Physics Frontiers

Jim talks with James Owen Weatherall about his work on viewing general relativity as an effective field theory and where it should give way to another theory. General relativity does a very good job of describing the world we see in astronomical observations, but certain results, e.g. singularities, and certain limits, e.g. the Planck scale, hint that there should be another theory that supersedes it. Jim Weatherall argues that this is in a high curvature regime.
Show Notes: http://frontiers.physicsfm.com/66

Jim talks with Michal Eckstein of the Copernicus Institute for Interdisciplinary Studies about how two different kinds of ordering, chronological and causal, give rise to a robust idea of time. Additionally, we discuss the Experiment Paradox, a generalization of other measurement-type paradoxes in physics.
Show Notes: http://frontiers.physicsfm.com/65

Jim talks with Antony Valentini about the difficulties of interpretation of quantum mechanics in light of quantum gravity. In particular, Antony discusses the failure of the Born Rule due to the impossibility of normalization (the fact that probabilities must sum to 100%) at that scale, and therefore the need to interpret the wavefunction as something more than merely the knowledge of the observer about the system. They spend some time talking about the de Broglie-Bohm interpretation in light of quantum gravity.
Show Notes: http://frontiers.physicsfm.com/72

Jim and Randy talk about how special relativity might be amended to incorporate a minimum length scale. Such scales are common in quantum gravity theories, and in the limit where both QM and GR are less important, QG should induce first order corrections to SR. We then talk about how these corrections seem to lead to unreasonable paradoxes.
Show Notes: http://frontiers.physicsfm.com/62

Jim talks with Gilad Gour of the University of Toronto about quantum resource theories. These are theories of largish systems that describe the relationships between possible states by the different levels of resources required for each. By using resources, a system can move from one state to another. This results in a partial order where between two states there could be two different states inaccessible to one another. Although (usually) these coalesce into an order based on a single property of thermodynamically-sized systems, the entropy, a few do not.
Show Notes: http://frontiers.physicsfm.com/68