The Time Traveler appeared suddenly in my study on New Year’s Eve, 2004. He was a stolid, grizzled man in a gray tunic and looked to be in his late-sixties or older. He also appeared to be the veteran of wars or of some terrible accident since he had livid scars on his face and neck and hands, some even visible in his scalp beneath a fuzz of gray hair cropped short in a military cut. One eye was covered by a black eyepatch. Before I could finish dialing 911 he announced in a husky voice that he was...