This question includes Genuine Artificial intelligence as life so long as it is self replicating and sapient. Hard science only please.

Can a sapient self replicating entity be designed to exclusively be made of carbon, oxygen, and hydrogen? No other elements. Just hydrocarbon, carbohydrate, and carbon allotropes chemistry. Carbon can be very hard or soft or stretchy with various electrical thermal optical mechanical and acoustic properties just by having different allotropes. Throw in hydrogen and you now have a variety of plastic rubber type things with even more variety. Living things are made of cells and cells are just tiny microbots typically a few hundred micrometers in diameter. Is this theoretically possible?

The idea is to have a cult of normal humans design the ultimate life form to replace them. I cant go too far into the story without knowing what that ultimate form would consist of. I like hydrogen and carbon due to its incredible strength and variety. Nanomechanical computers are fast stable and efficient and the best thing to make a nano mechanical computer out of is carbon nanorods.

  • 3
    $\begingroup$ What does "Hard science only" mean? We have a hard-science tag, but that means answers must be proven by including math and/or relevant citations. It's a useful but ruthless tag that has nothing to do with the "hard science" scifi genre. Considering we don't have a clue how to create synthetic hydrocarbon-based life, what do you mean by your statement? Also, I know of no substance in nature that's 100% hydrocarbon. Everything has some other chemicals involved. Just setting an expectation. $\endgroup$ Jul 26, 2021 at 18:18
  • $\begingroup$ @JBH Lots of natural substances contain only carbon and hydrogen. There’s the alkanes just to start with — methane, ethane, propane and so on. Also of course diamond and other allotropes of carbon. $\endgroup$
    – Mike Scott
    Jul 26, 2021 at 18:22
  • $\begingroup$ Hydrocarbon or carbohydrate. By hardscience I mean no handwaving or magic. It has to be based on current laws of physics. Like dyneema is a hydrocarbon polymer. Dyneema doped with electrically conductive carbon can be a muscle as well as connective tissue. Various hydrocarbons work as a solvent. Some carbon allotropes are ferromagnetic. As I mentioned, even microbots that behave as cells are considered life if it can self replicate and support a sapient CPU. $\endgroup$ Jul 26, 2021 at 18:27
  • $\begingroup$ @MikeScott Diamond, a mineral, is only carbon, not a hydrocarbon. I see your point about propane, ethane, methane, etc. But that's a long, long way away from making an artificially intelligent computer out of just hydrocarbons. But the point is very well taken, thanks. $\endgroup$ Jul 26, 2021 at 18:28
  • $\begingroup$ @VladimirSilver Thanks, please replace science-fiction with science-based, you'll get better answers. $\endgroup$ Jul 26, 2021 at 18:28

1 Answer 1


Observation trumps over theory.

The only life forms that we know is based on carbon, hydrogen, oxygen and nitrogen, plus a topping of phosphorus, sulfur and other elements.

You are taking just the first 3 of the group, so that alone seem pointing toward a "no, life cannot exist based only on C,H and O".

Consider also that the "magic" of life is based on executing very specific chemical reaction which often use enzymes to be be completed. Enzymes are made by carefully folded proteins, whose spatial arrangement strongly depends on the availability of nitrogen. With just C, H and O you can make very long chains, but it will be hard if not impossible to make and control a spatial geometry.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .