University of Naples Federico II
Talks by Flavio Mercati
KappaMinkowski: physics with noncommutative time
Flavio Mercati
University of Naples Federico II
The kappaMinkowski noncommutative spacetime has been studied for a long time as an example of quantum spacetime with nontrivial commutation relations between spatial and temporal coordinates which, at first sight, seem to break Poincaré invariance. However kappaMinkowski is invariant under a Hopfalgebra deformation of the Poincaré group, which involves some noncommutative structures that prevent the sharp localization of reference frames.
Compact spherically symmetric solutions and gravitational collapse in SD
Flavio Mercati
University of Naples Federico II
I will review the current status of our understanding of spherically symmetric compact solutions of Shape Dynamics, which have nontrivial degrees of freedom when matter is present. I will show some new solutions of GR in a CMC foliation: a single thin spherical shell of matter in equilibrium in a compact foliation of de Sitter, and the simplest possible model of a black hole or compact star. This is provided by a universe with the topology of a 3sphere with two thin spherical shells of dust.
TBA
Flavio Mercati
University of Naples Federico II
À la recherche du temps perdu  Templeton Frontiers Colloquia
Flavio Mercati
University of Naples Federico II
Augustine of Hippo declared he knew what time is until someone asked him. After 16 centuries we still largely ignore the true essence of time, but we made definite progress in studying its properties. The most striking, and somewhat intuitively (and tragically) obvious one is the irreversibility of its flow. And yet, our fundamental theories are timereversal invariant, they do not distinguish between past and future. This is usually accounted for by assuming an immensely special initial condition of the Universe, dressed with statistical arguments.
Shape Dynamics  1

Matteo Giuseppe Lostaglio Imperial College London

Tim Koslowski Universidad Nacional Autónoma De Mexico (UNAM)

Julian Barbour University of Oxford

Karim Thebault LudwigMaximiliansUniversitiät München (LMU)

Flavio Mercati University of Naples Federico II
What is motion? What is time?
Flavio Mercati
University of Naples Federico II
I give an account of the Machian approach to dynamics,
from Mach's critique of Newton to the work of Barbour, Bertotti, York and
O'Murchadha, which culminated in the theory of Shape Dynamics, a new and
original way of thinking about General Relativity. I conclude commenting on the
present research lines in Shape Dynamics, and the opportunity it offers to
solve the problem of time in quantum gravity.
Support for this colloquium is provided by The Templeton Frontiers Program.
Support for this colloquium is provided by The Templeton Frontiers Program.
Shape Dynamics: Relativity Without Relativity
Flavio Mercati
University of Naples Federico II
I review the bestmatching construction, and the striking properties of a Jacobitype action first introduced by Baierelein, Sharp and Wheeler. The simplest theories compatible with such an action principle must have a universal lightcone and gauge symmetry. I also describe the implementation of threedimensional conformal symmetries on the basis of the BSW action, which gives a firstprinciples derivation of York's solution of the initial value problem in General Relativity.
Relative Locality, KappaPoincaré and the Relativity Principle
Flavio Mercati
University of Naples Federico II
I briefly introduce the recently introduced idea of relativity of locality, which is a
consequence of a nonflat geometry of momentum space. Momentum space
can acquire nontrivial geometrical properties due to quantum gravity effects.
I study the relation of this framework with noncommutative geometry, and the
Quantum Group approach to noncommutative spaces.