Null dust solution: Difference between revisions

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	A ] is an ] of ] in which the ] is ]. Physically speaking, this means that it describes either ], or some kind of nongravitational ] which is described by a ] ] (such as ]), or ~~both~~. Null dusts include ] as a special case.		A ] is an ] of ] in which the ] is ]. The corresponding condition on the ] can be written

			<math>T_{ab} = \Phi k_{a} k_{b}</math>

			where <math>\Phi</math> is a scalar field and <math>k_{a}</math> is any ] vector field.

			Physically speaking, this means that a null dust describes either ], or some kind of nongravitational ] which is described by a ] ] (such as ]), or a combination of these two. Null dusts include ] as a special case.

			== References ==

			{{Book reference \| Author=Stephani, Hans; Kramer, Dietrich; Maccallum, Malcolm; Hoenselaers, Cornelius; & Herlt, Eduard \| Title=Exact Solutions of Einstein's Field Equations\| Publisher=Cambridge: Cambridge University Press \| Year=2003 \| ID=ISBN 0-521-46136-7}}

Revision as of 04:00, 24 May 2005

A null dust solution is an exact solution of Einstein's field equation in which the Einstein tensor is null. The corresponding condition on the stress-energy tensor can be written

$T_{ab}=\Phi k_{a}k_{b}$

where $\Phi$ is a scalar field and $k_{a}$ is any null vector field.

Physically speaking, this means that a null dust describes either gravitational radiation, or some kind of nongravitational radiation which is described by a relativistic classical field theory (such as electromagnetic radiation), or a combination of these two. Null dusts include vacuum solutions as a special case.

References

. ISBN 0-521-46136-7. {{cite book}}: Missing or empty |title= (help); Unknown parameter |Author= ignored (|author= suggested) (help); Unknown parameter |Publisher= ignored (|publisher= suggested) (help); Unknown parameter |Title= ignored (|title= suggested) (help); Unknown parameter |Year= ignored (|year= suggested) (help)