Concept
Entropy
A measure of the number of microscopic arrangements consistent with a system’s macroscopic state.
Updated Nov 1, 2026 · 1 min read · 4 connections
- Coined
- Rudolf Clausius, 1865
- Boltzmann formula
- S = k log W
- Unit
- Joules per kelvin
In thermodynamics
The second law of thermodynamics states that the entropy of an isolated system does not decrease over time. This asymmetry is often linked to the direction of time.
Statistical and informational views
Ludwig Boltzmann connected entropy to counting microstates, the starting point of statistical mechanics. Shannon’s measure in information theory has the same mathematical form, a link made concrete by Maxwell’s demon.