Physics Frontiers

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 talks with Ken Wharton about how to describe entangled states as sums over histories of particle paths using the path integral method. He shows how this works for Bell-type experiments, entanglements swapping, delayed choice experiments, and the triangle network. This leads to a second way to describe what happens quantum mechanically without introducing non-locality (but requiring other classical ideas to break down).Show Notes: http://frontiers.physicsfm.com/70

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

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 Blake Stacey about recent attempts to replace Born's rule. Born's rule is the principle used in quantum mechanics that associates quantum states to the probability of measurement. There has been a recent interest in Quantum Foundations to try to find a less arbitrary rationale for this procedure. Show Notes: http://frontiers.physicsfm.com/64

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

Randy tells Jim about developments of metrics describing isolated spacetime bubbles that could, possibly, move faster than light.Show Notes: http://frontiers.physicsfm.com/60