^^^^^^^^^^ Dark Energy ^^^^^^^^^ 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.According to 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 Plutos orbit. However, it comes to dominate the mass–energy of the universe because it is uniform across space.We do know this: Since space is everywhere, this dark energy force is everywhere, and its effects increase as space expands. In contrast, gravitys force is stronger when things are close together and weaker when they are far apart. Because gravity is weakening with the expansion of space.It sounds rather strange that we have no firm idea about what makes up most of the universe. Its as though we had explored all the land on the planet Earth and never in all our travels encountered an ocean. But now that weve caught sight of the waves, we want to know what this huge, strange, powerful entity really is. The leading theory, however, considers dark energy a property of space. Albert Einstein was the first to understand that space was not simply empty. He also understood that more space could continue to come into existence. In his theory of general relativity, Einstein included a cosmological constant to account for the stationary universe scientists thought existed. After Hubble announced the expanding universe, constant matches up with observations, scientists still arent certain just why it fits. Einstein called his constant his biggest blunder. But Einsteins blunder may be the best fit for dark energy. Predicting that empty space can have its own energy, the constant indicates that as more space emerges, more energy would be added to the universe, increasing its expansion.Although the cosmological.
Posted on: Wed, 24 Dec 2014 18:48:24 +0000
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