Chances are, you know someone with a killer ghost story. You might even believe you've encountered a ghost yourself. However, considering there's no scientific evidence that ghosts exist, why do some people think they've seen or heard them?
Christopher French, a professor emeritus of psychology at Goldsmiths, University of London, recently wrote a book about the science of the paranormal and said ghost sightings are often "sincere misinterpretations of things that do have a natural explanation."
