3 ms·

> Outside of carbon chemistry your ability to create replicable life plummets. Biologists may speculate if non carbon life is possible, but there's no doubt it

> Outside of carbon chemistry your ability to create replicable life plummets. Biologists may speculate if non carbon life is possible, but there's no doubt it would be limited. Arsenic or silicon just don't have the chemical complexity carbon does. Best argument for carbon I've seen so far is that despite carbon being just 0.02% of all elements on earth it became preferred engine of life. Although I can't rule out that under different temperature, pressures and radiation some other element might be preferred if it's reasonably abundant somewhere. In my opinion if there's mostly stable, reasonable energy gradient somewhere life will find a way if possible.

JProthero 3y ago
Might the low abundance of carbon on Earth compared to its ubiquity in biology be suggestive of some kind of panspermia? Although carbon is relatively scarce on Earth, it is the fourth most common element by mass in the universe (and in Earth's solar system) [1]. The four most common elements in the human body are the same as the four most common elements in the universe, albeit in different proportions [2]. [1] https://en.wikipedia.org/wiki/Abundance_of_the_elements#Universe https://en.wikipedia.org/wiki/Abundance_of_the_elements#Univ... [2] https://en.wikipedia.org/wiki/Abundance_of_the_elements#Human_body https://en.wikipedia.org/wiki/Abundance_of_the_elements#Huma...
- augustulus 3y ago
  is there a known reason carbon is so scarce on earth compared to the rest of the solar system?
  - JProthero 3y ago
    This doesn't seem to have been firmly established, but as far as I can tell it's currently thought to be related to how carbon in the solar system's protoplanetary disk behaved when it was vaporized after fusion began in the sun. The question was studied in this paper published in 2021 [1], which is discussed in this article [2]. The authors of the paper suggest that the material that formed the Earth was depleted of carbon early in the solar system's history due to solar activity, and that most of the carbon now on Earth was delivered to the planet later on directly from the interstellar medium. I should note a couple of clarifications to my first comment: the elemental abundance I mentioned for the universe and Earth's solar system does not include helium and neon, which are abundant, but are usually ignored in this context as they're noble gases. There is also estimated to be slightly more mass in the present-day universe in the form of iron than nitrogen due to the high mass of iron atoms (nitrogen is the fourth most abundant element by mass in the human body, but the body contains relatively little iron). The number of nitrogen atoms in the universe, however, is substantially higher than the number of iron atoms. The amount of iron in the early universe should also have been lower; the element is formed late in the stellar life cycle [3], whereas the other cosmologically abundant elements that are relevant to biology (carbon, nitrogen and oxygen) are formed earlier [4]. [1] https://arxiv.org/abs/2104.02702 https://arxiv.org/abs/2104.02702 [2] https://phys.org/news/2021-04-stardust-pale-blue-dot-carbon.html https://phys.org/news/2021-04-stardust-pale-blue-dot-carbon.... [3] https://en.wikipedia.org/wiki/Iron#Cosmogenesis https://en.wikipedia.org/wiki/Iron#Cosmogenesis [4] https://en.wikipedia.org/wiki/CNO_cycle https://en.wikipedia.org/wiki/CNO_cycle
augustulus 3y ago
it could be that carbon-based life somehow pre-empts x-based life when carbon exists in the environment, even if there’s more of x
- thsksbd 3y ago
  Sure, as a matter of logic in the absence of chemical knowledge. Once you study the various elements and realize that carbons' chemistry is uniquely rich with a set of capabilities other elements lack non carbon replication becomes meh. Silicon comes close, but the energies suck, elemental Si is too stable, and its oxide a solid.
  - scotty79 3y ago
    > oxide a solid At room temperature and pressure of rooms built by beings made of carbon.
    - thsksbd 3y ago
      But we know what happens at temperatures and pressures -> things break down and become less interesting. SiO2 is quartz. At a T high enough to melt it (never mind a vaporize it to have a cycle analogous to the C-CO2 cycle), Si chemistry breaks down. Carbon chemistry is unique because it occupies a unique chemical niche. It makes interesting and stable compounds at T high enough to have appreciable rates, but low enough that things don't just rip themselves apart. Not to mention at T high enough to vaporize SiO2 you won't have water, which is a pretty nifty solvent for life to have. Think of it this way. We know the bond strength of the various chemical bondings. We cant get around that and each type of bonding is responsible for several unique and fundamental moiety in biological replication.
      - anticensor 3y ago
        > Not to mention at T high enough to vaporize SiO2 you won't have water, which is a pretty nifty solvent for life to have. Yeah, not even iron could work as a solvent at that temperature.

JProthero 3y ago

Might the low abundance of carbon on Earth compared to its ubiquity in biology be suggestive of some kind of panspermia? Although carbon is relatively scarce on Earth, it is the fourth most common element by mass in the universe (and in Earth's solar system) [1]. The four most common elements in the human body are the same as the four most common elements in the universe, albeit in different proportions [2]. [1] https://en.wikipedia.org/wiki/Abundance_of_the_elements#Universe https://en.wikipedia.org/wiki/Abundance_of_the_elements#Univ... [2] https://en.wikipedia.org/wiki/Abundance_of_the_elements#Human_body https://en.wikipedia.org/wiki/Abundance_of_the_elements#Huma...

augustulus 3y ago
is there a known reason carbon is so scarce on earth compared to the rest of the solar system?
- JProthero 3y ago
  This doesn't seem to have been firmly established, but as far as I can tell it's currently thought to be related to how carbon in the solar system's protoplanetary disk behaved when it was vaporized after fusion began in the sun. The question was studied in this paper published in 2021 [1], which is discussed in this article [2]. The authors of the paper suggest that the material that formed the Earth was depleted of carbon early in the solar system's history due to solar activity, and that most of the carbon now on Earth was delivered to the planet later on directly from the interstellar medium. I should note a couple of clarifications to my first comment: the elemental abundance I mentioned for the universe and Earth's solar system does not include helium and neon, which are abundant, but are usually ignored in this context as they're noble gases. There is also estimated to be slightly more mass in the present-day universe in the form of iron than nitrogen due to the high mass of iron atoms (nitrogen is the fourth most abundant element by mass in the human body, but the body contains relatively little iron). The number of nitrogen atoms in the universe, however, is substantially higher than the number of iron atoms. The amount of iron in the early universe should also have been lower; the element is formed late in the stellar life cycle [3], whereas the other cosmologically abundant elements that are relevant to biology (carbon, nitrogen and oxygen) are formed earlier [4]. [1] https://arxiv.org/abs/2104.02702 https://arxiv.org/abs/2104.02702 [2] https://phys.org/news/2021-04-stardust-pale-blue-dot-carbon.html https://phys.org/news/2021-04-stardust-pale-blue-dot-carbon.... [3] https://en.wikipedia.org/wiki/Iron#Cosmogenesis https://en.wikipedia.org/wiki/Iron#Cosmogenesis [4] https://en.wikipedia.org/wiki/CNO_cycle https://en.wikipedia.org/wiki/CNO_cycle

augustulus 3y ago

it could be that carbon-based life somehow pre-empts x-based life when carbon exists in the environment, even if there’s more of x

thsksbd 3y ago
Sure, as a matter of logic in the absence of chemical knowledge. Once you study the various elements and realize that carbons' chemistry is uniquely rich with a set of capabilities other elements lack non carbon replication becomes meh. Silicon comes close, but the energies suck, elemental Si is too stable, and its oxide a solid.
- scotty79 3y ago
  > oxide a solid At room temperature and pressure of rooms built by beings made of carbon.
  - thsksbd 3y ago
    But we know what happens at temperatures and pressures -> things break down and become less interesting. SiO2 is quartz. At a T high enough to melt it (never mind a vaporize it to have a cycle analogous to the C-CO2 cycle), Si chemistry breaks down. Carbon chemistry is unique because it occupies a unique chemical niche. It makes interesting and stable compounds at T high enough to have appreciable rates, but low enough that things don't just rip themselves apart. Not to mention at T high enough to vaporize SiO2 you won't have water, which is a pretty nifty solvent for life to have. Think of it this way. We know the bond strength of the various chemical bondings. We cant get around that and each type of bonding is responsible for several unique and fundamental moiety in biological replication.
    - anticensor 3y ago
      > Not to mention at T high enough to vaporize SiO2 you won't have water, which is a pretty nifty solvent for life to have. Yeah, not even iron could work as a solvent at that temperature.