You may have noticed billboards and people handing out pamphlets in the subways claiming that the world will on May 21. Well, since that’s tomorrow, for today’s Please Explain we thought we’d investigate the long history of doomsday predictions. We’re joined by Jesus Rodriguez-Velasco, Professor in the Department of Latin American and Iberian Cultures at Columbia University, who teaches a class called “The End of the World.” John R. Hall, professor of sociology at the University of California Davis, and author of Apocalypse: From Antiquity to the Empire of Modernity. And Doug Weaver, Associate Professor of Religion at Baylor University.