For observatory status see [0]. It also gives the estimated detector range in megaparsecs (Mpc). Initial LIGO's "range" (the radius out to which LIGO could detect at least a binary neutron star (BNS) merger) was 15 Mpc. With the latest improvements is more in the 140 Mpc range. Meaning that it can see more than 9 times as far and that the area of space is increased by a factor of more than 800. This will greatly increase the number of gravitational waves being detected.

[0] https://online.ligo.org/

Beside the mentioned laboratories in the US, Italy and Japan, there is another one in Germany albeit of much smaller size [0]. The length of its arms are only 600m (1/3mi) each but it serves as testbed for technologies [1] that might later be used for other observatories.

[0] https://www.geo600.org/ , https://en.wikipedia.org/wiki/GEO600

[1] https://en.wikipedia.org/wiki/GEO600#Advanced

I absolutely love LIGO. YC actually did a great interview with one of the lead physicists on the project where he described some of the technical hardware and software challenges - https://www.youtube.com/watch?v=1D2j8nTjOZ4

Since learning about gravitational waves I was always curious if a type III civilization could potentially use them as a weapon.

The image at the top of the page is not a real image is it? We don't have real photos of black holes yet right? (except the one at https://www.nasa.gov/mission_pages/chandra/news/black-hole-i...)

> Typical gravitational-wave events change the length of the arms by only a fraction of the width of a proton. Sensing such minute changes requires painstaking isolation from noise coming from the environment and from the lasers themselves.

i find it utterly fascinating that we're able to detect such a minuscule deviation

Nice. There's even a citizen scientist initiative for LIGO [0]. I wonder what's the status on LISA though.

[0] https://www.zooniverse.org/projects/zooniverse/gravity-spy

Big LIGO nerd here. If interested, you can get public alerts of LIGO detected activity:

https://www.ligo.caltech.edu/page/GWPhoneAlerts

Michelson and Morley smile

https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_exper...

The LIGO song is required background music for this article: https://youtu.be/degD69wnZcY

are gravitational waves like, universal? could we use them as a timing reference, I wonder?

I was lucky to take a tour of the Livingston, LA facility. It's within about an hour's drive north of New Orleans. Very much worth a visit.

https://goo.gl/maps/9fLFCVqjumx1LSkXA

As someone who's worked on laboratory ultra-high vacuum systems the ~2m diameter by 4km long arms that are vacuum chambers are quite impressive.

A "fun fact" from the tour was that they had a road grading company construct the underlayer for the support of the arms. They asked the company to set the angle of the grading to equal the negative curvature of the earth as the arms have to be straight in space while a surface that's graded "flat" would end up following the curvature of the earth.