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In standard cosmology, there are three components of the universe: matter, radiation, and dark energy. This matter is anything whose energy density scales with the inverse cube of the scale factor, i.e., ρ ∝ a −3, while radiation is anything whose energy density scales to the inverse fourth power of the scale factor (ρ ∝ a −4).
In these models, the quintessence field has a density which closely tracks (but is less than) the radiation density until matter-radiation equality, which triggers quintessence to start having characteristics similar to dark energy, eventually dominating the universe. This naturally sets the low scale of the dark energy. [12]
Dark matter is called ‘dark’ because it’s invisible to us and does not measurably interact with anything other than gravity. It could be interspersed between the atoms that make up the Earth ...
The fraction of the total energy density of our (flat or almost flat) universe that is dark energy, , is estimated to be 0.669 ± 0.038 based on the 2018 Dark Energy Survey results using Type Ia supernovae [8] or 0.6847 ± 0.0073 based on the 2018 release of Planck satellite data, or more than 68.3 % (2018 estimate) of the mass–energy density ...
It is due to dark matter that galaxies are able to keep their shape, with the mass of dark matter creating enough gravitational force to hold the stars that make up a galaxy together. Dark energy, however, is a substance or force responsible for the accelerating expansion of the universe over time. [2]
The measured dark energy density is Ω Λ ≈ 0.690; the observed ordinary (baryonic) matter energy density is Ω b ≈ 0.0482 and the energy density of radiation is negligible. This leaves a missing Ω dm ≈ 0.258 which nonetheless behaves like matter (see technical definition section above) – dark matter.
Dark energy is one of the greatest mysteries in science today. One of the simplest explanations is that it is a “cosmological constant” – a result of the energy of empty space itself – an ...
Dark energy dominates the total energy (74%) while dark matter (22%) constitutes most of the mass. Of the remaining baryonic matter (4%), only one tenth is compact. In February 2015, the European-led research team behind the Planck cosmology probe released new data refining these values to 4.9% ordinary matter, 25.9% dark matter and 69.1% dark ...