International Research Fellowship Program: Theoretical Investigations of Gravitational Systems at the Interface of the Classical and the Quantum

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0853116RandonoThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Andrew C. Randono to work with Dr. Lee Smolin at Perimeter Institute for Theoretical Physics in Waterloo, Canada.In recent years, there have been significant developments in our understanding of classical and quantum gravity, which have evolved largely independently. Investigations at this interface are necessary in order to push both fields to the next level. The study of quantum gravity often reveals deep insights into the nature of classical gravity that lead to a richer understanding of the current framework of classical gravity as well as suggesting modifications to the established theory. In addition, history has shown that new revolutions in quantum gravity often emerge from new perspectives on and new formulations of classical gravity. The PI is conducting various research projects involving explorations of gravitational physics at the interface of classical and quantum gravity, with the ultimate goal enhancing our understanding of both theories to push them to the next stage. Among the projects being explored, the PI is investigating the nature of spin in classical and quantum gravity, and the emergence of Einstein gravity from a theory with a larger symmetry group. The first project entails a study of the nature of intrinsic spin to geometry. From the classical perspective, in addition to the well known spin-orbit coupling emerging from the gravitomagnetic analogy, there is strong evidence that spinors themselves give rise to a frame-dragging effect via their intrinsic spin, which could give rise to a gravitationally modulated coupling of intrinsic spin to intrinsic spin. The PI is determining the gauge independent properties of this interaction, and investigating the possible astrophysical effects from a potential spin induced pair binding of neutral particles such as astrophysical neutrinos and neutrons in a neutron star. The second project described involves an exploration of the consequences of the emergence of gravity from a more fundamental gravitational theory with a larger symmetry group. There is strong evidence that our current understanding of gravity based on the Lorentz group could be the symmetry broken phase of a more fundamental theory based on the de Sitter group. This evidence comes from the observationally from the existence of a small positive cosmological constant, and theoretically from the possibility of combining the spin connection and the tetrad into a single de Sitter connection. The PI is investigating the nature of instanton solutions and their possible significance in early universe cosmology. From the quantum perspective, the PI is investigating whether a fundamental de Sitter symmetry could lead to insight into the nature of the Immirzi parameter, a constant which appears to be necessary in the construction of Loop Quantum Gravity, which plays a fundamental role in the theory?s description of black hole entropy. The PI is investigating if the appearance of the Immirzi parameter could the by-product of the breaking of de Sitter symmetry to Lorentz symmetry, analogous to the emergence of the QCD-theta parameter.