Dark Energy

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What is the mysterious dark energy that's causing the expansion of the universe to accelerate? Is it some form of Einstein's famous cosmological constant, or is it an exotic repulsive force, dubbed "quintessence," that could make up as much as three-quarters of the cosmos? Scientists from Lawrence Berkeley National Laboratory (Berkeley Lab) and Dartmouth College believe there is a way to find out. | |

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The SuperNova/Acceleration Probe, SNAP, is a satellite designed to study dark energy through the discovery and precision measurement of thousands of distant supernovae.| | | |
In a paper to be published in Physical Review Letters, physicists Eric Linder of Berkeley Lab and Robert Caldwell of Dartmouth show that physics models of dark energy can be separated into distinct scenarios, which could be used to rule out Einstein's cosmological constant and explain the nature of dark energy. What's more, scientists should be able to determine which of these scenarios is correct with the experiments being planned for the Joint Dark Energy Mission (JDEM) that has been proposed by NASA and the U.S. Department of Energy. "Scientists have been arguing the question 'how precisely do we need to measure dark energy in order to know what it is?'" says Linder. "What we have done in our paper is suggest precision limits for the measurements. Fortunately, these limits should be within the range of the JDEM experiments." Linder and Caldwell are both members of the DOE-NASA science definition team for JDEM, which has the responsibility for drawing up the mission's scientific requirements. Linder is the leader of the theory group for SNAP — the SuperNova/Acceleration Probe, one of the proposed vehicles for carrying out the JDEM mission. Caldwell, a professor of physics and astronomy at Dartmouth, is one of the originators of the quintessence concept. In their paper in Physical Review Letters Linder and Caldwell describe two scenarios, one they call "thawing" and one...
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