I have been fascinated by ghosts since I was a child. Over the years, I have visited many haunted sites ranging from a church in Lincolnshire to a so-called 'Tree of Death' in Green Park, London.
But what exactly is a ghost?
A Recording? There is a theory that recordings of past events can be imprinted into the fabric of a building or even the ground. Under certain circumstances, these recordings are then played back like a videotape. This idea - known as a residual haunting - was first put forward by Thomas Lethbridge in books such as Ghost and Ghoul, published in 1961. It was later popularised in The Stone Tape, a TV play by Nigel Kneale, in the 1970's.
Spirits of the Dead? The spirit of a person is to thought to return from beyond the grave. They are aware of the living world and interact with or respond to it. This can involve communicating with the living, moving objects or even possession.
Hallucination? Some paranormal investigators believe that some ghost sightings are simply hallucinations caused by electromagnetic fields. Prolonged exposure to such fields is thought to cause headaches, fatigue, increased anxiety, decreased mental function and impaired vision. At extremely high levels, electromagnetic fields can cause flickering of vision and disorientation.