dark matter

From German Dunkle Materie; from Dunkle (“dark”) +‎ Materie (“matter”). Coined by Swiss astronomer Fritz Zwicky in German in 1933, to account for the apparent mass needed to account for galaxy clusters, where the mass of luminous matter did not add up to enough of a gravitational effect, inferring nonluminous matter must exist to account for the missing mass. The term gained new popularity due to the missing mass found in galaxies to account for galaxy rotation curves discovered by Vera Rubin in research published in English in the 1970s.

dark matter (uncountable)

1. (astronomy, astrophysics) Particles of matter that cannot be detected by their radiation but whose presence is inferred from gravitational effects.
   • 2001, Susan M. Fitzpatrick, John T. Brue, Carving Our Destiny: Scientific Research Faces a New Millennium,

     The evidence for dark matter in galaxies started to accumulate in the mid-1970s. By the following decade it became clear that essentially all galaxies, including our own Milky Way, are surrounded by extensive halos of dark matter.

   • 2004, L. Bergström, A. Goobar, Particle Astrophysics and the Dark Sector of the Universe, in John W. Mason (editor), Astrophysics Update, pages 124-125,

     On large scales like that of clusters of galaxies, gravitational lensing indicates that the dark matter is smoothly distributed, on the average.

2. (particle physics, cosmology) By restriction, particles that have mass, which does not readily interact with normal matter except through gravitational effects.

• dark energy
• dark sector
• dark light