Journal article

LTB spacetimes in terms of Dirac observables

Publication Details
Author(s): Giesel K, Tambornino J, Thiemann T
Publication year: 2010
Volume: 27
Journal issue: 10
ISSN: 0264-9381


The construction of Dirac observables, that is, gauge-invariant objects, in general relativity is technically more complicated than in other gauge theories such as the standard model due to its more complicated gauge group which is closely related to the group of spacetime diffeomorphisms. However, the explicit and usually cumbersome expression of Dirac observables in terms of gauge noninvariant quantities is irrelevant if their Poisson algebra is sufficiently simple. Precisely that can be achieved by employing the relational formalism and a specific type of matter proposed originally by Brown and Kuchar, namely pressureless dust fields. Moreover one is able to derive a compact expression for a physical Hamiltonian that drives their physical time evolution. The resulting gauge-invariant Hamiltonian system is obtained by Higgs-ing the dust scalar fields and has an infinite number of conserved charges which force the Goldstone bosons to decouple from the evolution. In previous publications we have shown that explicitly for cosmological perturbations. In this paper we analyse the spherically symmetric sector of the theory and it turns out that the solutions are in one-to-one correspondence with the class of Lemaitre-Tolman-Bondi metrics. Therefore, the theory is capable of properly describing the whole class of gravitational experiments that rely on the assumption of spherical symmetry.

How to cite
APA: Giesel, K., Tambornino, J., & Thiemann, T. (2010). LTB spacetimes in terms of Dirac observables. Classical and Quantum Gravity, 27(10).

MLA: Giesel, Kristina, Johannes Tambornino, and Thomas Thiemann. "LTB spacetimes in terms of Dirac observables." Classical and Quantum Gravity 27.10 (2010).

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