Why can gravitational waves be of interest to cosmologists ?
Cosmologists predict two types of B - modes , the first generated during cosmic inflation shortly after the big bang , and the second generated by gravitational lensing at later times.BICEP 2 announced in March 2014 that they had detected the first type of B - modes , consistent with inflation and gravitational waves in the early universe at the level of The second type of B - modes was discovered earlier using National Science Foundation 's South Pole Telescope with help from the Herschel Space Observatory .