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Spin foam quantum gravity is a non-perturbative, background independent approach to quantizing gravity. It formulates a path integral as a sum over quantum geometries encoded in group theoretic data as in loop quantum gravity; thus it is frequently seen as a way of defining a covariant dynamics for this theory. In this talk, I want to motivate quantum gravity as a manifestly background independent theory and define the gravitational path integral à la spin foams. As a regularisation, I introduce a triangulation and discuss how gravity can be formulated in the discrete, via Regge calculus in a piece-wise flat way. Then I discuss how quantum geometry is encoded in a spin foam and how it connects to Regge calculus in a putative semi-classical limit. I will review outstanding research challenges, in particular for the Lorentzian theory, and discuss concretely the construction of a cosmological model coupled to a scalar field.

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Sebastian Steinhaus, Friedrich-Schiller University Jena
Seminar Room 0.03, ETP
Contact: Nele Callebaut