“This is an interesting discovery you’ve made.”
What discovery? That we don’t have the ability to travel to distant stars to conduct experiments in their proximity? I think that’s common knowledge.
“Tell me then, what is the threshold for us being able to experimentally verify light sources?”
The threshold is the practical limit to our ability to conduct the experiment, not some set distance.
OK, what is the practical limit?
Let's take Alpha Centauri. Is measuring the distance between here and there a practical experiment?
There has to be some set distance that the experiment no longer becomes practical. Please share that distance.