Hi every one,
Been away for a long while but am back again.
Gravitational waves are distortions of space. If you wave a stick around you will cause gravitational waves albeit very tiny ones. When we look at the universe through a telescope back to the 380,000 year mark (after the big bang, we can't see past this mark because the universe was so hot and dense. The universe was opaque then.
The only radiation that can pass through this opaqueness is gravitational waves. If inflation is true, then inflation would have caused a special warp of space due to it's exceptional size and shape. If we eventually manage to detect gravitational waves, they can tell us whether inflation occurred or whether the universe is cyclic. (ie a gentler process)
Inflationary models predict that gravitational waves should be the cause of about 40% of the hot and cold spots of the CMB. The gravitational waves would also have an effect on the polarization of the CMB.
This would show up as E-mode and B-mode patterns similar to electromagnetic waves.
So far we have not had much success in detecting these waves, but when we do, much new information will come to light regarding inflation and or the cyclic (Ekpyrotic universe). This is how I understand it any way.
Also, remember that energy has mass, and there was a lot of radiation energy. (The Universe at this stage was very much dominated by radiation instead of mass)