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Comment by fifnir | Hacker News Reader

> We will decide it is alive but not understand fully what that means.

I don't understand fully what this comment means.

If alien life has DNA (chemistry) like ours, we learn that life as we know it either started somewhere and spread or was re-invented.

If it doesn't, but is obviously alive (move on its own will, hunts, i dont know) we learn that life can exist with different chemistries.

If it's not obviously alive but we determine anyway, whichever way we do that, we've learned of a new aspect of life.

what does "what that means" mean ? ? ?

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It means all of that. We find something we've never seen before. There's something about it that seems "alive". It's an instinctual feeling. We have to decide how "alive" that is. Is it alive like a human, a tree, bacteria, AI? I'm being general on purpose here. It's just neat that this conversation is still so relevant here on Earth. It's kind of like how alien the deep ocean still is to us.

I'm really enjoying this comment section conversation. I had to look up "Panspermia": the theory that life on Earth originated from microorganisms or chemical precursors of life present in outer space and able to initiate life on reaching a suitable environment. https://en.m.wikipedia.org/wiki/Panspermia

The odds that alien life would reinvent DNA are basically nil. If we find DNA based life elsewhere that is a slam-dunk for panspermia.

I agree, but I'm not too sure about that, but I also don't know enough chemistry to convincingly argue for the opposite..

Are there many varieties of self-replicating molecules? (which I understand is needed to start life) Maaaaybe there's only so many ways that this can get started and RNA is the "only" way to do it. In a similar way that we have a hard time imagining non-carbon life since no other element behaves in the ways that carbon does

Presuming we are exceptional finders. I think it's safe to presume the opposite though.

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