George R. R. Martin / Neil deGrasse Tyson

John Hodgman guest hosts for an exploration of universes. Yes, that's plural. how many universes are there? It's one of several questions that astrophysicist Neil deGrasse Tyson DOESN'T have the answer to, but Tyson wants us to love the questions themselves. 

And while Tyson counts universes, George R. R. Martin has created one. He's the author of the book series A Song of Ice and Fire, which is the basis for the new HBO series A Game of Thrones. Martin discusses his transformation from a science fiction and fantasy fan into a creator, and the effect that hardcore fantasy fans can have on the final product.