News FocusAstronomy

What Is Dark Energy?

Science  01 Jun 2012:
Vol. 336, Issue 6085, pp. 1090-1091
DOI: 10.1126/science.336.6085.1090-b

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Summary

Fourteen years ago, the discovery of dark energy rocked astronomy. Two teams of astronomers and astrophysicists studied distant stellar explosions called type Ia supernovae to measure how the universe has expanded over its 13.7-billion-year lifetime. They expected that the expansion would be slowing as galaxies pull toward one another with their gravity. To their shock, they found that the expansion is accelerating as if some bizarre "dark energy" is stretching space. The nature of dark energy is now perhaps the most profound mystery in cosmology and astrophysics. And it may remain forever so.