Many scientists believe that ghosts are fake, but parapsychologists believe ghosts are real. Spirits are electromagnetic fields. Brain waves can make people see and hear many things. Electromagnetic waves can affect the nervous system. This can cause somebody to hallucinate. The eye can act as a TV screen. Instead of the person taking in images, they are transmitted out.
Another explanation for "ghost sightings" may be that the mind is just trying to "let off a little steam." NASA has shown that the human eyeball has a resonant frequency. There are eighteen cycles a second. The eyeball starts to vibrate in response to infra-sound. This causes a serious smearing of vision. In at least two hauntings low frequency sound may to blame.
People can put, fake ghosts in their pictures. By using a flashlight, a cigarette, a flash pack, and a camera, a person can create the effect of a mysterious light. Turn on the flashlight and walk toward the camera. When you are four to five feet from the camera, turn off the flashlight and light a cigarette. Have a friend set off a flash using the flash pack. Snap the shutter of the camera closed. This will result in a picture with mysterious lights in the background.
In conclusion, there are many explanations for ghost sightings. Some sightings are a result of people playing tricks and others are a result of hallucinations.