ALT Two side-by-side cartoon schematics depict a heat engine as an entropy process analogous to arbitrage in economics. On the left schematic, a gray rectangle representing a heat engine receives energy from a hot reservoir above it — a red rectangle — a process depicted with a thick green down arrow. A blue rectangle sits below the heat engine, receiving energy from it — a process depicted with a thin green down arrow. Entropy exchange is represented with two white down arrows next to the two green down arrows. A thin green arrow points to the left of the heat engine, representing work output. In the right schematic is a similar pair of rectangles colored red and blue, but this time they both contain symbols of cash and sheep. A human symbol stands in place of the heat engine, with cash and green down arrows to the left of it and sheep and black up arrows to the right. A green arrow points to the left of the human towards a bank symbol.