Randy discusses what the Cosmological implications of a negative gravitational mass would be with Jim. If there were a negative gravitational mass (as opposed to inertial mass), then every time that an electron-positron pair was created in the vacuum, that would create a gravitational dipole. This in turn would create effects similar to dark matter, dark energy, and a cosmological constant -- and this in turn would have an effect on the origin of the universe. Show notes: http://frontiers.physicsfm.com/7