We’ve all heard it. We think we understand it: entropy is a measure of disorder. Combined with the Second Law of Thermodynamics—that the total entropy of a closed system may never decrease—it seems we have a profound statement that the Universe is destined to become less ordered.
The consequences are unsettling. Sure, the application of energy can reverse entropy locally, but if our society enters an energy-scarce regime, how can we maintain order? It makes intuitive sense: an energy-neglected infrastructure will rust and crumble. And the Second Law stands as a sentinel, unsympathetic to deniers of this fact.
You should call it entropy…nobody knows what entropy really is, so in a debate you will always have the advantage.
- If I took the system to zero temperature and then added energy until getting back to the original temperature, would the amount of energy required be different for the two configurations?
- Is there an intrinsic physical process by which one state may evolve to the other spontaneously? In other words, are the items continuously jostling about and changing configuration via collisions or some other form of agitation?
A narrative has developed around this theme that we take in low entropy energy and emit a high entropy wake of waste. That life displays marvelous order—permitted by continuous feeding of this low entropy energy—while death and decay represent higher entropy end states. That we extract low entropy concentrations of materials (ores) from the ground, then disperse the contents around the world in a higher entropy arrangement. The Second Law warns that there is no going back: at least not without substantial infusion of energy.
- Energy may be extracted when temperature differences exist (e.g., combustion chamber compared to ambient environment; solar surface temperature compared to Earth surface). Entropy measures of the energy itself are not meaningful.
- Net energy from fossil fuels may only be extracted once.
- Efficiencies are capped at 100%, and often are theoretically much lower as a consequence of the Second Law.