Problem issues in the unification of gravity and quantum theories

Abstract

A theory of everything (TOE) that fully explains and links together all physical aspects of the universe is the interest of all scientific community. But, finding such unifying theory is the major unsolved problem in physics. However currently, all the laws of physics and aspects are closely framed in two theoretical groups General relativity (GR) and Quantum field theory (QFT) where GR focuses on gravity for understanding the large structure of the universe with high mass while QFT focuses on non-gravitational forces in regions of small scale and low mass system of the universe. Both theories are successful in their region of application while all attempts to unify them for a century has remained unsuccessful. So, here in this thesis we have reviewed the attempts so far made in the unification of the theories. In our review, we have tried to see how far the unification attempts have gone deep in connecting and accommodating the standard physics from both. Especially, We have worked out the GR field equations in that how it has being used to incorporate quantum fields and then checked the contents of the physics therein as of the quantum principles seek. On the other hand, we reviewed the attempts from quantum perspective how gravity is being fit in quantum theory without much mathematical frameworks without loss of the fundamental frames. The conclusion of the review work is that there is no single theory that fully unifies gravity and quantum theories. However, the attempts seem successful where to focuss in the resolution of the connection problem, the so called dark-matter and dark-energ