I also agree with the CO2 statement (akin to my rule in the post that we only get to derive energy from burning fossil fuels once). These atomic-scale rearrangements change the way thermal energy can be stored into microstates (thermodynamic entropy) in a way that disordered books and papers in a room certainly do not.

Now, I have a bag full of salt (NaCl) and a bag full of another salt (suppose it’s KCl). I have a semi-permeable membrane between the bags. I built a molecular sieve using nanotechnology (meaning I borrow from nature the coding sequence for an ion channel and insert the relevant gene in an e-coli or some other host to manufacture it) that only allows potassium through to the bag containing sodium, and only allows sodium through to the bag containing potassium. I built this sieve to extract energy from the process of the ions flowing through the gradient.

Since the situation starts with one bag containing no sodium, and the other containing no potassium, I can extract useful work from this process. Second law means that if I want to reverse this situation, I have to pay a MINIMUM energy cost to reverse this situation equal to the useful work extracted from the process.

This is the same example as you gave above. If it isn’t the Second Law causing this situation, what is?

This is why we cannot remove the CO2 in the atmosphere and trap it permanently in hydrocarbons again without paying AT LEAST the energy cost of all that energy we obtained from burning hydrocarbons in the first place.

Other lifeforms stay at or slightly above room temperature.

I’m fully sympathetic to the real practicalities of marshaling scattered or disordered resources. But my main point is that nine times out of ten, the second law should be left out of the argument. It’s just not that spooky.

A narrative has developed around this theme that we take in low entropy energy (solar photons, gravitational energy, stored solar energy in chemical bonds and radioactive decay of stellar products) and emit a high entropy wake of waste (infrared photons, smaller molecules, lighter fission products). That life displays marvelous order (is a dissipative system far from thermodynamic equilibrium) — permitted by continuous feeding of this low entropy energy (if we stop eating exergy we die but we also die eventually because the genetic material which drives the continual reconstruction and repair deteriorates) — while death (inevitable) and decay represent higher entropy (not to the bacteria which feed on us causing the decay) end (not really end states but just some other states) states. That we extract low entropy concentrations of materials (ores) from the ground (concentrated by the interplay between the four fundamental forces and available energy), then disperse the contents around the world in a higher entropy arrangement (less exergy). The Second Law (tells us that these processes are irreversible) warns that there is no going back: at least not without substantial infusion of energy.(all the energy in the universe cannot reconstruct Napoleon from the scattered bits, could it?)

Human life happens when the “pockets” are shallowest, and “microscopic modes of motion” are relatively few in water. The energy cost of keeping a body at 37 is minimal, and the free energy available to make proteins/DNA etc maximal.

Then there’s the extremophiles…

Thanks for the great post.