[kennyc]

Accelerating universe' could be just an illusion
If true, theory would rid cosmology of its biggest headache — dark energy

In 1929, cosmologists discovered that the universe is expanding — that space-time, the fabric of the cosmos, is stretching. Then in 1998, light coming from exploding stars called supernovas suggested that the universe is not only expanding, but that it has recently begun expanding faster and faster; its expansion has entered an "accelerating phase." This was bad news for the fate of the cosmos: An accelerating universe is ultimately racing toward a "Big Rip," the moment at which its size will become infinite and, in a flash, everything in it will be torn apart.

The discovery was bad news for the state of cosmology, too. Because gravity pulls stuff inward rather than pushing it out, cosmologists believed that the expansion of the universe ought to be slowing down, as everything in it felt the gravitational tug of everything else. They didn't understand the mechanism that seemed to be opposing the force of gravity, so to explain their observations, they invoked the existence of "dark energy," a mysterious, invisible substance that permeates space and drives its outward expansion.

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http://www.msnbc.msn.com/id/44690771.../#.ToPQ0dREOi8