Related topics: galaxies , hubble space telescope , universe , dark matter , gravity
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
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.
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First volume of microbial encyclopedia published
Dec 23, 2009 |
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The Earth is estimated to have about a nonillion (1030) microbes in, on, around, and under it, comprised of an unknown but very large number of distinct species. Despite the widespread availability of microbi ...
An easy way to see the world's thinnest material
Nanotechnology / Nanomaterials
Dec 23, 2009 |
4.7 / 5 (10) |
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It's been used to dye the Chicago River green on St. Patrick's Day. It's been used to find latent blood stains at crime scenes. And now researchers at Northwestern University have used it to examine the thinnest material ...
Sniffing out clues to dogs' compulsive behavior
Dec 22, 2009 |
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(PhysOrg.com) -- At first glance, a dog chasing its tail seems a harmless, if fruitless, pursuit. But for many dogs and their owners, the habit has a dark side, one that means endless hours and energy spent ...
Titan's lakes could be explored by boat
Space & Earth / Space Exploration
Dec 22, 2009 |
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(PhysOrg.com) -- If a suggestion to be made to NASA comes to fruition, vast lakes thought to be filled with liquid hydrocarbons near the north pole of Saturn's moon Titan, may one day be explored by boat.
Physicists detect two candidate dark matter interactions, but say the data are not conclusive
Dec 18, 2009 |
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(PhysOrg.com) -- Scientists have spent decades searching for the elusive material known as dark matter, which is believed to make up 25 percent of the universe. On Thursday, Dec. 17, a team of physicists including ...
Tiny whispering gallery: Sensor can detect a single nanoparticle and take its measurement
Dec 18, 2009 |
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(PhysOrg.com) -- Nanotechnology has already made it to the shelves of your local pharmacy and grocery: nanoparticles are found in anti-odor socks, makeup, makeup remover, sunscreen, anti-graffiti paint, home ...
Their infinite wisdom
Dec 14, 2009 |
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(PhysOrg.com) -- Hotel guests come and go. But in the first decade of the 1900s, a pair of frequent Russian visitors to the Hotel Parisiana, near the Sorbonne on Paris' Left Bank, stood out vividly. The children ...
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 ...
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 ...
Saturn's Mysterious Hexagon Emerges from Winter Darkness
Space & Earth / Space Exploration
Dec 09, 2009 |
5 / 5 (23) |
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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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