Gravity seminar - Lu Heng Sunny Yu Seminar

Abstract: Quantum gravity, as defined in the Feynman path integral approach by a gravitational action and a functional measure over metrics, is in principle a unique theory. Nevertheless, the theory is infamously perturbatively nonrenormalisable. However, in the past decade, a wide array of modern analytical and numerical methods has been developed to study precisely such theories, and they have enjoyed wide success in multiple areas of physics and sciences. Not only have these methods produced many useful predictions with remarkable accuracies, perhaps more importantly, they revealed many significant new physics that would otherwise be invisible from perturbation theory to any order. In this talk, I explore the implications of these nonperturbative techniques when applied to the quantum theory of gravity. Using a variety of analytical and numerical methods, we derive a number of physical predictions on cosmology. In particular, we explore the unique alternative explanation for the various cosmological power spectra (including the galaxy- and CMB-spectrum) that is based on intrinsic gravitational fluctuations, as derived from nonperturbative quantum field-theoretical methods, as opposed to the current popular inflationary models, which are based on fluctuations of scalar fields. Finally, I will also compare these results to latest available cosmological observational data, explore how well do these results fit, and what we could expect in the future.

 

Talk slides