Gravitational lensing

ABSTRACT: In this thesis we study one of the most interesting aspects of the Einstein’s theory of gravity which can be examined practically by astronomers. In this natural phenomena, when a beam of light passes nearby a heavy object, due to the gravity of the object the beam of light bends toward the center of the object which causes a deflection from its original path. This is much like a lens located in the path of the beam of light which deflects it and that is why it is called Lensing Effect. The implications of the theoretical results, even from the very beginning of the general relativity, have been realized by the astronomers where they could not explain many unusual observatory datas which could not be analyzed without considering this effect. Nowadays, applying the theory of lensing, helps us to localize the observed objects in the space surrounding our Earth. Therefore, our preliminary aim is to go through the theory of lensing by considering the general relativity concepts introduced by Einstein and developed by other great physicists. Next we apply the theory for some known spacetimes like the Schwarzschild black hole, the Grumiller spacetime and regular Bardeen black hole. To complete our assessment, we shall study lensing by a wormhole too. Keywords: Lensing Effect, Einstein General Relativity, Schwarzschild Black Hole, Grumiller Spacetime, Bardeen Black Hole. …………………………………………………………………………………………………………………………………………………………………………………………………………