9 research outputs found
Non-linear instability of Kerr-type Cauchy horizons
Using the general solution to the Einstein equations on intersecting null
surfaces developed by Hayward, we investigate the non-linear instability of the
Cauchy horizon inside a realistic black hole. Making a minimal assumption about
the free gravitational data allows us to solve the field equations along a null
surface crossing the Cauchy Horizon. As in the spherical case, the results
indicate that a diverging influx of gravitational energy, in concert with an
outflux across the CH, is responsible for the singularity. The spacetime is
asymptotically Petrov type N, the same algebraic type as a gravitational shock
wave. Implications for the continuation of spacetime through the singularity
are briefly discussed.Comment: 11 pages RevTeX, two postscript figures included using epsf.st
Thermodynamics and classification of cosmological models in the Horava-Lifshitz theory of gravity
We study thermodynamics of cosmological models in the Horava-Lifshitz theory
of gravity, and systematically investigate the evolution of the universe filled
with a perfect fluid that has the equation of state , where and
denote, respectively, the pressure and energy density of the fluid, and
is an arbitrary real constant. Depending on specific values of the free
parameters involved in the models, we classify all of them into various cases.
In each case the main properties of the evolution are studied in detail,
including the periods of deceleration and/or acceleration, and the existence of
big bang, big crunch, and big rip singularities. We pay particular attention on
models that may give rise to a bouncing universe.Comment: revtex4, 21 figures. New references added & some changes made in
Introduction. Version to appear in JCA
Classifying geometries in general relativity III: classification in practice
This is the third in a series of papers concerning a project to set up a computer database of exact solutions in general relativity which can be accessed and updated by the user community. In this paper, we describe how the Cartan-Karlhede method for classifying a geometry is accomplished in practice. We give as an example the classification of the Edgar-Lugwig conformally flat pure radiation metrics
Classifying geometries in general relativity I: standard forms for symmetric spinors
This is the first in a series of papers concerning a project to set up a computer database of exact solutions in general relativity which can be accessed and updated by the user community. In this paper, we briefly discuss the Cartan-Karlhede invariant classification of geometries and the significance of the standard form of a spinor. We then present algorithms for putting the Weyl spinor, Ricci spinor and general spinors into standard form
Classifying geometries in general relativity II: Spinor tools
This is the second in a series of papers concerning a project to set up a computer database of exact solutions in general relativity which can be accessed and updated by the user community. In this paper, we discuss the choice of computer algebra platform and the general relativity application package. The derivative operators needed in the Cartan-Karlhede classification algorithm and the behaviour of symmetric spinors under frame rotations are then presented