Dust (relativity)
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2005-11-12T18:10:08Z
Hillman
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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]]