I read through the article and it didn't explain at all how studying quasars determined this. I wonder if there's a better breakdown as to how they were able to ascertain this. I know there's been some major announcements in the field thanks to quasar study so I'm curious as to how this ties into that.

[–] Phroon 3 points 1 year ago

Luckily there’s a preprint of the article on arXiv if you want to read the source material for the article.

My basic summary would be that they have a model for how variable a quasar should be over time, and they can see a difference in that variability depending on the quasar’s redshift, the distance from us. And that difference is right around what we expect from relativity.