Lisa Randall is a professor at Harvard University and MIT, a leading theoretical physicist, expert on string theory, and author of Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions. She works on one of the main two competing models of string theory in the quest to explain the fabric of reality. She talked about various topics in physics, including the fascinating idea that there may be extra or hidden dimensions, and offered cautious and reasoned opinions about seemingly fantastic ideas that surround these theories.

In the first hour, Art was joined by physicist Noah Mohr for a discussion on strategies to address global warming.