Why do scientists looks for water on other planets to prove life?

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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

18 Answers

Anonymous 0 Comments

We know what water-based life forms look like. We know pretty much everything we consider a life form needs water, and is made up of it more or less. We do not even know what to even look for, to find non-water-based life forms, if anything like that does exist (big IF). This is really the main thing.

Let’s say I tell you I want you to spot me something magnetic, but also please do it from a mile away (scaled down to make it feasible to the layman, but you know). You know metal is magnetic, so you might look for something metal. Might there be SOMETHING that is not metal, that is magnetic? Sure! But you likely wouldn’t know what that is, so you wouldn’t even know what to look for, and would look for what you do know. And of course, finding metal may not mean it is for sure magnetic, but it’s a pretty good start and your best lead there.

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