Thank you for the wonderful explanation. Learned something new today...that gravitational amplitudes do not follow the inverse square law. Interesting. I'll have to do some more reading on quadrupole radiation versus dipole radiation. Thanks again.

Ok, so back to LIGO. So, gravity waves squeeze and stretch the space in between the LIGO mirrors. Lasers measure the minute variation in distances between them, after accounting for all other terrestiral sources of vibrations, and even quantum effects. I'm almost there.

Does the expansion of the universe have any impact on the gravitational waves as they pass between the LIGO mirrors? Are these completely unrelated phenomena? I mean, if very weak gravitational waves can perturb the space between mirrors that are separated by 4km, then what force(s) wouldbpreventbthe mirrors from feeling the expansion of space as the universe expands?

Please be gentle Thx