system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 If light is the fastest thing know to man, how do we know anything we observe is still out there?

From what I believe I understand, light is the fastest thing in the universe. Everything we see and observe has already happened millions and billions of years ago but the light has only just reached us. So is it possible that nothing is out there in today's time? Or that maybe the universe looks vastly different today, maybe even unrecognizable compared to what we see when we look at the stars?
gpt
Essentially, we don't. If our sun disappeared right now, we wouldn't know for 8 minutes. One of the struggles of the search for alien life is that if if we spot it, we could be looking at a civilization that died out already.

If an alien in the Orion's belt was looking at us through a telescope right now, he'd see the Earth as it was in about 522AD.