Dark energy
hideIn physical cosmology and astronomy, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. Dark energy is the most popular way to explain recent observations that the universe appears to be expanding at an accelerating rate. In the standard model of cosmology, dark energy currently accounts for 74% of the total mass-energy of the universe.
Two proposed forms for dark energy are the cosmological constant, a constant energy density filling space homogeneously, and scalar fields such as quintessence or moduli, dynamic quantities whose energy density can vary in time and space. Contributions from scalar fields that are constant in space are usually also included in the cosmological constant. The cosmological constant is physically equivalent to vacuum energy. Scalar fields which do change in space can be difficult to distinguish from a cosmological constant because the change may be extremely slow.
High-precision measurements of the expansion of the universe are required to understand how the expansion rate changes over time. In general relativity, the evolution of the expansion rate is parameterized by the cosmological equation of state. Measuring the equation of state of dark energy is one of the biggest efforts in observational cosmology today.
Adding the cosmological constant to cosmology's standard FLRW metric leads to the Lambda-CDM model, which has been referred to as the "standard model" of cosmology because of its precise agreement with observations. Dark energy has been used as a crucial ingredient in a recent attempt to formulate a cyclic model for the universe.
For more information about Dark energy, read the full article at
Wikipedia.
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News tagged with dark energy
Ticking stellar time bomb identified (w/ Video)
Nov 17, 2009 |
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(PhysOrg.com) -- "One of the major problems in modern astrophysics is the fact that we still do not know exactly what kinds of stellar system explode as a Type Ia supernova," says Patrick Woudt, from the University ...
Aussie galaxy survey to lead to 'new physics'
Dec 08, 2009 |
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(PhysOrg.com) -- Australian astronomers have released the first set of data from the first project to look at the effects of "dark energy" halfway back in the Universe's lifetime.
Hunting for Planets in the Dark
Nov 19, 2009 |
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A proposed space mission that aims to measure dark energy could also detect planets that current surveys are unable to find.
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Atom smasher catches 1st high-energy collisions
Dec 09, 2009 |
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(AP) -- The world's largest atom smasher has recorded its first high-energy collisions of protons, a spokeswoman said Wednesday.
Restored machine to explore mysteries of Big Bang
Nov 21, 2009 |
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(AP) -- Scientists are preparing the world's largest atom smasher to explore the depths of matter after successfully restarting the $10 billion machine following more than a year of repairs.
City Tech physicist thinks small and big with CERN Large Hadron Collider research
Dec 11, 2009 |
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New York City College of Technology Physics Professor Giovanni Ossola thinks both small and big. He is currently developing a new tool that will lead to more precise computations involving the actions of particles (the smallest ...
Large Hadron Collider sends beams in 2 directions
Nov 23, 2009 |
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(AP) -- The world's largest atom smasher made another leap forward Monday by circulating beams of protons in opposite directions at the same time in the $10 billion machine after more than a year of repairs, ...
Research describes connections between Circadian and metabolic systems
Nov 17, 2009 |
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(PhysOrg.com) -- A paper by University of Notre Dame biologist Giles Duffield and a team of researchers offers new insights into a gene that plays a key role in modulating the body’s Circadian system and may ...
Spitzer Telescope Observes Baby Brown Dwarf
Nov 23, 2009 |
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(PhysOrg.com) -- NASA's Spitzer Space Telescope has contributed to the discovery of the youngest brown dwarf ever observed -- a finding that, if confirmed, may solve an astronomical mystery about how these ...
VISTA: Pioneering new survey telescope starts work
Dec 11, 2009 |
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VISTA is the latest telescope to be added to ESO's Paranal Observatory in the Atacama Desert of northern Chile. It is housed on the peak adjacent to the one hosting the ESO Very Large Telescope (VLT) and shares ...
NASA Supercomputer Ranks Among World's Fastest
Space & Earth / Space Exploration
Nov 19, 2009 |
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(PhysOrg.com) -- NASA's premiere supercomputer located at Ames Research Center, Moffett Field, Calif., has garnered the sixth spot on the Top500 list of the world's most powerful computers.
Crashing the size barrier
Nov 18, 2009 |
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Like surfers on monster waves, electrons can ride waves of plasma to very high energies in a very short distance. Scientists have proven that plasma acceleration works. Now they're developing it as a way to ...
Saturn's Mysterious Hexagon Emerges from Winter Darkness
Space & Earth / Space Exploration
Dec 09, 2009 |
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(PhysOrg.com) -- After waiting years for the sun to illuminate Saturn's north pole again, cameras aboard NASA's Cassini spacecraft have captured the most detailed images yet of the intriguing hexagon shape ...
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