What dictates that extra terrestrial life requires water in the same way as we do? Even on earth we have fish who can’t live in the open air, and people who can’t live underwater.
What is to say that ET can’t eat space rocks to obtain all of its nutrients, or even more, what is to say that they require nutrients at all?
Edit: Thanks for all the wonderful answers. Makes perfect sense. They aren’t so much saying we HAVE to have water to create life, more that we only know how that works and looking for the unknown in the vast expanse that is the universe would be the worlds largest needle in a haystack game.
In: Planetary Science
Scientists know what life on Earth looks like, so that’s what they’re looking for. Practically all life on Earth needs water, so if a planet has water, scientists can say that the planet could potentially harbour life (as we know it). They’re also looking for free atmospheric oxygen because it’s highly reactive and won’t remain atmospheric for long unless it’s being replenished through a biological process.
You’re asking why won’t scientists look for something else that they know nothing about. It may not even exist. If a process exists that allows for life that doesn’t require any nutrients, we have no idea what it could be. How could we possibly look for it?
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