Physics Ontology

One map of physics, three ways in. Drill down on any quantity to see its units, the equations it lives in, and how its values span the universe.

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SS
Thermodynamics

Entropy

Measure of disorder or unavailable thermal energy.

SI unit

joule per kelvin (J/K)

Dimension: [ ML2T−2Θ−1 ][\,M L^2 T^{-2} \Theta^{-1}\,]

Other units

  • joule per kelvin (J/K)

Order of magnitude

How values of entropy span the physical world (in J/K, log scale).

One bit (Boltzmann)
10-23 J/K
Melting ice (1 kg)
1.22 × 103 J/K
Lower limit10-23 J/KUpper limit104 J/K

Appears in 2 equations

Entropy Change
ΔS=QT\Delta S = \dfrac{Q}{T}
Boltzmann's Entropy Formula
S=kBln⁡WS = k_B \ln W

Associated scientists

Sadi CarnotLudwig Boltzmann