Perhaps the question is not whether something is out there but what is out there. When people see ghosts, are they actually experiencing a form of mental telepathy? Are they seeing remnants of an event from the past that has been imprinted somehow on the surroundings? Or are they seeing the projection of a person who has died?

Credible witnesses over decades, even centuries, have reported seeing things that have no rational explanation according to the laws that govern the natural world. About 33 percent of Americans believe in ghosts and UFOs, and almost half — 48 percent — believe in extrasensory perception, or ESP.

Most people who are interested in the paranormal are just average folks who have had an experience they cannot explain. An inexplicable experience changes a person's perception of the world. It leads people to search for answers. In essence, they become ghost hunters.