Famed ghost hunter Hans Holzer once told an interviewer, "There are three dirty words in my vocabulary: belief, disbelief and supernatural. They don't exist. There's no 'supernatural world.' Everything that exists is natural. Yet there is a dimension of existence that is as real as your living room, even if the average person cannot access it with all their senses." For five decades, this meticulous, Vienna-born researcher has been delving into manifestations...