I don't think the OP is right. The waves LIGO detected lasted for an instant because they were from a fleeting cosmic event - two black holes spiraling into eac

I don't think the OP is right. The waves LIGO detected lasted for an instant because they were from a fleeting cosmic event - two black holes spiraling into each other. But there's no reason as far as I know that a much more sensitive detector couldn't see waves from more mundane, longer-lasting events. Though - at that point, why not just send EM waves? They travel the same speed. Maybe gravitational waves could penetrate anything, if you're willing to spend planetary amounts of energy to do it?