Loop quantum gravity

Bjørn Solheim, FI

What do space and time look like on the very smallest scales ?  Do space and time really exist, or are they just emergent concepts that serve as useful approximations in some physical domains? Following Einstein's insights we are lead to believe that the answers to questions about microscopic geometry lie in finding a microscopic theory of gravity. Loop quantum gravity (LQG) is  a theory that encapsulates the core principles of quantum theory and general relativity (GR) with minimal extra assumptions. LQG can be seen both as a specific quantization of GR, and as a set of general methods for non-perturbative  quantization of diffeomorphism invariant theories in a background independent manner. LQG leads to a well-defined theory of (spatial) quantum geometry, where geometric variables like area and volume take discrete values. LQG has been "successfully" applied to cosmology and black holes where it eliminates the singularities and gives a fully quantum version of these gravitational systems. The presentation will focus on the foundations of LQG with some applications in cosmology.

(The slides are now available)