what is life?

[claymore]

we are always searching for planets where water might exist. Is there any possibility that life could start on a planet where water was not a prerequisite. could there be such a thing as non organic life?

[jake-the-peg]

A fundamental requirement of life is the ability to pass information from one generation to another.

This means you need to encode this information chemically.

If you did so with millions of seperate chemicals you have the problem of ordering them so that information becomes meaningful.

So you need a large molecule to organise the data.

Our life systems have solved that issue with carbon which is capable of forming huge chains.

Silicone (..-Si-O-Si-O-...) also can do this trick but carbon dioxide is soluable in water whereas silicon dioxides are not.

This is a significant problem as you'll need another solvent and that doesn't seem likely given how common water is in the Universe.

[dannyday5821]

remember jurassic park? a quote from there, has always stuck with me, which was "life will find a way"

this, i believe is true, for any given circumstance. i believe life will always find a way to live, regardless of reason or a known concsciousness. so, although i know pretty much nada in regards to science, my belief tells me otherwise.

Not only that...but heres something ive always struggled to understand. we can only base what we know about life, based on the things we have found and researched on earth. whats to say, we discover a new element, totally different, but perhaps with similar properties to water, that enables life to prosper in different environments. its a thought.

but, i presume we always search for water, because from what we know on earth, if we find water somewhere else on another planet, it means theres no reason, as far as were concerned, that life couldnt exist.

[wildwood]

Your question always generates another question... how do you define alien life?

In the immenseness of the universe nothing can be discounted completely. Earth didn't always have liquid water and Mars and some moons are believed to contain water in the form of underground ice and rocks.

Tongue in cheek - how do you know that the billions of star systems are not the equivalent of cells in our bodies of a gigantic alien life form?

I'll get my coat........

[Teddio]

Water is an excellent solvent but there are other non-aqueous solvents in which complex chemical reactions could take place, for example liquid ammonia, sulphur dioxide and hydrogen cyanide.

[claymore]

Just wondering Jake, how common is water in the universe, in percentage terms?