We clarify and discuss a misunderstanding between uniform completeness metric that has appeared in the literature study on Alexandrov topology for spacetime.

Semiclassical Einstein-Langevin equations for arbitrary small metric perturbations conformally coupled to a massless quantum scalar eld in a spatially at cosmological background are derived. Use is made of the fact that for this problem the in-in or closed time path e ective action is simply related to the Feynman and Vernon in uence functional which describes the e ect of the \environment", th...

Heuristic arguments and numerical simulations support the Belinskii et al (BKL) claim that the approach to the singularity in generic gravitational collapse is characterized by local Mixmaster dynamics (LMD). Here, one way to identify LMD in collapsing spatially inhomogeneous cosmologies is explored. By writing the metric of one spacetime in the standard variables of another, signatures for LMD...

We consider an exotic "compactification" of spacetime in which there are two infinite extra dimensions, using a global string instead of a domain wall. By having a negative cosmological constant we prove the existence of a nonsingular static solution using a dynamical systems argument. A nonsingular solution also exists in the absence of a cosmological constant with a time-dependent metric. We ...

Abstract We study the statistical mechanics for quantum scalar fields under the multiparameter rotating black hole spacetime in arbitrary D dimensions. The method of analysis is general in the sense that the metric does not depend on the explicit black hole solutions. The generalized Stefan-Boltzmann’s law for the scalar field is derived by considering the allowed energy region properly. Then t...

In this comment on the recently published paper “‘Global monopole in Asymptotically dS/ AdS Spacetime” [Phys. Rev. D 66 (2002), 107701], we reconsider global monopoles in asymptotic de Sitter/ Antide Sitter spacetime. In comparison to the mentioned publication, we find that the introduction of a cosmological constant can not render a positive mass of the global monopole. Moreover, we find (conf...

Maxwell’s equations with massive photons and magnetic monopoles are formulated using spacetime algebra. It is demonstrated that a single non-homogeneous multi-vectorial equation describes the theory. Two limiting cases are considered and their symmetries highlighted: massless photons with magnetic monopoles and finite photon mass in the absence of monopoles. Finally, it is shown that the EM-dua...

We discuss spherically symmetric black holes in the modified self-dual theory of gravity recently studied by Krasnov, obtained adding a Weyl-curvature dependent ‘cosmological term’ to the Plebanski lagrangian for general relativity. This type of modified gravity admits two different types of singularities: one is a true singularity for the theory where the fundamental fields of the theory, as w...