A power law in statistics is a relationship between quantities where one is proportional to the power of the other. Often such relations only hold over a given range. Template:
Subtypes include "square law" and "inverse-square law". Some physics examples:
A power law spectrum is a spectrum such that the flux at each frequency (or energy as per the energy-per-photon) is related to that frequency by a power law. A spectrum may be classified as basically power law, as opposed to, for example, a black-body spectrum. Cosmic rays' spectrum is basically power law.