It's actually pretty obvious and you all probably know it already, but it never occured to me before now and I have never read it mentioned in correlation with aliens before.
But basically, when you see a planet that is say 10 million light years away, you are actually seeing the planet as it was 10 million years ago. So even if you don't see something on it now, as long as it has the potential to be able to support life in the future/have life evolve there --- it means it may have already evolved and/or something might have inhabited that planet in the meantime! yay!
But basically, when you see a planet that is say 10 million light years away, you are actually seeing the planet as it was 10 million years ago. So even if you don't see something on it now, as long as it has the potential to be able to support life in the future/have life evolve there --- it means it may have already evolved and/or something might have inhabited that planet in the meantime! yay!