Hum, Four theoretical physicists, Edward W. Kolb, Sabino Matarrese , Alessio Notari and Antonio Riotto have proposed that the evolution of `cosmic ripples` solves the `mysterious Dark energy expansion of the universe` and accounts for its observed acceleration. "<i>We realized that you simply need to add this new key ingredient, the ripples of spacetime generated during the epoch of inflation, to Einstein's General Relativity to explain why the universe is accelerating today. It seems that the solution to the puzzle of acceleration involves the universe beyond our cosmic horizon. No mysterious dark energy is required.</i>" During the inflationary expansion early in the history of the universe, very tiny ripples in spacetime were generated, as predicted by Einstein's theory of General Relativity. These ripples were stretched by the expansion of the universe and extend today over a region , about 10<sup>80</sup> times bigger than our observable universe, (13.7 billion light years). Our "observable" universe is currently sitting in the dead centre of a `trough`… This, <b>IMHO</b>, although possible, seems very ad hoc; Probability wise, it seems that the universe should actually be surfing on the `slope` of this space-time ripple, resulting in a `directional` expansion rate. Also, others have noted that as the wavelength of the perturbations gets longer, the space time slope diminishes, so that the ripples would have no effect on the observable universe. Data from upcoming experiments (better observations of supernovae) will allow them to test their proposal. "<i>Whether Einstein was right when he first introduced the cosmological constant, or whether he was right when he later refuted the idea will soon be tested by a new round of precision cosmological observations. New data will soon allow us to distinguish between our explanation for the accelerated expansion of the universe and the dark energy solution.</i>" <b>Extracts from:</b> <a href="http://www.newscientist.com/article.ns?id=dn7167">Here</a>
