One property that characterizes a black hole is that it maximizes entropy in a finite region with a fixed surface area. It may be a more fundamental one than the existence of a horizon in the context of quantum gravity, where there is no notion of continuum geometry. Using this characterization, we consider the interior of a black hole in the 4D semi-classical Einstein equation. For...
A major challenge at the interface between quantum gravity and cosmology is to understand how cosmological structures can emerge from physics at the Planck scale. In this talk, I will provide a concrete example of such an emergence process by extracting the physics of scalar and isotropic cosmological perturbations from full quantum gravity, as described by a causally complete Barrett-Crane...
In this talk, I discuss recent advances in Lorentzian quantum cosmology using group field theory (GFT) condensate cosmology and effective spin foams.
First, in the GFT approach, I introduce the complete Barrett-Crane (cBC) TGFT model coupled to four scalar fields, establishing a connection between the causal character of quantum geometry and relational scalar clock and rods. This allows to...
"3D gravity in tetrad variables shows a rich symmetry structure that includes both rotations and Kalb-Ramond translations which has been instrumental in understanding its properties. Therefore, extensions of this type of symmetries to the four-dimensional case, like the $\mathfrak{isu}(2)$-algebra described in [1910.05642] for Loop Quantum Gravity, may be crucial in understanding states of...
Time-dependent reflective boundary conditions (i.e. a moving mirror) in a scalar field theory in 1+1 dimensions have the power to model key aspects of Hawking radiation. In particular, this valuable pedagogical tool allows one to understand how early thermal quanta could be purified by late field modes. In this talk, we discuss a mirror trajectory that mimics an evaporating black hole; with a...