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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σ\sigma
Quantum

Cross Section

Effective area quantifying interaction probability.

SI unit

square metre ()

Dimension: [L2][\,L^2\,]

Other units

  • square metre ()
  • barn (b)×1.00e-28

Order of magnitude

How values of cross section span the physical world (in , log scale).

Neutrino scattering
10-47
Nuclear reaction
10-28
Lower limit10-48 Upper limit10-24