News tagged with dark energy
One supernova type, two different sources
The exploding stars known as Type Ia supernovae serve an important role in measuring the universe, and were used to discover the existence of dark energy. They're bright enough to see across large distances, ...
May 07, 2012 |
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First-ever model simulation of the structuring of the observable universe
A team of researchers from the Laboratoire Univers et Theorie (France) coordinated by Jean-Michel Alimi has performed the first-ever computer model simulation of the structuring of the entire observable universe, ...
Apr 12, 2012 |
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'Cosmic mirages' confirm accelerated cosmic expansion
(Phys.org) -- An international team of researchers led by Masamune Oguri at Kavli IPMU and Naohisa Inada at Nara National College of Technology conduced an unprecedented survey of gravitationally lensed quasars, ...
Apr 11, 2012 |
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South Pole Telescope hones in on dark energy, neutrinos
Analysis of data from the 10-meter South Pole Telescope is providing new support for the most widely accepted explanation of dark energy — the source of the mysterious force that is responsible for the ...
Apr 02, 2012 |
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When dark energy turned on (Update)
(PhysOrg.com) -- Some six billion light years distant, almost halfway from now back to the big bang, the universe was undergoing an elemental change. Held back until then by the mutual gravitational attraction ...
Mar 30, 2012 |
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Swift narrows down origin of important supernova class
(PhysOrg.com) -- Studies using X-ray and ultraviolet observations from NASA's Swift satellite provide new insights into the elusive origins of an important class of exploding star called Type Ia supernovae. ...
Mar 20, 2012 |
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Detection of cosmic effect may bring universe's formation into sharper focus
(PhysOrg.com) -- The first observation of a cosmic effect theorized 40 years ago could provide astronomers with a more precise tool for understanding the forces behind the universe's formation and growth, ...
Mar 20, 2012 |
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Accident damages mirror on telescope slated for dark energy camera
An accident at the Blanco 4m telescope at Chile’s Cerro Tololo Inter-American Observatory has severely damaged a secondary mirror. The telescope is currently shut down for installation of the highly anticipated ...
Space & Earth / Space Exploration
Feb 27, 2012 |
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Leading the quest to crack cosmological mysteries
Sometimes a scientist can only laugh in the face of a seemingly insurmountable challenge.
Feb 13, 2012 |
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NASA's Galaxy Evolution explorer in standby mode
(PhysOrg.com) -- NASA's Galaxy Evolution Explorer, or Galex, was placed in standby mode today as engineers prepare to end mission operations, nearly nine years after the telescope's launch. The spacecraft ...
Space & Earth / Space Exploration
Feb 08, 2012 |
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Repulsive gravity as an alternative to dark energy (Part 2: In the quantum vacuum)
(PhysOrg.com) -- During the past few years, CERN physicist Dragan Hajdukovic has been investigating what he thinks may be a widely overlooked part of the cosmos: the quantum vacuum. He suggests that the quantum vacuum has ...
Feb 01, 2012 |
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Repulsive gravity as an alternative to dark energy (Part 1: In voids)
(PhysOrg.com) -- When scientists discovered in 1998 that the Universe is expanding at an accelerating rate, the possibility that dark energy could explain the observation was intriguing. But because there ...
Jan 31, 2012 |
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Hubble breaks new ground with discovery of distant exploding star
NASA's Hubble Space Telescope has looked deep into the distant universe and detected the feeble glow of a star that exploded more than 9 billion years ago. The sighting is the first finding of an ambitious ...
Jan 11, 2012 |
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Chandra finds largest galaxy cluster in early universe
(PhysOrg.com) -- An exceptional galaxy cluster, the largest seen in the distant universe, has been found using NASA's Chandra X-ray Observatory and the National Science Foundation-funded Atacama Cosmology ...
Jan 10, 2012 |
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Clearest picture yet of dark matter points the way to better understanding of dark energy
(PhysOrg.com) -- Two teams of physicists at the U.S. Department of Energy's Fermilab and Lawrence Berkeley National Laboratory (Berkeley Lab) have independently made the largest direct measurements of the ...
Jan 09, 2012 |
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Dark energy
In 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.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
