U.S. Department of Energy

Pacific Northwest National Laboratory

Dark Energy

The surprising discovery in 1998 that the expansion of the universe is accelerating, instead of slowing down due to gravity, has posed another significant question: what is the dark energy that is pushing our universe apart? While it may be an inherent feature of the universe, it could be something dynamic related to new particles or forces, or a failure of Einstein’s theory of General Relativity. Dark energy may explain why the expansion of the universe continues to accelerate rather than slow down, as would be expected if gravity predominated. Both dark matter and dark energy remain among the top mysteries of the universe, key topics of astrophysical research today.

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