The artist Robert Rauschenberg — born 100 years ago Tuesday — strove to incorporate the 'real world" into his work through found objects, magazine images, and his own photographic practice. Now, a new exhibit at the Museum of the City of New York shows his fascination with the city, and how he viewed it. Curator Sean Corcoran discusses the show "Robert Rauschenberg’s New York: Pictures from the Real World."