Relational physics from an emergent quantum gravity perspective ( Luca Marchetti, University of New Brunswick)

The relational approach to the problem of time and localization takes an entirely new dimension in quantum gravity contexts in which continuum notions as spacetime and geometry are understood as emergent. I argue that, in these cases, the relational strategy is best realized at an approximate and effective level, after suitable coarse-graining and only in terms of special quantum states. I also show a concrete realization of such effective relational strategy in the context of a cosmological application of the tensorial group field theory formalism for quantum gravity, both by focusing on a specific class of states and by using a “state-agnostic” approach. In both cases, I show how quantum effects impact the effective relational strategy, ultimately determining its regime of validity.