LIGO is so fucking cool as an engineering achievement
they made a machine so sensitive that it gets thrown off by:
- propeller aircraft flying above it
- HVAC from 300m away
- ravens pecking on frost-covered pipes connected to a cryopump
- the gravitational effects of a human walking within 5m of its mirror. yeah apparently humans exert enough gravity to throw it off so you can't go within 10m of it while it's in operation. they wrote an entire 11 page paper about this https://sci-hub.ru/https://journals.aps.org/prd/abstract/10.1103/PhysRevD.60.082001
that's just some of the things listed on the Wikipedia page (https://en.wikipedia.org/wiki/LIGO#Noise). somehow, despite all this, they managed to control all of these factors enough to detect the extremely faint gravitational waves they wanted to detect!