News tagged with dark energy
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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Closest Type Ia supernova in decades solves a cosmic mystery
Type Ia supernovae (SN Ia's) are the extraordinarily bright and remarkably similar "standard candles" astronomers use to measure cosmic growth, a technique that in 1998 led to the discovery of dark energy ...
Dec 14, 2011 |
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Saul Perlmutter receives Nobel Prize in physics
Saul Perlmutter, an astrophysicist at the U.S. Department of Energy's Lawrence Berkeley National Laboratory and a professor of physics at the University of California at Berkeley, has won the 2011 Nobel Prize ...
Oct 27, 2011 |
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A second look at supernovae light: Universe's expansion may be understood without dark energy
(PhysOrg.com) -- The 2011 Nobel Prize in physics, awarded just a few weeks ago, went to research on the light from Type 1a supernovae, which shows that the universe is expanding at an accelerating rate. The ...
Oct 24, 2011 |
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German scientists ready for the hunt on dark energy
The German and Russian partners of the new eROSITA X-ray space observatory have now agreed on how to split the data from the first four years of an all sky survey. This decision was announced today at the ...
Oct 20, 2011 |
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Dark matter mystery deepens
(PhysOrg.com) -- Like all galaxies, our Milky Way is home to a strange substance called dark matter. Dark matter is invisible, betraying its presence only through its gravitational pull. Without dark matter ...
Oct 17, 2011 |
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G299.2-2.9, a middle-aged supernova remnant
(PhysOrg.com) -- G299.2-2.9 is an intriguing supernova remnant found about 16,000 light years away in the Milky Way galaxy. Evidence points to G299.2-2.9 being the remains of a Type Ia supernova, where a white ...
Oct 13, 2011 |
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NOAO telescopes played major role in Nobel-prize winning projects
The 2011 Nobel Prize in Physics was awarded to Saul Perlmutter, Brian Schmidt, and Adam Riess for their discovery of the acceleration of the Universe, one of the more surprising cosmological results in modern astronomy. The ...
Oct 05, 2011 |
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Nobel winner thought prize call was 'student joke'
When a Swedish voice came down the line informing him he had a "very important call" Tuesday night, Australia's newest Nobel laureate Brian Schmidt assumed it was an elaborate undergraduate joke.
Oct 05, 2011 |
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Nature of universe is still a mystery to Nobel winners
They won the Nobel Prize for changing our understanding of the universe, but their discovery left an even larger mystery -- what is this dark energy that is propelling the universe to expand so fast? ...
Oct 04, 2011 |
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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.
