Let see, lets compare Si to C.
SiO2 is a solid and is also insoluble in everything that isn't ridiculously alkaline.
Analogues of hydrocarbons, polysilanes, are very unstable at room temperature (=they break down), and also they react with oxygen.
Silicones, formed by Si-O-Si-O chains with "R" (often alkyl groups) attached to the Si's, are very stable and are used in oven sealants and so on. The carbon analogue would be some kind of poly-aldehyde, which wouldn't be stable at all, and would very likely (like paraldehyde does) spontaneously react with oxygen.
Carbon is rather unique, as is oxygen. The amino acids are even worse, trying to imagine something else being as incredibly versatile as amino acids, peptides and proteins is very, very hard.
My bet is that higher alien life would all be carbon based, breathe oxygen and would be composed of amino acids and would most likely use some kind of carbohydrates for energy. These three have so many advantages it is highly unlikely that something else would spontaneously evolve.
Then the weirdness can start, but realistically, not before. All we "know" about sentient life in the universe is that it evolved from un-sentient life, so if an imaginary alien couldn't handle simple tools as well as crude weapons and fight/ run away from predators , the design is bad.
SiO2 is a solid and is also insoluble in everything that isn't ridiculously alkaline.
Analogues of hydrocarbons, polysilanes, are very unstable at room temperature (=they break down), and also they react with oxygen.
Silicones, formed by Si-O-Si-O chains with "R" (often alkyl groups) attached to the Si's, are very stable and are used in oven sealants and so on. The carbon analogue would be some kind of poly-aldehyde, which wouldn't be stable at all, and would very likely (like paraldehyde does) spontaneously react with oxygen.
Carbon is rather unique, as is oxygen. The amino acids are even worse, trying to imagine something else being as incredibly versatile as amino acids, peptides and proteins is very, very hard.
My bet is that higher alien life would all be carbon based, breathe oxygen and would be composed of amino acids and would most likely use some kind of carbohydrates for energy. These three have so many advantages it is highly unlikely that something else would spontaneously evolve.
Then the weirdness can start, but realistically, not before. All we "know" about sentient life in the universe is that it evolved from un-sentient life, so if an imaginary alien couldn't handle simple tools as well as crude weapons and fight/ run away from predators , the design is bad.
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