From Abracadabra to Zombies
In a nutshell: Ghost hunters are people who use lots of scientific equipment when they look for ghosts. Scientists don't think the equipment will do them much good.
Ghost hunters look for ghosts or evil spirits (demons) in haunted houses, graveyards, old hotels, and other places. It's likely that some of the first stories cavemen and cavewomen told their little cavechildren were stories about ghosts and demons. It seems just about everybody loves a good ghost story or a scary tale about some wicked demon's nasty tricks.
Are the ghosts and demons real? So far, scientists haven't found proof of a single ghost or demon. But that fact hasn't stopped many people from throwing a bunch of equipment into the trunk of a car and heading out to see if they can find proof that at least one ghost or demon exists.
You may have seen some of these ghost hunters on television. They load up with things like flashlights, EMF detectors, Geiger counters, Gaussmeters (more about these later), tape recorders, video recorders, motion detectors, thermometers, and sometimes even things like Ouija boards and dowsing rods.
These ghost hunters bring flashlights because they seem to always work in the dark. We don't really know what a ghost or demon is, but for some reason people who look for them are pretty sure they only come out at night. One problem with looking for something at night is that it's harder to see and easier to trick ourselves into thinking we see something that isn't really there.
EMF detectors and Gaussmeters measure electromagnetic fields, something that any physical thing will have. (These fields are not very large in small bodies and the range of these hand-held instruments is not very far.) If ghosts aren't physical, then an EMF detector won't do you any good. If ghosts have an electric or magnetic field around them, you wouldn't be able to tell the difference between a ghost and other physical things.
Geiger counters measure subatomic particles flying out of radioactive things, but if ghosts aren't physical, they don't have subatomic particles. A Geiger counter won't help you find a ghost unless it's radioactive.
Tape recorders record sounds and video recorders record things that reflect light, but whether any of the noises or blobs of light recorded by ghost hunters came from ghosts is anybody's guess.
Motion detectors measure when something moves, but whether anything that sets off a motion detector is a ghost is anyone's guess.
Thermometers measure temperature. Even if ghosts give off some form of heat, thermometers can't tell you what is giving off the heat unless the thermometer is in or very near the thing. If you turn on the lights, you might find that the change in temperature you measured came from a cat sleeping on the floor or a gust of wind coming through a crack in the wall.
Ghost hunters say that ghosts are a form of energy. When one of their instruments gives a reading, they say it's from a ghost. But it could be from many other things as well.
If we knew what ghosts or demons were made of, we might be able to invent a machine that could track them down. So far, ghost hunters are using devices that were created for other things besides ghost hunting. Why the ghost hunters think these machines will help them find ghosts is a mystery.
Serious scientists who study ghosts and haunted houses are called paranormal investigators or PIs. The main tool in their toolbox is a working brain that asks questions. They ask about the history of the place. They look for ordinary explanations of weird sounds or sights before they jump to the conclusion that they are dealing with a ghost or a demon. So far, the PIs have found no hard evidence for the existence of a single ghost or demon.
We don't know whether ghosts or demons exist. We don't know what ghosts or demons are made of, if they exist. For all we know, a ghost or demon might slip inside one of our electronic gizmos and make numbers appear on the screen that trick us into thinking they're not there! Or maybe the numbers are telling us that something exists nearby. But we probably knew that before we started our hunt.