Type Alias: Backbone

Backbone = "C" | "Si" | "S"

Which chemistry life is built from — derived, not assumed.

This is not speculative xenobiology. Everything below is the ordinary behaviour of the periodic table: bond energies we have measured, hydrolysis we have observed, abundances we have counted in stellar spectra. Given a world's temperature and composition, the chemistry that follows is not a choice anyone makes. It is what happens.

On Earth, carbon wins decisively and the reasons are quantitative: carbon self-bonds at 346 kJ/mol against silicon's 226, and carbon is roughly seven times more abundant. Long chains need both, so carbon it is.

But two of those facts are conditional. Si-Si and Si-O-Si chains hydrolyse in liquid water — which is why silicon chemistry is discounted for Earth and seriously discussed for hot, dry worlds, where silicones are stable and carbon chains are the ones falling apart. And abundance is set by a galaxy's enrichment history, not by anything universal.

So the backbone is SCORED from this world's actual temperature and actual abundances, and whatever wins is what tissue is made of. A player who lands on a hot silicate world is not playing a science-fiction variant. They are watching the same rules produce a different outcome.