Wednesday, January 30, 2008
Scientists may hold key to a cosmic enigma: study
Astrophysicists believe they are closing in on one of the cosmos' great mysteries: why the expansion of the Universe, triggered by the Big Bang, is accelerating.
The answer could be tantalisingly within reach, according to their study, released on Wednesday by the British weekly science journal Nature.A decade ago, astronomers were stunned to learn that the Universe was expanding more quickly than in the past.It had long been assumed that the mutual attraction of galaxies through gravity would slow the expansion of space, kicked off by the Big Bang some 14 billion years ago. Two very different theories have emerged to explain this shock discovery. One is that the Universe is filled with so-called dark energy, a substance that has been inferred but never seen. Dark energy cannot be detected with present technology as it neither emits nor reflects light or radiation. Dark energy, so the theory goes, counteracts the gravitational attraction that galaxies exert on each other and which would otherwise brake the cosmic expansion. The other possible explanation is that dark energy does not exist. If this were true, current theories about gravitational force as the prime mover in the Universe would be flawed -- they would only make sense if there are additional dimensions to space.