Isn't the Perfect Gravitational Detector in Space?

We're making waves with gravitational waves. Are there weirder than we think they are? And do they leave a lasting imprint on the universe? Do they last forever? The super tricky thing because you want to measure how space itself is expanding, but here on Earth things are kind of held together by other forces. So when they build their experiment, LIGO, they try to isolate those mirrors from anything around them.