> Can't we only measure the speed of things through time relative to other things that coexist at the same time? They weren't using speed. They were watching

> Can't we only measure the speed of things through time relative to other things that coexist at the same time? They weren't using speed. They were watching how fast a clock ticked back then, the clock being a quasar. The article was light on the details, but the difficulty seemed to be that quasar's aren't reliable clocks, so they needed to develop a statistical model to measure the ticking accurately. Developing the model was actual science being reported on. It happened to agree with Einstein's predictions. But even if they were using speed, gravity doesn't slow down light. It redshift's it. So there is something you could compare your speed to back then. Finally, we are comparing how fast time ticks for us now versus how fast a quasar ticked back then. I don't know if the quasar it still around, but if it is it's probably a very different beast now. In any case we are comparing two things that don't exist at the same time. In fact, my guess is it's downright difficult compare yourself to something that exists at the same time, because the speed of light is finite. That means by the time you receive the measurement, whatever you've measured has moved on.