Relying solely on unitarity and the consistency with large-distance black hole physics, we derive model-independent properties of the microscopic black holes and of shortdistance gravity in theories with N particle species. In this class of theories black holes can be as light as MP lanck/ √ N and be produced in particle collisions above this energy. We show, that the micro black holes must com...

This review gives an introduction into various attempts to understand the quantum nature of black holes. The first part focusses on thermodynamics of black holes, Hawking radiation, and the interpretation of entropy. The second part is devoted to the detailed treatment of black holes within canonical quantum gravity. The last part adds a brief discussion of black holes in string theory and quan...

We give several pieces of evidence to show that extremal black holes cannot be obtained as limits of non-extremal black holes. We review arguments in the literature showing that the entropy of extremal black holes is zero, while that of near-extremal ones obey the Bekenstein-Hawking formula. However, from the counting of degeneracy of quantum (BPS) states of string theory the entropy of extrema...

We consider charged rotating black holes in 5-dimensional EinsteinMaxwell theory. These black holes are asymptotically flat, they possess a regular horizon of spherical topology and two independent angular momenta associated with two distinct planes of rotation. We discuss their global and horizon properties, and derive a generalized Smarr formula. We construct these black holes numerically, fo...

There are a number of physical effects expected to be associated with black holes. Black holes are now a standard paradigm for explaining a large number of astrophysical phenomena such as quasars, gamma-ray bursts and X-ray binaries. Such astrophysical black holes are expected to be very simple, described to a good approximation by the Kerr stationary vacuum solution. Much smaller black holes m...

IntersectingM−branes are known to describe multi charged black holes. Using a configuration of such intersecting branes and antibranes, together with massless excitations living on them, we give a description of Schwarzschild black holes following Danielsson, Guijosa, and Kruczenski. We calculate the entropy of these black holes and find that it agrees, upto a numerical factor, with the entropy...

Non-supersymmetric black holes carrying both electric and magnetic charge with respect to a single Kaluza-Klein gauge field have much in common with supersymmetric black holes. Angular momentum conservation and other general physics principles underlies some of their basic features. Kaluza-Klein black holes are interpreted in string theory as bound states of D6-branes and D0branes. The microsco...

Using the quasi-normal modes frequency of extremal Reissner-Nordström black holes, we obtain area spectrum for these type of black holes. We show that the area and entropy black hole horizon are equally spaced. Our results for the spacing of the area spectrum differ from that of schwarzschild black holes. ∗E-mail: [email protected]

We study the entropy of extremal four dimensional black holes and five dimensional black holes and black rings is a unified framework using Sen’s entropy function and dimensional reduction. The five dimensional black holes and black rings we consider project down to either static or stationary black holes in four dimensions. The analysis is done in the context of two derivative gravity coupled ...