Grant: Discovery Grants Program - Individual

What is the nature of space and time? This is a question that has advanced the development of physics through the centuries. Physics was revolutionized at the beginning of the 20th century by two separate paradigm shifts: On the one hand, Einsteins vision of space and time as a unified and dynamical object that describes the gravitational force; on the other, the invention of quantum theory that prescribes an inherent fuzziness to fundamental matter. By the end of the 20th century, it became clear that both theories, taken separately, predict their own demise: Einsteins theory of gravitation predicts the collapse of matter to black holes, that crash more and more matter into a spacetime singularity. Quantum theory, describing the fundamental matter interactions, leads to infinities and therefore inconsistencies at very small distances. We need therefore a theory of quantum gravity that replaces smooth space time, on which 20th century physics is based, with a truly quantum space time. With space time itself becoming a fuzzy object, such a theory will again revolutionize our understanding of space and time. Currently, we have a number of approaches to a quantum theory of gravity, but they all face a key challenge: to show that quantum space time does lead to smooth space time, as we experience it in our everyday world. Only then can we accept a given approach as a theory of quantum gravity. This will be the main issue tackled by this research program. It is a very difficult task as it requires the bridging of an unprecedented number of magnitudes. It can be compared to deriving the hydrodynamics of water from the interactions between the hydrogen and oxygen atoms. There have been, however, a number of exciting developments which bring this task into reach. Most importantly, these allowed me to develop a framework of renormalization, applicable to non-perturbative quantum gravity approaches, which led to the construction of first numerical algorithms to tackle the continuum limit. This research program will expand the current analytical and numerical tools and use these to extract the continuum limit of quantum gravity models. This research will significantly advance our grasp on the dynamics encoded in quantum gravity models. Instead of being focussed on building particular models of quantum gravity, the methods that will be developed will allow a unified treatment and the derivation of universal as well as model dependent predictions. This will be key to derive physical predictions and to construct improved models, which will help us to unravel the notion of quantum space time. Quantum gravity research attracts excellent students and provides outreach efforts with exciting material. This will increase students choosing STEM subjects and keeps them motivated, which will, in turn help Canada to keep and expand its edge in the research and development sector.