I'm currently reading "The Black Hole War" by Leonard Susskind. I'm the book the author says that when predicting probability in quantum you can have positive, negative, or complex numbers. How is this possible? The book literally says, "Do not try to understand this. Just accept it." I asked the AP Physics teacher at my school but she never even heard of this before. Is it possible to explain this to someone with no calculus background? Thanks.