The usual materialist story of life I've heard is that life acts like an entropy pump, creating local reductions of entropy within the organism but increasing the entropy outside of the organism. (I think I've even seen that in The Sequences somewhere? But couldn't find it, feel encouraged to link it.) But I've come to think that might actually be wrong and life might increase entropy both inside and outside the organism.
Here's a rough account:
- We ought to expect entropy to increase, so a priori life is much more feasible if it increases entropy rather than decreasing entropy.
- Living matter is built mainly out of carbon and hydrogen, which is extracted from CO2 and H2O, leaving O2 as a result. Entropy breakdown:
- The O2 left over from breaking up CO2 ought to have somewhat lower entropy than the original CO2.
- The O2 left over from breaking up the original H2O ought to have... higher entropy because it's a gas now?
- The hydrocarbons don't have much entropy because they stick together into big chunks that therefore heavily constrain their DOFs, but they do have some entropy for various reasons, and they are much more tightly packed than air, so per volume they oughta have orders of magnitude more entropy density. (Claude estimates around 200x.)
- Organic matter also traps a lot of water which has a high entropy density.
- Usually you don't talk about entropy density rather than absolute entropy, but it's unclear to me what it means for organisms to "locally" increase/decrease entropy if not by density.
- Oxygen + hydrocarbons = lots of free energy, while water + carbon dioxide = not so much free energy. We usually associate free energy with low entropy, but that's relative to the burned state where the free energy has been released into thermal energy. In this case, we should instead think relative to an unlit state where the energy hasn't been collected at all. Less energy generally correlates to lower entropy.
Am I missing something?
If black hole entropy seems paradoxical to you, then I don't think you've really understood the concept. It's because we have no idea what's going on inside a black hole that they are maxentropy objects. Every possible microstate (internal arrangement of matter and energy) corresponds to the same macrostate (mass, charge, angular momentum, linear momentum). The natural logarithm of the number of possible microstates that corresponds to the current macrostate, times Boltzman's constant, is the entropy, and black hole necessarily maximize that.
Living things increase entropy in their environment, for sure, because they consume free energy in order to preserve the low-entropy aspects of their own internal structure. If this seems in contrast with what you've been told or taught about life to date, then I suspect you haven't had very good teachers.
Over time, internal entropy of an organism will increase until it dies, because the self-preservation and repair mechanisms are not perfect. But at any given moment, if you killed the organism, it would decay until it reached equilibrium with its environment, and the entropy of what used to be its body would increase more and faster. This is because the living organism had been acting to keep its own entropy lower than it would be otherwise.