The Nanograph Experiment Has Showed Gravitational Waves in the Universe

LIGO and Virgo can only really see gravitational waves that are about the size of their detector. The gravitational wave was much, much bigger than it wouldn't have an observable effect on their detector. It would wiggle too slowly. They've seen dozens and dozens of those. But they can't see things like super massive black hole mergers which are predicted to happen when galaxies collide. And they also can't see like echoes from the big bang itself which would leave gravitational waves with huge wavelengths.