Singularity Resolution in Quantum Gravity

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A complete understanding of the history of our universe is not possible without addressing the problems of singularities in classical gravity. Singularities, such as the big bang, are the boundaries of classical space and time where the classical physics stops. These singularities signal that the underlying theory, in this case Einstein's theory of General Relativity, has reached its limit of validity. Answers to fundamental questions such as the birth of the universe thus cannot be obtained using general relativity which is based on the classical notion of space and time. It is expected that a quantum theory of gravity would reveal new physics which provides important clues on the resolution of singularities. In this research, loop quantum gravity is used to explore the fate of singularities in different spacetimes, including cosmological and black hole spacetimes. Lessons from these investigations will be important to understand the quantum nature of spacetime, the physics of the very early universe and the final stages of the gravitational collapse. Research carried out in this project deals with analytical, phenomenological and numerical investigations of isotropic, anisotropic, black hole and inhomogeneous spacetimes to understand singularity resolution using techniques of loop quantum gravity. By a systematic study of quantization of these spacetimes and its relation with the effective descriptions, precise physics at the Planck scale will be extracted and phenomenological implications will be explored. This research also aims to address fundamental issues pertaining to the quantum probabilities for events, such as the quantum bounce, in a quantum universe. These investigations are expected to give valuable insights on the generic resolution of singularities in quantum gravity.