spacetoday.net: Dark energy found in early universe

Dark energy found in early universe

Posted: Fri, Nov 17, 2006, 7:37 AM ET (1237 GMT)
Hubble image of distant supernovae (STScI)

Dark energy, the mysterious force that is causing the expansion of the universe to accelerate, has existed in the universe for at least nine billion years, astronomers said Thursday. Astronomers used the Hubble Space Telescope to study a class of supernovae that serve as "standard candles", allowing astronomers to measure their distance and the rate of expansion of the universe. The study showed that dark energy existed as far back as nine billion years ago, or less than five billion years after the Big Bang, and at a strength similar to today. The results are consistent with a "cosmological constant" initially proposed by Albert Einstein, although scientists said they're still not sure what generates the dark energy.