Concept
Maxwell’s demon
A thought experiment in which an intelligent being appears to reduce entropy by sorting molecules.
Updated Oct 6, 2026 · 1 min read · 3 connections
- Proposed
- James Clerk Maxwell, 1867
- Resolved by
- Landauer and Bennett
The paradox
Maxwell imagined a being that opens a door between two chambers of gas to let only fast molecules pass one way. The demon would create a temperature difference without work, seemingly violating the second law of thermodynamics.
Resolution
Leo Szilárd, Rolf Landauer, and Charles Bennett showed that the demon must record and eventually erase information about the molecules. Erasing information has a minimum cost in entropy, so information theory and physics are bound together.