
 Professor
 Renate Loll
 Radboud University Nijmegen  The Netherlands
 Theoretical Physics
Quantum gravity made simple but not too simple
A gaping hole in our theoretical understanding of the four fundamental forces  electromagnetic, gravitational, weak and strong nuclear  are the dynamical quantum laws underlying Einstein's classical theory of general relativity ("gravity" for short). Constructing such a theory of Quantum Gravity should provide a description of gravitational interactions on ultrashort scales, and answer some fundamental questions on the ultimate nature of space and time.
I will explain why gravity is special, what makes quantizing gravity challenging and why it is an exciting subject to work on. I will introduce Causal Dynamical Triangulations (CDT), a nonperturbative path integral construction of a fundamental theory of quantum gravity. It is a firstprinciples approach, relying only on good old quantum field theory, but taking into account the dynamical nature of spacetime geometry. I will describe some highlights of this research program, including the emergence of semiclassical de Sitter geometry from nonperturbative "spacetime foam" and the counterintuitive phenomenon of dimensional reduction near the Planck scale.