ਫਾਟਕ:Cosmology/Selected article/3
In physical cosmology and astronomy, dark energy is an unknown form of energy which permeates all of space and tends to accelerate the expansion of the universe. Dark energy is the most accepted hypothesis to explain the observations since the 1990s indicating that the universe is expanding at an accelerating rate. According to the Planck mission team, and based on the standard model of cosmology, on a mass–energy equivalence basis, the observable universe contains 26.8% dark matter, 68.3% dark energy (for a total of 95.1%) and 4.9% ordinary matter. Again on a mass–energy equivalence basis, the density of dark energy (6.91 × 10−27 kg/m3) is very low: in the solar system, it is estimated only 6 tons of dark energy would be found within the radius of Pluto's orbit. However, it comes to dominate the mass–energy of the universe because it is uniform across space.