image-Lagoon Nebula, credit: Kitt Peak National Obsevatory
credit: Kitt Peak National Obsevatory

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What's happened to the
universe since the Big Bang?

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What would slow the expansion of the universe?

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What's causing the universe's expansion?

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Two independent teams of astronomers, both with NSF support, have concluded the expansion of the universe is accelerating.

While it has been known for many years that the universe has been continually expanding since the Big Bang, the discovery by these research teams has drawn an unexpected new picture of a universe that isgetting bigger at an ever increasing rate,driven by a yet unknown force.

It was previously unknown if thegravitational attraction between galaxieswould be enough to slow the expansion of the universe. However, NSF-funded astronomers Saul Perlmutter, Robert Kirshner and Alexi Filippenko, as well as a team of astronomers at Cerro Tololo Inter-American Observatory in Chile, an NSF facility, have discovered that not enough matter exists to slow the paceof the expanding universe.

In fact, expansion of the universe is actually speeding up. Science magazine named this discovery as the science discovery of the year in 1998.

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