Our Cosmos: the past, the present and the future

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Understanding our Cosmos, from its hot origins in the Big Bang to its enigmatic lockboxes of Black Holes, is amongst the most exhilarating and ambitious human endeavours. Building upon a solid foundation of my group's past record, the long term objective of my research program is to combine modern advances in high energy physics, mathematics, and data science to unravel our Cosmological Dynamics, from a multi-pronged, interdisciplinary, and innovative perspective that combines theory and observation. On the theoretical front, I plan to tackle the Big Bang singularity problem from the novel perspective of cuscuton gravity, a theory that I first pioneered in 2007 and is currently experiencing a renaissance. The problem is that Einstein's theory of General Relativity anticipates its own breakdown at a colossal early moment, known as the Big Bang singularity. In 2018, my team and I proved that a bouncing cosmology generated by cuscuton gravity, or a Cuscuton Bounce, with a smooth transition from an earlier contracting phase can evade this breakdown without any of the pathologies that plague earlier proposals, a possible watershed for resolving the age-old cosmological singularity problem. This proposal plans to build upon this success, to construct a self-consistent and testable theory of cuscuton bounce that could predict the seeds of cosmic structures, examine its mathematical properties, and explore its connection to a more fundamental paradigm for Quantum Gravity. On the observational front, I plan to exploit the groundbreaking discovery of gravitational waves, which won the Physics Nobel prize in 2017, to design a systematic and novel framework to probe cosmological models. For example, the recent measurements of the expansion rate of the universe have become a topic of controversy, known as the Hubble tension, a problem that can be addressed through Multi-Messenger Astronomy. In contrast to prior approaches, ours is a more statistically rigorous, yet practical, inference methodology for cross-correlating gravitational wave dark sirens and galaxy surveys, which is based on Bayesian forward modelling. While we have just wrapped up the groundwork for this program, this proposal aims to explore its practical implementation for the next generation of gravitational wave and galaxy surveys. This proposal is the continuation of an ambitious program that employs interdisciplinary and out-of-the-box thinking to push the frontiers of cosmology, and puts Canada in the forefront of scientific discovery. Students and Postdoctoral Researchers of diverse backgrounds are an integral part of this program, collaborating and contributing to an atmosphere of inquiry, innovation, and inclusivity. Meanwhile, they acquire invaluable and highly transferable skills, ranging from mathematical, numerical, and data science skills to analytic thinking and teamwork, enabling them to succeed and excel in a wide range of careers, from academia to industry and finance.