Dust (relativity) 3064919 28130530 2005-11-12T18:10:08Z Hillman 276528 Correction, added preliminary categorization. Please see talk page for my query about motivation for this article In [[special relativity|special]] and [[general relativity]], '''dust''' is the name conventionally given to a configuration of matter which can be interpreted as small bodies ("dust particles") which interact only gravitationally. The [[number density]] <math>n</math> of dust is defined as the number of particles per unit volume in the (unique) inertial frame in which the particles are at rest. Dust possesses a ''number flux [[four vector]]'' <math>\vec{N}</math> which defines the fluxes across coordinate planes defined by :<math>\vec{N} =n \, \vec{U}</math> where <math>\vec{U}</math> is the [[four velocity]] of the particles. ==See also== *[[Dust solution]], for more about exact dust solutions in general relativity {{Relativity-stub}} [[Category:Relativity]]