Senior Research Associate in Physics at Caltech, Sean Carroll discussed such topics as time & time travel, dark matter and dark energy. If time travel were to be developed, he suggested it would resemble space flight rather than a stationary machine that disappeared. Gravity causes a curvature of space/time, he noted, so if a person were to travel near a black hole for a day, 500 years might have passed back home, and when they returned, it would be as though they had gone into the future.
Dark matter, which has been inferred from the study of galaxies and galaxy clusters, is a type of mass that doesn't "bump into" ordinary particles that make up our known atomic structure, he explained. Carroll compared dark matter to neutrinos, particles that were initially hypothetical but now more understood. In contrast to dark matter, dark energy is evenly distributed throughout the universe and exists in-between galaxies.
Carroll also spoke about Big Bang theories and speculated that "baby universes" could be born on an ongoing basis, when a tiny black hole is formed that opens into a new universe. He believes there will be a definitive understanding of the Big Bang within 50 years.
The first hour of the show featured news and Open Lines.