When Steven Spielberg was a child growing up in Arizona, his father, who was an electrical engineer, came home from work with a small transistor. “This,” his father said to Steven, “is the future.” Spielberg looked at the transistor and then quickly swallowed it. “I swallowed the future!” Spielberg told me, sounding gleeful. We were in his Southwestern-style, haciendalike offices on the Universal Studios lot in Burbank on a chilly winter day. He was wearing a brown sweater under a leather flight jacket, corduroy pants, and sneakers. Although he is 76, Spielberg has the infectious bounce and enthusiasm of a happily engaged teenager. He is the most important filmmaker in the world, having directed so many classic movies that it’s easy to forget some: Among others, there is Jaws, E.T.,…