The underlying dynamics are reversible, if weirdly. Black holes have non-zero temperature and emit Hawking radiation, slowly evaporating in the process.
And yes, entropy is a scalar, and it’s well defined both an overall system and for each subset of that system. What keeps the entropy of a living thing lower than that of an undifferentiated soup of molecules? Structures that separate and organize those molecules. That’s what I mean by aspects.
Others have already noted that it seems like you’re asking a hard-to-parse set of nonstandard questions, so sorry for any misunderstandings on my part.
You’re right that internally, organisms control the production and flow of entropy, rather than the absolute entropy as such. So if you’re asking whether the entropy of the body is higher than it would be if it were cooled to a lower room temperature, then yes. But that means the answer to your question depends on whether the organism is currently in Phoenix in summer or Canada in winter, or whether it’s warm or cold blooded. I’m not sure this question is interesting in regards to how likely life was to evolve in the first place. I suspect not very.
We ought to expect entropy to increase, so a priori life is much more feasible if it increases entropy rather than decreasing entropy.
Is spontaneous freezing of ice at low temperature a violation of the second law? No, because as described you wouldn’t be measuring the same system over time. You’d be measuring “Water” one one side and “Ice but not the heat given off” on the other. This also is why most of the rest of your bullet points are not really related to the second law as such. You can’t count the entropy of O2 evolved in photosynthesis while ignoring that of the C and the H and the absorbed photons and the emitted waste heat.
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.
It means, how fast is the total entropy of the combined system increasing, and where is the entropy going?
If I mix together (dissolve) a pile of food small molecules (Water, sugars, amino acids, fatty acids, glycerol, nucleic acids, mineral salts), with the same elemental composition and temperature as my body, which has higher entropy? The former.
If I cool the pile but add enough extra sugar that, if burned, would heat it to body temperature, then what’s the answer? I’m not sure. But if I did the sugar burning to raise the temperature, consumed ambient O2, and emitted CO2 and H2O in the process, then the resulting system (hot solution + emitted gases) has even more entropy than the initially-warm pile.
Over the course of my life, my body built itself up out of exactly those kinds of components, creating a lower-entropy-than-a-solution-of-food-molecules body and a high entropy stream of waste gases, liquids, solids, and heat. This is the sense in which bodies are low-entropy.
The underlying dynamics are reversible, if weirdly. Black holes have non-zero temperature and emit Hawking radiation, slowly evaporating in the process.
And yes, entropy is a scalar, and it’s well defined both an overall system and for each subset of that system. What keeps the entropy of a living thing lower than that of an undifferentiated soup of molecules? Structures that separate and organize those molecules. That’s what I mean by aspects.
Others have already noted that it seems like you’re asking a hard-to-parse set of nonstandard questions, so sorry for any misunderstandings on my part.
You’re right that internally, organisms control the production and flow of entropy, rather than the absolute entropy as such. So if you’re asking whether the entropy of the body is higher than it would be if it were cooled to a lower room temperature, then yes. But that means the answer to your question depends on whether the organism is currently in Phoenix in summer or Canada in winter, or whether it’s warm or cold blooded. I’m not sure this question is interesting in regards to how likely life was to evolve in the first place. I suspect not very.
Is spontaneous freezing of ice at low temperature a violation of the second law? No, because as described you wouldn’t be measuring the same system over time. You’d be measuring “Water” one one side and “Ice but not the heat given off” on the other. This also is why most of the rest of your bullet points are not really related to the second law as such. You can’t count the entropy of O2 evolved in photosynthesis while ignoring that of the C and the H and the absorbed photons and the emitted waste heat.
It means, how fast is the total entropy of the combined system increasing, and where is the entropy going?
If I mix together (dissolve) a pile of food small molecules (Water, sugars, amino acids, fatty acids, glycerol, nucleic acids, mineral salts), with the same elemental composition and temperature as my body, which has higher entropy? The former.
If I cool the pile but add enough extra sugar that, if burned, would heat it to body temperature, then what’s the answer? I’m not sure. But if I did the sugar burning to raise the temperature, consumed ambient O2, and emitted CO2 and H2O in the process, then the resulting system (hot solution + emitted gases) has even more entropy than the initially-warm pile.
Over the course of my life, my body built itself up out of exactly those kinds of components, creating a lower-entropy-than-a-solution-of-food-molecules body and a high entropy stream of waste gases, liquids, solids, and heat. This is the sense in which bodies are low-entropy.