What is dark energy?

Dark Energy

In physical cosmology and astronomy, dark energy is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe. Dark energy is the most accepted hypothesis to explain observations since the 1990s that indicate that the universe is expanding at an accelerating rate. According to the Planck mission team, and based on the standard model of cosmology, the total mass–energy of the universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy.

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Some articles on dark energy:

Thermodynamics Of The Universe - Dark Energy and Cosmic Inflation
... Dark energy is a hypothetical form of energy that permeates all of space, and causes an acceleration in the expansion of the universe due to its strong ... According to the equation above, Thus the more negative the pressure is, the less the energy density reduces as the universe expands ... In other words, Dark energy dilutes less than any other form of energy, and will therefore eventually dominate the universe, as all other energy densities gets diluted faster with the expansion of the universe ...
Dark Energy - See Also
... De Sitter relativity The Dark Energy Survey Vacuum state. ...
The Hubble Constant - Derivation of The Hubble Parameter - Matter- and Dark Energy-dominated Universe
... If the universe is both matter-dominated and dark energy- dominated, then the above equation for the Hubble parameter will also be a function of the ... So now where is the mass density of the dark energy ... the mass density of the universe evolves with time, If w is constant, Therefore for dark energy with a constant equation of state w ...
Beyond The Standard Model - Problems With The Standard Model - Experimental Observations Not Explained
... Dark matter and dark energy ... tell us the standard model explains about 4% of the energy present in the universe ... Of the missing 96%, about 24% should be dark matter, which would behave just like other matter, but which only interacts weakly with the standard model fields ...
Matter-dominated Era
... say that when the Universe was about 5 billion years old, this era ended and was replaced by the dark-energy-dominated era ... This change of the perspective occurred when the cosmological constant or dark energy was first observed in the late 1990s ... In the matter-dominated era, the energy density of matter exceeds the energy density of radiation in the universe (and it should exceed the vacuum energy density i.e ...

Famous quotes containing the words energy and/or dark:

    Crime is naught but misdirected energy. So long as every institution of today, economic, political, social, and moral, conspires to misdirect human energy into wrong channels; so long as most people are out of place doing the things they hate to do, living a life they loathe to live, crime will be inevitable.
    Emma Goldman (1869–1940)

    This seems a long while ago, and yet it happened since Milton wrote his Paradise Lost. But its antiquity is not the less great for that, for we do not regulate our historical time by the English standard, nor did the English by the Roman, nor the Roman by the Greek.... From this September afternoon, and from between these now cultivated shores, those times seemed more remote than the dark ages.
    Henry David Thoreau (1817–1862)