For years, scientists have known that continents float around on the Earth's surface like ice bergs on the ocean. But what happens deep beneath our feet? A new theory envisions graveyards for continents and a life cycle not unlike the weather. He dispenses with the usual Japanese greeting ritual. Business cards presented with both hands, bowing, drinking tea -- there's no time for such formalities. He has to explain the history of the planet, nearly five billion years, in just one hour. "Hi, I'm Shige," he says, waving his hands in the air. Then he dashes into his office, a...