Editing Universe (section)

=== Dark matter ===
{{Main|Dark matter}}
Dark matter is a hypothetical kind of [[matter]] that is invisible to the entire [[electromagnetic spectrum]], but which accounts for most of the matter in the universe. The existence and properties of dark matter are inferred from its gravitational effects on visible matter, radiation, and the [[Observable universe#Large-scale structure|large-scale structure]] of the universe. Other than [[neutrinos]], a form of [[hot dark matter]], dark matter has not been detected directly, making it one of the greatest mysteries in modern [[astrophysics]]. Dark matter neither [[blackbody spectrum|emits]] nor absorbs light or any other [[electromagnetic radiation]] at any significant level. Dark matter is estimated to constitute 26.8% of the total mass–energy and 84.5% <!--26.8/(4.9 + 26.8)--> of the total matter in the universe.<ref name="DarkMatter">Sean Carroll, Ph.D., Caltech, 2007, The Teaching Company, ''Dark Matter, Dark Energy: The Dark Side of the Universe'', Guidebook Part 2. p. 46, Accessed October 7, 2013, "...dark matter: An invisible, essentially collisionless component of matter that makes up about 25 percent of the energy density of the universe... it's a different kind of particle... something not yet observed in the laboratory..."</ref><ref name=planckcam>{{cite web |url=http://www.cam.ac.uk/research/news/planck-captures-portrait-of-the-young-universe-revealing-earliest-light |title=Planck captures portrait of the young universe, revealing earliest light |date=March 21, 2013 |publisher=University of Cambridge |access-date=March 21, 2013 |archive-date=April 17, 2019 |archive-url=https://web.archive.org/web/20190417165900/https://www.cam.ac.uk/research/news/planck-captures-portrait-of-the-young-universe-revealing-earliest-light |url-status=live }}</ref>