Сантиметр-грамм-секунд жүйесінің нұсқасы: Гаусс бірліктері

Variant of the centimetre–gram–second unit system

Gaussian units constitute a metric system of physical units. This system is the most common of the several electromagnetic unit systems based on cgs (centimetre–gram–second) units. It is also called the Gaussian unit system, Gaussian cgs units, or often just cgs units. The term "cgs units" is ambiguous and therefore to be avoided if possible: there are several variants of cgs with conflicting definitions of electromagnetic quantities and units. SI units predominate in most fields, and continue to increase in popularity at the expense of Gaussian units. In technical, scientific literature (such as theoretical physics and astronomy), Gaussian units were predominant until recent decades, but are now getting progressively less so. but the 9th SI Brochure makes no mention of CGS systems. Natural units may be used in more theoretical and abstract fields of physics, particularly particle physics and string theory.

One difference between Gaussian and SI units is in the factors of 4π in various formulas. With SI electromagnetic units, called rationalized, Maxwell's equations have no explicit factors of 4π in the formulae, whereas the inverse square force laws – Coulomb's law and the Biot–Savart law – do have a factor of 4π attached to the With Gaussian units, called unrationalized (and unlike Heaviside–Lorentz units), the situation is reversed: two of Maxwell's equations have factors of 4π in the formulas, while both of the inverse square force laws, Coulomb's law and the Biot–Savart law, have no factor of 4π attached to in the denominator. (The quantity 4π appears because is the surface area of the sphere of radius r, which reflects the geometry of the configuration. For details, see the articles Relation between Gauss's law and Coulomb's law and Inverse square law.)