We study Einstein gravity in a finite spatial region. By requiring a well-defined varia-tional principle, we identify all local boundary conditions, derive surface observables, and compute their… (More)

We describe a deformation of the observable algebra of quantum gravity in which the loop algebra is extended to framed loops. This allows an alternative nonperturbative quantization which is suitable… (More)

One obtains Bell’s inequalities if one posits a hypothetical joint probability distribution, or measure, whose marginals yield the probabilities produced by the spin measurements in question. The… (More)

The discrete picture of geometry arising from the loop representation of quantum gravity can be extended by a quantum deformation. The operators for area and volume defined in the q-deformation of… (More)

Within the causal set approach to quantum gravity, a discrete analog of a spacelike region is an “antichain”, which is a set of unrelated elements. In the continuum spacetime approximation of the… (More)

An important question that discrete approaches to quantum gravity must address is how continuum features of spacetime can be recovered from the discrete substructure. Here, we examine this question… (More)

Two theories of special relativity with an additional invariant scale, “doubly special relativity” (DSR), are tested with calculations of particle process kinematics. Using the Judes-Visser modified… (More)

The Lorentzian Hamiltonian constraint is solved for isotropic loop quantum cosmology coupled to a massless scalar field. As in the Euclidean case, the discreteness of quantum geometry removes the… (More)

Two theories of special relativity with an additional invariant scale, “doubly special relativity” (DSR), are tested with calculations of particle process kinematics. Using the Judes-Visser modified… (More)

We present a computational tool for calculating the “spatial” homology groups of a causal set. Localisation in the causal set is provided by an inextendible antichain which is the analog of a… (More)