On the algebraic classification of spacetimes

Algebraic classification of numerical spacetimes and black-hole-binary remnants

Spacetimes admitting quasi-conformal curvature tensor

‎The object of the present paper is to study spacetimes admitting‎ ‎quasi-conformal curvature tensor‎. ‎At first we prove that a quasi-conformally flat spacetime is Einstein‎ ‎and hence it is of constant curvature and the energy momentum tensor of such a spacetime satisfying‎ ‎Einstein's field equation with cosmological constant is covariant constant‎. ‎Next‎, ‎we prove that if the perfect flui...

v 1 2 7 M ar 1 99 8 Connes duality in Lorentzian geometry

The Connes formula giving the dual description for the distance between points of a Riemannian manifold is extended to the Lorentzian case. It resulted that its validity essentially depends on the global structure of spacetime. The duality principle classifying spacetimes is introduced. The algebraic account of the theory is suggested as a framework for quantization along the lines proposed by ...

Quantum Field Theory on Certain Non-Globally Hyperbolic Spacetimes

We study real linear scalar eld theory on two simple non-globally hyperbolic spacetimes containing closed timelike curves within the framework proposed by Kay for algebraic quantum eld theory on non-globally hyperbolic spacetimes. In this context, a spacetime (M; g) is said to be `F-quantum compatible' with a eld theory if it admits a -algebra of local observables for that theory which satis es...

Note on (conformally) semi-symmetric spacetimes

We prove that conformally semi-symmetric spacetimes are actually semisymmetric. We also present a complete refined classification of the semi-symmetric spacetimes. PACS numbers: 04.20.Cv, 02.40.Ky, 04.20.Jb