Does Life Really Depend on Water?

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Good day.
I am by no means an expert in the fields of chemistry or biology. Far from it. But I've had this question for a while, I've done some research and was unable to find a very clear answer.
Science are looking for liquid water on planets and their satellites because apparently life is dependent on water and where there's water, there's probably life. I would like to know why? Sure, on Earth, most life depends on water. I understand that. And as far as I know, most life on Earth are Carbon based. What I would like to know is why does it seem impossible for different, extraterrestrial, life which are perhaps not Carbon based at all to be dependent on other forms of liquid instead?
Maybe this is not a good question as I said, I do not know much about either chemistry or biology but why isn't it possible for, let's say, an Oxygen based life form to exist by means of liquid Nitrogen? Or something similar? Shouldn't science be looking for any type of liquid instead of just water?
I hope this doesn't seem too outrageous and I hope someone would be able to help me answer these questions. Thanks!

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Type: Question • Score: 1 • Views: 2,843 • Replies: 14

View best answer, chosen by StephanRoelofse

@StephanRoelofse,

The type of life we are familiar with depends on water especially in early development.

By looking for liquid environments (planets, moons, etc) they are only trying to maximize probabilities of discovery based on the only data point we have (ourselves). Also, we might not even recognize other forms of life even if we saw it.

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@rosborne979,

Thanks for your reply. I guess this makes sense. We are only choosing to search for life in a form that we are familiar with. It doesn't necessarily mean that other forms of life does not exist.

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@StephanRoelofse,

Liquid water is an excellent mixer. Other liquid elements not so much.
I am not an expert on chemestry either, but this is the reason I am aware of why water is made a big deal in the search for alien life as WE know it.

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@StephanRoelofse,

Quote:

Maybe this is not a good question

Indeed Steve it's a fine q and one I've long pondered. Considering the fact that recent studies indicate more planets than stars I'd guess that here and there in the Univ, some 'life' is based on other substances, depending on the sphere's relationship to its sun

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@StephanRoelofse,

water is a fuid that is one of the "best universal solvents". Its polr (It has a plus and minus side) and its a major molecule that sports hydrogen bonds so its almost indestructible. It is waaay better than anything else to preserve a liquidus state over a wide range f comfort.

Weve always kidded about Si based life but the liquidus "Siliceous acid" requires so many specialized chem environmental conditions. Sam thing with ammonia, its mix as a hydroxide is just water and ammonia

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Water has an arrow range in which it is liquid. Fluids like ethane or methane might be more common, but we don't know what type of life might evolve in that environment.

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@dalehileman,

People are always talking about "life as we know it". I just thought that with the immense amount of planets out there. Life as we know it, is just a very very small part of life that actually exists. With such an old and large universe, clearly the possibilities for life has to be near endless? I get it, that water is a great solvent. I just wondered if there might be a possibility that life can exist completely independent of water. Or perhaps independent of any form of liquid at all? Might it be possible for organic molecules to form in a gas?

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@StephanRoelofse,

I have no way of proving it but I think that water is a necessity to any beginning of carbon based life. Its a special liquid that is polar, is durable (based on the H bonds holding the molecule together), and it's polarity can affect surface reactions of other molecules especially polymers and fatty acids and esters, as well as various linkages.

All evidence we have from this planet about the origins of life, seem to occur only in palludal and alluvial basins (ponds, lakes and streams)
We do see extremophilic archea, but even these exist in the water phases like steam and ice.

Sci fi books were written about silica based life and the more we look at that the more unlikely it appears.

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@StephanRoelofse,

StephanRoelofse wrote:

Life as we know it, is just a very very small part of life that actually exists. With such an old and large universe, clearly the possibilities for life has to be near endless?

We really need another (or many more) data points to work with before we can start making educated guesses. That's partly why it's so important to find even simple biology on other worlds. It could tell us a lot about the variety that life can take.

At the moment we only know of one form of life, and it all uses DNA and evolved in water. And I think it's very tempting and a bit too easy just to assume that all life would follow that pattern, or even that a predominance of life would follow that pattern. We just don't know yet.

Need more data. Smile

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Listen to Farmerman. His responses on this thread are relevant and scientifically correct (including was he says about carbon the importance of water being polar) and he understands the science. If I could, I would give him the red ribbon.

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@StephanRoelofse,

Very interesting discussion.

Probably carbon is the most promising candidate to be the basis for life. I think because it is able to form long chains and it can form more complex chains than for example silicon. A necessary condition to store and transfer information which is necessary for life (coding proteins and so on..).

Some people have said that life may be very different on other plantes than here on Earth. I totally agree, but totally different does not necessarily mean not carbon based.
We have DNA to store information. The molecules from alien species that do that job might be very different and hence these life-forms may be too.

1 Reply

@helmi15,

a thought experiment based on your choice of indespensable molecules.
In the human body, what is the strongest chemical bond of which we are certain??

Does Life Really Depend on Water?

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