Editing Big Bang (section)

=== Mass-energy density ===
[[File:UniverseComposition.svg|thumb|right|375px|Estimated relative distribution for components of the energy density of the universe. (In February 2015, the European-led research team behind the [[Planck (spacecraft)|Planck cosmology probe]] released new data refining these values to 4.9% ordinary matter, 25.9% dark matter and 69.1% dark energy.)]]
In Big Bang cosmology, the [[mass–energy equivalence|mass–energy]] density controls the shape and evolution of the universe. By combining astronomical observations with known laws of [[thermodynamics]] and [[particle physics]], cosmologists have worked out the components of the density over the lifespan of the universe. In the current universe, luminous [[matter]], the stars, planets, and so on makes up less than 5% of the density. [[Dark matter]] accounts for 27%  and [[dark energy]] the remaining 68%.<ref name="NASA Planck Mission">{{cite web |url=http://www.nasa.gov/mission_pages/planck/news/planck20130321.html |title=Planck Mission Brings Universe into Sharp Focus |website=NASA Mission Pages |date=21 March 2013 |access-date=1 May 2016 |archive-date=12 November 2020 |archive-url=https://web.archive.org/web/20201112001039/http://www.nasa.gov/mission_pages/planck/news/planck20130321.html |url-status=dead }}</ref>