Alternative Forms of Life?

[Morse]

The universe is infinite in its volume, and within the infinite universe there is an infinite amount of Planets and other formations composed of and containing X (X also being infinite but not increasing?) amount of matter. Now for the sake of this idea, we will assume that with an infinite amount of planets with infinite variance in conditions, there is life besides that found on Earth.

 

My question is, can life evolve from an elemental composition radically different from that of a humans? Under the conditions found on Earth, Oxygen and Carbon were the most ideal/only way for life to form. But is there a specific reason on Planet X, that X conditions made it more ideal for, say, iron based life to form?

 

Would we even be able to answer said question? Since our entire understanding of biology is based off of phenomena examined on earth, and we could not accurately detail the conditions required to form life with alternative composition because we have neither the cause nor the effect?

 

Sorry if the question itself reveals my ignorance, I'm only in high school

[iNow]

The universe is infinite in its volume, and within the infinite universe there is an infinite amount of Planets and other formations composed of and containing X

Well, while the numbers are very very very unfathomably large, they are not infinite. There are a finite number of planets and other formations... there's just a whole lot of 'em.

 

The universe itself may be infinite, but we really don't know on that one.

 

 

My question is, can life evolve from an elemental composition radically different from that of a humans?

Even here on earth life can evolve of different elements than humans. I'm thinking of things like extremophiles...

http://en.wikipedia.org/wiki/Extremophile

 

 

Under the conditions found on Earth, Oxygen and Carbon were the most ideal/only way for life to form. But is there a specific reason on Planet X, that X conditions made it more ideal for, say, iron based life to form?

Well, due to basic chemistry, there are some limitations. The molecules need to be able to change in specific ways to support life. However, as far as I know, silicon has been suggested to be rather possible as a base of life (one which is different than the carbon we're all used to).

 

 

Would we even be able to answer said question?

Well, there's always a chance we could be wrong, but... yes, absolutely we can answer it... or at least have lots of fun trying.

 

Enjoy.

[Morse]

Ahh, thank you. I had not even considered extremophiles, and yes you are right. Given the correct amount of time it would be plausible for extremophiles (as we know them) to develop into complex organisms in exactly the same way we did.

 

 

Well, due to basic chemistry, there are some limitations. The molecules need to be able to change in specific ways to support life. However, as far as I know, silicon has been suggested to be rather possible as a base of life (one which is different than the carbon we're all used to).

 

Yes, but can we account for every possible chemical reaction? I agree that there are limits, but we cannot define said limits at this time.

 

Thank you for the response! I'm looking forward to exploring this forum.

[Sisyphus]

Well, while the numbers are very very very unfathomably large, they are not infinite. There are a finite number of planets and other formations... there's just a whole lot of 'em.

 

The universe itself may be infinite, but we really don't know on that one.

 

If the universe is infinite, there is almost certainly also an infinite amount of stuff in it.

 

Well, due to basic chemistry, there are some limitations. The molecules need to be able to change in specific ways to support life. However, as far as I know, silicon has been suggested to be rather possible as a base of life (one which is different than the carbon we're all used to).

 

We think molecules need to change in specific ways to support life. But the definition of life is slippery. For example, a robot could be "alive" without employing traditional biochem, which would be a "proof of concept" that it could exist in other ways (though not that it could arise independently, although if the universe is infinite...).

 

I do think you could make an educated guess that life which is superficially at all like us would very very likely also resemble us in fundamental chemistry, or at least be one of a very few types of variations.

[ajb]

fe. However, as far as I know, silicon has been suggested to be rather possible as a base of life (one which is different than the carbon we're all used to).

 

Silicon has indeed been suggested. It is also in group 4 of the periodic table. However, the structural properties of the oxides is very different.

 

I found this web page on the oxides of carbon and silicon. It should help.

[Mr Skeptic]

Well, while the numbers are very very very unfathomably large, they are not infinite. There are a finite number of planets and other formations... there's just a whole lot of 'em.

 

The universe itself may be infinite, but we really don't know on that one.

 

Well, the basic premise in astronomy is that there is nothing particularly special about any one part of the universe, ie matter density, star density, etc. should be roughly equal everywhere at large scales. Therefore, an infinite universe does imply infinite planets. However, we are not certain whether the universe is infinite.

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Consecutive posts merged

Now for the sake of this idea, we will assume that with an infinite amount of planets with infinite variance in conditions, there is life besides that found on Earth.

 

I don't think it is necessary to assume that; if it is possible for life to form (which it is since we are here), given an infinite amount of chances it should happen an infinite amount of times. (Though with a small enough likelihood we wouldn't expect any to be near us)

 

My question is, can life evolve from an elemental composition radically different from that of a humans? Under the conditions found on Earth, Oxygen and Carbon were the most ideal/only way for life to form. But is there a specific reason on Planet X, that X conditions made it more ideal for, say, iron based life to form?

 

Not in the sense of complex chemicals like ours. Iron can't form the sort of complex molecules that carbon can. Silicon, on the other hand, can. However silicon compounds are less stable than carbon ones, so that could be a problem.

 

The elements we are build of are basically the lightest (and therefore most common) elements that can form these sorts of chemicals. So I would expect alien life to be composed largely of carbon, hydrogen, nitrogen, oxygen like we are.

 

However, if we have a radically different planet (say it orbited very close to the sun for a while) it could lose most of its lighter elements, so any life forming would have to make use of other elements.

 

I think robots of a certain complexity could be considered alive, and they really have a wide range of elements they could be composed of. However, I don't think robots can form naturally. Robots as we know them are formed from very unnatural components at large scales, and the requirements for one component to form would make it pretty much impossible for another. On the other hand, robots created by organic creatures might out-survive them, so we could still meet robotic aliens. Would this count as an answer to your question?

 

Would we even be able to answer said question? Since our entire understanding of biology is based off of phenomena examined on earth, and we could not accurately detail the conditions required to form life with alternative composition because we have neither the cause nor the effect?

 

Sorry if the question itself reveals my ignorance, I'm only in high school

 

Don't worry about it, lots of very educated, very intelligent people have been arguing about this and can't quite agree.

Edited October 7, 2009 by Mr Skeptic
Consecutive posts merged.

[CharonY]

In fact, Paul Davies, a Templeton award winning physicist argued that there may be life on earth based on different properties but biologists are too focused on DNA based lifeforms to recognize them. Not that I would be inclined to agree, but it highlights that this is an ongoing discussion (with different levels of quality, of course).

[Moontanman]

Here is some information on possible biochemistries.

 

http://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry