Testing Einstein: Is Dark Energy Constant?

Nearly a decade ago, astronomers discovered the surprising existence of dark energy-a mysterious force that pushes galaxies apart and accelerates the expansion of the universe. Also known as the energy density of the vacuum, dark energy is a property of space itself. Scientists have many questions about the nature of dark energy. One question that soon may be answered: Is the energy density of the vacuum constant over cosmic time?

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<p><a href="http://www.physorg.com/news111333429.html">Testing Einstein: Is Dark Energy Constant?</a></p> <p>Nearly a decade ago, astronomers discovered the surprising existence of dark energy-a mysterious force that pushes galaxies apart and accelerates the expansion of the universe. Also known as the energy density of the vacuum, dark energy is a property of space itself. Scientists have many questions about the nature of dark energy. One question that soon may be answered: Is the energy density of the vacuum constant over cosmic time?</p>