Math & science · 1850

Laws of thermodynamics

Clausius and Kelvin state the first and second laws, and entropy enters physics.

The laws set what engines, refrigerators and chemical reactions can and cannot do. Kelvin's absolute temperature scale (1848) came from the same work.

See it in the living tree Wikipedia

Arcs above join it to what it stood on, arcs below to what it led to. The bar places this stretch on the tree's whole timeline.

What it built on 2

Conservation of energy 1847
Carnot's heat engine theory 1824

What it led to 7

Heat pump 1856
Internal combustion engine 1876
Statistical mechanics 1877
Liquid air (Linde) 1895
Greenhouse effect quantified 1896
Haber-Bosch process 1910
Superconductivity 1911

Related measurements

The dashed line marks when it first worked.

Energy used per dollar of GDP Latest: 1.21 kWh per $ (2022) Source: Our World in Data

UK coal production since 1700 Latest: 2.17M tonnes (2019) Source: Our World in Data

World primary energy by source Latest: 178k TWh (2025) Source: Our World in Data