Sharif Digital Repository

In the era of precision cosmology it is desirable to know if the collapse of an overdensity region within a FRW cosmological model leads to a black hole similar to that of Schwarzschild. Even the simple question of an event horizon within a dynamical universe is not a trivial one. This subject of studying collapsing over-densities within an expanding universe is called ”cosmological black holes”. Our aim is to construct such a black hole in the simplest possible scenario and study its similarities and differences to the familiar Schwarzschild one in vacuum. Therefore questions of rotating or charged black holes are not dealt with in our work. We insist, however, that the solution is dynamic... 

We have tried this for the first time to reperesent a comprehensive description of the evolution of a perfect fluid in inhomogeneous relativistic models.We solve Einstein equations using numerical methods.In this procedure we can evaluate the effect of pressure in perfect fluid evolution.Also we look at the behavior of the various horizons, and in the end we will present a cosmological model to a black hole  

Truth and Method is one of the two or three most important works of this century on the philosophy of humanistic studies. The book is powerful, exciting, but undeniably difficult. Published when Gadamer was sixty, it gathers the ripe fruit of a lifetime's reading, teaching, and thinking. Because it is immersed in German philosophy and scholarship, the book is even more challenging for an American reader. An emerging body of commentary in English as well as the many shorter essays Gadamer has, happily, lived to write and which are increasingly available in translation provide additional means of access to his thought. Truth and Method, however, remains his magnum opus, the comprehensive and... 

One of the main subjects that has been vastly studied recently, is the final fate of Black holes with Hawking radiation. Radiation of a black hole changes the black hole, thus horizons of the black hole will also have dynamics. For a radiating black hole the inward flux of matter and the flux of radiation are two important factors for determining black hole energymomentum tensor that determine dynamics of different kinds of horizons. Quantum flux calculation needs choosing a proper quantum state as vacuum for calculating the expectation value of energy-momentum tensor. In this thesis we have attempted to write a useful reference and we hope it could help the reader to prepare for studying... 

Black holes are a general set of solutions of Einstein’s general relativity. Their most important feature is the horizon, which is basically a region that separates the space-time into two causally disconnected regions. Studying the general features of black holes, classifying this family of solutions and studying the dynamics of particles and fields in the background of a given black hole are famous subjects in the field of classical black hole physics which are going to be covered in this thesis. By putting different conditions on the equations, we will get different solutions like Schwarzschild, Reissner-Nordstrom, Kerr, Kerr-Newman and etc, each of them having specific features. Then we...