We have shown that the dynamics of the scalar eld (x) = \G ?1 (x)" in Brans-Dicke theories of gravity makes the surface area of the black hole horizon oscillatory during its dynamical evolution. It explicitly explains why the area theorem does not hold in Brans-Dicke theory. However, we show that there exists a certain non-decreasing quantity deened on the event horizon which is proportional to...

In recent work, Hollands, Kov\'acs and Reall have built on previous work of Wall to provide a definition dynamical black hole entropy for gravitational effective field theories (EFTs). This satisfies second law mechanics quadratic order in perturbations around stationary hole. We determine the explicit form this EFT 4d vacuum gravity including terms action with up 6 derivatives. An open questio...

A black hole solution to three dimensional general relativity with a negative cosmological constant has recently been found. We show that a slight modification of this solution yields an exact solution to string theory. This black hole is equivalent (under duality) to the previously discussed three dimensional black string solution. Since the black string is asymptotically flat and the black ho...

When restricted to the horizon of a black hole, the " gauge " algebra of surface deformations in general relativity contains a physically important Virasoro subalgebra with a calculable central charge. The fields in any quantum theory of gravity must transform under this algebra; that is, they must admit a conformal field theory description. With the aid of Cardy's formula for the asymptotic de...

The black hole final state proposal implements manifest unitarity in the process of black hole formation and evaporation in quantum gravity, by postulating a unique final state boundary condition at the singularity. We argue that this proposal can be embedded in the gauge/gravity context by invoking a path integral formalism inspired by the Schwinger-Keldysh like thermo-field double constructio...

Naked singularities in the gravitational backgrounds dual to gauge theories can be hidden behind the black hole horizon. We present an exact black hole solution in the Klebanov-Tseytlin geometry [hepth/0002159]. Our solution realizes Maldacena dual of the finite temperatureN = 1 duality cascade of [hep-th/0007191] above the temperature of the chiral symmetry breaking. We compare the BekensteinH...

We present the spacetime of a five-dimensional static black hole within EinsteinMaxwell theory. The solution represents a Kaluza-Klein black hole, whereby the solution is wholly five-dimensional near the horizon, but becomes effectively fourdimensional (with a compact fifth dimension) at the spatial infinity. The black-hole is electrically charged and so has two horizons, with a horizon geometr...

We consider T-duality of the quasilocal black hole thermodynamics for the three-dimensional low energy effective string theory. Quasilocal thermodynamic variables in the first law are explicitly calculated on a general axisymmetric three-dimensional black hole solution and corresponding dual one. Physical meaning of the dual invariance of the black hole entropy is considered in terms of the Euc...