Editing Observable universe (section)

=== Mass of ordinary matter ===
The mass of the observable universe is often quoted as 10<sup>53</sup>&nbsp;kg.<ref name="Paul Davies 2006 43">{{cite book |author=Davies |first=Paul |url=https://archive.org/details/cosmicjackpotwhy0000davi/page/43 |title=The Goldilocks Enigma |date=2006 |publisher=First Mariner Books |isbn=978-0618592265 |page=[https://archive.org/details/cosmicjackpotwhy0000davi/page/43 43–]}}</ref> In this context, mass refers to ordinary (baryonic) matter and includes the [[interstellar medium]] (ISM) and the [[intergalactic medium]] (IGM). However, it excludes [[dark matter]] and [[dark energy]]. This quoted value for the mass of ordinary matter in the universe can be estimated based on critical density. The calculations are for the observable universe only as the volume of the whole is unknown and may be infinite.