B holes are among the strangest predictions of Einstein’s general theory of relativity: regions of spacetime in which gravity is so strong that nothing—not even light—can escape. More precisely, a black hole is a singularity in spacetime surrounded by an event horizon, a surface that acts as a perfect one-way membrane: matter and radiation can enter the event horizon, but, once inside, can neve...

We have shown that the dynamics of the scalar field φ(x) = “G−1(x)” in BransDicke 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 defined on the event horizon which is proportional t...

We study the thermodynamic properties associated with black hole horizon and cosmological horizon for the Gauss-Bonnet solution in de Sitter space. When the Gauss-Bonnet coefficient is positive, a locally stable small black hole appears in the case of spacetime dimension d = 5, the stable small black hole disappears and the Gauss-Bonnet black hole is always unstable quantum mechanically when d ...

We construct a new class of asymptotically flat black hole solutions in EinsteinYang-Mills and Einstein-Yang-Mills-dilaton theory. These black hole solutions are static, and they have a regular event horizon. However, they possess only axial symmetry. Like their regular counterparts, the black hole solutions are characterized by two integers, the winding number n and the node number k of the ga...

The first law of black hole mechanics was derived by Wald in a general covariant theory of gravity for stationary variations about a stationary black hole. Although it has many advantages, there are several ambiguous points in the derivation. In this paper we point out them and give a clearer derivation of it. After that, we show that there remains a problem when we consider non-stationary pert...

We argue that bound states of branes have a size that is of the same order as the horizon radius of the corresponding black hole. Thus the interior of a black hole is not ‘empty space with a central singularity’, and Hawking radiation can pick up information from the degrees of freedom of the hole. Talk given at ‘Quantum Theory and Symmetries’, Cincinnati, September 2003.

In string theory, black-hole backgrounds are far from unique and there are large families of completely smooth, horizonless geometries with the same structure as a black hole from infinity down to the neighborhood of the black-hole horizon. These microstate geometries cap off in foam of topological bubbles. I review some of the recent progress in constructing these smooth horizonless geometries...

In this paper we calculate leading order correction due to small statistical fluctuations around equilibrium, to the Bekenstein-Hawking entropy formula for the Achucarro-Oritz black hole, which is the most general two-dimensional black hole derived from the three-dimensional rotating Banados-Teitelboim-Zanelli black hole. Then we obtain the same correction to the Cardy-Verlinde entropy formula ...

We propose a simple procedure for evaluating the main attributes of a Schwarzschild’s black hole: Bekenstein-Hawking entropy, Hawking temperature and Bekenstein’s quantization of the surface area. We make use of the condition that the circumference of a great circle on the black hole horizon contains finite and whole number of the corresponding reduced Compton’s wavelength. It is essentially an...