Jim talks to Randy about the different ways in which the equivalence principle of general relativity can be formulated. More than just the equivalence of accelerations, the different possible meanings of the equivalence principle mean different things about how gravity works. From weak to strong, from Einstein's equivalence principle to Schiff's conjecture, the implications of these theories are explored.
Show Notes: http://frontiers.physicsfm.com/27
Randy introduces Jim to several ways in which people have theorized that gravity can be used to propel an object through space. The slingshot effect is the only proven method here, but people have found many ways that theoretically could induce propulsion taking advantage of non-commutative motions in space-time, negative inertia, artificially-induced gravitational dipoles, and creating bubbles in space-time.
Show Notes: http://frontiers.physicsfm.com/25
Randy tells Jim about the island of stability: a theoretically predicted oasis of stable nuclear isotopes that researchers keep getting nearer and nearer to discovering. Randy and Jim talk about what they are, how researchers are trying to produce the isotopes, and the theoretical methods that predict their existence.
Show Notes: http://frontiers.physicsfm.com/24
Jim and Randy discuss quasiparticles recently found in condensed matter systems that mirror particles theorized nearly a hundred years ago, but never found in the vacuum. Weyl particles are massless fermions, and once it was hoped that neutrinos would turn out to be this kind of particle, and Majorana fermions have real-valued wave functions and therefore many strange and possibly useful properties.
Show Notes: http://frontiers.physicsfm.com/22
Randy tells Jim about a theory that complements other theories of fundamental physics based upon a phase space symmetry between the 4-position and the 4-momentum of a particle. The upshot of the theory is that there should be a second time dimension and a fourth space dimension, both macroscopic in extent, and the physics we see are 4D projections from the larger 6D space-time.
Show notes: http://frontiers.physicsfm.com/18