Life on other planets

All i keep hearing is that life cant exist without water. How do we know this? I mean just because life on THIS planet cant exist without it is not to say that life on other planets cant. I mean life on other planets may not be carbon based as we are. It may be silicone based or something else.

Isnt it really ignorant to say that no life can exist without water based on one planet that we know of (Earth) and one lifeform?.

I dont just mean intelligent life(is there such a thing?). I mean any life form be it intelligent,bacterial,microbial etc etc etc.

Paul,

I don't think anyone seriously suggests that life CAN'T exist without water, just it's a lot less likely. When you see some of the inhospitable places life exists on this planet. For example, Balbriggan, Clondalkin, Killiney?? Who'd have thought it eh? Seriously though, primitive life has been found in some really strange places like black smokers at the bottom of the dark ocean where they thrive on sulphur.

When you hear people say, oh life can;t exist there, there is no water, they are ususally referring to places in the solar system. From what we know of life at present, water is a pre-requisite. So no water makes life extremely unlikely at best.

You can speculate all you like about silicone based life forms etc, but until there is at least some science to suggest that life could take that form, there is really not a lot of point in worrying too much about it.
From what we know, life is far more likely in places with water. If you're looking for an egg, then look in a hen house:)

Seriously though, primitive life has been found in some really strange places like black smokers at the bottom of the dark ocean where they thrive on sulphur.


Thats exactly what i was thinking of when i posted.

Granted it desnt help my comment due to the fact they live in water.............but the water is not what they thrive on.............its the sulphur.

So it shows that not all life is dependent on water.

From what we know, life is far more likely in places with water. If you're looking for an egg, then look in a hen house:)

True enough but isnt that taking a very narrow minded approach? indeed isnt it restricting us from maybe finding life on other planets is we are only looking in places where water may or could exist?

No harm in widening the scope a bit and taking a chance on planets that have no water or the chance that they may have had or ever will have water.

Just because we know one way to bulid a wall................doesnt mean there are not other ways. We just have not considered them yet cuz the way we know works best for us.


Isnt a lot of science based primerily on theory? so isnt it possible in theory to assume that there can be life forms existing that are not carbon based and dependent on water?

Its free to theorize. Just dont dismiss it as theoretically impossible based on the finding of this planet.[/i]

Granted it desnt help my comment due to the fact they live in water.............but the water is not what they thrive on.............its the sulphur.

So it shows that not all life is dependent on water.

No it shows that they can get their energy by oxidising sulphur. They are still dependant on water needing water within them to oxidise the sulphur (or iron or other metals that these things 'feed' on).

Isnt a lot of science based primerily on theory? so isnt it possible in theory to assume that there can be life forms existing that are not carbon based and dependent on water?

Possible, but if life is to be anything remotely like we see on Earth the elements used will need to be able to form into large chains - an equivalent to hydrocarbons in Earth life. The best hope for this is Silicon, its in the same group in the periodic table and can form long chains.

One reason that's give that this is unlikely is a practical one. Carbon combines with oxygen in earth based life. This produces carbon dioxide which is easy to excrete since it is a gas. Silicon dioxide is a solid which would make excretion difficult.

I read somewhere once that Silicon can not produce an equivalent to carbohydrates, which would mean that organisms effectively cannot store energy.

You might find this interesting en.wikipedia.org/wiki/Alternative_biochemistry

Of course our 'first contact' if it happens may be with silicon 'life' if sci-fi theories are correct. Whatever ancient carbon civilisation that existed may have created silicon based beings and it is them that we might encounter!

True enough but isnt that taking a very narrow minded approach?

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Paul, maybe when we've looked in all the hen houses then we can look elsewhere. But until then why go searching places where life is less likely. Up to know we haven't even gotten close to looking in all the hen houses.

Look where the water is, if you don't find any there then examine other possibilities. Just because life could form from other basic compounds like silicone does not mean that it actually does.

Why would you want to spend money sending a probe to look for life in Jupiter's clouds when most of Mars is as yet unexplored. There is likely an water ocean under the ice crust of europa. We haven't gone there yet. When we've looked in all these places then it makes sense to look in the less likely places.

Why would you want to spend money sending a probe to look for life in Jupiter's clouds when most of Mars is as yet unexplored. There is likely an water ocean under the ice crust of europa. We haven't gone there yet. When we've looked in all these places then it makes sense to look in the less likely places.

I'd rather have a close look at Venus's atmosphere before bothering with Jupiter.