Keywords relevant to mass-energy ingredients of the observable universe:
  1. dark energy: The dominant mass-energy ingredient in the modern/local observable universe in the Λ-CDM model. Constant dark energy (which is the assumption of the Λ-CDM model) is equivalent in its effect on the expansion of the universe and the cosmic scale factor a(t) to a cosmological constant (AKA Lambda, Λ). Hence, dark energy is often given the symbol Λ. According to Planck 2018, Ω_Λ=0.6847.
  2. inflaton: See Wikipedia: inflaton.
  3. "matter" (AKA ): A shorthand for non-relativistic matter: i.e., matter moving at velocities << vacuum light speed c = 2.99792458*10**5 km/s ≅ 3*10**5 km/s = 1 ly/y Li-39--40 The mass-energy non-negligible contribution of to the observable universe is only its rest mass mass-energy. consists of Baryonic matter (i.e., protons, neutrons, and electrons) and dark matter (meaning in this context cold dark matter (CDM)). The secondary mass-energy ingredient in the modern/local observable universe in the Λ-CDM model. According to Planck 2018, Ω_matter=0.3153.
  4. "radiation": A shorthand for extreme relativistic particles important in cosmology. includes cosmic microwave background (CMB) which is always since it consists of photons. Before ∼ 1.2 Myr, cosmic neutrino background probably consisted of relativistic particles, and so is considered part of before that time and certainly up to the recombination era t = 377,770(3200) y = 1.192*10**13 s. See Wikipedia: Neutrio: Neutrino mass for summed neutrino mass < 0.3 eV = 300 meV, Lesgourgue & Verde 2017, p. 3 for z_nr_i = m_i/(0.53 meV) - 1 <∼ 600 and Nick Gnedin, before or circa 2013, Cosmological Calculator for the Flat Universe for t(z=600) = 1.177 Myr for the Λ-CDM model. In the modern/local observable universe, is negligible as a mass-energy ingredient.
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File: Cosmology file: keywords_cosmic_mass_energy.html.