NobleSavage
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So what are the odds of non-carbon based life form?
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skepticalbip
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50:50
Either there is or there isn't.
Either there is or there isn't.
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Valjean
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I don't think we know enough about abiogenesis to formulate any odds.
It would be nice if we could compare the biology of a thousand different, unconnected planets and measure the percentage of carbon vs non carbon based life forms -- but we ain't there yet.
It would be nice if we could compare the biology of a thousand different, unconnected planets and measure the percentage of carbon vs non carbon based life forms -- but we ain't there yet.
Jokodo
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The odds relative to what?
Assuming that non-carbon based life is not intrinsically impossible and furthermore assuming an infinite universe, the odds that non-carbon based life has arisen somewhere in the universe is essentially 1.0. The odds of anything that isn't outright impossible are 1.0 in an infinite universe, including the odds of a world that is identical to ours in every respect except you having the screen name "Jokodo" and me having the screen name "NobleSavage" - if the probability of that happening is only, say 1 in 10^1000000000000 on any individual planet, it just means we'd have to check 10^1000000000000 planets, or roughly 10^999999999977 the volume of the visible universe, to find it. Since we don't know whether the universe is finite or infinite (and how big it is if finite), there's no way could estimate those global odds even if we knew everything there is to know about non-carbon based lifeforms.
So you must mean either of the two following:
1) the odds of non-carbon based life arising on any individual planet, or
2) the odds of non-carbon based life relative to carbon based life, i.e. if we ever make contact with extraterrestrial lifeforms, how likely are they to have a biology that is not based on carbon.
I'd say "very low" for both.
Also, you need to define life.
Assuming that non-carbon based life is not intrinsically impossible and furthermore assuming an infinite universe, the odds that non-carbon based life has arisen somewhere in the universe is essentially 1.0. The odds of anything that isn't outright impossible are 1.0 in an infinite universe, including the odds of a world that is identical to ours in every respect except you having the screen name "Jokodo" and me having the screen name "NobleSavage" - if the probability of that happening is only, say 1 in 10^1000000000000 on any individual planet, it just means we'd have to check 10^1000000000000 planets, or roughly 10^999999999977 the volume of the visible universe, to find it. Since we don't know whether the universe is finite or infinite (and how big it is if finite), there's no way could estimate those global odds even if we knew everything there is to know about non-carbon based lifeforms.
So you must mean either of the two following:
1) the odds of non-carbon based life arising on any individual planet, or
2) the odds of non-carbon based life relative to carbon based life, i.e. if we ever make contact with extraterrestrial lifeforms, how likely are they to have a biology that is not based on carbon.
I'd say "very low" for both.
Also, you need to define life.
NobleSavage
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Ok, the me change the title to, "lets speculate about non-carbon based life"
Valjean
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That's better.
So when our computers eventually achieve self awareness and adaptive artificial intelligence, would they then be life forms?
Is intelligent, carbon based life just a successive, serial community; part of a normal ecological succession that eventually produces a climax stage of non-organic life?
Or perhaps the usual course of evolution is for intelligent life to develop WWW technology, then wearable interactive devices, then plug in interfaces like implanted USB ports, then implanted interfaces, at which point, coupled with other mechanical and sensory assist technology, we become cyborgs.
Perhaps the organic component in advanced civilizations becomes reduced to a small internal organ, maybe a once free living organelle like a mitochondrion or chloroplast.
Maybe the universe is largely populated by intelligent, self replicating machine life.
So when our computers eventually achieve self awareness and adaptive artificial intelligence, would they then be life forms?
Is intelligent, carbon based life just a successive, serial community; part of a normal ecological succession that eventually produces a climax stage of non-organic life?
Or perhaps the usual course of evolution is for intelligent life to develop WWW technology, then wearable interactive devices, then plug in interfaces like implanted USB ports, then implanted interfaces, at which point, coupled with other mechanical and sensory assist technology, we become cyborgs.
Perhaps the organic component in advanced civilizations becomes reduced to a small internal organ, maybe a once free living organelle like a mitochondrion or chloroplast.
Maybe the universe is largely populated by intelligent, self replicating machine life.
NobleSavage
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One of the definitions for life, if I can remember back to when I had biology, was the ability to reproduce. But "reproduce" doesn't say much. An artificial intelligence can easily be programed to do: cp ai /home/new_ai
In terms of a terrestrial type environment there's basically no chance of a non-carbon life form unless it's synthetic.
Our basic chemistry is simply the only one that's viable at our temperature range.
While superficially it looks like silicon should work where carbon does in practice it doesn't work very well. Silicon doesn't like making the long chain molecules that are the driving force of life. You can make Si-O-Si-O-Si type chains (common in rocks) but when you go trying to cap off the ends with hydrogen you have a big problem: the molecule is explosive.
For an oxidizer the realistic choices are from columns 16 and 17 in the periodic table. Column 17 has a big problem, though--they bind too well, it's awfully hard for them to react. This might not be insurmountable at higher temperatures but the atomic abundance is another matter--oxygen is far more common than anything from column 17 and it will react with them. To have say a chlorine atmosphere you need to have enough chlorine to react with all that oxygen--remember it's two chlorine atoms per oxygen atom--and you're not going to find that. Furthermore, you must have enough chlorine to react with all the places in the environment normally taken up by oxygen (remember those Si-O based rocks???) and that's an even greater hurdle. It's not going to happen.
Going down column 16 we find sulfur. Oops, a solid at room temperature. Again, possibly a high temperature chemistry but not viable in our environment. Once again atomic frequency also prevents it--sulfur and oxygen react. You're not going to get a sulfur-based ecology unless there is more sulfur than oxygen. (I'm not sure about how it fares in the environment.)
You also need a solvent. In anything like our environment there's only one: water.
We don't really know enough about super-cold chemistry to say life is impossible on something like Titan, though.
Our basic chemistry is simply the only one that's viable at our temperature range.
While superficially it looks like silicon should work where carbon does in practice it doesn't work very well. Silicon doesn't like making the long chain molecules that are the driving force of life. You can make Si-O-Si-O-Si type chains (common in rocks) but when you go trying to cap off the ends with hydrogen you have a big problem: the molecule is explosive.
For an oxidizer the realistic choices are from columns 16 and 17 in the periodic table. Column 17 has a big problem, though--they bind too well, it's awfully hard for them to react. This might not be insurmountable at higher temperatures but the atomic abundance is another matter--oxygen is far more common than anything from column 17 and it will react with them. To have say a chlorine atmosphere you need to have enough chlorine to react with all that oxygen--remember it's two chlorine atoms per oxygen atom--and you're not going to find that. Furthermore, you must have enough chlorine to react with all the places in the environment normally taken up by oxygen (remember those Si-O based rocks???) and that's an even greater hurdle. It's not going to happen.
Going down column 16 we find sulfur. Oops, a solid at room temperature. Again, possibly a high temperature chemistry but not viable in our environment. Once again atomic frequency also prevents it--sulfur and oxygen react. You're not going to get a sulfur-based ecology unless there is more sulfur than oxygen. (I'm not sure about how it fares in the environment.)
You also need a solvent. In anything like our environment there's only one: water.
We don't really know enough about super-cold chemistry to say life is impossible on something like Titan, though.