concept

Entropy export

How a living system maintains its own order without breaking the second law of thermodynamics: it keeps its entropy low not by avoiding entropy production but by shipping that entropy outward. A biosphere receives photons from a very hot star — few photons, each energetic, low entropy — uses them to do work, then radiates infrared heat at low temperature: many photons, each feeble, high entropy. That difference pays for all the order inside. It is why matter can circulate indefinitely in an ecosystem while energy never can: a planet is nearly closed materially and wide open thermodynamically.