Comment by sitkack

I skipped the article, went directly to the paper https://arxiv.org/abs/2412.05542

It is very readable. This measures absolute distance.

LIGO was its own thing https://en.wikipedia.org/wiki/LIGO many people, big vacuum.

Two sites, one by Hanford the other in a swamp https://www.ligo.caltech.edu/WA https://www.ligo.caltech.edu/LA