noun[mass noun] Astronomy
(In some cosmological theories) non-luminous material which is postulated to exist in space and which could take either of two forms: weakly interacting particles ( cold dark matter) or high-energy randomly moving particles created soon after the Big Bang ( hot dark matter).
- According to cosmological theory, soon after the Big Bang, cold dark matter formed the universe's first large-scale structures, which then collapsed under their own weight to form vast halos.
- Identification of the different energetic particles, including dark matter, is done by pulse shape discrimination.
- Most astronomers believe that dark matter exists - even though it has never been seen, and no one knows what it might be.
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