O2 is a triplet state molecule, so it has huge kinetic barriers for reactions. > No alien species advanced enough to look at us would assume we’d burn just because we have 0.21 Po2

The fact that there is excess of a reactant really means that there is an ability for interesting reactions, and therefore life. Ash cannot be animate because it’s (basically) at ground level and does not have the free energy to do anything.

What they should be thinking is, O2 is very reactive. There must be some active chemical process, powered by a pervasive energy source going on at massive scale replenishing it constantly. What on Xebron 5 could that be?

>Maybe they're looking at us and think "What 21% O2? Surely no life could exist there, everything would just burn down immediately!"

I swear, this is an exact line from a Ray Bradbury story that I read as a child.

Also Clarke, in the title essay of 'Report on Planet Three'. The flaw in this argument is that an out-of-equilibrium concentration of oxygen implies a process to maintain it.