STUDY OF COSMOLOGICAL MODELS IN MODIFIED THEORIES OF GRAVITATION

Abstract

This introductory chapter gives a short review of the basic mathematical equations which govern the evolution of the Universe. This chapter also describes several issues related to gravitation and cosmology, namely, problems related to the early inflation and the late-time cosmic acceleration. Some modified theories of gravity are briefly introduced which explain the dark energy and dark matter phenomena. The foundation of this chapter provides the motivation of the work carried out in this thesis. Cosmology is the study of the origin and evolution of the entire Universe on the large scale of space and time. The study of cosmology depends crucially on our understanding of the gravitational interaction. Our understanding of the Universe has increased dramatically in recent years - both observationally and theoretically. In recent years, cosmology has become a prominent branch of science after many astronomical observations. The most crucial observation is the accelerated expansion of the Universe. Let us begin the introduction with the concept of space-time geometry of the Universe.