I have a friend who has a strange theory on ghosts....

If and when we see a psychic entity such as spirits, ghosts and other phenomena, we do not actually see them by the use of the eye. That is, light is not entering the eye from the phenomena but, the phenomenon is picked up directly by the optic and auditory nerves. Before this can happen, the mind under certain conditions drifts towards the upper and lower end of the visual electromagnetic spectrum. Thus, we may believe we see a ghost, but actually the phenomenon is projected into that part of the brain. People such as mediums can at will, can drift to that part of the spectrum when needed. The rest of us have to rely on ambient conditions for this to happen.

Do you believe it?