Welcome. I am a theoretical physicist at the Perimeter Institute. My work lays at the interface between general relativity, quantum field theory, and thermodynamics. The main objective of my research is to understand what is the quantum nature of space-time.
I work on loop quantum gravity, and I am contributing to the development of its covariant spin-foam formulation. In this theory, space-time arises as a foam-like excitation of a topologically invariant vacuum. My focus is on extracting from it physical predictions relevant for early cosmology and black hole physics.
Presently I am investigating the thermodynamic properties of causal horizons in spin-foam quantum gravity and in quantum field theory. I hold that the entropy of black holes and of cosmological horizons is due to quantum correlations across the horizon, i.e. to entanglement.--
26Nov2012. Check my new paper arxiv:1211.0522 on "Horizon entanglement entropy and universality of the graviton coupling". The punchline is that an energy-flux through the horizon results in a change δS in the entanglement entropy of the near-horizon state. Because gravity couples universally to the energy-momentum tensor, the gravitational back-reaction is universal and given by δA/4G, the Bekenstein-Hawking formula.
The quantum field theory calculation of arxiv:1211.0522 can be understood as a perturbative version of the recent derivation of the Bekenstein-Hawking entropy from loop quantum gravity, arxiv:1204.5122. See my International LQG Seminar for a recent presentation:
Thinking about the problem of quantum gravity often leads me into explorations in other branches of physics. See my paper on quantum surfaces and polymer physics, arxiv:1011.5628.I also work on theoretical cosmology. See my article with Carlo Rovelli on the problem of the cosmological constant. An abridged version has appeared in Nature.