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arXiv · 1302.0800

Geometric Boundary Data for the Gravitational Field

H-O. Kreiss·J. Winicour
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Abstract

An outstanding issue in the treatment of boundaries in general relativity is the lack of a local geometric interpretation of the necessary boundary data. For the Cauchy problem, the initial data is supplied by the 3-metric and extrinsic curvature of the initial Cauchy hypersurface.. This Cauchy data determines a solution to Einstein's equations which is unique up to a diffeomorphism. Here, we show how three pieces of boundary data, which are associated locally with the geometry of the boundary, likewise determine a solution of the initial-boundary value problem which is unique up to a diffeomorphism. One piece of this data, constructed from the extrinsic curvature of the boundary, determines the dynamical evolution of the boundary. The other two pieces constitute a conformal class of rank-2, positive definite metrics, which represent the two gravitational degrees of freedom.

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H-O. Kreiss, J. Winicour. 2013-02-04. Geometric Boundary Data for the Gravitational Field. https://doi.org/10.1088/0264-9381/31/6/065004

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