Why do we all think that aliens are carbon based? Can't they be Silicon based, or even compuond based. Conditions would exist on their planet to permit existence of such life-forms.
Anythings possible. We shouldn't be baised towards carbon.

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Physics, chemistry, and biology favor carbon based life. We have no reason to believe that any other combination of elements not centered on carbon can achieve spontaneous generation and evolve to sentient complexity. In competition with carbon based critters each will lose to the greater stability of the carbon based critters.

Our bias is reasonable.

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For those inclined to oppose human meddling with the structure of the universe or the composition and configuration of objects and groups of objects within the universe, consider:
Whether there is a limit to the magnitude of a modulation of chaos below which order remains invariant? Or, is order but a fiction invented by perspectives applied over finite, however large, time intervals?

On Titan,there's a lot of nitrogen and ammonium...so don't you think there would be nitrogen- or ammonium-based life there?

Nope. More complex molecules are needed.

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For those inclined to oppose human meddling with the structure of the universe or the composition and configuration of objects and groups of objects within the universe, consider:
Whether there is a limit to the magnitude of a modulation of chaos below which order remains invariant? Or, is order but a fiction invented by perspectives applied over finite, however large, time intervals?

Geez, Gourdy! Earthly DNA consisted of A G C and T. It was that simple. Don't you think that in another environmnet with different conditions from our own, that life may just yet be possible in some other different manner?

Yes, but carbon based. Maybe different at the amino acid and protein level, different chirality but equivalent complexity (RNA,DNA, etc.,) and carbon based.

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For those inclined to oppose human meddling with the structure of the universe or the composition and configuration of objects and groups of objects within the universe, consider:
Whether there is a limit to the magnitude of a modulation of chaos below which order remains invariant? Or, is order but a fiction invented by perspectives applied over finite, however large, time intervals?

The reason we are carbon based and that biologists feel it is the best, if not the only, method of creating complex biological life is because carbon can have up to four other atoms form molcules with a single carbon atom. Carbon has four empty slots in it outer electron shell that can be filled and this allows for some very complex chemistry to occur. Some have speculated that since silicon also has four open slots in its outer electron shell that maybe it could also from a basis for complex biological life, but we've found no examples of it, or any possible precursor chemicals such as silcon based amino acid type compounds that could form the basis of such a life form.

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...and we'll be saying a big hello to all intelligent life forms everywhere; and to everyone else out there, the secret is to bang the rocks together, guys...

Most likely we are unique, and if any other life forms can exist elsewhere in the Universe, it will be us.

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If God existed, science would be meaningless.

What if silicon based life can exist elsewhere because the conditions are just right for silicon to form long-lasting polymers ? You know, on our planet, the conditions are also just right.
It's possible.

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I think It's already happenning...Computers. h34r:

Yes, but computers are not spontaneous life. We are searching for life which has evolved on its own, not with help from other life.

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In one of Isaac Asimov´s books he tells how an alien civilization discovers the archaeological remains of an even earlier galactic civilization that had disappeared thousands of years earlier. In their investigations one particular archaeologist - who´s considered an outcast even in their society - discovers a planet of robots who were left more or less to their own devices as a sociological experiment by the super advanced but extinct civilization. This planet of robots had been forgotten for millions of years but this archaeologist discovers its whereabouts & makes a couple of trips there. The end of the story comes when he is discovered & his (forbidden) activities are questioned & he defends himself by saying that his activities had been discovered by the robots & that they had the right to live & they had in fact dismantled his own spacecraft & had discovered FTL & were about to leave their solar system & explore the galaxy. We then discover on the last page of the book that the planet of robots was in fact the Earth & the "Robots" were humans!! :P

So who knows if we appeared without outside intervention!!!! :P

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I liked that story. But our biologists are sure that we came into existence spontaneously. I, too belive it, because we have created amino acids in the lab by simulating conditions on the early earth.

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Carbon is usually the best because it's electron field is perfectly half full. (4 out of 8 electrons) Because of that, it bonds readily with itself. Some of the strongest materials on the planet, such as diamonds, and corundum are based from carbon.

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"Human curiosity and the desire to make the intangible tangible, has led us into a new age where the New World has been settled, and the West has been won. But if you think that we, the human race, has conquered everything there is to conquer, then just look to the sky--at space--last and greatest of the frontiers."

Corundum isn't a carbon-based mineral.

It isn't? Oops..sorry. I know coal, graphite, and diamonds are though. Coal can be turned into graphite, and graphite into diamond (by metamorphism-intense heat and pressure)

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"Human curiosity and the desire to make the intangible tangible, has led us into a new age where the New World has been settled, and the West has been won. But if you think that we, the human race, has conquered everything there is to conquer, then just look to the sky--at space--last and greatest of the frontiers."

Corundum is aluminum oxide.

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...and we'll be saying a big hello to all intelligent life forms everywhere; and to everyone else out there, the secret is to bang the rocks together, guys...

Jeez man, have you like memorized all the main minerals and their components or something?

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"Human curiosity and the desire to make the intangible tangible, has led us into a new age where the New World has been settled, and the West has been won. But if you think that we, the human race, has conquered everything there is to conquer, then just look to the sky--at space--last and greatest of the frontiers."

I Googled the word and it came up. Google can tell you anything! B) Ask it "How many grains in an ounce?" and it will come up with the conversion factor. It'll do all sorts of things if you just ask it.

And I don't work for them.

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...and we'll be saying a big hello to all intelligent life forms everywhere; and to everyone else out there, the secret is to bang the rocks together, guys...

Thats what I think we are. An experement. They took neanderthals, and geneticly mutated them, and created us, and then put us here to see what we'd do, and how we'd flourish in our surroundings. I bet they also have this synthesised in a lab of some sort, and we destroyed ourself and the planet.

We could just have evolved from them you know? I don't think that we were the results of an experiment.

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Limericks, written by me: http://limericker.blogspot.com

"Anything" is not possible. Only those things permitted by the laws of physics are possible, the only caveat being that we have an incomplete knowledge of what those laws are. Life, as we understand it, is not posible based on silicon.

The reason for this is that, while silicon (Si) has 4 bonding electrons available, like carbon ( C ), Si is a bigger atom; it makes longer & weaker bonds. One result of this is that Si only makes single bonds, while C will double bond. So, for instance CO2 is a closed shell molecule, because the C has double bonded to each of the O, whereas SiO2 has only two single Si-O bonds, and still has two electrons available to bond. So the Si electrons aren't used up until you get SiO4, but since the bonds are single, SiO4 has 4 loose electrons looking for bonds, one for each O atom. The bottom line is that Si forms crystals with O and does nothing greatly interesting with H. On the other hand, C forms a gas with O (CO or CO2), and creates a suite of noncrystalline molecules that are the basis of organic chemistry. If you create a definition of "life" that is sufficiently non-commital as to exactly what "life" is, then perhaps you can claim that Si based life can exist ("living crystals" that transmit information by moving crystal defects). But that is not "life as we know it".

And here's another point. Look at the relative abundances of the elements (the plot is probably representative of the abundances in the present universe). Aside from the obvious H and He, the next most abundant elements in the universe are, in order, O, C & N (it might be easier to look at the table). We already know that "CHON" is the basis for organic chemistry, and it's no coincidence that "CHON" are also the most abundant elements in the universe. The Si relative abundance is only about 1/10 that of C. So Si is both underabundant, and deficient in double bonds. It just does not work for "life as we know it".

We should be biased towards what we know. That is not to say that imaginative ideas are not welcome, but we learn best, I think, by extrapolating (even if by a long reach), from what we know. A simplistic look at Si, seeing that it has 4 loose electrons, animates that idea of Si based life. But we should not stop there and just say "anything's possible". We should look more closely and see what really is possible, and what that means.

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