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Subject: ELFT HÍRADÓ
- From: "Szabados,L." <lbszab AT rmki.kfki.hu>
- To: fizinfo AT lists.kfki.hu
- Subject: [Fizinfo] Relativitaselmeleti szeminarium
- Date: Mon, 8 Jul 2013 13:59:26 +0200 (CEST)
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- List-id: ELFT HÍRADÓ <fizinfo.lists.kfki.hu>
Eloado: Prof Osvaldo Moreschi
Univ. Nac. de Córdoba, Argentina
Az eloadas cime: Unambiguous notion of total intrinsic angular momentum
in general relativity
t: 2013 julius 15 (hetfo), 14.00
(x,y,z): KFKI RMKI III. epulet, tanacsterem
The notion of total angular momentum at future null infinity has been the subject of numerous works. Different author have employed a variety of approaches that yielded nonequivalent definitions.
The key problem at future null infinity is that the symmetry group is not the ten dimensional Poincare group, but the infinite dimensional BMS group. This in turn leads to the problem of supertranslation ambiguities.
Almost all of the suggested definitions, for the general case, suffer from the so called problem of supertranslations. However, in the past we have provided with a definition of intrinsic angular momentum which have circumvented those problems and also provided at the same time with the notion of center of mass at future null infinity. This approach was based on the notion of charge integrals of the Riemann tensor.
In the case of a spacetime with axial symmetry, due to the conservation
property of Komar integrals, it is tempting to use this as the appropriate notion of total angular momentum at future null infinity. But in a realistic situation the spacetime will not have any symmetries and the problem remains.
We present here a new notion of intrinsic angular momentum at future null
infinity, based on the charge integrals approach, that is suitable for the general case of radiating spacetimes without symmetries, that do not suffer from supertranslations ambiguities, and in the case of axial symmetry it reduces to the Komar integral.
- [Fizinfo] Relativitaselmeleti szeminarium, Szabados,L., 07/08/2013
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