Search Talks

Analyzing the artificial gravitational field inside a rotating cylinder to discover hints about the nature of real gravitational fields.
Learning Outcomes:
• How to compare relativistic effects of an accelerated observer who is inside the rotating cylinder to observers at rest in the inertial reference frame outside the rotating cylinder.
• Understanding that the relative time dilation effect decreases as the rotating observer moves toward the axis of rotation, and how this suggests that a real gravitational field might warp time.
• Understanding that the circumference of the cylinder as measured by the rotating observers increases, and how this suggests that a real gravitational field might warp space.

The spacetime diagram of a rotating Bob is analyzed, leading us to conclude that his spatial geometry is curved.
Learning Outcomes:
• Understanding the physical effects of the rotation on the rotating observers, metal panels of the cylinder and so forth.
• Understanding the properties of a rotating cylinder using a spacetime diagram.
• Understanding curved spaces: The negatively curved space of a rotating observer and the positively curved space representing the real gravitational field of the Sun.

Amanda Peet received her Ph.D. at Stanford University and currently is Associate Professor at the University of Toronto, her “intellectual home base.” She is also an Affiliate Member of Perimeter Institute. Amanda's goal is to understand the fundamental dynamics of all forces and particles seen so far in Nature, especially gravity. Broadly: She studies the quantum dynamics of interactions between gravity and matter using string theory, with applications to black holes and cosmology, and links to gauge theory and particle physics. Past work has focused on the black hole information paradox, black hole entropy, D-brane models of black holes, duality, holography, building of new geometries, spacetime singularity resolution, and cosmology. Amanda continues to develop these interests, as well as develop others as new particle accelerator data from LHC and cosmological data (further) influence the field.

In deBroglie-Bohm theory the quantum state plays the role of a guiding agent. In this seminar we will explore if this is a universal feature shared by all hidden variable theories or merely a peculiar feature of deBroglie-Bohm theory. We present the bare bones of a model in which the quantum state represents a probability distribution and does not act as a guiding agent. The theory is also psi-epistemic according to Spekken\'s and Harrigan\'s definition. For simplicity we develop the model for a 1D discrete lattice but the generalization to higher dimensions is straightforward. The ontic state consists of a definite particle position and in addition possible non-local links between spatially separated lattice points. These non-local links comes in two types: directed links and non-directed links. Entanglement manifests itself through these links. Interestingly, this ontology seems to be the simplest possible and immediately suggested by the structure of quantum theory itself. For N lattice points there are N*3^(N(N-1)) ontic states growing exponentially with the Hilbert space dimension N as expected. We further require that the evolution of the probability distribution on the ontic state space is dictated by a master equation with non-negative transition rates. It is then easy to show that one can reproduce the Schroedinger equation if an only if there are positive solutions to a gigantic system of linear equations. This is a highly non-trivial problem and whether there exists such positive solutions or not is still not clear to me. Alternatively one can view this set of linear equations as constraints on the possible types of Hamiltonians. We end by speculating how one might incorporate gravity into this theory by requiring permutation invariance of the dynamical evolution law.