"The ground-based LIGO experiment might someday detect a gravitational wave, but theres been no luck so far. The Space-based LISA experiment should detect gravitational waves with more precision. The first version will launch in 2015, but the real experiment probably wont be operational until 2030."
Robert Forward (SF writer, scientist, all around smart guy) was searching for Gravity Waves at UCLA in the late 50's. There may have been earlier experiments. But so far we have zero evidence that they exist. Very odd. Very strange.
http://www.scientificamerican.com/article/gravity-waves-cmb-b-mode-polarization/
While I agree they have found evidence of gravity waves, I reject their trying to tie to the Big Bang.