Equations · equation

Second Law of Thermodynamics

Thermodynamics · 1865

Equation: ΔS ≥ 0
Field: Thermodynamics
Named After: Sadi Carnot · Rudolf Clausius
Symbols: ΔS change in total entropy of an isolated system · equality only for reversible processes
Year: 1865

Significance

Disorder never decreases on its own: heat flows hot to cold, engines can't be perfect, and time gets its arrow. Born from Carnot's steam-engine analysis, named by Clausius — arguably the most unbreakable law in physics.

Minerals

Anhydrite Gypsum

Timeline

Theories

Statistical Mechanics

Machines

Watt Steam Engine Steam Turbine Vapour-Compression Refrigerator

Related

Boltzmann Entropy Shannon Entropy Heat Equation Gibbs Free Energy

Required By

Carnot Efficiency Gibbs Free Energy

Referenced by

equation

Boltzmann Entropy Carnot Efficiency Gibbs Free Energy Heat Equation Shannon Entropy

event

machine

Steam Turbine Vapour-Compression Refrigerator Watt Steam Engine

theory

Statistical Mechanics

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From the Equations database in Notion, last edited 2026-08-15. This page is the row, rendered by the build; nothing on it is written by hand.