August 19, 2009

New Limits on Gravitational Waves From the Big Bang

Written by Nancy Atkinson

Artists concept of graviational waves. Credit: NASA

The only way to know what the Universe was like at the moment of the Big Bang requires analysis of gravitational waves created when the Universe began. Scientists working with the Laser Interferometer Gravitational-Wave Observatory (LIGO) say their initial investigations of these gravitiation waves have turned up nothing.

But that's a good thing. Not detecting the waves provides constraints about the initial conditions of the universe, and narrows the field of where we actually do need to look in order to find them.

Much like it produced the cosmic microwave background, the Big Bang is believed to have created a flood of gravitational waves — ripples in the fabric of space and time. From our current understanding, gravitational waves are the only known form of information that can reach us undistorted from the beginnings of the Universe.

They would be observed as a "stochastic" or random background, and would carry with them information about their violent origins and about the nature of gravity that cannot be obtained by conventional astronomical tools. The existence of the waves was predicted by Albert Einstein in 1916 in his general theory of relativity.

Analysis of data taken over a two-year period, from 2005 to 2007, yields that the stochastic background of gravitational waves has not yet been discovered. But the nondiscovery of the background, described in a new paper in the August 20 Nature, offers its own brand of insight into the universe's earliest history.

Full article here:

http://www.universetoday.com/2009/08/19/new-limits-on-gravitational-waves-from-the-big-bang/