What do people (including scientists) seem to assume....

[Princess Luna]

life on other planets will exist under the same conditions as earth? I hear scientists say, that water on other planets could mean life. But i can't help but think that, doesn't life on our planet use water because organisms evolved to use what was already here? Lets say there is a planet with seas of mercury, couldn't life evolve to use mercury in the same way we use water? The ocean on this world is radically from the surface, yet life exists in it and vice versa. Sorry if i sound like a idiot. :blushing:

[Luisrah]

life on other planets will exist under the same conditions as earth? I hear scientists say, that water on other planets could mean life. But i can't help but think that, doesn't life on our planet use water because organisms evolved to use what was already here? Lets say there is a planet with seas of mercury, couldn't life evolve to use mercury in the same way we use water? The ocean on this world is radically from the surface, yet life exists in it and vice versa. Sorry if i sound like a idiot. :blushing:

Well, it is quite possible that life exists in a completely different manner than ours.
But we know one things, life can exist with water, carbon, oxygen, etc.
Since we know that, and are not sure about there existing life with other components, then it is more probable that we will find life if we look for planets with conditions similar to the earth.

Besides, life is so complex that I think that if there are other ''lives'', then they are few. Why? Because life is extremely complex.
Water is the base of our life because of its characteristics, it's hydrogen conections, the energy it will take to heat etc etc and all the connections between our main components may not exist so deeply between other sets of components.

Sorry for the lack of technical terms, but I don't really know them in english.

It's a bit like this. You have 100 people with different characteristics each. Some of those 100 get along very well because their characteristics match, and those form one set that is suitable for life. It is possible that there is another set of people that gets along well enough to form a different form of life, but since it is so complex and there are so many things needed, then there is either a little number of other ''sets'', or they can only create simple life.

[Ocean Seal]

life on other planets will exist under the same conditions as earth? I hear scientists say, that water on other planets could mean life. But i can't help but think that, doesn't life on our planet use water because organisms evolved to use what was already here? Lets say there is a planet with seas of mercury, couldn't life evolve to use mercury in the same way we use water? The ocean on this world is radically from the surface, yet life exists in it and vice versa. Sorry if i sound like a idiot. :blushing:
I see what you're saying. Our vision of life is very carbon centric. The difference lies in the elemental structure. Mercury is a metal, and it seems rather difficult to see how it could fullfill the same purpose as water which dissolves substances, has a high specific heat (to stop evaporation), highly stable, and can contribute a hydrogen for covalent bonding with carbon. However, I believe that silicon based life may be possible and that could change our entire understanding of the necessity of water. We need to study our semi-silicon based life more thoroughly for a better understanding of what life could need.

[Zav]

Perhaps it has to do with the illusion of the superiority of man.

[ÑóẊîöʼn]

It's a case of sticking to what we know. Sure, there could be silicon-based ecologies out there, or forms of life that use methane or ammonia as solvents instead of water - such things have been the subject of speculative fiction - but how would we know what to look for?

At least with Earthlike life, we have a clear picture of what clues could indicate its presence.

[Revolution starts with U]

The problem with silicon based life, and this is not a joke, is that their poop would be large hard blocks.... very hard to pass that.
It's not impossible, it is just that all the evidence points to water and carbon based life as the most convenient and practical form of life possible.
Remember tho that scientists were holding open the possiblity of Titan, a liquid methane based environment, having abundant life.

[∞]

I think the problem is that acidic molecules have the tendency to eat up self-replicating molecules. I mean we are now starting to discover species of fish that are able to survive in sulfuric hotbeds, so this opinion on water might need some reconsidering. However I don't think it needs to be interpreted as "If there is no water, there is not life," It sounds more like "If it has water, then there is life."

[CornetJoyce]

Considering that our species has learned to thrive on hot air, there's no telling what the Martians have accomplished.

[Dr Mindbender]

The reason our understanding of bio chemistry is carbon-centric is because carbon is the only known element that shows the chain forming behaviour that is necessary for the formation of sugars, proteins and other complex structures that are necessary to sustain DNA and by extension, life. Metallic structures would be poor hosts for life due to their chemical properties.

it makes sense to assume, from empirical evidence that the same trends are consistent throughout the universe.