I don't really pay an awful lot of attention to thinks related to life in space, mainly other areas is where my interests are more concentrated at.

I have picked up the idea that without water, life will not exist but is that only assumed because all life on our planet requires water? Maybe life on other planets don't need water.

Sorry if this is a very silly question, I know very little about biology.

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It has some interesting properties.
It's an excellent solvent, which means that various complex molecules can be held in suspension in the liquid, free to interact. It's liquid across a relatively wide temperature range, which means these complex molecules are less likely to end up frozen in place or lying on a dry lake bed if the temperature shifts. It has a high specific heat capacity, so it is slow to change temperature, producing a more stable environment. And solid water floats on liquid water (a very unusual property), so an insulating layer forms over freezing water, which serves again to preserve the liquid phase.
It's also cosmically common, which means we don't need to specify unusual conditions for a planet to end up with a watery environment.

And, of course, we know it's possible for life to exist in water, since we have an example of that already.

Grant Hutchison

Partially because all life that we know of requires water to live, and everywhere on our own mudball we've found water, even for extreme definitions of "water", we've found life.

It's entirely possible that something, somewhere, needs no water to live, but if there is, we don't know a testable mechanism for this yet.

It's pretty much the same answer as to why SETI searches radio waves. Because we know our own species emits/leaks EM in the radio band, we already know how to detect EM, and we don't really know how to detect most other forms of communication we can think of over stellar distances.

We have some pretty good ideas on how to find larger quantities of water molecules on other planets. You search what you know, first.

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grant hutchison: Thanks. Your answer was much more simpler than what I was expecting. It was just basic facts about water that you recited but I was just not aware of thinking about it that way.

Moose: That's an interesting way of viewing the scenario from.

Thanks people!

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Pleasure.
I may put that in my sig: "Grant Hutchison: Providing much simpler answers than you expected."

Grant Hutchison

Let me fix that for you : Water is considered an essential for LIFE AS WE KNOW IT on other planets.

...We're just starting to poke our noses out of the womb and we're lookin' for what we know and understand. That does not neccesarily mean we're the only game in town...

Life as we don't know it might not need water-
this on-line book has a chapters which discusses alternatives to water.
The Limits of Organic Life in Planetary Systems (check out chapter 6)
the rest of it is an interesting read too.

I think that much, perhaps most of the life in the universe might not use water as a primary solvent- particularly if that life has been created artificially and is robotic in nature.

On the other hand, true self-replicating robots might require water to reproduce- In fact they might be very similar to biologically evolved life in composition. The whole question of artificial self-replicating devices is still pretty much all speculation at the moment.

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LOL, love it!

It has a nice podcast too ...

I feel obligated to plug my advisor's book:
http://www.amazon.com/Life-We-Not-Kn...7945239&sr=8-2

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