NEW YORK (Nov. 17) - The Hubble Space Telescope has shown that a mysterious form of energy first conceived by Albert Einstein, then rejected by the famous physicist as his “greatest blunder,” appears to have been fueling the expansion of the universe for most of its history.

This so-called “dark energy” has been pushing the universe outward for at least 9 billion years, astronomers said Thursday.

“This is the first time we have significant, discrete data from back then,” said Adam Riess, a professor of astronomy at Johns Hopkins University and researcher at NASA’s Space Telescope Science Institute.

He and several colleagues used the Hubble to observe 23 supernovae - exploding white dwarf stars - so distant that their light took more than half the history of the universe to reach the orbiting telescope. That means the supernovae existed when the universe was less than half its current age of approximately 13.7 billion years.

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