John Wells speaks with astrophysicist Neil deGrasse Tyson who has co-written "To Infinity and Beyond: A Journey of Cosmic Discovery" with StarTalk senior producer Lindsey Walker. (0:45)Then, as much as you might think it’s just a craving – sugar is an addiction! We speak with neuroscientist Dr. Nicole Avena, who pioneered research on sugar addiction and has a new book on the subject called "Sugarless." (25:42)