Jim Rantschler and Randy Morrison discuss physics from elementary particles to cosmological effects at the limits of our theoretical knowledge or have recently emerged.
https://www.podomatic.com/podcasts/physicsfrontiers-rantschler
Gravitational Alternatives to Dark Energy
Jim and Randy discuss how modifications to general relativity can be used to mimic the effects of dark energy. They discuss various forms of gravitational theory that can do the job, as well as the field particles that mediate their "fifth force."
Show Notes: http://frontiers.physicsfm.com/29