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
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.
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 ...
Do we need dark matter?
Nov 12, 2009 |
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It's the biggest problem in physics: the matter we can see in the universe accounts for just five per cent of the observed gravity that holds galaxies together.
Precise picture of early Universe supports 'dark matter' theory
Nov 02, 2009 |
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A detailed picture of the seeds of structures in the universe has been unveiled by an international team co-led by a Cardiff University scientist.
Scientists use world's fastest supercomputer to model origins of the unseen universe
Oct 26, 2009 |
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Understanding dark energy is the number one issue in explaining the universe, according to Salman Habib, of the Laboratory's Nuclear and Particle Physics, Astrophysics and Cosmology group.
Science at the petascale: Roadrunner supercomputer results unveiled
Oct 26, 2009 |
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The world's fastest supercomputer, Roadrunner, at Los Alamos National Laboratory has completed its initial "shakedown" phase doing accelerated petascale computer modeling and simulations of a variety of unclassified, fundamental ...
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Cosmic archaeology: Astrophysicists use new spectrographs to look far back into the history of the universe
Oct 13, 2009 |
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(PhysOrg.com) -- The distant past of the universe is moving closer. Astronomers are using special spectrographs to investigate galaxies in the depths of the universe as part of the Sloan Digital Sky Survey ...
First light for BOSS -- a new kind of search for dark energy
Oct 01, 2009 |
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BOSS, the Baryon Oscillation Spectroscopic Survey, is the most ambitious attempt yet to map the expansion history of the Universe using the technique known as baryon acoustic oscillation (BAO). A part of the ...
A Theory of Dark Matter
Sep 08, 2009 |
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Among the most astounding, unexpected, and important achievements of the past century (or even more) have been the discoveries of dark matter and dark energy, collectively dubbed the "dark sector."
Variability of type 1a supernovae has implications for dark energy studies
Aug 12, 2009 |
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(PhysOrg.com) -- The stellar explosions known as type 1a supernovae have long been used as "standard candles," their uniform brightness giving astronomers a way to measure cosmic distances and the expansion ...
Dark Energy From the Ground Up: Make Way for BigBOSS
Aug 07, 2009 |
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(PhysOrg.com) -- Several ways have been proposed to examine dark energy, in hopes of finding out just what it is. One of them, "supernovae" for short, certainly works: it's how dark energy was discovered in ...
Australia gets $72 million for the Giant Magellan Telescope
Jul 28, 2009 |
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Pasadena, CA-The Australian government has announced that it will provide $88.4 million AUD ($72.4 million USD) to help fund the revolutionary 25-meter Giant Magellan Telescope (GMT) to be sited at Las Campanas ...
NASA celebrates Chandra X-Ray Observatory's 10th anniversary (w/ Video)
Jul 23, 2009 |
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Ten years ago, on July 23, 1999, NASA's Chandra X-ray Observatory was launched aboard the space shuttle Columbia and deployed into orbit. Chandra has doubled its original five-year mission, ushering in an ...
Queen's astronomers propose new supernova interpretation
Jun 09, 2009 |
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In a controversial new paper in the journal Nature, astronomers from Queen's University Belfast have proposed a new physical interpretation of a supernova discovered on 7th November 2008.
Radio telescopes extend astronomy's best 'yardstick'
Jun 08, 2009 |
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Radio astronomers have directly measured the distance to a faraway galaxy, providing a valuable "yardstick" for calibrating large astronomical distances and demonstrating a vital method that could help determine the elusive ...
