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Big-Bang Effect Widening Universe, Team Theorizes

'Dark matter' isn't necessary to explain the accelerating expansion, some physicists say.

March 26, 2005|From Reuters

A group of physicists is battling what it considers the cosmological equivalent of the boogeyman: an enormous dark force, which nobody has ever seen, driving galaxies apart.

Conventional wisdom holds that a theoretical "dark energy" makes up some 70% of the universe, and could be the determining factor in whether the universe is destroyed billions of years from now. But Italian and American cosmologists have another explanation for the accelerating expansion of the universe: They say the expansion is an overlooked aftereffect of the Big Bang, which brought about the universe.

"No mysterious dark energy is required," said Antonio Riotto at Italy's National Nuclear Physics Institute in Padova.

Since the late 1990s, scientists have used dark energy to explain an apparent antigravity force pushing galaxies away from each other at an accelerating rate.

And they have employed a variety of theories -- such as new dimensions -- to justify their belief in the existence of dark energy.

For The Record
Los Angeles Times Thursday March 31, 2005 Home Edition Main News Part A Page 2 National Desk 1 inches; 39 words Type of Material: Correction
Expanding universe -- A headline with a Science File article in Saturday's Section A about the expansion of the universe used the term "dark matter." It was the role of dark energy in the expansion that was being debated.

Edward W. Kolb, of the U.S. Department of Energy's Fermi National Accelerator Laboratory, and the Italians said the universe's accelerating expansion was the result of long ripples in the fabric of space-time created by the Big Bang. Because the ripples stretch beyond the observable universe, they have not been properly accounted for, the scientists said.

"These long-wavelength swells grow with time and give an extra expansion to the universe," Kolb said.

The long-ripples idea could change theories about the ultimate fate of the universe, particularly whether it will collapse in a "big crunch," be completely blown apart in a "big rip," or just drift steadily until galaxies are so far away from each other they cannot be seen -- in effect, taking stars from the sky.

The long-ripples theory would tend to suggest infinite drift and eventual "cosmic darkness," Riotto said.

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