Out of Time — John Marsden

James often finds himself gazing out the window at night, wondering about other worlds, and what it might be like to live somewhere else. But it is all just a dream--until the memorable night he slips into the laboratory of his friend, Mr. Woodforde. Brilliant but eccentric, the elderly physicist lets James in on a secret. For years, he has been working on a secret project: a time machine.

Welcome aboard, James. Next stop: the Past. Or...the Future....