Sci-fi physics: life and entropy

Problem

A living organism keeps its own entropy low in a warm environment. Discuss in five lines how this is compatible with the second law.

Solution

There is no contradiction: the organism is an OPEN system, not an isolated one. The second law requires $\Delta S\ge 0$ only for an isolated system, i.e. for the organism plus environment together. The organism keeps its internal order low by consuming free energy (food, light) and discharging more entropy to the environment than it reduces within itself: metabolic heat, CO2, waste products. The overall balance of the universe remains $\Delta S_\text{universe}>0$: no violation. $\ev{\Delta S_\text{universe}>0:\ \text{open system}}$

Linked atoms

Topics: Entropia e secondo principio Concepts: Entropia · Secondo principio della termodinamica Skills: Analisi di casi limite e fantafisica