Editing Dimensionless physical constant (section)

=== Cosmological constants ===
The [[cosmological constant]], which can be thought of as the density of [[dark energy]] in the universe, is a fundamental constant in [[physical cosmology]] that has a dimensionless value of approximately 10<sup>−122</sup>.<ref>[[Robert Jaffe (physicist)|Jaffe, R. L.]], & Taylor, W., ''The Physics of Energy'' (Cambridge: Cambridge University Press, 2018), [https://books.google.com/books?id=drZDDwAAQBAJ&pg=PA419&redir_esc=y#v=onepage&q&f=false p. 419].</ref> Other dimensionless constants are the measure of homogeneity in the universe, denoted by ''Q'', which is explained below by Martin Rees, the baryon mass per photon, the cold dark matter mass per photon and the neutrino mass per photon.<ref name="Tegmark2014">{{cite book |first=Max |last=Tegmark |date=2014 |title=Our Mathematical Universe: My Quest for the Ultimate Nature of Reality |publisher=Knopf Doubleday Publishing Group |isbn=9780307599803 |page=[https://archive.org/details/ourmathematicalu0000tegm/page/252 252] |title-link=Our Mathematical Universe: My Quest for the Ultimate Nature of Reality }}</ref>