Terry Gross

Technologies like GPS and social media are posing new challenges to interpreting the Constitution's guarantees of privacy and free speech. Law professor and journalist Jeffrey Rosen says we're now in an era the Founding Fathers could never have imagined, in which private companies are determining the rules for what can be shared.

Theoretical physicist Michio Kaku descries some of the inventions he thinks will appear in the coming century -- including Internet-ready contact lenses, space elevators and driverless cars -- in his book Physics of the Future.

Tim Arango, the Baghdad bureau chief for The New York Times, shares personal stories from his time covering the war, including how he tracked down the subject of a famous photograph. He also talks about what the U.S. troop withdrawal means for the future of Iraq -- and what will happen after the troops are gone.