprises 26.8% of the Universe. Models of how elements such as helium were formed during the first few minutes after the Big Bang imply that only about 20% of the dark matter can consist of so-called baryonic matter, the protons and neutrons that make up stars, galaxies, and our everyday world. The composition of the remaining 80% is unknown, although various possibilities, including hypothetical particles such as axions and photinos, have been suggested. See also Cold Dark Matter; Hot Dark Matter; Macho; Non-Baryonic Matter; Wimp Space Exploration The theoretical matter that, according to certain modern theories of cosmology, is thought to make up over 90% of the mass of the universe but so far remains undetected. Measurements of the mass of galaxies using modern theories showed large discrepancies in the expected values, which led scientists to the conclusion that a theoretical substance that cannot be seen had to account for a significant proportion of the universe. Dark matter, if shown to exist, would account for many currently unexplained gravitational effects in the movement of galaxies. Theories of the composition of dark matter include unknown atomic particles (cold dark matter) or fast-moving neutrinos (hot dark matter) or a combination of both. Other theories postulate that massively dense objects such as black holes form the majority of the ‘missing’ mass in the universe. In 1993, astronomers identified part of the dark matter in the form of stray planets and brown dwarfs, and, possibly, stars that have failed to ignite. These objects are known as massive astrophysical compact halo objects (MACHOs) and may make up approximately half of the dark matter in the Milky Way's halo. In July 2003, the first detailed map of the dark matter distribution in a galaxy cluster was reported. An international team of astronomers studied galaxy cluster CL0024+1654, one of the largest structures in the known universe, using the Hubble Space Telescope. The cluster is mainly composed of dark matter that is only detectable by analysing the gravitational interaction between objects. The researchers targeted 39 regions of the cluster and were able to show gravitational warping, known as weak gravitational lensing, of images of galaxies beyond the cluster, caused by the presence of dark matter. The astronomers used their accumulated data to create the first dark matter map of a galaxy cluster.
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