Poltergeist

A poltergeist (German for mischievous ghost) is widely believed to be an invisible ghost that interacts with others by moving and influencing inanimate objects. Stories featuring poltergeists typically focus heavily on raps, thumps, knocks, footsteps, and bed-shaking, all without a discernable point of origin. Many stories detail objects being thrown about the room, furniture being moved, and even people being levitated! A few poltergeists have even been know to speak (The Bell Witch, 1817; Gef, the Talking Mongoose, 1931). Although most poltergeist stories depict a malevolent entity, some have been described as benevolent spirits who help the living by relocating sought-after or forgotten possessions, or even by warning those around them of imminent danger. The haunting by a poltergeist is called infestation. Most classic modern poltergeist stories originate in England, though the word itself is German.

In parapsychology, poltergeist activity is defined as a type of uncontrolled psychokinesis. Almost seventy years of research by the Rhine Research Center (Raleigh-Durham, NC USA) has led to the hypothesis among parapsychologists that the "poltergeist effect" is a form of psychokinesis generated by a living human mind (typically a prepubescent female). According to researchers at the Rhine Center, the "poltergeist effect" is the outward manifestation of psychological trauma.

Recurrent Spontaneous Psychokinesis (RSPK) is a phrase suggested by parapsychologist W. G. Roll to denote poltergeist phenomena.

William Roll and Harry Price are perhaps two of the most famous poltergeist investigators in the annals of parapsychology.

Although poltergeist stories date back to the first century, most evidence to support the existence of poltergeists is anecdotal. Indeed, many of the stories below have several versions and/or inconsistencies.

Famous alleged poltergeist infestations :

The Bell Witch (1817)
The haunting of the Fox Sisters (1848) - arguably one of the most famous, as it started the Spiritualism movement.
The Borley Rectory phenomena (1929)
The Enfield Poltergeist (1977)

Both the name and concept of the poltergeist became famous to modern audiences by the Poltergeist movies and the subsequent TV series Poltergeist - The Legacy. The first Poltergeist movie actually gave an excellent depiction (during the first half of the film) of a "typical" poltergeist infestation, right down to the depiction of the "focus" as a prepubescent girl.

There is a poltergeist named Peeves in the Harry Potter books. Peeves, however, does not conform to the classic definition of a poltergeist. The fact that he manifests visually would seem to indicate that he is a ghost. Perhaps J.K. Rowling wrote Peeves to be more of a literal translation of the word poltergeist, as Peeves is quite noisy and mischievous.

Some people theorize that potergeists are caused by the Hutchison effect.