system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Can a planet without conditions similar to earth support any life at all, or have we just not found organisms that require other conditions?

So if a planet has an atmosphere of 90% hydrogen and we say it is "uninhabitable." Does that  mean no organism at all could survive? Or is it that we just don't know about organisms that could survive in those conditions?
gpt
It's the latter. We only know life on earth -- life as we know it. It's possible there could be exotic forms of life elsewhere, but we have no idea what it would look like or how to find it. So we focus on the life we understand, because that's what we're best at finding.

To some degree though, we know the chemicals our life is based on are probably some of the best for "life". Carbon has specific properties that make it very nice for replication and other life functions. Silicon is very similar to carbon, which is why you often hear about people looking for "silicon based life" -- it's the most likely other element that could produce organisms that follow similar mechanics as ours.