Six Thousand Years of Solar Energy

Solar energy goes back a long ways.  In this conversation with physicist John Perlin and the Old Mole's Bill Resnick, we learn just how far back -- to the ancient Chinese and the Romans.  With today's technology, solar power is ready to generate nearly all of our electricity.  John Perlin is the author, most recently, of Let It Shine: The Six-Thousand Year Story of Solar Energy.