News tagged with dark energy
Model describes universe with no big bang, no beginning, and no end
(PhysOrg.com) -- By suggesting that mass, time, and length can be converted into one another as the universe evolves, Wun-Yi Shu has proposed a new class of cosmological models that may fit observations of the universe better ...
Jul 29, 2010 |
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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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Can R2 gravity explain dark matter?
(PhysOrg.com) -- "In many ways, the standard model of cosmology works very well," Jose Cembranos tells PhysOrg. "However, there are very basic features that we just do not know. We have dark energy and dark matter. They d ...
Apr 20, 2009 |
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Durham astronomers' doubts about the 'dark side'
(PhysOrg.com) -- New research by astronomers in the Physics Department at Durham University suggests that the conventional wisdom about the content of the Universe may be wrong. Graduate student Utane Sawangwit ...
Jun 14, 2010 |
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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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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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Physicists propose mechanism that explains the origins of both dark matter and 'normal' matter
(PhysOrg.com) -- Through precise cosmological measurements, scientists know that about 4.6% of the energy of the Universe is made of baryonic matter (normal atoms), about 23% is made of dark matter, and the ...
Dec 10, 2010 |
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What will the Large Hadron Collider reveal?
With its successful test run at the end of 2009, the Large Hadron Collider near Geneva, Switzerland, seized the world record for the highest-energy particle collisions created by mankind. We can now reflect ...
Jan 07, 2010 |
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Antimatter gravity could explain Universe's expansion
(PhysOrg.com) -- In 1998, scientists discovered that the Universe is expanding at an accelerating rate. Currently, the most widely accepted explanation for this observation is the presence of an unidentified ...
Apr 13, 2011 |
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Gas rich galaxies confirm prediction of modified gravity theory
(PhysOrg.com) -- Recent data for gas rich galaxies precisely match predictions of a modified theory of gravity know as MOND according to a new analysis by University of Maryland Astronomy Professor Stacy McGaugh. ...
Feb 23, 2011 |
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Dark Energy From the Ground Up: Make Way for BigBOSS
(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 ...
Aug 07, 2009 |
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A Theory of Dark Matter
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."
Sep 08, 2009 |
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Dark Energy Measurement Sheds New Light on Universe's Expansion
(PhysOrg.com) -- Through observations of massive galaxy clusters, scientists have made the most precise measurements to date of the effects of dark energy and gravity on cosmological scales. This work is an ...
Jul 15, 2010 |
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World's most powerful atom smasher restarts: CERN
Scientists have restarted the world's most powerful atom-smasher overnight, the European Organisation for Nuclear Research (CERN) said Sunday, as they launch a new bid to uncover the secrets of the universe.
Feb 28, 2010 |
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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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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.
